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[SCM] gawk branch, feature/latex-support, created. gawk-4.1.0-4975-g0f23
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From: |
Arnold Robbins |
|
Subject: |
[SCM] gawk branch, feature/latex-support, created. gawk-4.1.0-4975-g0f23965e |
|
Date: |
Wed, 21 Dec 2022 15:46:35 -0500 (EST) |
This is an automated email from the git hooks/post-receive script. It was
generated because a ref change was pushed to the repository containing
the project "gawk".
The branch, feature/latex-support has been created
at 0f23965e6ad5f3ad5c20fa9d8dd7a62909789204 (commit)
- Log -----------------------------------------------------------------
http://git.sv.gnu.org/cgit/gawk.git/commit/?id=0f23965e6ad5f3ad5c20fa9d8dd7a62909789204
commit 0f23965e6ad5f3ad5c20fa9d8dd7a62909789204
Author: Arnold D. Robbins <arnold@skeeve.com>
Date: Wed Dec 21 22:46:08 2022 +0200
Preliminary LaTeX support in gawktexi.in.
diff --git a/doc/ChangeLog b/doc/ChangeLog
index 779319f4..acaa51b4 100644
--- a/doc/ChangeLog
+++ b/doc/ChangeLog
@@ -1,3 +1,7 @@
+2022-12-21 Arnold D. Robbins <arnold@skeeve.com>
+
+ * gawktexi.in: Add LaTeX support.
+
2022-12-21 Arnold D. Robbins <arnold@skeeve.com>
* gawktexi.in (Sample Debugging Session): End gawk invocation
diff --git a/doc/gawk.info b/doc/gawk.info
index f2f91ef6..373511f2 100644
--- a/doc/gawk.info
+++ b/doc/gawk.info
@@ -1,23 +1,23 @@
-This is gawk.info, produced by makeinfo version 6.8 from gawk.texi.
+This is gawk.info, produced by makeinfo version 7.0.1 from gawk.texi.
-Copyright (C) 1989, 1991, 1992, 1993, 1996-2005, 2007, 2009-2022
+Copyright © 1989, 1991, 1992, 1993, 1996â2005, 2007, 2009â2022
Free Software Foundation, Inc.
- This is Edition 5.2 of 'GAWK: Effective AWK Programming: A User's
-Guide for GNU Awk', for the 5.2.2 (or later) version of the GNU
+ This is Edition 5.2 of âGAWK: Effective AWK Programming: A Userâs
+Guide for GNU Awkâ, for the 5.2.2 (or later) version of the GNU
implementation of AWK.
Permission is granted to copy, distribute and/or modify this document
under the terms of the GNU Free Documentation License, Version 1.3 or
any later version published by the Free Software Foundation; with the
-Invariant Sections being "GNU General Public License", with the
-Front-Cover Texts being "A GNU Manual", and with the Back-Cover Texts as
+Invariant Sections being âGNU General Public Licenseâ, with the
+Front-Cover Texts being âA GNU Manualâ, and with the Back-Cover Texts as
in (a) below. A copy of the license is included in the section entitled
-"GNU Free Documentation License".
+âGNU Free Documentation Licenseâ.
- a. The FSF's Back-Cover Text is: "You have the freedom to copy and
- modify this GNU manual."
+ a. The FSFâs Back-Cover Text is: âYou have the freedom to copy and
+ modify this GNU manual.â
INFO-DIR-SECTION Text creation and manipulation
START-INFO-DIR-ENTRY
* Gawk: (gawk). A text scanning and processing language.
@@ -34,27 +34,27 @@ File: gawk.info, Node: Top, Next: Foreword3, Up: (dir)
General Introduction
********************
-This file documents 'awk', a program that you can use to select
+This file documents âawkâ, a program that you can use to select
particular records in a file and perform operations upon them.
- Copyright (C) 1989, 1991, 1992, 1993, 1996-2005, 2007, 2009-2022
+ Copyright © 1989, 1991, 1992, 1993, 1996â2005, 2007, 2009â2022
Free Software Foundation, Inc.
- This is Edition 5.2 of 'GAWK: Effective AWK Programming: A User's
-Guide for GNU Awk', for the 5.2.2 (or later) version of the GNU
+ This is Edition 5.2 of âGAWK: Effective AWK Programming: A Userâs
+Guide for GNU Awkâ, for the 5.2.2 (or later) version of the GNU
implementation of AWK.
Permission is granted to copy, distribute and/or modify this document
under the terms of the GNU Free Documentation License, Version 1.3 or
any later version published by the Free Software Foundation; with the
-Invariant Sections being "GNU General Public License", with the
-Front-Cover Texts being "A GNU Manual", and with the Back-Cover Texts as
+Invariant Sections being âGNU General Public Licenseâ, with the
+Front-Cover Texts being âA GNU Manualâ, and with the Back-Cover Texts as
in (a) below. A copy of the license is included in the section entitled
-"GNU Free Documentation License".
+âGNU Free Documentation Licenseâ.
- a. The FSF's Back-Cover Text is: "You have the freedom to copy and
- modify this GNU manual."
+ a. The FSFâs Back-Cover Text is: âYou have the freedom to copy and
+ modify this GNU manual.â
* Menu:
@@ -64,14 +64,14 @@ in (a) below. A copy of the license is included in the
section entitled
* Preface:: What this Info file is about; brief
history and acknowledgments.
* Getting Started:: A basic introduction to using
- 'awk'. How to run an 'awk'
+ âawkâ. How to run an âawkâ
program. Command-line syntax.
-* Invoking Gawk:: How to run 'gawk'.
+* Invoking Gawk:: How to run âgawkâ.
* Regexp:: All about matching things using regular
expressions.
* Reading Files:: How to read files and manipulate fields.
-* Printing:: How to print using 'awk'. Describes
- the 'print' and 'printf'
+* Printing:: How to print using âawkâ. Describes
+ the âprintâ and âprintfâ
statements. Also describes redirection of
output.
* Expressions:: Expressions are the basic building blocks
@@ -80,37 +80,37 @@ in (a) below. A copy of the license is included in the
section entitled
* Arrays:: The description and use of arrays. Also
includes array-oriented control statements.
* Functions:: Built-in and user-defined functions.
-* Library Functions:: A Library of 'awk' Functions.
-* Sample Programs:: Many 'awk' programs with complete
+* Library Functions:: A Library of âawkâ Functions.
+* Sample Programs:: Many âawkâ programs with complete
explanations.
* Advanced Features:: Stuff for advanced users, specific to
- 'gawk'.
-* Internationalization:: Getting 'gawk' to speak your
+ âgawkâ.
+* Internationalization:: Getting âgawkâ to speak your
language.
-* Debugger:: The 'gawk' debugger.
-* Namespaces:: How namespaces work in 'gawk'.
+* Debugger:: The âgawkâ debugger.
+* Namespaces:: How namespaces work in âgawkâ.
* Arbitrary Precision Arithmetic:: Arbitrary precision arithmetic with
- 'gawk'.
+ âgawkâ.
* Dynamic Extensions:: Adding new built-in functions to
- 'gawk'.
-* Language History:: The evolution of the 'awk'
+ âgawkâ.
+* Language History:: The evolution of the âawkâ
language.
-* Installation:: Installing 'gawk' under various
+* Installation:: Installing âgawkâ under various
operating systems.
-* Notes:: Notes about adding things to 'gawk'
+* Notes:: Notes about adding things to âgawkâ
and possible future work.
* Basic Concepts:: A very quick introduction to programming
concepts.
* Glossary:: An explanation of some unfamiliar terms.
* Copying:: Your right to copy and distribute
- 'gawk'.
+ âgawkâ.
* GNU Free Documentation License:: The license for this Info file.
* Index:: Concept and Variable Index.
-* History:: The history of 'gawk' and
- 'awk'.
+* History:: The history of âgawkâ and
+ âawkâ.
* Names:: What name to use to find
- 'awk'.
+ âawkâ.
* This Manual:: Using this Info file. Includes
sample input files that you can use.
* Conventions:: Typographical Conventions.
@@ -118,23 +118,23 @@ in (a) below. A copy of the license is included in the
section entitled
this Info file.
* How To Contribute:: Helping to save the world.
* Acknowledgments:: Acknowledgments.
-* Running gawk:: How to run 'gawk' programs;
+* Running gawk:: How to run âgawkâ programs;
includes command-line syntax.
* One-shot:: Running a short throwaway
- 'awk' program.
+ âawkâ program.
* Read Terminal:: Using no input files (input from the
keyboard instead).
-* Long:: Putting permanent 'awk'
+* Long:: Putting permanent âawkâ
programs in files.
-* Executable Scripts:: Making self-contained 'awk'
+* Executable Scripts:: Making self-contained âawkâ
programs.
-* Comments:: Adding documentation to 'gawk'
+* Comments:: Adding documentation to âgawkâ
programs.
* Quoting:: More discussion of shell quoting
issues.
* DOS Quoting:: Quoting in Windows Batch Files.
* Sample Data Files:: Sample data files for use in the
- 'awk' programs illustrated in
+ âawkâ programs illustrated in
this Info file.
* Very Simple:: A very simple example.
* Two Rules:: A less simple one-line example using
@@ -142,11 +142,11 @@ in (a) below. A copy of the license is included in the
section entitled
* More Complex:: A more complex example.
* Statements/Lines:: Subdividing or combining statements
into lines.
-* Other Features:: Other Features of 'awk'.
-* When:: When to use 'gawk' and when to
+* Other Features:: Other Features of âawkâ.
+* When:: When to use âgawkâ and when to
use other things.
* Intro Summary:: Summary of the introduction.
-* Command Line:: How to run 'awk'.
+* Command Line:: How to run âawkâ.
* Options:: Command-line options and their
meanings.
* Other Arguments:: Input file names and variable
@@ -154,13 +154,13 @@ in (a) below. A copy of the license is included in the
section entitled
* Naming Standard Input:: How to specify standard input with
other files.
* Environment Variables:: The environment variables
- 'gawk' uses.
+ âgawkâ uses.
* AWKPATH Variable:: Searching directories for
- 'awk' programs.
+ âawkâ programs.
* AWKLIBPATH Variable:: Searching directories for
- 'awk' shared libraries.
+ âawkâ shared libraries.
* Other Environment Variables:: The environment variables.
-* Exit Status:: 'gawk''s exit status.
+* Exit Status:: âgawkââs exit status.
* Include Files:: Including other files into your
program.
* Loading Shared Libraries:: Loading shared libraries into your
@@ -173,7 +173,7 @@ in (a) below. A copy of the license is included in the
section entitled
* Regexp Operators:: Regular Expression Operators.
* Regexp Operator Details:: The actual details.
* Interval Expressions:: Notes on interval expressions.
-* Bracket Expressions:: What can go between '[...]'.
+* Bracket Expressions:: What can go between â[...]â.
* Leftmost Longest:: How much text matches.
* Computed Regexps:: Using Dynamic Regexps.
* GNU Regexp Operators:: Operators specific to GNU software.
@@ -181,9 +181,9 @@ in (a) below. A copy of the license is included in the
section entitled
* Regexp Summary:: Regular expressions summary.
* Records:: Controlling how data is split into
records.
-* awk split records:: How standard 'awk' splits
+* awk split records:: How standard âawkâ splits
records.
-* gawk split records:: How 'gawk' splits records.
+* gawk split records:: How âgawkâ splits records.
* Fields:: An introduction to fields.
* Nonconstant Fields:: Nonconstant Field Numbers.
* Changing Fields:: Changing the Contents of a Field.
@@ -193,7 +193,7 @@ in (a) below. A copy of the license is included in the
section entitled
* Regexp Field Splitting:: Using regexps as the field separator.
* Single Character Fields:: Making each character a separate
field.
-* Command Line Field Separator:: Setting 'FS' from the command
+* Command Line Field Separator:: Setting âFSâ from the command
line.
* Full Line Fields:: Making the full line be a single
field.
@@ -206,42 +206,42 @@ in (a) below. A copy of the license is included in the
section entitled
* Splitting By Content:: Defining Fields By Content
* More CSV:: More on CSV files.
* FS versus FPAT:: A subtle difference.
-* Testing field creation:: Checking how 'gawk' is
+* Testing field creation:: Checking how âgawkâ is
splitting records.
* Multiple Line:: Reading multiline records.
* Getline:: Reading files under explicit program
- control using the 'getline'
+ control using the âgetlineâ
function.
-* Plain Getline:: Using 'getline' with no
+* Plain Getline:: Using âgetlineâ with no
arguments.
-* Getline/Variable:: Using 'getline' into a variable.
-* Getline/File:: Using 'getline' from a file.
-* Getline/Variable/File:: Using 'getline' into a variable
+* Getline/Variable:: Using âgetlineâ into a variable.
+* Getline/File:: Using âgetlineâ from a file.
+* Getline/Variable/File:: Using âgetlineâ into a variable
from a file.
-* Getline/Pipe:: Using 'getline' from a pipe.
-* Getline/Variable/Pipe:: Using 'getline' into a variable
+* Getline/Pipe:: Using âgetlineâ from a pipe.
+* Getline/Variable/Pipe:: Using âgetlineâ into a variable
from a pipe.
-* Getline/Coprocess:: Using 'getline' from a coprocess.
-* Getline/Variable/Coprocess:: Using 'getline' into a variable
+* Getline/Coprocess:: Using âgetlineâ from a coprocess.
+* Getline/Variable/Coprocess:: Using âgetlineâ into a variable
from a coprocess.
* Getline Notes:: Important things to know about
- 'getline'.
-* Getline Summary:: Summary of 'getline' Variants.
+ âgetlineâ.
+* Getline Summary:: Summary of âgetlineâ Variants.
* Read Timeout:: Reading input with a timeout.
* Retrying Input:: Retrying input after certain errors.
* Command-line directories:: What happens if you put a directory on
the command line.
* Input Summary:: Input summary.
* Input Exercises:: Exercises.
-* Print:: The 'print' statement.
-* Print Examples:: Simple examples of 'print'
+* Print:: The âprintâ statement.
+* Print Examples:: Simple examples of âprintâ
statements.
* Output Separators:: The output separators and how to
change them.
* OFMT:: Controlling Numeric Output With
- 'print'.
-* Printf:: The 'printf' statement.
-* Basic Printf:: Syntax of the 'printf' statement.
+ âprintâ.
+* Printf:: The âprintfâ statement.
+* Basic Printf:: Syntax of the âprintfâ statement.
* Control Letters:: Format-control letters.
* Format Modifiers:: Format-specification modifiers.
* Printf Examples:: Several examples.
@@ -249,10 +249,10 @@ in (a) below. A copy of the license is included in the
section entitled
files and pipes.
* Special FD:: Special files for I/O.
* Special Files:: File name interpretation in
- 'gawk'. 'gawk' allows
+ âgawkâ. âgawkâ allows
access to inherited file descriptors.
* Other Inherited Files:: Accessing other open files with
- 'gawk'.
+ âgawkâ.
* Special Network:: Special files for network
communications.
* Special Caveats:: Things to watch out for.
@@ -269,7 +269,7 @@ in (a) below. A copy of the license is included in the
section entitled
* Regexp Constants:: Regular Expression constants.
* Using Constant Regexps:: When and how to use a regexp constant.
* Standard Regexp Constants:: Regexp constants in standard
- 'awk'.
+ âawkâ.
* Strong Regexp Constants:: Strongly typed regexp constants.
* Variables:: Variables give names to values for
later use.
@@ -279,30 +279,30 @@ in (a) below. A copy of the license is included in the
section entitled
This is an advanced method of input.
* Conversion:: The conversion of strings to numbers
and vice versa.
-* Strings And Numbers:: How 'awk' Converts Between
+* Strings And Numbers:: How âawkâ Converts Between
Strings And Numbers.
* Locale influences conversions:: How the locale may affect conversions.
-* All Operators:: 'gawk''s operators.
-* Arithmetic Ops:: Arithmetic operations ('+',
- '-', etc.)
+* All Operators:: âgawkââs operators.
+* Arithmetic Ops:: Arithmetic operations (â+â,
+ â-â, etc.)
* Concatenation:: Concatenating strings.
* Assignment Ops:: Changing the value of a variable or a
field.
* Increment Ops:: Incrementing the numeric value of a
variable.
* Truth Values and Conditions:: Testing for true and false.
-* Truth Values:: What is "true" and what is
- "false".
+* Truth Values:: What is âtrueâ and what is
+ âfalseâ.
* Typing and Comparison:: How variables acquire types and how
this affects comparison of numbers and
- strings with '<', etc.
+ strings with â<â, etc.
* Variable Typing:: String type versus numeric type.
* Comparison Operators:: The comparison operators.
* POSIX String Comparison:: String comparison with POSIX rules.
* Boolean Ops:: Combining comparison expressions using
- boolean operators '||' ("or"),
- '&&' ("and") and '!'
- ("not").
+ boolean operators â||â (âorâ),
+ â&&â (âandâ) and â!â
+ (ânotâ).
* Conditional Exp:: Conditional expressions select between
two subexpressions under control of a
third subexpression.
@@ -325,12 +325,12 @@ in (a) below. A copy of the license is included in the
section entitled
* Empty:: The empty pattern, which matches every
record.
* Using Shell Variables:: How to use shell variables with
- 'awk'.
+ âawkâ.
* Action Overview:: What goes into an action.
* Statements:: Describes the various control
statements in detail.
* If Statement:: Conditionally execute some
- 'awk' statements.
+ âawkâ statements.
* While Statement:: Loop until some condition is
satisfied.
* Do Statement:: Do specified action while looping
@@ -348,14 +348,14 @@ in (a) below. A copy of the license is included in the
section entitled
* Next Statement:: Stop processing the current input
record.
* Nextfile Statement:: Stop processing the current file.
-* Exit Statement:: Stop execution of 'awk'.
+* Exit Statement:: Stop execution of âawkâ.
* Built-in Variables:: Summarizes the predefined variables.
* User-modified:: Built-in variables that you change to
- control 'awk'.
-* Auto-set:: Built-in variables where 'awk'
+ control âawkâ.
+* Auto-set:: Built-in variables where âawkâ
gives you information.
-* ARGC and ARGV:: Ways to use 'ARGC' and
- 'ARGV'.
+* ARGC and ARGV:: Ways to use âARGCâ and
+ âARGVâ.
* Pattern Action Summary:: Patterns and Actions summary.
* Array Basics:: The basics of arrays.
* Array Intro:: Introduction to Arrays
@@ -363,20 +363,20 @@ in (a) below. A copy of the license is included in the
section entitled
array.
* Assigning Elements:: How to change an element of an array.
* Array Example:: Basic Example of an Array
-* Scanning an Array:: A variation of the 'for'
+* Scanning an Array:: A variation of the âforâ
statement. It loops through the
- indices of an array's existing
+ indices of an arrayâs existing
elements.
* Controlling Scanning:: Controlling the order in which arrays
are scanned.
* Numeric Array Subscripts:: How to use numbers as subscripts in
- 'awk'.
+ âawkâ.
* Uninitialized Subscripts:: Using Uninitialized variables as
subscripts.
-* Delete:: The 'delete' statement removes an
+* Delete:: The âdeleteâ statement removes an
element from an array.
* Multidimensional:: Emulating multidimensional arrays in
- 'awk'.
+ âawkâ.
* Multiscanning:: Scanning multidimensional arrays.
* Arrays of Arrays:: True multidimensional arrays.
* Arrays Summary:: Summary of arrays.
@@ -385,15 +385,15 @@ in (a) below. A copy of the license is included in the
section entitled
* Boolean Functions:: A function that returns Boolean
values.
* Numeric Functions:: Functions that work with numbers,
- including 'int()', 'sin()'
- and 'rand()'.
+ including âint()â, âsin()â
+ and ârand()â.
* String Functions:: Functions for string manipulation,
- such as 'split()', 'match()'
- and 'sprintf()'.
+ such as âsplit()â, âmatch()â
+ and âsprintf()â.
* Gory Details:: More than you want to know about
- '\' and '&' with
- 'sub()', 'gsub()', and
- 'gensub()'.
+ â\â and â&â with
+ âsub()â, âgsub()â, and
+ âgensub()â.
* I/O Functions:: Functions for files and shell
commands.
* Time Functions:: Functions for dealing with timestamps.
@@ -407,7 +407,7 @@ in (a) below. A copy of the license is included in the
section entitled
* Function Example:: An example function definition and
what it does.
* Function Calling:: Calling user-defined functions.
-* Calling A Function:: Don't use spaces.
+* Calling A Function:: Donât use spaces.
* Variable Scope:: Controlling variable scope.
* Pass By Value/Reference:: Passing parameters.
* Function Caveats:: Other points to know about functions.
@@ -422,11 +422,11 @@ in (a) below. A copy of the license is included in the
section entitled
variables in library functions.
* General Functions:: Functions that are of general use.
* Strtonum Function:: A replacement for the built-in
- 'strtonum()' function.
+ âstrtonum()â function.
* Assert Function:: A function for assertions in
- 'awk' programs.
+ âawkâ programs.
* Round Function:: A function for rounding if
- 'sprintf()' does not do it
+ âsprintf()â does not do it
correctly.
* Cliff Random Function:: The Cliff Random Number Generator.
* Ordinal Functions:: Functions for using characters as
@@ -460,22 +460,22 @@ in (a) below. A copy of the license is included in the
section entitled
* Library Exercises:: Exercises.
* Running Examples:: How to run these examples.
* Clones:: Clones of common utilities.
-* Cut Program:: The 'cut' utility.
-* Egrep Program:: The 'egrep' utility.
-* Id Program:: The 'id' utility.
-* Split Program:: The 'split' utility.
-* Tee Program:: The 'tee' utility.
-* Uniq Program:: The 'uniq' utility.
-* Wc Program:: The 'wc' utility.
+* Cut Program:: The âcutâ utility.
+* Egrep Program:: The âegrepâ utility.
+* Id Program:: The âidâ utility.
+* Split Program:: The âsplitâ utility.
+* Tee Program:: The âteeâ utility.
+* Uniq Program:: The âuniqâ utility.
+* Wc Program:: The âwcâ utility.
* Bytes vs. Characters:: Modern character sets.
* Using extensions:: A brief intro to extensions.
-* wc program:: Code for 'wc.awk'.
-* Miscellaneous Programs:: Some interesting 'awk'
+* wc program:: Code for âwc.awkâ.
+* Miscellaneous Programs:: Some interesting âawkâ
programs.
* Dupword Program:: Finding duplicated words in a
document.
* Alarm Program:: An alarm clock.
-* Translate Program:: A program similar to the 'tr'
+* Translate Program:: A program similar to the âtrâ
utility.
* Labels Program:: Printing mailing labels.
* Word Sorting:: A program to produce a word usage
@@ -485,7 +485,7 @@ in (a) below. A copy of the license is included in the
section entitled
* Extract Program:: Pulling out programs from Texinfo
source files.
* Simple Sed:: A Simple Stream Editor.
-* Igawk Program:: A wrapper for 'awk' that
+* Igawk Program:: A wrapper for âawkâ that
includes files.
* Anagram Program:: Finding anagrams from a dictionary.
* Signature Program:: People do amazing things with too much
@@ -493,34 +493,34 @@ in (a) below. A copy of the license is included in the
section entitled
* Programs Summary:: Summary of programs.
* Programs Exercises:: Exercises.
* Nondecimal Data:: Allowing nondecimal input data.
-* Boolean Typed Values:: Values with 'number|bool' type.
+* Boolean Typed Values:: Values with ânumber|boolâ type.
* Array Sorting:: Facilities for controlling array
traversal and sorting arrays.
* Controlling Array Traversal:: How to use PROCINFO["sorted_in"].
-* Array Sorting Functions:: How to use 'asort()' and
- 'asorti()'.
+* Array Sorting Functions:: How to use âasort()â and
+ âasorti()â.
* Two-way I/O:: Two-way communications with another
process.
-* TCP/IP Networking:: Using 'gawk' for network
+* TCP/IP Networking:: Using âgawkâ for network
programming.
-* Profiling:: Profiling your 'awk' programs.
+* Profiling:: Profiling your âawkâ programs.
* Persistent Memory:: Preserving data between runs.
* Extension Philosophy:: What should be built-in and what
should not.
* Advanced Features Summary:: Summary of advanced features.
* I18N and L10N:: Internationalization and Localization.
-* Explaining gettext:: How GNU 'gettext' works.
+* Explaining gettext:: How GNU âgettextâ works.
* Programmer i18n:: Features for the programmer.
* Translator i18n:: Features for the translator.
* String Extraction:: Extracting marked strings.
-* Printf Ordering:: Rearranging 'printf' arguments.
-* I18N Portability:: 'awk'-level portability
+* Printf Ordering:: Rearranging âprintfâ arguments.
+* I18N Portability:: âawkâ-level portability
issues.
* I18N Example:: A simple i18n example.
-* Gawk I18N:: 'gawk' is also
+* Gawk I18N:: âgawkâ is also
internationalized.
* I18N Summary:: Summary of I18N stuff.
-* Debugging:: Introduction to 'gawk'
+* Debugging:: Introduction to âgawkâ
debugger.
* Debugging Concepts:: Debugging in General.
* Debugging Terms:: Additional Debugging Concepts.
@@ -540,19 +540,19 @@ in (a) below. A copy of the license is included in the
section entitled
* Limitations:: Limitations and future plans.
* Debugging Summary:: Debugging summary.
* Global Namespace:: The global namespace in standard
- 'awk'.
+ âawkâ.
* Qualified Names:: How to qualify names with a namespace.
* Default Namespace:: The default namespace.
* Changing The Namespace:: How to change the namespace.
* Naming Rules:: Namespace and Component Naming Rules.
* Internal Name Management:: How names are stored internally.
* Namespace Example:: An example of code using a namespace.
-* Namespace And Features:: Namespaces and other 'gawk'
+* Namespace And Features:: Namespaces and other âgawkâ
features.
* Namespace Summary:: Summarizing namespaces.
* Computer Arithmetic:: A quick intro to computer math.
* Math Definitions:: Defining terms used.
-* MPFR features:: The MPFR features in 'gawk'.
+* MPFR features:: The MPFR features in âgawkâ.
* MPFR On Parole:: MPFR features are on parole!
* MPFR Intro:: MPFR General introduction.
* FP Math Caution:: Things to know.
@@ -566,7 +566,7 @@ in (a) below. A copy of the license is included in the
section entitled
* Setting precision:: How to set the precision.
* Setting the rounding mode:: How to set the rounding mode.
* Arbitrary Precision Integers:: Arbitrary Precision Integer Arithmetic
- with 'gawk'.
+ with âgawkâ.
* Checking for MPFR:: How to check if MPFR is available.
* POSIX Floating Point Problems:: Standards Versus Existing Practice.
* Floating point summary:: Summary of floating point discussion.
@@ -580,7 +580,7 @@ in (a) below. A copy of the license is included in the
section entitled
* Constructor Functions:: Functions for creating values.
* API Ownership of MPFR and GMP Values:: Managing MPFR and GMP Values.
* Registration Functions:: Functions to register things with
- 'gawk'.
+ âgawkâ.
* Extension Functions:: Registering extension functions.
* Exit Callback Functions:: Registering an exit callback.
* Extension Version String:: Registering a version string.
@@ -588,13 +588,13 @@ in (a) below. A copy of the license is included in the
section entitled
* Output Wrappers:: Registering an output wrapper.
* Two-way processors:: Registering a two-way processor.
* Printing Messages:: Functions for printing messages.
-* Updating ERRNO:: Functions for updating 'ERRNO'.
+* Updating ERRNO:: Functions for updating âERRNOâ.
* Requesting Values:: How to get a value.
* Accessing Parameters:: Functions for accessing parameters.
* Symbol Table Access:: Functions for accessing global
variables.
* Symbol table by name:: Accessing variables by name.
-* Symbol table by cookie:: Accessing variables by "cookie".
+* Symbol table by cookie:: Accessing variables by âcookieâ.
* Cached values:: Creating and using cached values.
* Array Manipulation:: Functions for working with arrays.
* Array Data Types:: Data types for working with arrays.
@@ -608,35 +608,35 @@ in (a) below. A copy of the license is included in the
section entitled
* Extension GMP/MPFR Versioning:: Version information about GMP and
MPFR.
* Extension API Informational Variables:: Variables providing information about
- 'gawk''s invocation.
+ âgawkââs invocation.
* Extension API Boilerplate:: Boilerplate code for using the API.
* Changes from API V1:: Changes from V1 of the API.
-* Finding Extensions:: How 'gawk' finds compiled
+* Finding Extensions:: How âgawkâ finds compiled
extensions.
* Extension Example:: Example C code for an extension.
* Internal File Description:: What the new functions will do.
* Internal File Ops:: The code for internal file operations.
* Using Internal File Ops:: How to use an external extension.
* Extension Samples:: The sample extensions that ship with
- 'gawk'.
+ âgawkâ.
* Extension Sample File Functions:: The file functions sample.
-* Extension Sample Fnmatch:: An interface to 'fnmatch()'.
-* Extension Sample Fork:: An interface to 'fork()' and
+* Extension Sample Fnmatch:: An interface to âfnmatch()â.
+* Extension Sample Fork:: An interface to âfork()â and
other process functions.
* Extension Sample Inplace:: Enabling in-place file editing.
* Extension Sample Ord:: Character to value to character
conversions.
-* Extension Sample Readdir:: An interface to 'readdir()'.
+* Extension Sample Readdir:: An interface to âreaddir()â.
* Extension Sample Revout:: Reversing output sample output
wrapper.
* Extension Sample Rev2way:: Reversing data sample two-way
processor.
* Extension Sample Read write array:: Serializing an array to a file.
* Extension Sample Readfile:: Reading an entire file into a string.
-* Extension Sample Time:: An interface to 'gettimeofday()'
- and 'sleep()'.
+* Extension Sample Time:: An interface to âgettimeofday()â
+ and âsleep()â.
* Extension Sample API Tests:: Tests for the API.
-* gawkextlib:: The 'gawkextlib' project.
+* gawkextlib:: The âgawkextlibâ project.
* Extension summary:: Extension summary.
* Extension Exercises:: Exercises.
* V7/SVR3.1:: The major changes between V7 and
@@ -644,52 +644,52 @@ in (a) below. A copy of the license is included in the
section entitled
* SVR4:: Minor changes between System V
Releases 3.1 and 4.
* POSIX:: New features from the POSIX standard.
-* BTL:: New features from Brian Kernighan's
- version of 'awk'.
-* POSIX/GNU:: The extensions in 'gawk' not
- in POSIX 'awk'.
+* BTL:: New features from Brian Kernighanâs
+ version of âawkâ.
+* POSIX/GNU:: The extensions in âgawkâ not
+ in POSIX âawkâ.
* Feature History:: The history of the features in
- 'gawk'.
+ âgawkâ.
* Common Extensions:: Common Extensions Summary.
* Ranges and Locales:: How locales used to affect regexp
ranges.
* Contributors:: The major contributors to
- 'gawk'.
+ âgawkâ.
* History summary:: History summary.
-* Gawk Distribution:: What is in the 'gawk'
+* Gawk Distribution:: What is in the âgawkâ
distribution.
* Getting:: How to get the distribution.
* Extracting:: How to extract the distribution.
* Distribution contents:: What is in the distribution.
-* Unix Installation:: Installing 'gawk' under
+* Unix Installation:: Installing âgawkâ under
various versions of Unix.
-* Quick Installation:: Compiling 'gawk' under Unix.
+* Quick Installation:: Compiling âgawkâ under Unix.
* Compiling with MPFR:: Building with MPFR.
* Shell Startup Files:: Shell convenience functions.
* Additional Configuration Options:: Other compile-time options.
-* Configuration Philosophy:: How it's all supposed to work.
+* Configuration Philosophy:: How itâs all supposed to work.
* Compiling from Git:: Compiling from Git.
* Building the Documentation:: Building the Documentation.
* Non-Unix Installation:: Installation on Other Operating
Systems.
* PC Installation:: Installing and Compiling
- 'gawk' on Microsoft Windows.
+ âgawkâ on Microsoft Windows.
* PC Binary Installation:: Installing a prepared distribution.
-* PC Compiling:: Compiling 'gawk' for
+* PC Compiling:: Compiling âgawkâ for
Windows32.
-* PC Using:: Running 'gawk' on Windows32.
-* Cygwin:: Building and running 'gawk'
+* PC Using:: Running âgawkâ on Windows32.
+* Cygwin:: Building and running âgawkâ
for Cygwin.
-* MSYS:: Using 'gawk' In The MSYS
+* MSYS:: Using âgawkâ In The MSYS
Environment.
-* OpenVMS Installation:: Installing 'gawk' on OpenVMS.
-* OpenVMS Compilation:: How to compile 'gawk' under
+* OpenVMS Installation:: Installing âgawkâ on OpenVMS.
+* OpenVMS Compilation:: How to compile âgawkâ under
OpenVMS.
-* OpenVMS Dynamic Extensions:: Compiling 'gawk' dynamic
+* OpenVMS Dynamic Extensions:: Compiling âgawkâ dynamic
extensions on OpenVMS.
-* OpenVMS Installation Details:: How to install 'gawk' under
+* OpenVMS Installation Details:: How to install âgawkâ under
OpenVMS.
-* OpenVMS Running:: How to run 'gawk' under
+* OpenVMS Running:: How to run âgawkâ under
OpenVMS.
* OpenVMS GNV:: The OpenVMS GNV Project.
* Bugs:: Reporting Problems and Bugs.
@@ -700,16 +700,16 @@ in (a) below. A copy of the license is included in the
section entitled
performance issue.
* Asking for help:: Dealing with non-bug questions.
* Maintainers:: Maintainers of non-*nix ports.
-* Other Versions:: Other freely available 'awk'
+* Other Versions:: Other freely available âawkâ
implementations.
* Installation summary:: Summary of installation.
-* Compatibility Mode:: How to disable certain 'gawk'
+* Compatibility Mode:: How to disable certain âgawkâ
extensions.
-* Additions:: Making Additions To 'gawk'.
+* Additions:: Making Additions To âgawkâ.
* Accessing The Source:: Accessing the Git repository.
* Adding Code:: Adding code to the main body of
- 'gawk'.
-* New Ports:: Porting 'gawk' to a new
+ âgawkâ.
+* New Ports:: Porting âgawkâ to a new
operating system.
* Derived Files:: Why derived files are kept in the Git
repository.
@@ -742,64 +742,64 @@ Foreword to the Third Edition
*****************************
Arnold Robbins and I are good friends. We were introduced in 1990 by
-circumstances--and our favorite programming language, AWK. The
+circumstancesâand our favorite programming language, AWK. The
circumstances started a couple of years earlier. I was working at a new
job and noticed an unplugged Unix computer sitting in the corner. No
one knew how to use it, and neither did I. However, a couple of days
-later, it was running, and I was 'root' and the one-and-only user. That
+later, it was running, and I was ârootâ and the one-and-only user. That
day, I began the transition from statistician to Unix programmer.
On one of many trips to the library or bookstore in search of books
on Unix, I found the gray AWK book, a.k.a. Alfred V. Aho, Brian W.
-Kernighan, and Peter J. Weinberger's 'The AWK Programming Language'
-(Addison-Wesley, 1988). 'awk''s simple programming paradigm--find a
-pattern in the input and then perform an action--often reduced complex
-or tedious data manipulations to a few lines of code. I was excited to
-try my hand at programming in AWK.
-
- Alas, the 'awk' on my computer was a limited version of the language
-described in the gray book. I discovered that my computer had "old
-'awk'" and the book described "new 'awk'." I learned that this was
+Kernighan, and Peter J. Weinbergerâs âThe AWK Programming Languageâ
+(Addison-Wesley, 1988). âawkââs simple programming paradigmâfind a
+pattern in the input and then perform an actionâoften reduced complex or
+tedious data manipulations to a few lines of code. I was excited to try
+my hand at programming in AWK.
+
+ Alas, the âawkâ on my computer was a limited version of the language
+described in the gray book. I discovered that my computer had âold
+âawkââ and the book described ânew âawkâ.â I learned that this
was
typical; the old version refused to step aside or relinquish its name.
-If a system had a new 'awk', it was invariably called 'nawk', and few
-systems had it. The best way to get a new 'awk' was to 'ftp' the source
-code for 'gawk' from 'prep.ai.mit.edu'. 'gawk' was a version of new
-'awk' written by David Trueman and Arnold, and available under the GNU
+If a system had a new âawkâ, it was invariably called ânawkâ, and few
+systems had it. The best way to get a new âawkâ was to âftpâ the
source
+code for âgawkâ from âprep.ai.mit.eduâ. âgawkâ was a version of
new
+âawkâ written by David Trueman and Arnold, and available under the GNU
General Public License.
- (Incidentally, it's no longer difficult to find a new 'awk'. 'gawk'
+ (Incidentally, itâs no longer difficult to find a new âawkâ.
âgawkâ
ships with GNU/Linux, and you can download binaries or source code for
-almost any system; my wife uses 'gawk' on her VMS box.)
+almost any system; my wife uses âgawkâ on her VMS box.)
My Unix system started out unplugged from the wall; it certainly was
-not plugged into a network. So, oblivious to the existence of 'gawk'
-and the Unix community in general, and desiring a new 'awk', I wrote my
-own, called 'mawk'. Before I was finished, I knew about 'gawk', but it
-was too late to stop, so I eventually posted to a 'comp.sources'
+not plugged into a network. So, oblivious to the existence of âgawkâ
+and the Unix community in general, and desiring a new âawkâ, I wrote my
+own, called âmawkâ. Before I was finished, I knew about âgawkâ, but it
+was too late to stop, so I eventually posted to a âcomp.sourcesâ
newsgroup.
A few days after my posting, I got a friendly email from Arnold
introducing himself. He suggested we share design and algorithms and
-attached a draft of the POSIX standard so that I could update 'mawk' to
-support language extensions added after publication of 'The AWK
-Programming Language'.
+attached a draft of the POSIX standard so that I could update âmawkâ to
+support language extensions added after publication of âThe AWK
+Programming Languageâ.
Frankly, if our roles had been reversed, I would not have been so
-open and we probably would have never met. I'm glad we did meet. He is
-an AWK expert's AWK expert and a genuinely nice person. Arnold
+open and we probably would have never met. Iâm glad we did meet. He is
+an AWK expertâs AWK expert and a genuinely nice person. Arnold
contributes significant amounts of his expertise and time to the Free
Software Foundation.
- This book is the 'gawk' reference manual, but at its core it is a
+ This book is the âgawkâ reference manual, but at its core it is a
book about AWK programming that will appeal to a wide audience. It is a
definitive reference to the AWK language as defined by the 1987 Bell
Laboratories release and codified in the 1992 POSIX Utilities standard.
On the other hand, the novice AWK programmer can study a wealth of
-practical programs that emphasize the power of AWK's basic idioms:
+practical programs that emphasize the power of AWKâs basic idioms:
data-driven control flow, pattern matching with regular expressions, and
associative arrays. Those looking for something new can try out
-'gawk''s interface to network protocols via special '/inet' files.
+âgawkââs interface to network protocols via special â/inetâ files.
The programs in this book make clear that an AWK program is typically
much smaller and faster to develop than a counterpart written in C.
@@ -808,19 +808,19 @@ design in AWK to get it running quickly and expose
problems early.
Often, the interpreted performance is adequate and the AWK prototype
becomes the product.
- The new 'pgawk' (profiling 'gawk'), produces program execution
+ The new âpgawkâ (profiling âgawkâ), produces program execution
counts. I recently experimented with an algorithm that for n lines of
input, exhibited ~ C n^2 performance, while theory predicted ~ C n log n
-behavior. A few minutes poring over the 'awkprof.out' profile
-pinpointed the problem to a single line of code. 'pgawk' is a welcome
-addition to my programmer's toolbox.
+behavior. A few minutes poring over the âawkprof.outâ profile
+pinpointed the problem to a single line of code. âpgawkâ is a welcome
+addition to my programmerâs toolbox.
Arnold has distilled over a decade of experience writing and using
-AWK programs, and developing 'gawk', into this book. If you use AWK or
+AWK programs, and developing âgawkâ, into this book. If you use AWK or
want to learn how, then read this book.
Michael Brennan
- Author of 'mawk'
+ Author of âmawkâ
March 2001
@@ -829,8 +829,8 @@ File: gawk.info, Node: Foreword4, Next: Preface, Prev:
Foreword3, Up: Top
Foreword to the Fourth Edition
******************************
-Some things don't change. Thirteen years ago I wrote: "If you use AWK
-or want to learn how, then read this book." True then, and still true
+Some things donât change. Thirteen years ago I wrote: âIf you use AWK
+or want to learn how, then read this book.â True then, and still true
today.
Learning to use a programming language is about more than mastering
@@ -845,10 +845,10 @@ performance reasons happens less, because more often the
prototype is
fast enough.
Of course, there are computing operations that are best done in C or
-C++. With 'gawk' 4.1 and later, you do not have to choose between
+C++. With âgawkâ 4.1 and later, you do not have to choose between
writing your program in AWK or in C/C++. You can write most of your
program in AWK and the aspects that require C/C++ capabilities can be
-written in C/C++, and then the pieces glued together when the 'gawk'
+written in C/C++, and then the pieces glued together when the âgawkâ
module loads the C/C++ module as a dynamic plug-in. *note Dynamic
Extensions::, has all the details, and, as expected, many examples to
help you learn the ins and outs.
@@ -857,7 +857,7 @@ help you learn the ins and outs.
think you will too.
Michael Brennan
- Author of 'mawk'
+ Author of âmawkâ
October 2014
@@ -869,61 +869,61 @@ Preface
Several kinds of tasks occur repeatedly when working with text files.
You might want to extract certain lines and discard the rest. Or you
may need to make changes wherever certain patterns appear, but leave the
-rest of the file alone. Such jobs are often easy with 'awk'. The 'awk'
+rest of the file alone. Such jobs are often easy with âawkâ. The
âawkâ
utility interprets a special-purpose programming language that makes it
easy to handle simple data-reformatting jobs.
- The GNU implementation of 'awk' is called 'gawk'; if you invoke it
+ The GNU implementation of âawkâ is called âgawkâ; if you invoke it
with the proper options or environment variables, it is fully compatible
-with the POSIX(1) specification of the 'awk' language and with the Unix
-version of 'awk' maintained by Brian Kernighan. This means that all
-properly written 'awk' programs should work with 'gawk'. So most of the
-time, we don't distinguish between 'gawk' and other 'awk'
+with the POSIX(1) specification of the âawkâ language and with the Unix
+version of âawkâ maintained by Brian Kernighan. This means that all
+properly written âawkâ programs should work with âgawkâ. So most of
the
+time, we donât distinguish between âgawkâ and other âawkâ
implementations.
- Using 'awk' you can:
+ Using âawkâ you can:
- * Manage small, personal databases
+ ⢠Manage small, personal databases
- * Generate reports
+ ⢠Generate reports
- * Validate data
+ ⢠Validate data
- * Produce indexes and perform other document-preparation tasks
+ ⢠Produce indexes and perform other document-preparation tasks
- * Experiment with algorithms that you can adapt later to other
+ ⢠Experiment with algorithms that you can adapt later to other
computer languages
- In addition, 'gawk' provides facilities that make it easy to:
+ In addition, âgawkâ provides facilities that make it easy to:
- * Extract bits and pieces of data for processing
+ ⢠Extract bits and pieces of data for processing
- * Sort data
+ ⢠Sort data
- * Perform simple network communications
+ ⢠Perform simple network communications
- * Profile and debug 'awk' programs
+ ⢠Profile and debug âawkâ programs
- * Extend the language with functions written in C or C++
+ ⢠Extend the language with functions written in C or C++
- This Info file teaches you about the 'awk' language and how you can
+ This Info file teaches you about the âawkâ language and how you can
use it effectively. You should already be familiar with basic system
-commands, such as 'cat' and 'ls',(2) as well as basic shell facilities,
+commands, such as âcatâ and âlsâ,(2) as well as basic shell facilities,
such as input/output (I/O) redirection and pipes.
- Implementations of the 'awk' language are available for many
+ Implementations of the âawkâ language are available for many
different computing environments. This Info file, while describing the
-'awk' language in general, also describes the particular implementation
-of 'awk' called 'gawk' (which stands for "GNU 'awk'"). 'gawk' runs on a
+âawkâ language in general, also describes the particular implementation
+of âawkâ called âgawkâ (which stands for âGNU âawkââ).
âgawkâ runs on a
broad range of Unix systems, ranging from Intel-architecture PC-based
-computers up through large-scale systems. 'gawk' has also been ported
+computers up through large-scale systems. âgawkâ has also been ported
to macOS, z/OS, Microsoft Windows (all versions), and OpenVMS.(3)
* Menu:
-* History:: The history of 'gawk' and
- 'awk'.
-* Names:: What name to use to find 'awk'.
+* History:: The history of âgawkâ and
+ âawkâ.
+* Names:: What name to use to find âawkâ.
* This Manual:: Using this Info file. Includes sample
input files that you can use.
* Conventions:: Typographical Conventions.
@@ -942,60 +942,60 @@ as on traditional Unix-based systems. If you are using
some other
operating system, you still need to be familiar with the ideas of I/O
redirection and pipes.
- (3) Some other, obsolete systems to which 'gawk' was once ported are
+ (3) Some other, obsolete systems to which âgawkâ was once ported are
no longer supported and the code for those systems has been removed.
File: gawk.info, Node: History, Next: Names, Up: Preface
-History of 'awk' and 'gawk'
+History of âawkâ and âgawkâ
===========================
Recipe for a Programming Language
- 1 part 'egrep' 1 part 'snobol'
- 2 parts 'ed' 3 parts C
+ 1 part âegrepâ 1 part âsnobolâ
+ 2 parts âedâ 3 parts C
- Blend all parts well using 'lex' and 'yacc'. Document minimally and
+ Blend all parts well using âlexâ and âyaccâ. Document minimally and
release.
- After eight years, add another part 'egrep' and two more parts C.
+ After eight years, add another part âegrepâ and two more parts C.
Document very well and release.
- The name 'awk' comes from the initials of its designers: Alfred V.
+ The name âawkâ comes from the initials of its designers: Alfred V.
Aho, Peter J. Weinberger, and Brian W. Kernighan. The original version
-of 'awk' was written in 1977 at AT&T Bell Laboratories. In 1985, a new
+of âawkâ was written in 1977 at AT&T Bell Laboratories. In 1985, a new
version made the programming language more powerful, introducing
user-defined functions, multiple input streams, and computed regular
expressions. This new version became widely available with Unix System
V Release 3.1 (1987). The version in System V Release 4 (1989) added
-some new features and cleaned up the behavior in some of the "dark
-corners" of the language. The specification for 'awk' in the POSIX
+some new features and cleaned up the behavior in some of the âdark
+cornersâ of the language. The specification for âawkâ in the POSIX
Command Language and Utilities standard further clarified the language.
-Both the 'gawk' designers and the original 'awk' designers at Bell
+Both the âgawkâ designers and the original âawkâ designers at Bell
Laboratories provided feedback for the POSIX specification.
- Paul Rubin wrote 'gawk' in 1986. Jay Fenlason completed it, with
+ Paul Rubin wrote âgawkâ in 1986. Jay Fenlason completed it, with
advice from Richard Stallman. John Woods contributed parts of the code
as well. In 1988 and 1989, David Trueman, with help from me, thoroughly
-reworked 'gawk' for compatibility with the newer 'awk'. Circa 1994, I
+reworked âgawkâ for compatibility with the newer âawkâ. Circa 1994, I
became the primary maintainer. Current development focuses on bug
fixes, performance improvements, standards compliance, and,
occasionally, new features.
In May 1997, Jürgen Kahrs felt the need for network access from
-'awk', and with a little help from me, set about adding features to do
-this for 'gawk'. At that time, he also wrote the bulk of 'TCP/IP
-Internetworking with 'gawk'' (a separate document, available as part of
-the 'gawk' distribution). His code finally became part of the main
-'gawk' distribution with 'gawk' version 3.1.
-
- John Haque rewrote the 'gawk' internals, in the process providing an
-'awk'-level debugger. This version became available as 'gawk' version
+âawkâ, and with a little help from me, set about adding features to do
+this for âgawkâ. At that time, he also wrote the bulk of âTCP/IP
+Internetworking with âgawkââ (a separate document, available as part of
+the âgawkâ distribution). His code finally became part of the main
+âgawkâ distribution with âgawkâ version 3.1.
+
+ John Haque rewrote the âgawkâ internals, in the process providing an
+âawkâ-level debugger. This version became available as âgawkâ version
4.0 in 2011.
*Note Contributors:: for a full list of those who have made important
-contributions to 'gawk'.
+contributions to âgawkâ.
File: gawk.info, Node: Names, Next: This Manual, Prev: History, Up: Preface
@@ -1003,32 +1003,32 @@ File: gawk.info, Node: Names, Next: This Manual,
Prev: History, Up: Preface
A Rose by Any Other Name
========================
-The 'awk' language has evolved over the years. Full details are
+The âawkâ language has evolved over the years. Full details are
provided in *note Language History::. The language described in this
-Info file is often referred to as "new 'awk'." By analogy, the original
-version of 'awk' is referred to as "old 'awk'."
+Info file is often referred to as ânew âawkâ.â By analogy, the original
+version of âawkâ is referred to as âold âawkâ.â
- On most current systems, when you run the 'awk' utility you get some
-version of new 'awk'.(1) If your system's standard 'awk' is the old
+ On most current systems, when you run the âawkâ utility you get some
+version of new âawkâ.(1) If your systemâs standard âawkâ is the old
one, you will see something like this if you try the following test
program:
$ awk 1 /dev/null
- error-> awk: syntax error near line 1
- error-> awk: bailing out near line 1
+ errorâ awk: syntax error near line 1
+ errorâ awk: bailing out near line 1
-In this case, you should find a version of new 'awk', or just install
-'gawk'!
+In this case, you should find a version of new âawkâ, or just install
+âgawkâ!
Throughout this Info file, whenever we refer to a language feature
-that should be available in any complete implementation of POSIX 'awk',
-we simply use the term 'awk'. When referring to a feature that is
-specific to the GNU implementation, we use the term 'gawk'.
+that should be available in any complete implementation of POSIX âawkâ,
+we simply use the term âawkâ. When referring to a feature that is
+specific to the GNU implementation, we use the term âgawkâ.
---------- Footnotes ----------
- (1) Only Solaris systems still use an old 'awk' for the default 'awk'
-utility. A more modern 'awk' lives in '/usr/xpg6/bin' on these systems.
+ (1) Only Solaris systems still use an old âawkâ for the default
âawkâ
+utility. A more modern âawkâ lives in â/usr/xpg6/binâ on these
systems.
File: gawk.info, Node: This Manual, Next: Conventions, Prev: Names, Up:
Preface
@@ -1036,151 +1036,151 @@ File: gawk.info, Node: This Manual, Next:
Conventions, Prev: Names, Up: Pref
Using This Book
===============
-The term 'awk' refers to a particular program as well as to the language
+The term âawkâ refers to a particular program as well as to the language
you use to tell this program what to do. When we need to be careful, we
-call the language "the 'awk' language," and the program "the 'awk'
-utility." This Info file explains both how to write programs in the
-'awk' language and how to run the 'awk' utility. The term "'awk'
-program" refers to a program written by you in the 'awk' programming
+call the language âthe âawkâ language,â and the program âthe
âawkâ
+utility.â This Info file explains both how to write programs in the
+âawkâ language and how to run the âawkâ utility. The term ââawkâ
+programâ refers to a program written by you in the âawkâ programming
language.
- Primarily, this Info file explains the features of 'awk' as defined
-in the POSIX standard. It does so in the context of the 'gawk'
+ Primarily, this Info file explains the features of âawkâ as defined
+in the POSIX standard. It does so in the context of the âgawkâ
implementation. While doing so, it also attempts to describe important
-differences between 'gawk' and other 'awk' implementations.(1) Finally,
-it notes any 'gawk' features that are not in the POSIX standard for
-'awk'.
+differences between âgawkâ and other âawkâ implementations.(1)
Finally,
+it notes any âgawkâ features that are not in the POSIX standard for
+âawkâ.
There are sidebars scattered throughout the Info file. They add a
more complete explanation of points that are relevant, but not likely to
be of interest on first reading. All appear in the index, under the
-heading "sidebar."
+heading âsidebar.â
- Most of the time, the examples use complete 'awk' programs. Some of
-the more advanced minor nodes show only the part of the 'awk' program
+ Most of the time, the examples use complete âawkâ programs. Some of
+the more advanced minor nodes show only the part of the âawkâ program
that illustrates the concept being described.
Although this Info file is aimed principally at people who have not
-been exposed to 'awk', there is a lot of information here that even the
-'awk' expert should find useful. In particular, the description of
-POSIX 'awk' and the example programs in *note Library Functions::, and
+been exposed to âawkâ, there is a lot of information here that even the
+âawkâ expert should find useful. In particular, the description of
+POSIX âawkâ and the example programs in *note Library Functions::, and
in *note Sample Programs::, should be of interest.
This Info file is split into several parts, as follows:
- * Part I describes the 'awk' language and the 'gawk' program in
+ ⢠Part I describes the âawkâ language and the âgawkâ program in
detail. It starts with the basics, and continues through all of
- the features of 'awk'. It contains the following chapters:
+ the features of âawkâ. It contains the following chapters:
- - *note Getting Started::, provides the essentials you need to
- know to begin using 'awk'.
+ â *note Getting Started::, provides the essentials you need to
+ know to begin using âawkâ.
- - *note Invoking Gawk::, describes how to run 'gawk', the
- meaning of its command-line options, and how it finds 'awk'
+ â *note Invoking Gawk::, describes how to run âgawkâ, the
+ meaning of its command-line options, and how it finds âawkâ
program source files.
- - *note Regexp::, introduces regular expressions in general, and
- in particular the flavors supported by POSIX 'awk' and 'gawk'.
+ â *note Regexp::, introduces regular expressions in general, and
+ in particular the flavors supported by POSIX âawkâ and
âgawkâ.
- - *note Reading Files::, describes how 'awk' reads your data.
+ â *note Reading Files::, describes how âawkâ reads your data.
It introduces the concepts of records and fields, as well as
- the 'getline' command. I/O redirection is first described
+ the âgetlineâ command. I/O redirection is first described
here. Network I/O is also briefly introduced here.
- - *note Printing::, describes how 'awk' programs can produce
- output with 'print' and 'printf'.
+ â *note Printing::, describes how âawkâ programs can produce
+ output with âprintâ and âprintfâ.
- - *note Expressions::, describes expressions, which are the
+ â *note Expressions::, describes expressions, which are the
basic building blocks for getting most things done in a
program.
- - *note Patterns and Actions::, describes how to write patterns
+ â *note Patterns and Actions::, describes how to write patterns
for matching records, actions for doing something when a
- record is matched, and the predefined variables 'awk' and
- 'gawk' use.
+ record is matched, and the predefined variables âawkâ and
+ âgawkâ use.
- - *note Arrays::, covers 'awk''s one-and-only data structure:
+ â *note Arrays::, covers âawkââs one-and-only data structure:
the associative array. Deleting array elements and whole
- arrays is described, as well as sorting arrays in 'gawk'. The
- major node also describes how 'gawk' provides arrays of
+ arrays is described, as well as sorting arrays in âgawkâ. The
+ major node also describes how âgawkâ provides arrays of
arrays.
- - *note Functions::, describes the built-in functions 'awk' and
- 'gawk' provide, as well as how to define your own functions.
- It also discusses how 'gawk' lets you call functions
+ â *note Functions::, describes the built-in functions âawkâ and
+ âgawkâ provide, as well as how to define your own functions.
+ It also discusses how âgawkâ lets you call functions
indirectly.
- * Part II shows how to use 'awk' and 'gawk' for problem solving.
+ ⢠Part II shows how to use âawkâ and âgawkâ for problem solving.
There is lots of code here for you to read and learn from. This
part contains the following chapters:
- - *note Library Functions::, provides a number of functions
- meant to be used from main 'awk' programs.
+ â *note Library Functions::, provides a number of functions
+ meant to be used from main âawkâ programs.
- - *note Sample Programs::, provides many sample 'awk' programs.
+ â *note Sample Programs::, provides many sample âawkâ programs.
- Reading these two chapters allows you to see 'awk' solving real
+ Reading these two chapters allows you to see âawkâ solving real
problems.
- * Part III focuses on features specific to 'gawk'. It contains the
+ ⢠Part III focuses on features specific to âgawkâ. It contains the
following chapters:
- - *note Advanced Features::, describes a number of advanced
+ â *note Advanced Features::, describes a number of advanced
features. Of particular note are the abilities to control the
order of array traversal, have two-way communications with
another process, perform TCP/IP networking, and profile your
- 'awk' programs.
+ âawkâ programs.
- - *note Internationalization::, describes special features for
+ â *note Internationalization::, describes special features for
translating program messages into different languages at
runtime.
- - *note Debugger::, describes the 'gawk' debugger.
+ â *note Debugger::, describes the âgawkâ debugger.
- - *note Namespaces::, describes how 'gawk' allows variables
+ â *note Namespaces::, describes how âgawkâ allows variables
and/or functions of the same name to be in different
namespaces.
- - *note Arbitrary Precision Arithmetic::, describes advanced
+ â *note Arbitrary Precision Arithmetic::, describes advanced
arithmetic facilities.
- - *note Dynamic Extensions::, describes how to add new variables
- and functions to 'gawk' by writing extensions in C or C++.
+ â *note Dynamic Extensions::, describes how to add new variables
+ and functions to âgawkâ by writing extensions in C or C++.
- * Part IV provides the appendices, the Glossary, and two licenses
- that cover the 'gawk' source code and this Info file, respectively.
+ ⢠Part IV provides the appendices, the Glossary, and two licenses
+ that cover the âgawkâ source code and this Info file, respectively.
It contains the following appendices:
- - *note Language History::, describes how the 'awk' language has
+ â *note Language History::, describes how the âawkâ language has
evolved since its first release to the present. It also
- describes how 'gawk' has acquired features over time.
+ describes how âgawkâ has acquired features over time.
- - *note Installation::, describes how to get 'gawk', how to
+ â *note Installation::, describes how to get âgawkâ, how to
compile it on POSIX-compatible systems, and how to compile and
use it on different non-POSIX systems. It also describes how
- to report bugs in 'gawk' and where to get other freely
- available 'awk' implementations.
+ to report bugs in âgawkâ and where to get other freely
+ available âawkâ implementations.
- - *note Notes::, describes how to disable 'gawk''s extensions,
- as well as how to contribute new code to 'gawk', and some
- possible future directions for 'gawk' development.
+ â *note Notes::, describes how to disable âgawkââs extensions,
+ as well as how to contribute new code to âgawkâ, and some
+ possible future directions for âgawkâ development.
- - *note Basic Concepts::, provides some very cursory background
+ â *note Basic Concepts::, provides some very cursory background
material for those who are completely unfamiliar with computer
programming.
- - The *note Glossary::, defines most, if not all, of the
+ â The *note Glossary::, defines most, if not all, of the
significant terms used throughout the Info file. If you find
- terms that you aren't familiar with, try looking them up here.
+ terms that you arenât familiar with, try looking them up here.
- - *note Copying::, and *note GNU Free Documentation License::,
- present the licenses that cover the 'gawk' source code and
+ â *note Copying::, and *note GNU Free Documentation License::,
+ present the licenses that cover the âgawkâ source code and
this Info file, respectively.
---------- Footnotes ----------
(1) All such differences appear in the index under the entry
-"differences in 'awk' and 'gawk'."
+âdifferences in âawkâ and âgawkâ.â
File: gawk.info, Node: Conventions, Next: Manual History, Prev: This
Manual, Up: Preface
@@ -1195,47 +1195,47 @@ both the printed and online versions of the
documentation. This minor
node briefly documents the typographical conventions used in Texinfo.
Examples you would type at the command line are preceded by the
-common shell primary and secondary prompts, '$' and '>', respectively.
-Input that you type is shown 'like this'. Output from the command is
-preceded by the glyph "-|". This typically represents the command's
-standard output. Error messages and other output on the command's
-standard error are preceded by the glyph "error->". For example:
+common shell primary and secondary prompts, â$â and â>â, respectively.
+Input that you type is shown âlike thisâ. Output from the command is
+preceded by the glyph ââ£â. This typically represents the commandâs
+standard output. Error messages and other output on the commandâs
+standard error are preceded by the glyph âerrorââ. For example:
$ echo hi on stdout
- -| hi on stdout
+ ⣠hi on stdout
$ echo hello on stderr 1>&2
- error-> hello on stderr
+ errorâ hello on stderr
- Characters that you type at the keyboard look 'like this'. In
-particular, there are special characters called "control characters."
-These are characters that you type by holding down both the 'CONTROL'
-key and another key, at the same time. For example, a 'Ctrl-d' is typed
-by first pressing and holding the 'CONTROL' key, next pressing the 'd'
+ Characters that you type at the keyboard look âlike thisâ. In
+particular, there are special characters called âcontrol characters.â
+These are characters that you type by holding down both the âCONTROLâ
+key and another key, at the same time. For example, a âCtrl-dâ is typed
+by first pressing and holding the âCONTROLâ key, next pressing the âdâ
key, and finally releasing both keys.
For the sake of brevity, throughout this Info file, we refer to Brian
-Kernighan's version of 'awk' as "BWK 'awk'." (*Note Other Versions::
-for information on his and other versions.)
+Kernighanâs version of âawkâ as âBWK âawkâ.â (*Note Other
Versions:: for
+information on his and other versions.)
Dark Corners
------------
- Dark corners are basically fractal--no matter how much you
- illuminate, there's always a smaller but darker one.
- -- _Brian Kernighan_
+ Dark corners are basically fractalâno matter how much you
+ illuminate, thereâs always a smaller but darker one.
+ â _Brian Kernighan_
- Until the POSIX standard (and 'GAWK: Effective AWK Programming'),
-many features of 'awk' were either poorly documented or not documented
-at all. Descriptions of such features (often called "dark corners") are
-noted in this Info file with "(d.c.)." They also appear in the index
-under the heading "dark corner."
+ Until the POSIX standard (and âGAWK: Effective AWK Programmingâ),
+many features of âawkâ were either poorly documented or not documented
+at all. Descriptions of such features (often called âdark cornersâ) are
+noted in this Info file with â(d.c.).â They also appear in the index
+under the heading âdark corner.â
But, as noted by the opening quote, any coverage of dark corners is
by definition incomplete.
- Extensions to the standard 'awk' language that are supported by more
-than one 'awk' implementation are marked "(c.e.)," and listed in the
-index under "common extensions" and "extensions, common."
+ Extensions to the standard âawkâ language that are supported by more
+than one âawkâ implementation are marked â(c.e.),â and listed in the
+index under âcommon extensionsâ and âextensions, common.â
File: gawk.info, Node: Manual History, Next: How To Contribute, Prev:
Conventions, Up: Preface
@@ -1251,17 +1251,17 @@ editor. GNU Emacs is the most widely used version of
Emacs today.
The GNU(1) Project is an ongoing effort on the part of the Free
Software Foundation to create a complete, freely distributable,
POSIX-compliant computing environment. The FSF uses the GNU General
-Public License (GPL) to ensure that its software's source code is always
+Public License (GPL) to ensure that its softwareâs source code is always
available to the end user. A copy of the GPL is included for your
reference (*note Copying::). The GPL applies to the C language source
-code for 'gawk'. To find out more about the FSF and the GNU Project
-online, see the GNU Project's home page (https://www.gnu.org). This
-Info file may also be read from GNU's website
+code for âgawkâ. To find out more about the FSF and the GNU Project
+online, see the GNU Projectâs home page (https://www.gnu.org). This
+Info file may also be read from GNUâs website
(https://www.gnu.org/software/gawk/manual/).
A shell, an editor (Emacs), highly portable optimizing C, C++, and
Objective-C compilers, a symbolic debugger and dozens of large and small
-utilities (such as 'gawk'), have all been completed and are freely
+utilities (such as âgawkâ), have all been completed and are freely
available. The GNU operating system kernel (the HURD), has been
released but remains in an early stage of development.
@@ -1272,20 +1272,20 @@ systems.(2) Many GNU/Linux distributions are available
for download
from the Internet.
The Info file itself has gone through multiple previous editions.
-Paul Rubin wrote the very first draft of 'The GAWK Manual'; it was
+Paul Rubin wrote the very first draft of âThe GAWK Manualâ; it was
around 40 pages long. Diane Close and Richard Stallman improved it,
yielding a version that was around 90 pages and barely described the
-original, "old" version of 'awk'.
+original, âoldâ version of âawkâ.
I started working with that version in the fall of 1988. As work on
it progressed, the FSF published several preliminary versions (numbered
-0.X). In 1996, edition 1.0 was released with 'gawk' 3.0.0. The FSF
-published the first two editions under the title 'The GNU Awk User's
-Guide'.
+0.X). In 1996, edition 1.0 was released with âgawkâ 3.0.0. The FSF
+published the first two editions under the title âThe GNU Awk Userâs
+Guideâ.
This edition maintains the basic structure of the previous editions.
For FSF edition 4.0, the content was thoroughly reviewed and updated.
-All references to 'gawk' versions prior to 4.0 were removed. Of
+All references to âgawkâ versions prior to 4.0 were removed. Of
significant note for that edition was the addition of *note Debugger::.
For FSF edition 5.0, the content has been reorganized into parts, and
@@ -1298,9 +1298,9 @@ on submitting problem reports electronically.
---------- Footnotes ----------
- (1) GNU stands for "GNU's Not Unix."
+ (1) GNU stands for âGNUâs Not Unix.â
- (2) The terminology "GNU/Linux" is explained in the *note Glossary::.
+ (2) The terminology âGNU/Linuxâ is explained in the *note Glossary::.
File: gawk.info, Node: How To Contribute, Next: Acknowledgments, Prev:
Manual History, Up: Preface
@@ -1308,22 +1308,22 @@ File: gawk.info, Node: How To Contribute, Next:
Acknowledgments, Prev: Manual
How to Contribute
=================
-As the maintainer of GNU 'awk', I once thought that I would be able to
-manage a collection of publicly available 'awk' programs and I even
+As the maintainer of GNU âawkâ, I once thought that I would be able to
+manage a collection of publicly available âawkâ programs and I even
solicited contributions. Making things available on the Internet helps
-keep the 'gawk' distribution down to manageable size.
+keep the âgawkâ distribution down to manageable size.
The initial collection of material, such as it is, is still available
at <ftp://ftp.freefriends.org/arnold/Awkstuff>.
- In the hopes of doing something broader, I acquired the 'awklang.org'
+ In the hopes of doing something broader, I acquired the âawklang.orgâ
domain. Late in 2017, a volunteer took on the task of managing it.
- If you have written an interesting 'awk' program that you would like
+ If you have written an interesting âawkâ program that you would like
to share with the rest of the world, please see <http://www.awklang.org>
-and use the "Contact" link.
+and use the âContactâ link.
- If you have written a 'gawk' extension, please see *note
+ If you have written a âgawkâ extension, please see *note
gawkextlib::.
@@ -1332,15 +1332,15 @@ File: gawk.info, Node: Acknowledgments, Prev: How To
Contribute, Up: Preface
Acknowledgments
===============
-The initial draft of 'The GAWK Manual' had the following
+The initial draft of âThe GAWK Manualâ had the following
acknowledgments:
Many people need to be thanked for their assistance in producing
this manual. Jay Fenlason contributed many ideas and sample
programs. Richard Mlynarik and Robert Chassell gave helpful
- comments on drafts of this manual. The paper 'A Supplemental
- Document for AWK' by John W. Pierce of the Chemistry Department at
- UC San Diego, pinpointed several issues relevant both to 'awk'
+ comments on drafts of this manual. The paper âA Supplemental
+ Document for AWKâ by John W. Pierce of the Chemistry Department at
+ UC San Diego, pinpointed several issues relevant both to âawkâ
implementation and to this manual, that would otherwise have
escaped us.
@@ -1354,45 +1354,45 @@ acknowledgements:
The following people (in alphabetical order) provided helpful
comments on various versions of this book: Rick Adams, Dr. Nelson
H.F. Beebe, Karl Berry, Dr. Michael Brennan, Rich Burridge, Claire
- Cloutier, Diane Close, Scott Deifik, Christopher ("Topher") Eliot,
+ Cloutier, Diane Close, Scott Deifik, Christopher (âTopherâ) Eliot,
Jeffrey Friedl, Dr. Darrel Hankerson, Michal Jaegermann, Dr.
Richard J. LeBlanc, Michael Lijewski, Pat Rankin, Miriam Robbins,
Mary Sheehan, and Chuck Toporek.
Robert J. Chassell provided much valuable advice on the use of
Texinfo. He also deserves special thanks for convincing me _not_
- to title this Info file 'How to Gawk Politely'. Karl Berry helped
+ to title this Info file âHow to Gawk Politelyâ. Karl Berry helped
significantly with the TeX part of Texinfo.
I would like to thank Marshall and Elaine Hartholz of Seattle and
Dr. Bert and Rita Schreiber of Detroit for large amounts of quiet
vacation time in their homes, which allowed me to make significant
- progress on this Info file and on 'gawk' itself.
+ progress on this Info file and on âgawkâ itself.
Phil Hughes of SSC contributed in a very important way by loaning
me his laptop GNU/Linux system, not once, but twice, which allowed
me to do a lot of work while away from home.
David Trueman deserves special credit; he has done a yeoman job of
- evolving 'gawk' so that it performs well and without bugs.
- Although he is no longer involved with 'gawk', working with him on
+ evolving âgawkâ so that it performs well and without bugs.
+ Although he is no longer involved with âgawkâ, working with him on
this project was a significant pleasure.
The intrepid members of the GNITS mailing list, and most notably
Ulrich Drepper, provided invaluable help and feedback for the
design of the internationalization features.
- Chuck Toporek, Mary Sheehan, and Claire Cloutier of O'Reilly &
+ Chuck Toporek, Mary Sheehan, and Claire Cloutier of OâReilly &
Associates contributed significant editorial help for this Info
- file for the 3.1 release of 'gawk'.
+ file for the 3.1 release of âgawkâ.
Dr. Nelson Beebe, Andreas Buening, Dr. Manuel Collado, Antonio
Colombo, Stephen Davies, Scott Deifik, Akim Demaille, Daniel Richard G.,
Juan Manuel Guerrero, Darrel Hankerson, Michal Jaegermann, Jürgen Kahrs,
Stepan Kasal, John Malmberg, Chet Ramey, Pat Rankin, Andrew Schorr,
Corinna Vinschen, and Eli Zaretskii (in alphabetical order) make up the
-current 'gawk' "crack portability team." Without their hard work and
-help, 'gawk' would not be nearly the robust, portable program it is
+current âgawkâ âcrack portability team.â Without their hard work and
+help, âgawkâ would not be nearly the robust, portable program it is
today. It has been and continues to be a pleasure working with this
team of fine people.
@@ -1401,7 +1401,7 @@ people. *Note Contributors:: for the full list.
Thanks to Michael Brennan for the Forewords.
- Thanks to Patrice Dumas for the new 'makeinfo' program. Thanks to
+ Thanks to Patrice Dumas for the new âmakeinfoâ program. Thanks to
Karl Berry for his past work on Texinfo, and to Gavin Smith, who
continues to work to improve the Texinfo markup language.
@@ -1410,9 +1410,9 @@ reviewers for the 2015 edition of this Info file. Their
feedback helped
improve the final work.
I would also like to thank Brian Kernighan for his invaluable
-assistance during the testing and debugging of 'gawk', and for his
+assistance during the testing and debugging of âgawkâ, and for his
ongoing help and advice in clarifying numerous points about the
-language. We could not have done nearly as good a job on either 'gawk'
+language. We could not have done nearly as good a job on either âgawkâ
or its documentation without his help.
Brian is in a class by himself as a programmer and technical author.
@@ -1437,33 +1437,33 @@ March, 2020
File: gawk.info, Node: Getting Started, Next: Invoking Gawk, Prev: Preface,
Up: Top
-1 Getting Started with 'awk'
+1 Getting Started with âawkâ
****************************
-The basic function of 'awk' is to search files for lines (or other units
+The basic function of âawkâ is to search files for lines (or other units
of text) that contain certain patterns. When a line matches one of the
-patterns, 'awk' performs specified actions on that line. 'awk'
+patterns, âawkâ performs specified actions on that line. âawkâ
continues to process input lines in this way until it reaches the end of
the input files.
- Programs in 'awk' are different from programs in most other
-languages, because 'awk' programs are "data driven" (i.e., you describe
+ Programs in âawkâ are different from programs in most other
+languages, because âawkâ programs are âdata drivenâ (i.e., you describe
the data you want to work with and then what to do when you find it).
-Most other languages are "procedural"; you have to describe, in great
+Most other languages are âproceduralâ; you have to describe, in great
detail, every step the program should take. When working with
procedural languages, it is usually much harder to clearly describe the
-data your program will process. For this reason, 'awk' programs are
+data your program will process. For this reason, âawkâ programs are
often refreshingly easy to read and write.
- When you run 'awk', you specify an 'awk' "program" that tells 'awk'
-what to do. The program consists of a series of "rules" (it may also
-contain "function definitions", an advanced feature that we will ignore
+ When you run âawkâ, you specify an âawkâ âprogramâ that tells
âawkâ
+what to do. The program consists of a series of ârulesâ (it may also
+contain âfunction definitionsâ, an advanced feature that we will ignore
for now; *note User-defined::). Each rule specifies one pattern to
search for and one action to perform upon finding the pattern.
- Syntactically, a rule consists of a "pattern" followed by an
-"action". The action is enclosed in braces to separate it from the
-pattern. Newlines usually separate rules. Therefore, an 'awk' program
+ Syntactically, a rule consists of a âpatternâ followed by an
+âactionâ. The action is enclosed in braces to separate it from the
+pattern. Newlines usually separate rules. Therefore, an âawkâ program
looks like this:
PATTERN { ACTION }
@@ -1472,9 +1472,9 @@ looks like this:
* Menu:
-* Running gawk:: How to run 'gawk' programs; includes
+* Running gawk:: How to run âgawkâ programs; includes
command-line syntax.
-* Sample Data Files:: Sample data files for use in the 'awk'
+* Sample Data Files:: Sample data files for use in the âawkâ
programs illustrated in this Info file.
* Very Simple:: A very simple example.
* Two Rules:: A less simple one-line example using two
@@ -1482,19 +1482,19 @@ looks like this:
* More Complex:: A more complex example.
* Statements/Lines:: Subdividing or combining statements into
lines.
-* Other Features:: Other Features of 'awk'.
-* When:: When to use 'gawk' and when to use
+* Other Features:: Other Features of âawkâ.
+* When:: When to use âgawkâ and when to use
other things.
* Intro Summary:: Summary of the introduction.
File: gawk.info, Node: Running gawk, Next: Sample Data Files, Up: Getting
Started
-1.1 How to Run 'awk' Programs
+1.1 How to Run âawkâ Programs
=============================
-There are several ways to run an 'awk' program. If the program is
-short, it is easiest to include it in the command that runs 'awk', like
+There are several ways to run an âawkâ program. If the program is
+short, it is easiest to include it in the command that runs âawkâ, like
this:
awk 'PROGRAM' INPUT-FILE1 INPUT-FILE2 ...
@@ -1509,96 +1509,96 @@ variations of each.
* Menu:
-* One-shot:: Running a short throwaway 'awk'
+* One-shot:: Running a short throwaway âawkâ
program.
* Read Terminal:: Using no input files (input from the keyboard
instead).
-* Long:: Putting permanent 'awk' programs in
+* Long:: Putting permanent âawkâ programs in
files.
-* Executable Scripts:: Making self-contained 'awk' programs.
-* Comments:: Adding documentation to 'gawk'
+* Executable Scripts:: Making self-contained âawkâ programs.
+* Comments:: Adding documentation to âgawkâ
programs.
* Quoting:: More discussion of shell quoting issues.
File: gawk.info, Node: One-shot, Next: Read Terminal, Up: Running gawk
-1.1.1 One-Shot Throwaway 'awk' Programs
+1.1.1 One-Shot Throwaway âawkâ Programs
---------------------------------------
-Once you are familiar with 'awk', you will often type in simple programs
+Once you are familiar with âawkâ, you will often type in simple programs
the moment you want to use them. Then you can write the program as the
-first argument of the 'awk' command, like this:
+first argument of the âawkâ command, like this:
awk 'PROGRAM' INPUT-FILE1 INPUT-FILE2 ...
where PROGRAM consists of a series of patterns and actions, as described
earlier.
- This command format instructs the "shell", or command interpreter, to
-start 'awk' and use the PROGRAM to process records in the input file(s).
-There are single quotes around PROGRAM so the shell won't interpret any
-'awk' characters as special shell characters. The quotes also cause the
-shell to treat all of PROGRAM as a single argument for 'awk', and allow
+ This command format instructs the âshellâ, or command interpreter, to
+start âawkâ and use the PROGRAM to process records in the input file(s).
+There are single quotes around PROGRAM so the shell wonât interpret any
+âawkâ characters as special shell characters. The quotes also cause the
+shell to treat all of PROGRAM as a single argument for âawkâ, and allow
PROGRAM to be more than one line long.
- This format is also useful for running short or medium-sized 'awk'
+ This format is also useful for running short or medium-sized âawkâ
programs from shell scripts, because it avoids the need for a separate
-file for the 'awk' program. A self-contained shell script is more
+file for the âawkâ program. A self-contained shell script is more
reliable because there are no other files to misplace.
- Later in this chapter, in *note Very Simple::, we'll see examples of
+ Later in this chapter, in *note Very Simple::, weâll see examples of
several short, self-contained programs.
File: gawk.info, Node: Read Terminal, Next: Long, Prev: One-shot, Up:
Running gawk
-1.1.2 Running 'awk' Without Input Files
+1.1.2 Running âawkâ Without Input Files
---------------------------------------
-You can also run 'awk' without any input files. If you type the
+You can also run âawkâ without any input files. If you type the
following command line:
awk 'PROGRAM'
-'awk' applies the PROGRAM to the "standard input", which usually means
+âawkâ applies the PROGRAM to the âstandard inputâ, which usually means
whatever you type on the keyboard. This continues until you indicate
-end-of-file by typing 'Ctrl-d'. (On non-POSIX operating systems, the
+end-of-file by typing âCtrl-dâ. (On non-POSIX operating systems, the
end-of-file character may be different.)
As an example, the following program prints a friendly piece of
-advice (from Douglas Adams's 'The Hitchhiker's Guide to the Galaxy'), to
+advice (from Douglas Adamsâs âThe Hitchhikerâs Guide to the Galaxyâ),
to
keep you from worrying about the complexities of computer programming:
$ awk 'BEGIN { print "Don\47t Panic!" }'
- -| Don't Panic!
+ ⣠Don't Panic!
- 'awk' executes statements associated with 'BEGIN' before reading any
+ âawkâ executes statements associated with âBEGINâ before reading any
input. If there are no other statements in your program, as is the case
-here, 'awk' just stops, instead of trying to read input it doesn't know
-how to process. The '\47' is a magic way (explained later) of getting a
+here, âawkâ just stops, instead of trying to read input it doesnât know
+how to process. The â\47â is a magic way (explained later) of getting a
single quote into the program, without having to engage in ugly shell
quoting tricks.
NOTE: If you use Bash as your shell, you should execute the command
- 'set +H' before running this program interactively, to disable the
- C shell-style command history, which treats '!' as a special
+ âset +Hâ before running this program interactively, to disable the
+ C shell-style command history, which treats â!â as a special
character. We recommend putting this command into your personal
startup file.
- This next simple 'awk' program emulates the 'cat' utility; it copies
+ This next simple âawkâ program emulates the âcatâ utility; it copies
whatever you type on the keyboard to its standard output (why this works
is explained shortly):
$ awk '{ print }'
Now is the time for all good men
- -| Now is the time for all good men
+ ⣠Now is the time for all good men
to come to the aid of their country.
- -| to come to the aid of their country.
+ ⣠to come to the aid of their country.
Four score and seven years ago, ...
- -| Four score and seven years ago, ...
+ ⣠Four score and seven years ago, ...
What, me worry?
- -| What, me worry?
+ ⣠What, me worry?
Ctrl-d
@@ -1607,19 +1607,19 @@ File: gawk.info, Node: Long, Next: Executable
Scripts, Prev: Read Terminal,
1.1.3 Running Long Programs
---------------------------
-Sometimes 'awk' programs are very long. In these cases, it is more
+Sometimes âawkâ programs are very long. In these cases, it is more
convenient to put the program into a separate file. In order to tell
-'awk' to use that file for its program, you type:
+âawkâ to use that file for its program, you type:
awk -f SOURCE-FILE INPUT-FILE1 INPUT-FILE2 ...
- The '-f' instructs the 'awk' utility to get the 'awk' program from
+ The â-fâ instructs the âawkâ utility to get the âawkâ program
from
the file SOURCE-FILE (*note Options::). Any file name can be used for
SOURCE-FILE. For example, you could put the program:
BEGIN { print "Don't Panic!" }
-into the file 'advice'. Then this command:
+into the file âadviceâ. Then this command:
awk -f advice
@@ -1627,119 +1627,119 @@ does the same thing as this one:
awk 'BEGIN { print "Don\47t Panic!" }'
-This was explained earlier (*note Read Terminal::). Note that you don't
+This was explained earlier (*note Read Terminal::). Note that you donât
usually need single quotes around the file name that you specify with
-'-f', because most file names don't contain any of the shell's special
-characters. Notice that in 'advice', the 'awk' program did not have
+â-fâ, because most file names donât contain any of the shellâs special
+characters. Notice that in âadviceâ, the âawkâ program did not have
single quotes around it. The quotes are only needed for programs that
-are provided on the 'awk' command line. (Also, placing the program in a
+are provided on the âawkâ command line. (Also, placing the program in a
file allows us to use a literal single quote in the program text,
-instead of the magic '\47'.)
+instead of the magic â\47â.)
- If you want to clearly identify an 'awk' program file as such, you
-can add the extension '.awk' to the file name. This doesn't affect the
-execution of the 'awk' program but it does make "housekeeping" easier.
+ If you want to clearly identify an âawkâ program file as such, you
+can add the extension â.awkâ to the file name. This doesnât affect the
+execution of the âawkâ program but it does make âhousekeepingâ easier.
File: gawk.info, Node: Executable Scripts, Next: Comments, Prev: Long, Up:
Running gawk
-1.1.4 Executable 'awk' Programs
+1.1.4 Executable âawkâ Programs
-------------------------------
-Once you have learned 'awk', you may want to write self-contained 'awk'
-scripts, using the '#!' script mechanism. You can do this on many
-systems.(1) For example, you could update the file 'advice' to look
+Once you have learned âawkâ, you may want to write self-contained âawkâ
+scripts, using the â#!â script mechanism. You can do this on many
+systems.(1) For example, you could update the file âadviceâ to look
like this:
#! /bin/awk -f
BEGIN { print "Don't Panic!" }
-After making this file executable (with the 'chmod' utility), simply
-type 'advice' at the shell and the system arranges to run 'awk' as if
-you had typed 'awk -f advice':
+After making this file executable (with the âchmodâ utility), simply
+type âadviceâ at the shell and the system arranges to run âawkâ as if
+you had typed âawk -f adviceâ:
$ chmod +x advice
$ ./advice
- -| Don't Panic!
+ ⣠Don't Panic!
-Self-contained 'awk' scripts are useful when you want to write a program
+Self-contained âawkâ scripts are useful when you want to write a program
that users can invoke without their having to know that the program is
-written in 'awk'.
+written in âawkâ.
- Understanding '#!'
+ Understanding â#!â
- 'awk' is an "interpreted" language. This means that the 'awk'
+ âawkâ is an âinterpretedâ language. This means that the âawkâ
utility reads your program and then processes your data according to the
-instructions in your program. (This is different from a "compiled"
+instructions in your program. (This is different from a âcompiledâ
language such as C, where your program is first compiled into machine
-code that is executed directly by your system's processor.) The 'awk'
-utility is thus termed an "interpreter". Many modern languages are
+code that is executed directly by your systemâs processor.) The âawkâ
+utility is thus termed an âinterpreterâ. Many modern languages are
interpreted.
- The line beginning with '#!' lists the full file name of an
+ The line beginning with â#!â lists the full file name of an
interpreter to run and a single optional initial command-line argument
to pass to that interpreter. The operating system then runs the
interpreter with the given argument and the full argument list of the
executed program. The first argument in the list is the full file name
-of the 'awk' program. The rest of the argument list contains either
-options to 'awk', or data files, or both. (Note that on many systems
-'awk' is found in '/usr/bin' instead of in '/bin'.)
+of the âawkâ program. The rest of the argument list contains either
+options to âawkâ, or data files, or both. (Note that on many systems
+âawkâ is found in â/usr/binâ instead of in â/binâ.)
Some systems limit the length of the interpreter name to 32
characters. Often, this can be dealt with by using a symbolic link.
- You should not put more than one argument on the '#!' line after the
-path to 'awk'. It does not work. The operating system treats the rest
-of the line as a single argument and passes it to 'awk'. Doing this
-leads to confusing behavior--most likely a usage diagnostic of some sort
-from 'awk'.
+ You should not put more than one argument on the â#!â line after the
+path to âawkâ. It does not work. The operating system treats the rest
+of the line as a single argument and passes it to âawkâ. Doing this
+leads to confusing behaviorâmost likely a usage diagnostic of some sort
+from âawkâ.
- Finally, the value of 'ARGV[0]' (*note Built-in Variables::) varies
-depending upon your operating system. Some systems put 'awk' there,
-some put the full pathname of 'awk' (such as '/bin/awk'), and some put
-the name of your script ('advice'). (d.c.) Don't rely on the value of
-'ARGV[0]' to provide your script name.
+ Finally, the value of âARGV[0]â (*note Built-in Variables::) varies
+depending upon your operating system. Some systems put âawkâ there,
+some put the full pathname of âawkâ (such as â/bin/awkâ), and some put
+the name of your script (âadviceâ). (d.c.) Donât rely on the value of
+âARGV[0]â to provide your script name.
---------- Footnotes ----------
- (1) The '#!' mechanism works on GNU/Linux systems, BSD-based systems,
+ (1) The â#!â mechanism works on GNU/Linux systems, BSD-based systems,
and commercial Unix systems.
File: gawk.info, Node: Comments, Next: Quoting, Prev: Executable Scripts,
Up: Running gawk
-1.1.5 Comments in 'awk' Programs
+1.1.5 Comments in âawkâ Programs
--------------------------------
-A "comment" is some text that is included in a program for the sake of
+A âcommentâ is some text that is included in a program for the sake of
human readers; it is not really an executable part of the program.
Comments can explain what the program does and how it works. Nearly all
programming languages have provisions for comments, as programs are
typically hard to understand without them.
- In the 'awk' language, a comment starts with the number sign
-character ('#') and continues to the end of the line. The '#' does not
-have to be the first character on the line. The 'awk' language ignores
+ In the âawkâ language, a comment starts with the number sign
+character (â#â) and continues to the end of the line. The â#â does not
+have to be the first character on the line. The âawkâ language ignores
the rest of a line following a number sign. For example, we could have
-put the following into 'advice':
+put the following into âadviceâ:
# This program prints a nice, friendly message. It helps
# keep novice users from being afraid of the computer.
BEGIN { print "Don't Panic!" }
- You can put comment lines into keyboard-composed throwaway 'awk'
-programs, but this usually isn't very useful; the purpose of a comment
+ You can put comment lines into keyboard-composed throwaway âawkâ
+programs, but this usually isnât very useful; the purpose of a comment
is to help you or another person understand the program when reading it
at a later time.
CAUTION: As mentioned in *note One-shot::, you can enclose short to
medium-sized programs in single quotes, in order to keep your shell
- scripts self-contained. When doing so, _don't_ put an apostrophe
+ scripts self-contained. When doing so, _donât_ put an apostrophe
(i.e., a single quote) into a comment (or anywhere else in your
program). The shell interprets the quote as the closing quote for
the entire program. As a result, usually the shell prints a
- message about mismatched quotes, and if 'awk' actually runs, it
+ message about mismatched quotes, and if âawkâ actually runs, it
will probably print strange messages about syntax errors. For
example, look at the following:
@@ -1749,16 +1749,16 @@ at a later time.
The shell sees that the first two quotes match, and that a new
quoted object begins at the end of the command line. It therefore
prompts with the secondary prompt, waiting for more input. With
- Unix 'awk', closing the quoted string produces this result:
+ Unix âawkâ, closing the quoted string produces this result:
$ awk '{ print "hello" } # let's be cute'
> '
- error-> awk: can't open file be
- error-> source line number 1
+ errorâ awk: can't open file be
+ errorâ source line number 1
- Putting a backslash before the single quote in 'let's' wouldn't
+ Putting a backslash before the single quote in âlet'sâ wouldnât
help, because backslashes are not special inside single quotes.
- The next node describes the shell's quoting rules.
+ The next node describes the shellâs quoting rules.
File: gawk.info, Node: Quoting, Prev: Comments, Up: Running gawk
@@ -1770,8 +1770,8 @@ File: gawk.info, Node: Quoting, Prev: Comments, Up:
Running gawk
* DOS Quoting:: Quoting in Windows Batch Files.
-For short to medium-length 'awk' programs, it is most convenient to
-enter the program on the 'awk' command line. This is best done by
+For short to medium-length âawkâ programs, it is most convenient to
+enter the program on the âawkâ command line. This is best done by
enclosing the entire program in single quotes. This is true whether you
are entering the program interactively at the shell prompt, or writing
it as part of a larger shell script:
@@ -1781,47 +1781,47 @@ it as part of a larger shell script:
Once you are working with the shell, it is helpful to have a basic
knowledge of shell quoting rules. The following rules apply only to
POSIX-compliant, Bourne-style shells (such as Bash, the GNU Bourne-Again
-Shell). If you use the C shell, you're on your own.
+Shell). If you use the C shell, youâre on your own.
Before diving into the rules, we introduce a concept that appears
-throughout this Info file, which is that of the "null", or empty,
+throughout this Info file, which is that of the ânullâ, or empty,
string.
The null string is character data that has no value. In other words,
-it is empty. It is written in 'awk' programs like this: '""'. In the
-shell, it can be written using single or double quotes: '""' or ''''.
+it is empty. It is written in âawkâ programs like this: â""â. In the
+shell, it can be written using single or double quotes: â""â or â''â.
Although the null string has no characters in it, it does exist. For
example, consider this command:
$ echo ""
-Here, the 'echo' utility receives a single argument, even though that
+Here, the âechoâ utility receives a single argument, even though that
argument has no characters in it. In the rest of this Info file, we use
-the terms "null string" and "empty string" interchangeably. Now, on to
+the terms ânull stringâ and âempty stringâ interchangeably. Now, on to
the quoting rules:
- * Quoted items can be concatenated with nonquoted items as well as
+ ⢠Quoted items can be concatenated with nonquoted items as well as
with other quoted items. The shell turns everything into one
argument for the command.
- * Preceding any single character with a backslash ('\') quotes that
+ ⢠Preceding any single character with a backslash (â\â) quotes that
character. The shell removes the backslash and passes the quoted
character on to the command.
- * Single quotes protect everything between the opening and closing
+ ⢠Single quotes protect everything between the opening and closing
quotes. The shell does no interpretation of the quoted text,
passing it on verbatim to the command. It is _impossible_ to embed
a single quote inside single-quoted text. Refer back to *note
Comments:: for an example of what happens if you try.
- * Double quotes protect most things between the opening and closing
+ ⢠Double quotes protect most things between the opening and closing
quotes. The shell does at least variable and command substitution
on the quoted text. Different shells may do additional kinds of
processing on double-quoted text.
Because certain characters within double-quoted text are processed
- by the shell, they must be "escaped" within the text. Of note are
- the characters '$', '`', '\', and '"', all of which must be
+ by the shell, they must be âescapedâ within the text. Of note are
+ the characters â$â, â`â, â\â, and â"â, all of which must
be
preceded by a backslash within double-quoted text if they are to be
passed on literally to the program. (The leading backslash is
stripped first.) Thus, the example seen in *note Read Terminal:::
@@ -1831,23 +1831,23 @@ the quoting rules:
could instead be written this way:
$ awk "BEGIN { print \"Don't Panic!\" }"
- -| Don't Panic!
+ ⣠Don't Panic!
Note that the single quote is not special within double quotes.
- * Null strings are removed when they occur as part of a non-null
+ ⢠Null strings are removed when they occur as part of a non-null
command-line argument, while explicit null objects are kept. For
- example, to specify that the field separator 'FS' should be set to
+ example, to specify that the field separator âFSâ should be set to
the null string, use:
awk -F "" 'PROGRAM' FILES # correct
- Don't use this:
+ Donât use this:
awk -F"" 'PROGRAM' FILES # wrong!
- In the second case, 'awk' attempts to use the text of the program
- as the value of 'FS', and the first file name as the text of the
+ In the second case, âawkâ attempts to use the text of the program
+ as the value of âFSâ, and the first file name as the text of the
program! This results in syntax errors at best, and confusing
behavior at worst.
@@ -1855,35 +1855,35 @@ the quoting rules:
shell quoting tricks, like this:
$ awk 'BEGIN { print "Here is a single quote <'"'"'>" }'
- -| Here is a single quote <'>
+ ⣠Here is a single quote <'>
This program consists of three concatenated quoted strings. The first
and the third are single-quoted, and the second is double-quoted.
- This can be "simplified" to:
+ This can be âsimplifiedâ to:
$ awk 'BEGIN { print "Here is a single quote <'\''>" }'
- -| Here is a single quote <'>
+ ⣠Here is a single quote <'>
Judge for yourself which of these two is the more readable.
Another option is to use double quotes, escaping the embedded,
-'awk'-level double quotes:
+âawkâ-level double quotes:
$ awk "BEGIN { print \"Here is a single quote <'>\" }"
- -| Here is a single quote <'>
+ ⣠Here is a single quote <'>
This option is also painful, because double quotes, backslashes, and
-dollar signs are very common in more advanced 'awk' programs.
+dollar signs are very common in more advanced âawkâ programs.
A third option is to use the octal escape sequence equivalents (*note
Escape Sequences::) for the single- and double-quote characters, like
so:
$ awk 'BEGIN { print "Here is a single quote <\47>" }'
- -| Here is a single quote <'>
+ ⣠Here is a single quote <'>
$ awk 'BEGIN { print "Here is a double quote <\42>" }'
- -| Here is a double quote <">
+ ⣠Here is a double quote <">
This works nicely, but you should comment clearly what the escape
sequences mean.
@@ -1892,14 +1892,14 @@ sequences mean.
this:
$ awk -v sq="'" 'BEGIN { print "Here is a single quote <" sq ">" }'
- -| Here is a single quote <'>
+ ⣠Here is a single quote <'>
- (Here, the two string constants and the value of 'sq' are
-concatenated into a single string that is printed by 'print'.)
+ (Here, the two string constants and the value of âsqâ are
+concatenated into a single string that is printed by âprintâ.)
- If you really need both single and double quotes in your 'awk'
+ If you really need both single and double quotes in your âawkâ
program, it is probably best to move it into a separate file, where the
-shell won't be part of the picture and you can say what you mean.
+shell wonât be part of the picture and you can say what you mean.
File: gawk.info, Node: DOS Quoting, Up: Quoting
@@ -1911,7 +1911,7 @@ Although this Info file generally only worries about
POSIX systems and
the POSIX shell, the following issue arises often enough for many users
that it is worth addressing.
- The "shells" on Microsoft Windows systems use the double-quote
+ The âshellsâ on Microsoft Windows systems use the double-quote
character for quoting, and make it difficult or impossible to include an
escaped double-quote character in a command-line script. The following
example, courtesy of Jeroen Brink, shows how to escape the double quotes
@@ -1925,8 +1925,8 @@ as follows:
gawk "{ print \"\042\" $0 \"\042\" }" FILE
- In this example the '\042' is the octal code for a double-quote;
-'gawk' converts it into a real double-quote for output by the 'print'
+ In this example the â\042â is the octal code for a double-quote;
+âgawkâ converts it into a real double-quote for output by the âprintâ
statement.
In MS-Windows escaping double-quotes is a little tricky because you
@@ -1944,14 +1944,14 @@ MS-Windows rule for double-quoting a string is the
following:
3. Surround the resulting string by double-quotes.
- So to double-quote the one-liner script '{ print "\"" $0 "\"" }' from
+ So to double-quote the one-liner script â{ print "\"" $0 "\"" }â from
the previous example you would do it this way:
gawk "{ print \"\\\"\" $0 \"\\\"\" }" FILE
-However, the use of '\042' instead of '\\\"' is also possible and easier
+However, the use of â\042â instead of â\\\"â is also possible and
easier
to read, because backslashes that are not followed by a double-quote
-don't need duplication.
+donât need duplication.
File: gawk.info, Node: Sample Data Files, Next: Very Simple, Prev: Running
gawk, Up: Getting Started
@@ -1960,17 +1960,17 @@ File: gawk.info, Node: Sample Data Files, Next: Very
Simple, Prev: Running ga
===============================
Many of the examples in this Info file take their input from two sample
-data files. The first, 'mail-list', represents a list of peoples' names
+data files. The first, âmail-listâ, represents a list of peoplesâ names
together with their email addresses and information about those people.
-The second data file, called 'inventory-shipped', contains information
+The second data file, called âinventory-shippedâ, contains information
about monthly shipments. In both files, each line is considered to be
-one "record".
+one ârecordâ.
- In 'mail-list', each record contains the name of a person, his/her
+ In âmail-listâ, each record contains the name of a person, his/her
phone number, his/her email address, and a code for his/her relationship
with the author of the list. The columns are aligned using spaces. An
-'A' in the last column means that the person is an acquaintance. An 'F'
-in the last column means that the person is a friend. An 'R' means that
+âAâ in the last column means that the person is an acquaintance. An
âFâ
+in the last column means that the person is a friend. An âRâ means that
the person is a relative:
Amelia 555-5553 amelia.zodiacusque@gmail.com F
@@ -1985,7 +1985,7 @@ the person is a relative:
Samuel 555-3430 samuel.lanceolis@shu.edu A
Jean-Paul 555-2127 jeanpaul.campanorum@nyu.edu R
- The data file 'inventory-shipped' represents information about
+ The data file âinventory-shippedâ represents information about
shipments during the year. Each record contains the month, the number
of green crates shipped, the number of red boxes shipped, the number of
orange bags shipped, and the number of blue packages shipped,
@@ -2011,8 +2011,8 @@ the data for the two years:
Mar 24 75 70 495
Apr 21 70 74 514
- The sample files are included in the 'gawk' distribution, in the
-directory 'awklib/eg/data'.
+ The sample files are included in the âgawkâ distribution, in the
+directory âawklib/eg/dataâ.
File: gawk.info, Node: Very Simple, Next: Two Rules, Prev: Sample Data
Files, Up: Getting Started
@@ -2020,57 +2020,57 @@ File: gawk.info, Node: Very Simple, Next: Two Rules,
Prev: Sample Data Files,
1.3 Some Simple Examples
========================
-The following command runs a simple 'awk' program that searches the
-input file 'mail-list' for the character string 'li' (a grouping of
-characters is usually called a "string"; the term "string" is based on
-similar usage in English, such as "a string of pearls" or "a string of
-cars in a train"):
+The following command runs a simple âawkâ program that searches the
+input file âmail-listâ for the character string âliâ (a grouping of
+characters is usually called a âstringâ; the term âstringâ is based on
+similar usage in English, such as âa string of pearlsâ or âa string of
+cars in a trainâ):
awk '/li/ { print $0 }' mail-list
-When lines containing 'li' are found, they are printed because
-'print $0' means print the current line. (Just 'print' by itself means
+When lines containing âliâ are found, they are printed because
+âprint $0â means print the current line. (Just âprintâ by itself means
the same thing, so we could have written that instead.)
- You will notice that slashes ('/') surround the string 'li' in the
-'awk' program. The slashes indicate that 'li' is the pattern to search
-for. This type of pattern is called a "regular expression", which is
+ You will notice that slashes (â/â) surround the string âliâ in the
+âawkâ program. The slashes indicate that âliâ is the pattern to search
+for. This type of pattern is called a âregular expressionâ, which is
covered in more detail later (*note Regexp::). The pattern is allowed
-to match parts of words. There are single quotes around the 'awk'
-program so that the shell won't interpret any of it as special shell
+to match parts of words. There are single quotes around the âawkâ
+program so that the shell wonât interpret any of it as special shell
characters.
Here is what this program prints:
$ awk '/li/ { print $0 }' mail-list
- -| Amelia 555-5553 amelia.zodiacusque@gmail.com F
- -| Broderick 555-0542 broderick.aliquotiens@yahoo.com R
- -| Julie 555-6699 julie.perscrutabor@skeeve.com F
- -| Samuel 555-3430 samuel.lanceolis@shu.edu A
+ ⣠Amelia 555-5553 amelia.zodiacusque@gmail.com F
+ ⣠Broderick 555-0542 broderick.aliquotiens@yahoo.com R
+ ⣠Julie 555-6699 julie.perscrutabor@skeeve.com F
+ ⣠Samuel 555-3430 samuel.lanceolis@shu.edu A
- In an 'awk' rule, either the pattern or the action can be omitted,
+ In an âawkâ rule, either the pattern or the action can be omitted,
but not both. If the pattern is omitted, then the action is performed
for _every_ input line. If the action is omitted, the default action is
to print all lines that match the pattern.
- Thus, we could leave out the action (the 'print' statement and the
-braces) in the previous example and the result would be the same: 'awk'
-prints all lines matching the pattern 'li'. By comparison, omitting the
-'print' statement but retaining the braces makes an empty action that
+ Thus, we could leave out the action (the âprintâ statement and the
+braces) in the previous example and the result would be the same: âawkâ
+prints all lines matching the pattern âliâ. By comparison, omitting the
+âprintâ statement but retaining the braces makes an empty action that
does nothing (i.e., no lines are printed).
- Many practical 'awk' programs are just a line or two long. Following
+ Many practical âawkâ programs are just a line or two long. Following
is a collection of useful, short programs to get you started. Some of
-these programs contain constructs that haven't been covered yet. (The
+these programs contain constructs that havenât been covered yet. (The
description of the program will give you a good idea of what is going
-on, but you'll need to read the rest of the Info file to become an 'awk'
-expert!) Most of the examples use a data file named 'data'. This is
+on, but youâll need to read the rest of the Info file to become an âawkâ
+expert!) Most of the examples use a data file named âdataâ. This is
just a placeholder; if you use these programs yourself, substitute your
-own file names for 'data'.
+own file names for âdataâ.
- Some of the following examples use the output of 'ls -l' as input.
-'ls' is a system command that gives you a listing of the files in a
-directory. With the '-l' option, this listing includes each file's size
+ Some of the following examples use the output of âls -lâ as input.
+âlsâ is a system command that gives you a listing of the files in a
+directory. With the â-lâ option, this listing includes each fileâs size
and the date the file was last modified. Its output looks like this:
-rw-r--r-- 1 arnold user 1933 Nov 7 13:05 Makefile
@@ -2084,43 +2084,43 @@ and the date the file was last modified. Its output
looks like this:
The first field contains read-write permissions, the second field
contains the number of links to the file, and the third field identifies
-the file's owner. The fourth field identifies the file's group. The
-fifth field contains the file's size in bytes. The sixth, seventh, and
+the fileâs owner. The fourth field identifies the fileâs group. The
+fifth field contains the fileâs size in bytes. The sixth, seventh, and
eighth fields contain the month, day, and time, respectively, that the
file was last modified. Finally, the ninth field contains the file
name.
For future reference, note that there is often more than one way to
-do things in 'awk'. At some point, you may want to look back at these
+do things in âawkâ. At some point, you may want to look back at these
examples and see if you can come up with different ways to do the same
things shown here:
- * Print every line that is longer than 80 characters:
+ ⢠Print every line that is longer than 80 characters:
awk 'length($0) > 80' data
The sole rule has a relational expression as its pattern and has no
- action--so it uses the default action, printing the record.
+ actionâso it uses the default action, printing the record.
- * Print the length of the longest input line:
+ ⢠Print the length of the longest input line:
awk '{ if (length($0) > max) max = length($0) }
END { print max }' data
- The code associated with 'END' executes after all input has been
- read; it's the other side of the coin to 'BEGIN'.
+ The code associated with âENDâ executes after all input has been
+ read; itâs the other side of the coin to âBEGINâ.
- * Print the length of the longest line in 'data':
+ ⢠Print the length of the longest line in âdataâ:
expand data | awk '{ if (x < length($0)) x = length($0) }
END { print "maximum line length is " x }'
This example differs slightly from the previous one: the input is
- processed by the 'expand' utility to change TABs into spaces, so
+ processed by the âexpandâ utility to change TABs into spaces, so
the widths compared are actually the right-margin columns, as
opposed to the number of input characters on each line.
- * Print every line that has at least one field:
+ ⢠Print every line that has at least one field:
awk 'NF > 0' data
@@ -2128,34 +2128,34 @@ things shown here:
to create a new file similar to the old file but from which the
blank lines have been removed).
- * Print seven random numbers from 0 to 100, inclusive:
+ ⢠Print seven random numbers from 0 to 100, inclusive:
awk 'BEGIN { for (i = 1; i <= 7; i++)
print int(101 * rand()) }'
- * Print the total number of bytes used by FILES:
+ ⢠Print the total number of bytes used by FILES:
ls -l FILES | awk '{ x += $5 }
END { print "total bytes: " x }'
- * Print the total number of kilobytes used by FILES:
+ ⢠Print the total number of kilobytes used by FILES:
ls -l FILES | awk '{ x += $5 }
END { print "total K-bytes:", x / 1024 }'
- * Print a sorted list of the login names of all users:
+ ⢠Print a sorted list of the login names of all users:
awk -F: '{ print $1 }' /etc/passwd | sort
- * Count the lines in a file:
+ ⢠Count the lines in a file:
awk 'END { print NR }' data
- * Print the even-numbered lines in the data file:
+ ⢠Print the even-numbered lines in the data file:
awk 'NR % 2 == 0' data
- If you used the expression 'NR % 2 == 1' instead, the program would
+ If you used the expression âNR % 2 == 1â instead, the program would
print the odd-numbered lines.
@@ -2164,43 +2164,43 @@ File: gawk.info, Node: Two Rules, Next: More Complex,
Prev: Very Simple, Up:
1.4 An Example with Two Rules
=============================
-The 'awk' utility reads the input files one line at a time. For each
-line, 'awk' tries the patterns of each rule. If several patterns match,
+The âawkâ utility reads the input files one line at a time. For each
+line, âawkâ tries the patterns of each rule. If several patterns match,
then several actions execute in the order in which they appear in the
-'awk' program. If no patterns match, then no actions run.
+âawkâ program. If no patterns match, then no actions run.
After processing all the rules that match the line (and perhaps there
-are none), 'awk' reads the next line. (However, *note Next Statement::
+are none), âawkâ reads the next line. (However, *note Next Statement::
and also *note Nextfile Statement::.) This continues until the program
-reaches the end of the file. For example, the following 'awk' program
+reaches the end of the file. For example, the following âawkâ program
contains two rules:
/12/ { print $0 }
/21/ { print $0 }
-The first rule has the string '12' as the pattern and 'print $0' as the
-action. The second rule has the string '21' as the pattern and also has
-'print $0' as the action. Each rule's action is enclosed in its own
+The first rule has the string â12â as the pattern and âprint $0â as the
+action. The second rule has the string â21â as the pattern and also has
+âprint $0â as the action. Each ruleâs action is enclosed in its own
pair of braces.
- This program prints every line that contains the string '12' _or_ the
-string '21'. If a line contains both strings, it is printed twice, once
+ This program prints every line that contains the string â12â _or_ the
+string â21â. If a line contains both strings, it is printed twice, once
by each rule.
This is what happens if we run this program on our two sample data
-files, 'mail-list' and 'inventory-shipped':
+files, âmail-listâ and âinventory-shippedâ:
$ awk '/12/ { print $0 }
> /21/ { print $0 }' mail-list inventory-shipped
- -| Anthony 555-3412 anthony.asserturo@hotmail.com A
- -| Camilla 555-2912 camilla.infusarum@skynet.be R
- -| Fabius 555-1234 fabius.undevicesimus@ucb.edu F
- -| Jean-Paul 555-2127 jeanpaul.campanorum@nyu.edu R
- -| Jean-Paul 555-2127 jeanpaul.campanorum@nyu.edu R
- -| Jan 21 36 64 620
- -| Apr 21 70 74 514
-
-Note how the line beginning with 'Jean-Paul' in 'mail-list' was printed
+ ⣠Anthony 555-3412 anthony.asserturo@hotmail.com A
+ ⣠Camilla 555-2912 camilla.infusarum@skynet.be R
+ ⣠Fabius 555-1234 fabius.undevicesimus@ucb.edu F
+ ⣠Jean-Paul 555-2127 jeanpaul.campanorum@nyu.edu R
+ ⣠Jean-Paul 555-2127 jeanpaul.campanorum@nyu.edu R
+ ⣠Jan 21 36 64 620
+ ⣠Apr 21 70 74 514
+
+Note how the line beginning with âJean-Paulâ in âmail-listâ was printed
twice, once for each rule.
@@ -2209,10 +2209,10 @@ File: gawk.info, Node: More Complex, Next:
Statements/Lines, Prev: Two Rules,
1.5 A More Complex Example
==========================
-Now that we've mastered some simple tasks, let's look at what typical
-'awk' programs do. This example shows how 'awk' can be used to
+Now that weâve mastered some simple tasks, letâs look at what typical
+âawkâ programs do. This example shows how âawkâ can be used to
summarize, select, and rearrange the output of another utility. It uses
-features that haven't been covered yet, so don't worry if you don't
+features that havenât been covered yet, so donât worry if you donât
understand all the details:
ls -l | awk '$6 == "Nov" { sum += $5 }
@@ -2221,49 +2221,49 @@ understand all the details:
This command prints the total number of bytes in all the files in the
current directory that were last modified in November (of any year).
- As a reminder, the output of 'ls -l' gives you a listing of the files
-in a directory, including each file's size and the date the file was
+ As a reminder, the output of âls -lâ gives you a listing of the files
+in a directory, including each fileâs size and the date the file was
last modified. The first field contains read-write permissions, the
second field contains the number of links to the file, and the third
-field identifies the file's owner. The fourth field identifies the
-file's group. The fifth field contains the file's size in bytes. The
+field identifies the fileâs owner. The fourth field identifies the
+fileâs group. The fifth field contains the fileâs size in bytes. The
sixth, seventh, and eighth fields contain the month, day, and time,
respectively, that the file was last modified. Finally, the ninth field
contains the file name.
- The '$6 == "Nov"' in our 'awk' program is an expression that tests
-whether the sixth field of the output from 'ls -l' matches the string
-'Nov'. Each time a line has the string 'Nov' for its sixth field, 'awk'
-performs the action 'sum += $5'. This adds the fifth field (the file's
-size) to the variable 'sum'. As a result, when 'awk' has finished
-reading all the input lines, 'sum' is the total of the sizes of the
-files whose lines matched the pattern. (This works because 'awk'
+ The â$6 == "Nov"â in our âawkâ program is an expression that tests
+whether the sixth field of the output from âls -lâ matches the string
+âNovâ. Each time a line has the string âNovâ for its sixth field,
âawkâ
+performs the action âsum += $5â. This adds the fifth field (the fileâs
+size) to the variable âsumâ. As a result, when âawkâ has finished
+reading all the input lines, âsumâ is the total of the sizes of the
+files whose lines matched the pattern. (This works because âawkâ
variables are automatically initialized to zero.)
- After the last line of output from 'ls' has been processed, the 'END'
-rule executes and prints the value of 'sum'. In this example, the value
-of 'sum' is 80600.
+ After the last line of output from âlsâ has been processed, the
âENDâ
+rule executes and prints the value of âsumâ. In this example, the value
+of âsumâ is 80600.
- These more advanced 'awk' techniques are covered in later minor nodes
+ These more advanced âawkâ techniques are covered in later minor nodes
(*note Action Overview::). Before you can move on to more advanced
-'awk' programming, you have to know how 'awk' interprets your input and
-displays your output. By manipulating fields and using 'print'
+âawkâ programming, you have to know how âawkâ interprets your input and
+displays your output. By manipulating fields and using âprintâ
statements, you can produce some very useful and impressive-looking
reports.
File: gawk.info, Node: Statements/Lines, Next: Other Features, Prev: More
Complex, Up: Getting Started
-1.6 'awk' Statements Versus Lines
+1.6 âawkâ Statements Versus Lines
=================================
-Most often, each line in an 'awk' program is a separate statement or
+Most often, each line in an âawkâ program is a separate statement or
separate rule, like this:
awk '/12/ { print $0 }
/21/ { print $0 }' mail-list inventory-shipped
- However, 'gawk' ignores newlines after any of the following symbols
+ However, âgawkâ ignores newlines after any of the following symbols
and keywords:
, { ? : || && do else
@@ -2271,8 +2271,8 @@ and keywords:
A newline at any other point is considered the end of the statement.(1)
If you would like to split a single statement into two lines at a
-point where a newline would terminate it, you can "continue" it by
-ending the first line with a backslash character ('\'). The backslash
+point where a newline would terminate it, you can âcontinueâ it by
+ending the first line with a backslash character (â\â). The backslash
must be the final character on the line in order to be recognized as a
continuation character. A backslash followed by a newline is allowed
anywhere in the statement, even in the middle of a string or regular
@@ -2282,37 +2282,37 @@ expression. For example:
on the next line/ { print $1 }'
We have generally not used backslash continuation in our sample
-programs. 'gawk' places no limit on the length of a line, so backslash
+programs. âgawkâ places no limit on the length of a line, so backslash
continuation is never strictly necessary; it just makes programs more
readable. For this same reason, as well as for clarity, we have kept
most statements short in the programs presented throughout the Info
file.
- Backslash continuation is most useful when your 'awk' program is in a
+ Backslash continuation is most useful when your âawkâ program is in a
separate source file instead of entered from the command line. You
-should also note that many 'awk' implementations are more particular
+should also note that many âawkâ implementations are more particular
about where you may use backslash continuation. For example, they may
not allow you to split a string constant using backslash continuation.
-Thus, for maximum portability of your 'awk' programs, it is best not to
+Thus, for maximum portability of your âawkâ programs, it is best not to
split your lines in the middle of a regular expression or a string.
CAUTION: _Backslash continuation does not work as described with
- the C shell._ It works for 'awk' programs in files and for
+ the C shell._ It works for âawkâ programs in files and for
one-shot programs, _provided_ you are using a POSIX-compliant
shell, such as the Unix Bourne shell or Bash. But the C shell
behaves differently! There you must use two backslashes in a row,
followed by a newline. Note also that when using the C shell,
- _every_ newline in your 'awk' program must be escaped with a
+ _every_ newline in your âawkâ program must be escaped with a
backslash. To illustrate:
% awk 'BEGIN { \
? print \\
? "hello, world" \
? }'
- -| hello, world
+ ⣠hello, world
- Here, the '%' and '?' are the C shell's primary and secondary
- prompts, analogous to the standard shell's '$' and '>'.
+ Here, the â%â and â?â are the C shellâs primary and secondary
+ prompts, analogous to the standard shellâs â$â and â>â.
Compare the previous example to how it is done with a
POSIX-compliant shell:
@@ -2321,72 +2321,72 @@ split your lines in the middle of a regular expression
or a string.
> print \
> "hello, world"
> }'
- -| hello, world
+ ⣠hello, world
- 'awk' is a line-oriented language. Each rule's action has to begin
+ âawkâ is a line-oriented language. Each ruleâs action has to begin
on the same line as the pattern. To have the pattern and action on
separate lines, you _must_ use backslash continuation; there is no other
option.
Another thing to keep in mind is that backslash continuation and
-comments do not mix. As soon as 'awk' sees the '#' that starts a
+comments do not mix. As soon as âawkâ sees the â#â that starts a
comment, it ignores _everything_ on the rest of the line. For example:
$ gawk 'BEGIN { print "dont panic" # a friendly \
> BEGIN rule
> }'
- error-> gawk: cmd. line:2: BEGIN rule
- error-> gawk: cmd. line:2: ^ syntax error
+ errorâ gawk: cmd. line:2: BEGIN rule
+ errorâ gawk: cmd. line:2: ^ syntax error
In this case, it looks like the backslash would continue the comment
onto the next line. However, the backslash-newline combination is never
-even noticed because it is "hidden" inside the comment. Thus, the
-'BEGIN' is noted as a syntax error.
+even noticed because it is âhiddenâ inside the comment. Thus, the
+âBEGINâ is noted as a syntax error.
- If you're interested, see
+ If youâre interested, see
<https://lists.gnu.org/archive/html/bug-gawk/2022-10/msg00025.html> for
a source code patch that allows lines to be continued when inside
-parentheses. This patch was not added to 'gawk' since it would quietly
-decrease the portability of 'awk' programs.
+parentheses. This patch was not added to âgawkâ since it would quietly
+decrease the portability of âawkâ programs.
- When 'awk' statements within one rule are short, you might want to
+ When âawkâ statements within one rule are short, you might want to
put more than one of them on a line. This is accomplished by separating
-the statements with a semicolon (';'). This also applies to the rules
+the statements with a semicolon (â;â). This also applies to the rules
themselves. Thus, the program shown at the start of this minor node
could also be written this way:
/12/ { print $0 } ; /21/ { print $0 }
NOTE: The requirement that states that rules on the same line must
- be separated with a semicolon was not in the original 'awk'
+ be separated with a semicolon was not in the original âawkâ
language; it was added for consistency with the treatment of
statements within an action.
---------- Footnotes ----------
- (1) The '?' and ':' referred to here is the three-operand conditional
+ (1) The â?â and â:â referred to here is the three-operand
conditional
expression described in *note Conditional Exp::. Splitting lines after
-'?' and ':' is a minor 'gawk' extension; if '--posix' is specified
+â?â and â:â is a minor âgawkâ extension; if â--posixâ is
specified
(*note Options::), then this extension is disabled.
File: gawk.info, Node: Other Features, Next: When, Prev: Statements/Lines,
Up: Getting Started
-1.7 Other Features of 'awk'
+1.7 Other Features of âawkâ
===========================
-The 'awk' language provides a number of predefined, or "built-in",
-variables that your programs can use to get information from 'awk'.
+The âawkâ language provides a number of predefined, or âbuilt-inâ,
+variables that your programs can use to get information from âawkâ.
There are other variables your program can set as well to control how
-'awk' processes your data.
+âawkâ processes your data.
- In addition, 'awk' provides a number of built-in functions for doing
-common computational and string-related operations. 'gawk' provides
+ In addition, âawkâ provides a number of built-in functions for doing
+common computational and string-related operations. âgawkâ provides
built-in functions for working with timestamps, performing bit
manipulation, for runtime string translation (internationalization),
determining the type of a variable, and array sorting.
- As we develop our presentation of the 'awk' language, we will
+ As we develop our presentation of the âawkâ language, we will
introduce most of the variables and many of the functions. They are
described systematically in *note Built-in Variables:: and in *note
Built-in::.
@@ -2394,31 +2394,31 @@ Built-in::.
File: gawk.info, Node: When, Next: Intro Summary, Prev: Other Features,
Up: Getting Started
-1.8 When to Use 'awk'
+1.8 When to Use âawkâ
=====================
-Now that you've seen some of what 'awk' can do, you might wonder how
-'awk' could be useful for you. By using utility programs, advanced
+Now that youâve seen some of what âawkâ can do, you might wonder how
+âawkâ could be useful for you. By using utility programs, advanced
patterns, field separators, arithmetic statements, and other selection
-criteria, you can produce much more complex output. The 'awk' language
+criteria, you can produce much more complex output. The âawkâ language
is very useful for producing reports from large amounts of raw data,
such as summarizing information from the output of other utility
-programs like 'ls'. (*Note More Complex::.)
+programs like âlsâ. (*Note More Complex::.)
- Programs written with 'awk' are usually much smaller than they would
-be in other languages. This makes 'awk' programs easy to compose and
-use. Often, 'awk' programs can be quickly composed at your keyboard,
-used once, and thrown away. Because 'awk' programs are interpreted, you
+ Programs written with âawkâ are usually much smaller than they would
+be in other languages. This makes âawkâ programs easy to compose and
+use. Often, âawkâ programs can be quickly composed at your keyboard,
+used once, and thrown away. Because âawkâ programs are interpreted, you
can avoid the (usually lengthy) compilation part of the typical
edit-compile-test-debug cycle of software development.
- Complex programs have been written in 'awk', including a complete
+ Complex programs have been written in âawkâ, including a complete
retargetable assembler for eight-bit microprocessors (*note Glossary::,
for more information), and a microcode assembler for a special-purpose
-Prolog computer. The original 'awk''s capabilities were strained by
+Prolog computer. The original âawkââs capabilities were strained by
tasks of such complexity, but modern versions are more capable.
- If you find yourself writing 'awk' scripts of more than, say, a few
+ If you find yourself writing âawkâ scripts of more than, say, a few
hundred lines, you might consider using a different programming
language. The shell is good at string and pattern matching; in
addition, it allows powerful use of the system utilities. Python offers
@@ -2435,53 +2435,53 @@ File: gawk.info, Node: Intro Summary, Prev: When,
Up: Getting Started
1.9 Summary
===========
- * Programs in 'awk' consist of PATTERN-ACTION pairs.
+ ⢠Programs in âawkâ consist of PATTERNâACTION pairs.
- * An ACTION without a PATTERN always runs. The default ACTION for a
- pattern without one is '{ print $0 }'.
+ ⢠An ACTION without a PATTERN always runs. The default ACTION for a
+ pattern without one is â{ print $0 }â.
- * Use either 'awk 'PROGRAM' FILES' or 'awk -f PROGRAM-FILE FILES' to
- run 'awk'.
+ ⢠Use either âawk 'PROGRAM' FILESâ or âawk -f PROGRAM-FILE FILESâ
to
+ run âawkâ.
- * You may use the special '#!' header line to create 'awk' programs
+ ⢠You may use the special â#!â header line to create âawkâ
programs
that are directly executable.
- * Comments in 'awk' programs start with '#' and continue to the end
+ ⢠Comments in âawkâ programs start with â#â and continue to the
end
of the same line.
- * Be aware of quoting issues when writing 'awk' programs as part of a
+ ⢠Be aware of quoting issues when writing âawkâ programs as part of a
larger shell script (or MS-Windows batch file).
- * You may use backslash continuation to continue a source line.
+ ⢠You may use backslash continuation to continue a source line.
Lines are automatically continued after a comma, open brace,
- question mark, colon, '||', '&&', 'do', and 'else'.
+ question mark, colon, â||â, â&&â, âdoâ, and âelseâ.
File: gawk.info, Node: Invoking Gawk, Next: Regexp, Prev: Getting Started,
Up: Top
-2 Running 'awk' and 'gawk'
+2 Running âawkâ and âgawkâ
**************************
-This major node covers how to run 'awk', both POSIX-standard and
-'gawk'-specific command-line options, and what 'awk' and 'gawk' do with
-nonoption arguments. It then proceeds to cover how 'gawk' searches for
-source files, reading standard input along with other files, 'gawk''s
-environment variables, 'gawk''s exit status, using include files, and
+This major node covers how to run âawkâ, both POSIX-standard and
+âgawkâ-specific command-line options, and what âawkâ and âgawkâ do
with
+nonoption arguments. It then proceeds to cover how âgawkâ searches for
+source files, reading standard input along with other files, âgawkââs
+environment variables, âgawkââs exit status, using include files, and
obsolete and undocumented options and/or features.
Many of the options and features described here are discussed in more
detail later in the Info file; feel free to skip over things in this
-major node that don't interest you right now.
+major node that donât interest you right now.
* Menu:
-* Command Line:: How to run 'awk'.
+* Command Line:: How to run âawkâ.
* Options:: Command-line options and their meanings.
* Other Arguments:: Input file names and variable assignments.
* Naming Standard Input:: How to specify standard input with other
files.
-* Environment Variables:: The environment variables 'gawk' uses.
-* Exit Status:: 'gawk''s exit status.
+* Environment Variables:: The environment variables âgawkâ uses.
+* Exit Status:: âgawkââs exit status.
* Include Files:: Including other files into your program.
* Loading Shared Libraries:: Loading shared libraries into your program.
* Obsolete:: Obsolete Options and/or features.
@@ -2491,26 +2491,26 @@ major node that don't interest you right now.
File: gawk.info, Node: Command Line, Next: Options, Up: Invoking Gawk
-2.1 Invoking 'awk'
+2.1 Invoking âawkâ
==================
-There are two ways to run 'awk'--with an explicit program or with one or
+There are two ways to run âawkââwith an explicit program or with one or
more program files. Here are templates for both of them; items enclosed
in [...] in these templates are optional:
- 'awk' [OPTIONS] '-f' PROGFILE ['--'] FILE ...
- 'awk' [OPTIONS] ['--'] ''PROGRAM'' FILE ...
+ âawkâ [OPTIONS] â-fâ PROGFILE [â--â] FILE ...
+ âawkâ [OPTIONS] [â--â] â'PROGRAM'â FILE ...
- In addition to traditional one-letter POSIX-style options, 'gawk'
+ In addition to traditional one-letter POSIX-style options, âgawkâ
also supports GNU long options.
- It is possible to invoke 'awk' with an empty program:
+ It is possible to invoke âawkâ with an empty program:
awk '' datafile1 datafile2
-Doing so makes little sense, though; 'awk' exits silently when given an
-empty program. (d.c.) If '--lint' has been specified on the command
-line, 'gawk' issues a warning that the program is empty.
+Doing so makes little sense, though; âawkâ exits silently when given an
+empty program. (d.c.) If â--lintâ has been specified on the command
+line, âgawkâ issues a warning that the program is empty.
File: gawk.info, Node: Options, Next: Other Arguments, Prev: Command Line,
Up: Invoking Gawk
@@ -2522,124 +2522,124 @@ Options begin with a dash and consist of a single
character. GNU-style
long options consist of two dashes and a keyword. The keyword can be
abbreviated, as long as the abbreviation allows the option to be
uniquely identified. If the option takes an argument, either the
-keyword is immediately followed by an equals sign ('=') and the
-argument's value, or the keyword and the argument's value are separated
+keyword is immediately followed by an equals sign (â=â) and the
+argumentâs value, or the keyword and the argumentâs value are separated
by whitespace (spaces or TABs). If a particular option with a value is
given more than once, it is (usually) the last value that counts.
- Each long option for 'gawk' has a corresponding POSIX-style short
+ Each long option for âgawkâ has a corresponding POSIX-style short
option. The long and short options are interchangeable in all contexts.
The following list describes options mandated by the POSIX standard:
-'-F FS'
-'--field-separator FS'
- Set the 'FS' variable to FS (*note Field Separators::).
+â-F FSâ
+â--field-separator FSâ
+ Set the âFSâ variable to FS (*note Field Separators::).
-'-f SOURCE-FILE'
-'--file SOURCE-FILE'
- Read the 'awk' program source from SOURCE-FILE instead of in the
+â-f SOURCE-FILEâ
+â--file SOURCE-FILEâ
+ Read the âawkâ program source from SOURCE-FILE instead of in the
first nonoption argument. This option may be given multiple times;
- the 'awk' program consists of the concatenation of the contents of
+ the âawkâ program consists of the concatenation of the contents of
each specified SOURCE-FILE.
- Files named with '-f' are treated as if they had '@namespace "awk"'
+ Files named with â-fâ are treated as if they had â@namespace
"awk"â
at their beginning. *Note Changing The Namespace::, for more
information on this advanced feature.
-'-v VAR=VAL'
-'--assign VAR=VAL'
+â-v VAR=VALâ
+â--assign VAR=VALâ
Set the variable VAR to the value VAL _before_ execution of the
program begins. Such variable values are available inside the
- 'BEGIN' rule (*note Other Arguments::).
+ âBEGINâ rule (*note Other Arguments::).
- The '-v' option can only set one variable, but it can be used more
- than once, setting another variable each time, like this: 'awk
- -v foo=1 -v bar=2 ...'.
+ The â-vâ option can only set one variable, but it can be used more
+ than once, setting another variable each time, like this: âawk
+ -v foo=1 -v bar=2 ...â.
- CAUTION: Using '-v' to set the values of the built-in
- variables may lead to surprising results. 'awk' will reset
+ CAUTION: Using â-vâ to set the values of the built-in
+ variables may lead to surprising results. âawkâ will reset
the values of those variables as it needs to, possibly
ignoring any initial value you may have given.
-'-W GAWK-OPT'
+â-W GAWK-OPTâ
Provide an implementation-specific option. This is the POSIX
convention for providing implementation-specific options. These
options also have corresponding GNU-style long options. Note that
the long options may be abbreviated, as long as the abbreviations
- remain unique. The full list of 'gawk'-specific options is
+ remain unique. The full list of âgawkâ-specific options is
provided next.
-'--'
+â--â
Signal the end of the command-line options. The following
- arguments are not treated as options even if they begin with '-'.
- This interpretation of '--' follows the POSIX argument parsing
+ arguments are not treated as options even if they begin with â-â.
+ This interpretation of â--â follows the POSIX argument parsing
conventions.
- This is useful if you have file names that start with '-', or in
+ This is useful if you have file names that start with â-â, or in
shell scripts, if you have file names that will be specified by the
- user that could start with '-'. It is also useful for passing
- options on to the 'awk' program; see *note Getopt Function::.
+ user that could start with â-â. It is also useful for passing
+ options on to the âawkâ program; see *note Getopt Function::.
- The following list describes 'gawk'-specific options:
+ The following list describes âgawkâ-specific options:
-'-b'
-'--characters-as-bytes'
- Cause 'gawk' to treat all input data as single-byte characters. In
- addition, all output written with 'print' or 'printf' is treated as
+â-bâ
+â--characters-as-bytesâ
+ Cause âgawkâ to treat all input data as single-byte characters. In
+ addition, all output written with âprintâ or âprintfâ is treated
as
single-byte characters.
- Normally, 'gawk' follows the POSIX standard and attempts to process
+ Normally, âgawkâ follows the POSIX standard and attempts to process
its input data according to the current locale (*note Locales::).
This can often involve converting multibyte characters into wide
characters (internally), and can lead to problems or confusion if
the input data does not contain valid multibyte characters. This
- option is an easy way to tell 'gawk', "Hands off my data!"
+ option is an easy way to tell âgawkâ, âHands off my data!â
-'-c'
-'--traditional'
- Specify "compatibility mode", in which the GNU extensions to the
- 'awk' language are disabled, so that 'gawk' behaves just like BWK
- 'awk'. *Note POSIX/GNU::, which summarizes the extensions. Also
+â-câ
+â--traditionalâ
+ Specify âcompatibility modeâ, in which the GNU extensions to the
+ âawkâ language are disabled, so that âgawkâ behaves just like BWK
+ âawkâ. *Note POSIX/GNU::, which summarizes the extensions. Also
see *note Compatibility Mode::.
-'-C'
-'--copyright'
+â-Câ
+â--copyrightâ
Print the short version of the General Public License and then
exit.
-'-d'[FILE]
-'--dump-variables'['='FILE]
+â-dâ[FILE]
+â--dump-variablesâ[â=âFILE]
Print a sorted list of global variables, their types, and final
values to FILE. If no FILE is provided, print this list to a file
- named 'awkvars.out' in the current directory. No space is allowed
- between the '-d' and FILE, if FILE is supplied.
+ named âawkvars.outâ in the current directory. No space is allowed
+ between the â-dâ and FILE, if FILE is supplied.
Having a list of all global variables is a good way to look for
typographical errors in your programs. You would also use this
option if you have a large program with a lot of functions, and you
- want to be sure that your functions don't inadvertently use global
+ want to be sure that your functions donât inadvertently use global
variables that you meant to be local. (This is a particularly easy
- mistake to make with simple variable names like 'i', 'j', etc.)
+ mistake to make with simple variable names like âiâ, âjâ, etc.)
-'-D'[FILE]
-'--debug'['='FILE]
- Enable debugging of 'awk' programs (*note Debugging::). By
+â-Dâ[FILE]
+â--debugâ[â=âFILE]
+ Enable debugging of âawkâ programs (*note Debugging::). By
default, the debugger reads commands interactively from the
keyboard (standard input). The optional FILE argument allows you
to specify a file with a list of commands for the debugger to
- execute noninteractively. No space is allowed between the '-D' and
+ execute noninteractively. No space is allowed between the â-Dâ and
FILE, if FILE is supplied.
-'-e' PROGRAM-TEXT
-'--source' PROGRAM-TEXT
+â-eâ PROGRAM-TEXT
+â--sourceâ PROGRAM-TEXT
Provide program source code in the PROGRAM-TEXT. This option
allows you to mix source code in files with source code that you
enter on the command line. This is particularly useful when you
have library functions that you want to use from your command-line
programs (*note AWKPATH Variable::).
- Note that 'gawk' treats each string as if it ended with a newline
- character (even if it doesn't). This makes building the total
+ Note that âgawkâ treats each string as if it ended with a newline
+ character (even if it doesnât). This makes building the total
program easier.
CAUTION: Prior to version 5.0, there was no requirement that
@@ -2647,288 +2647,288 @@ The following list describes options mandated by the
POSIX standard:
following worked:
$ gawk -e 'BEGIN { a = 5 ;' -e 'print a }'
- -| 5
+ ⣠5
However, this is no longer true. If you have any scripts that
rely upon this feature, you should revise them.
This is because each PROGRAM-TEXT is treated as if it had
- '@namespace "awk"' at its beginning. *Note Changing The
+ â@namespace "awk"â at its beginning. *Note Changing The
Namespace::, for more information.
-'-E' FILE
-'--exec' FILE
- Similar to '-f', read 'awk' program text from FILE. There are two
- differences from '-f':
+â-Eâ FILE
+â--execâ FILE
+ Similar to â-fâ, read âawkâ program text from FILE. There are two
+ differences from â-fâ:
- * This option terminates option processing; anything else on the
- command line is passed on directly to the 'awk' program.
+ ⢠This option terminates option processing; anything else on the
+ command line is passed on directly to the âawkâ program.
- * Command-line variable assignments of the form 'VAR=VALUE' are
+ ⢠Command-line variable assignments of the form âVAR=VALUEâ are
disallowed.
This option is particularly necessary for World Wide Web CGI
applications that pass arguments through the URL; using this option
prevents a malicious (or other) user from passing in options,
- assignments, or 'awk' source code (via '-e') to the CGI
- application.(1) This option should be used with '#!' scripts
+ assignments, or âawkâ source code (via â-eâ) to the CGI
+ application.(1) This option should be used with â#!â scripts
(*note Executable Scripts::), like so:
#! /usr/local/bin/gawk -E
AWK PROGRAM HERE ...
-'-g'
-'--gen-pot'
- Analyze the source program and generate a GNU 'gettext' portable
+â-gâ
+â--gen-potâ
+ Analyze the source program and generate a GNU âgettextâ portable
object template file on standard output for all string constants
that have been marked for translation. *Note
Internationalization::, for information about this option.
-'-h'
-'--help'
- Print a "usage" message summarizing the short- and long-style
- options that 'gawk' accepts and then exit.
-
-'-i' SOURCE-FILE
-'--include' SOURCE-FILE
- Read an 'awk' source library from SOURCE-FILE. This option is
- completely equivalent to using the '@include' directive inside your
- program. It is very similar to the '-f' option, but there are two
- important differences. First, when '-i' is used, the program
+â-hâ
+â--helpâ
+ Print a âusageâ message summarizing the short- and long-style
+ options that âgawkâ accepts and then exit.
+
+â-iâ SOURCE-FILE
+â--includeâ SOURCE-FILE
+ Read an âawkâ source library from SOURCE-FILE. This option is
+ completely equivalent to using the â@includeâ directive inside your
+ program. It is very similar to the â-fâ option, but there are two
+ important differences. First, when â-iâ is used, the program
source is not loaded if it has been previously loaded, whereas with
- '-f', 'gawk' always loads the file. Second, because this option is
- intended to be used with code libraries, 'gawk' does not recognize
+ â-fâ, âgawkâ always loads the file. Second, because this option
is
+ intended to be used with code libraries, âgawkâ does not recognize
such files as constituting main program input. Thus, after
- processing an '-i' argument, 'gawk' still expects to find the main
- source code via the '-f' option or on the command line.
+ processing an â-iâ argument, âgawkâ still expects to find the main
+ source code via the â-fâ option or on the command line.
- Files named with '-i' are treated as if they had '@namespace "awk"'
+ Files named with â-iâ are treated as if they had â@namespace
"awk"â
at their beginning. *Note Changing The Namespace::, for more
information.
-'-I'
-'--trace'
+â-Iâ
+â--traceâ
Print the internal byte code names as they are executed when
running the program. The trace is printed to standard error. Each
- "op code" is preceded by a '+' sign in the output.
+ âop codeâ is preceded by a â+â sign in the output.
-'-l' EXT
-'--load' EXT
+â-lâ EXT
+â--loadâ EXT
Load a dynamic extension named EXT. Extensions are stored as
system shared libraries. This option searches for the library
- using the 'AWKLIBPATH' environment variable. The correct library
+ using the âAWKLIBPATHâ environment variable. The correct library
suffix for your platform will be supplied by default, so it need
not be specified in the extension name. The extension
- initialization routine should be named 'dl_load()'. An alternative
- is to use the '@load' keyword inside the program to load a shared
+ initialization routine should be named âdl_load()â. An alternative
+ is to use the â@loadâ keyword inside the program to load a shared
library. This advanced feature is described in detail in *note
Dynamic Extensions::.
-'-L'[VALUE]
-'--lint'['='VALUE]
+â-Lâ[VALUE]
+â--lintâ[â=âVALUE]
Warn about constructs that are dubious or nonportable to other
- 'awk' implementations. No space is allowed between the '-L' and
- VALUE, if VALUE is supplied. Some warnings are issued when 'gawk'
+ âawkâ implementations. No space is allowed between the â-Lâ and
+ VALUE, if VALUE is supplied. Some warnings are issued when âgawkâ
first reads your program. Others are issued at runtime, as your
program executes. The optional argument may be one of the
following:
- 'fatal'
+ âfatalâ
Cause lint warnings become fatal errors. This may be drastic,
but its use will certainly encourage the development of
- cleaner 'awk' programs.
+ cleaner âawkâ programs.
- 'invalid'
+ âinvalidâ
Only issue warnings about things that are actually invalid are
issued. (This is not fully implemented yet.)
- 'no-ext'
- Disable warnings about 'gawk' extensions.
+ âno-extâ
+ Disable warnings about âgawkâ extensions.
Some warnings are only printed once, even if the dubious constructs
- they warn about occur multiple times in your 'awk' program. Thus,
- when eliminating problems pointed out by '--lint', you should take
+ they warn about occur multiple times in your âawkâ program. Thus,
+ when eliminating problems pointed out by â--lintâ, you should take
care to search for all occurrences of each inappropriate construct.
- As 'awk' programs are usually short, doing so is not burdensome.
+ As âawkâ programs are usually short, doing so is not burdensome.
-'-M'
-'--bignum'
+â-Mâ
+â--bignumâ
Select arbitrary-precision arithmetic on numbers. This option has
- no effect if 'gawk' is not compiled to use the GNU MPFR and MP
+ no effect if âgawkâ is not compiled to use the GNU MPFR and MP
libraries (*note Arbitrary Precision Arithmetic::).
As of version 5.2, the arbitrary precision arithmetic features in
- 'gawk' are "on parole." The primary maintainer is no longer
- willing to support this feature, but another member of the
- development team has stepped up to take it over. As long as this
- situation remains stable, MPFR will be supported. If it changes,
- the MPFR support will be removed from 'gawk'.
-
-'-n'
-'--non-decimal-data'
+ âgawkâ are âon parole.â The primary maintainer is no longer
willing
+ to support this feature, but another member of the development team
+ has stepped up to take it over. As long as this situation remains
+ stable, MPFR will be supported. If it changes, the MPFR support
+ will be removed from âgawkâ.
+
+â-nâ
+â--non-decimal-dataâ
Enable automatic interpretation of octal and hexadecimal values in
input data (*note Nondecimal Data::).
CAUTION: This option can severely break old programs. Use
with care. Also note that this option may disappear in a
- future version of 'gawk'.
+ future version of âgawkâ.
-'-N'
-'--use-lc-numeric'
- Force the use of the locale's decimal point character when parsing
+â-Nâ
+â--use-lc-numericâ
+ Force the use of the localeâs decimal point character when parsing
numeric input data (*note Locales::).
-'-o'[FILE]
-'--pretty-print'['='FILE]
- Enable pretty-printing of 'awk' programs. Implies '--no-optimize'.
+â-oâ[FILE]
+â--pretty-printâ[â=âFILE]
+ Enable pretty-printing of âawkâ programs. Implies
â--no-optimizeâ.
By default, the output program is created in a file named
- 'awkprof.out' (*note Profiling::). The optional FILE argument
+ âawkprof.outâ (*note Profiling::). The optional FILE argument
allows you to specify a different file name for the output. No
- space is allowed between the '-o' and FILE, if FILE is supplied.
+ space is allowed between the â-oâ and FILE, if FILE is supplied.
NOTE: In the past, this option would also execute your
program. This is no longer the case.
-'-O'
-'--optimize'
- Enable 'gawk''s default optimizations on the internal
+â-Oâ
+â--optimizeâ
+ Enable âgawkââs default optimizations on the internal
representation of the program. At the moment, this includes just
simple constant folding.
Optimization is enabled by default. This option remains primarily
for backwards compatibility. However, it may be used to cancel the
- effect of an earlier '-s' option (see later in this list).
+ effect of an earlier â-sâ option (see later in this list).
-'-p'[FILE]
-'--profile'['='FILE]
- Enable profiling of 'awk' programs (*note Profiling::). Implies
- '--no-optimize'. By default, profiles are created in a file named
- 'awkprof.out'. The optional FILE argument allows you to specify a
+â-pâ[FILE]
+â--profileâ[â=âFILE]
+ Enable profiling of âawkâ programs (*note Profiling::). Implies
+ â--no-optimizeâ. By default, profiles are created in a file named
+ âawkprof.outâ. The optional FILE argument allows you to specify a
different file name for the profile file. No space is allowed
- between the '-p' and FILE, if FILE is supplied.
+ between the â-pâ and FILE, if FILE is supplied.
The profile contains execution counts for each statement in the
program in the left margin, and function call counts for each
function.
-'-P'
-'--posix'
- Operate in strict POSIX mode. This disables all 'gawk' extensions
- (just like '--traditional') and disables all extensions not allowed
+â-Pâ
+â--posixâ
+ Operate in strict POSIX mode. This disables all âgawkâ extensions
+ (just like â--traditionalâ) and disables all extensions not allowed
by POSIX. *Note Common Extensions:: for a summary of the extensions
- in 'gawk' that are disabled by this option. Also, the following
+ in âgawkâ that are disabled by this option. Also, the following
additional restrictions apply:
- * Newlines are not allowed after '?' or ':' (*note Conditional
+ ⢠Newlines are not allowed after â?â or â:â (*note
Conditional
Exp::).
- * Specifying '-Ft' on the command line does not set the value of
- 'FS' to be a single TAB character (*note Field Separators::).
+ ⢠Specifying â-Ftâ on the command line does not set the value of
+ âFSâ to be a single TAB character (*note Field Separators::).
- * The locale's decimal point character is used for parsing input
+ ⢠The localeâs decimal point character is used for parsing input
data (*note Locales::).
- If you supply both '--traditional' and '--posix' on the command
- line, '--posix' takes precedence. 'gawk' issues a warning if both
+ If you supply both â--traditionalâ and â--posixâ on the command
+ line, â--posixâ takes precedence. âgawkâ issues a warning if both
options are supplied.
-'-r'
-'--re-interval'
+â-râ
+â--re-intervalâ
Allow interval expressions (*note Regexp Operators::) in regexps.
- This is now 'gawk''s default behavior. Nevertheless, this option
+ This is now âgawkââs default behavior. Nevertheless, this option
remains for backward compatibility.
-'-s'
-'--no-optimize'
- Disable 'gawk''s default optimizations on the internal
+â-sâ
+â--no-optimizeâ
+ Disable âgawkââs default optimizations on the internal
representation of the program.
-'-S'
-'--sandbox'
- Disable the 'system()' function, input redirections with 'getline',
- output redirections with 'print' and 'printf', and dynamic
- extensions. Also, disallow adding file names to 'ARGV' that were
- not there when 'gawk' started running. This is particularly useful
- when you want to run 'awk' scripts from questionable sources and
- need to make sure the scripts can't access your system (other than
+â-Sâ
+â--sandboxâ
+ Disable the âsystem()â function, input redirections with
âgetlineâ,
+ output redirections with âprintâ and âprintfâ, and dynamic
+ extensions. Also, disallow adding file names to âARGVâ that were
+ not there when âgawkâ started running. This is particularly useful
+ when you want to run âawkâ scripts from questionable sources and
+ need to make sure the scripts canât access your system (other than
the specified input data files).
-'-t'
-'--lint-old'
+â-tâ
+â--lint-oldâ
Warn about constructs that are not available in the original
- version of 'awk' from Version 7 Unix (*note V7/SVR3.1::).
+ version of âawkâ from Version 7 Unix (*note V7/SVR3.1::).
-'-V'
-'--version'
- Print version information for this particular copy of 'gawk'. This
- allows you to determine if your copy of 'gawk' is up to date with
+â-Vâ
+â--versionâ
+ Print version information for this particular copy of âgawkâ. This
+ allows you to determine if your copy of âgawkâ is up to date with
respect to whatever the Free Software Foundation is currently
distributing. It is also useful for bug reports (*note Bugs::).
-'--'
+â--â
Mark the end of all options. Any command-line arguments following
- '--' are placed in 'ARGV', even if they start with a minus sign.
+ â--â are placed in âARGVâ, even if they start with a minus sign.
In compatibility mode, as long as program text has been supplied, any
other options are flagged as invalid with a warning message but are
otherwise ignored.
In compatibility mode, as a special case, if the value of FS supplied
-to the '-F' option is 't', then 'FS' is set to the TAB character
-('"\t"'). This is true only for '--traditional' and not for '--posix'
+to the â-Fâ option is âtâ, then âFSâ is set to the TAB character
+(â"\t"â). This is true only for â--traditionalâ and not for
â--posixâ
(*note Field Separators::).
- The '-f' option may be used more than once on the command line. If
-it is, 'awk' reads its program source from all of the named files, as if
+ The â-fâ option may be used more than once on the command line. If
+it is, âawkâ reads its program source from all of the named files, as if
they had been concatenated together into one big file. This is useful
-for creating libraries of 'awk' functions. These functions can be
+for creating libraries of âawkâ functions. These functions can be
written once and then retrieved from a standard place, instead of having
-to be included in each individual program. The '-i' option is similar
+to be included in each individual program. The â-iâ option is similar
in this regard. (As mentioned in *note Definition Syntax::, function
names must be unique.)
- With standard 'awk', library functions can still be used, even if the
-program is entered at the keyboard, by specifying '-f /dev/tty'. After
-typing your program, type 'Ctrl-d' (the end-of-file character) to
-terminate it. (You may also use '-f -' to read program source from the
+ With standard âawkâ, library functions can still be used, even if the
+program is entered at the keyboard, by specifying â-f /dev/ttyâ. After
+typing your program, type âCtrl-dâ (the end-of-file character) to
+terminate it. (You may also use â-f -â to read program source from the
standard input, but then you will not be able to also use the standard
input as a source of data.)
- Because it is clumsy using the standard 'awk' mechanisms to mix
-source file and command-line 'awk' programs, 'gawk' provides the '-e'
+ Because it is clumsy using the standard âawkâ mechanisms to mix
+source file and command-line âawkâ programs, âgawkâ provides the
â-eâ
option. This does not require you to preempt the standard input for
your source code, and it allows you to easily mix command-line and
-library source code (*note AWKPATH Variable::). As with '-f', the '-e'
-and '-i' options may also be used multiple times on the command line.
+library source code (*note AWKPATH Variable::). As with â-fâ, the â-eâ
+and â-iâ options may also be used multiple times on the command line.
- If no '-f' option (or '-e' option for 'gawk') is specified, then
-'awk' uses the first nonoption command-line argument as the text of the
+ If no â-fâ option (or â-eâ option for âgawkâ) is specified, then
+âawkâ uses the first nonoption command-line argument as the text of the
program source code. Arguments on the command line that follow the
-program text are entered into the 'ARGV' array; 'awk' does _not_
+program text are entered into the âARGVâ array; âawkâ does _not_
continue to parse the command line looking for options.
- If the environment variable 'POSIXLY_CORRECT' exists, then 'gawk'
-behaves in strict POSIX mode, exactly as if you had supplied '--posix'.
+ If the environment variable âPOSIXLY_CORRECTâ exists, then âgawkâ
+behaves in strict POSIX mode, exactly as if you had supplied â--posixâ.
Many GNU programs look for this environment variable to suppress
-extensions that conflict with POSIX, but 'gawk' behaves differently: it
+extensions that conflict with POSIX, but âgawkâ behaves differently: it
suppresses all extensions, even those that do not conflict with POSIX,
-and behaves in strict POSIX mode. If '--lint' is supplied on the
-command line and 'gawk' turns on POSIX mode because of
-'POSIXLY_CORRECT', then it issues a warning message indicating that
+and behaves in strict POSIX mode. If â--lintâ is supplied on the
+command line and âgawkâ turns on POSIX mode because of
+âPOSIXLY_CORRECTâ, then it issues a warning message indicating that
POSIX mode is in effect. You would typically set this variable in your
-shell's startup file. For a Bourne-compatible shell (such as Bash), you
-would add these lines to the '.profile' file in your home directory:
+shellâs startup file. For a Bourne-compatible shell (such as Bash), you
+would add these lines to the â.profileâ file in your home directory:
POSIXLY_CORRECT=true
export POSIXLY_CORRECT
For a C shell-compatible shell,(2) you would add this line to the
-'.login' file in your home directory:
+â.loginâ file in your home directory:
setenv POSIXLY_CORRECT true
- Having 'POSIXLY_CORRECT' set is not recommended for daily use, but it
+ Having âPOSIXLY_CORRECTâ set is not recommended for daily use, but it
is good for testing the portability of your programs to other
environments.
@@ -2936,7 +2936,7 @@ environments.
(1) For more detail, please see Section 4.4 of RFC 3875
(http://www.ietf.org/rfc/rfc3875). Also see the explanatory note sent
-to the 'gawk' bug mailing list
+to the âgawkâ bug mailing list
(https://lists.gnu.org/archive/html/bug-gawk/2014-11/msg00022.html).
(2) Not recommended.
@@ -2949,58 +2949,58 @@ File: gawk.info, Node: Other Arguments, Next: Naming
Standard Input, Prev: Op
Any additional arguments on the command line are normally treated as
input files to be processed in the order specified. However, an
-argument that has the form 'VAR=VALUE', assigns the value VALUE to the
-variable VAR--it does not specify a file at all. (See *note Assignment
-Options::.) In the following example, 'count=1' is a variable
+argument that has the form âVAR=VALUEâ, assigns the value VALUE to the
+variable VARâit does not specify a file at all. (See *note Assignment
+Options::.) In the following example, âcount=1â is a variable
assignment, not a file name:
awk -f program.awk file1 count=1 file2
-As a side point, should you really need to have 'awk' process a file
-named 'count=1' (or any file whose name looks like a variable
-assignment), precede the file name with './', like so:
+As a side point, should you really need to have âawkâ process a file
+named âcount=1â (or any file whose name looks like a variable
+assignment), precede the file name with â./â, like so:
awk -f program.awk file1 ./count=1 file2
- All the command-line arguments are made available to your 'awk'
-program in the 'ARGV' array (*note Built-in Variables::). Command-line
-options and the program text (if present) are omitted from 'ARGV'. All
+ All the command-line arguments are made available to your âawkâ
+program in the âARGVâ array (*note Built-in Variables::). Command-line
+options and the program text (if present) are omitted from âARGVâ. All
other arguments, including variable assignments, are included. As each
-element of 'ARGV' is processed, 'gawk' sets 'ARGIND' to the index in
-'ARGV' of the current element. ('gawk' makes the full command line,
-including program text and options, available in 'PROCINFO["argv"]';
+element of âARGVâ is processed, âgawkâ sets âARGINDâ to the index
in
+âARGVâ of the current element. (âgawkâ makes the full command line,
+including program text and options, available in âPROCINFO["argv"]â;
*note Auto-set::.)
- Changing 'ARGC' and 'ARGV' in your 'awk' program lets you control how
-'awk' processes the input files; this is described in more detail in
+ Changing âARGCâ and âARGVâ in your âawkâ program lets you
control how
+âawkâ processes the input files; this is described in more detail in
*note ARGC and ARGV::.
The distinction between file name arguments and variable-assignment
-arguments is made when 'awk' is about to open the next input file. At
+arguments is made when âawkâ is about to open the next input file. At
that point in execution, it checks the file name to see whether it is
-really a variable assignment; if so, 'awk' sets the variable instead of
+really a variable assignment; if so, âawkâ sets the variable instead of
reading a file.
Therefore, the variables actually receive the given values after all
previously specified files have been read. In particular, the values of
-variables assigned in this fashion are _not_ available inside a 'BEGIN'
-rule (*note BEGIN/END::), because such rules are run before 'awk' begins
+variables assigned in this fashion are _not_ available inside a âBEGINâ
+rule (*note BEGIN/END::), because such rules are run before âawkâ begins
scanning the argument list.
The variable values given on the command line are processed for
escape sequences (*note Escape Sequences::). (d.c.)
- In some very early implementations of 'awk', when a variable
+ In some very early implementations of âawkâ, when a variable
assignment occurred before any file names, the assignment would happen
-_before_ the 'BEGIN' rule was executed. 'awk''s behavior was thus
+_before_ the âBEGINâ rule was executed. âawkââs behavior was thus
inconsistent; some command-line assignments were available inside the
-'BEGIN' rule, while others were not. Unfortunately, some applications
-came to depend upon this "feature." When 'awk' was changed to be more
-consistent, the '-v' option was added to accommodate applications that
+âBEGINâ rule, while others were not. Unfortunately, some applications
+came to depend upon this âfeature.â When âawkâ was changed to be more
+consistent, the â-vâ option was added to accommodate applications that
depended upon the old behavior.
The variable assignment feature is most useful for assigning to
-variables such as 'RS', 'OFS', and 'ORS', which control input and output
+variables such as âRSâ, âOFSâ, and âORSâ, which control input and
output
formats, before scanning the data files. It is also useful for
controlling state if multiple passes are needed over a data file. For
example:
@@ -3008,32 +3008,32 @@ example:
awk 'pass == 1 { PASS 1 STUFF }
pass == 2 { PASS 2 STUFF }' pass=1 mydata pass=2 mydata
- Given the variable assignment feature, the '-F' option for setting
-the value of 'FS' is not strictly necessary. It remains for historical
+ Given the variable assignment feature, the â-Fâ option for setting
+the value of âFSâ is not strictly necessary. It remains for historical
compatibility.
- Quoting Shell Variables On The 'awk' Command Line
+ Quoting Shell Variables On The âawkâ Command Line
- Small 'awk' programs are often embedded in larger shell scripts, so
-it's worthwhile to understand some shell basics. Consider the
+ Small âawkâ programs are often embedded in larger shell scripts, so
+itâs worthwhile to understand some shell basics. Consider the
following:
f=""
awk '{ print("hi") }' $f
- In this case, 'awk' reads from standard input instead of trying to
-open any command line files. To the unwary, this looks like 'awk' is
+ In this case, âawkâ reads from standard input instead of trying to
+open any command line files. To the unwary, this looks like âawkâ is
hanging.
- However 'awk' doesn't see an explicit empty string. When a variable
-expansion is the null string, _and_ it's not quoted, the shell simply
+ However âawkâ doesnât see an explicit empty string. When a variable
+expansion is the null string, _and_ itâs not quoted, the shell simply
removes it from the command line. To demonstrate:
$ f=""
$ awk 'BEGIN { print ARGC }' $f
- -| 1
+ ⣠1
$ awk 'BEGIN { print ARGC }' "$f"
- -| 2
+ ⣠2
File: gawk.info, Node: Naming Standard Input, Next: Environment Variables,
Prev: Other Arguments, Up: Invoking Gawk
@@ -3045,160 +3045,160 @@ Often, you may wish to read standard input together
with other files.
For example, you may wish to read one file, read standard input coming
from a pipe, and then read another file.
- The way to name the standard input, with all versions of 'awk', is to
-use a single, standalone minus sign or dash, '-'. For example:
+ The way to name the standard input, with all versions of âawkâ, is to
+use a single, standalone minus sign or dash, â-â. For example:
SOME_COMMAND | awk -f myprog.awk file1 - file2
-Here, 'awk' first reads 'file1', then it reads the output of
-SOME_COMMAND, and finally it reads 'file2'.
+Here, âawkâ first reads âfile1â, then it reads the output of
+SOME_COMMAND, and finally it reads âfile2â.
- You may also use '"-"' to name standard input when reading files with
-'getline' (*note Getline/File::). And, you can even use '"-"' with the
-'-f' option to read program source code from standard input (*note
+ You may also use â"-"â to name standard input when reading files with
+âgetlineâ (*note Getline/File::). And, you can even use â"-"â with the
+â-fâ option to read program source code from standard input (*note
Options::).
- In addition, 'gawk' allows you to specify the special file name
-'/dev/stdin', both on the command line and with 'getline'. Some other
-versions of 'awk' also support this, but it is not standard. (Some
-operating systems provide a '/dev/stdin' file in the filesystem;
-however, 'gawk' always processes this file name itself.)
+ In addition, âgawkâ allows you to specify the special file name
+â/dev/stdinâ, both on the command line and with âgetlineâ. Some other
+versions of âawkâ also support this, but it is not standard. (Some
+operating systems provide a â/dev/stdinâ file in the filesystem;
+however, âgawkâ always processes this file name itself.)
File: gawk.info, Node: Environment Variables, Next: Exit Status, Prev:
Naming Standard Input, Up: Invoking Gawk
-2.5 The Environment Variables 'gawk' Uses
+2.5 The Environment Variables âgawkâ Uses
=========================================
-A number of environment variables influence how 'gawk' behaves.
+A number of environment variables influence how âgawkâ behaves.
* Menu:
-* AWKPATH Variable:: Searching directories for 'awk'
+* AWKPATH Variable:: Searching directories for âawkâ
programs.
-* AWKLIBPATH Variable:: Searching directories for 'awk' shared
+* AWKLIBPATH Variable:: Searching directories for âawkâ shared
libraries.
* Other Environment Variables:: The environment variables.
File: gawk.info, Node: AWKPATH Variable, Next: AWKLIBPATH Variable, Up:
Environment Variables
-2.5.1 The 'AWKPATH' Environment Variable
+2.5.1 The âAWKPATHâ Environment Variable
----------------------------------------
-The previous minor node described how 'awk' program files can be named
-on the command line with the '-f' option. In most 'awk'
+The previous minor node described how âawkâ program files can be named
+on the command line with the â-fâ option. In most âawkâ
implementations, you must supply a precise pathname for each program
-file, unless the file is in the current directory. But with 'gawk', if
-the file name supplied to the '-f' or '-i' options does not contain a
-directory separator '/', then 'gawk' searches a list of directories
-(called the "search path") one by one, looking for a file with the
+file, unless the file is in the current directory. But with âgawkâ, if
+the file name supplied to the â-fâ or â-iâ options does not contain a
+directory separator â/â, then âgawkâ searches a list of directories
+(called the âsearch pathâ) one by one, looking for a file with the
specified name.
The search path is a string consisting of directory names separated
-by colons.(1) 'gawk' gets its search path from the 'AWKPATH'
+by colons.(1) âgawkâ gets its search path from the âAWKPATHâ
environment variable. If that variable does not exist, or if it has an
-empty value, 'gawk' uses a default path (described shortly).
+empty value, âgawkâ uses a default path (described shortly).
The search path feature is particularly helpful for building
-libraries of useful 'awk' functions. The library files can be placed in
+libraries of useful âawkâ functions. The library files can be placed in
a standard directory in the default path and then specified on the
command line with a short file name. Otherwise, you would have to type
the full file name for each file.
- By using the '-i' or '-f' options, your command-line 'awk' programs
-can use facilities in 'awk' library files (*note Library Functions::).
-Path searching is not done if 'gawk' is in compatibility mode. This is
-true for both '--traditional' and '--posix'. *Note Options::.
+ By using the â-iâ or â-fâ options, your command-line âawkâ
programs
+can use facilities in âawkâ library files (*note Library Functions::).
+Path searching is not done if âgawkâ is in compatibility mode. This is
+true for both â--traditionalâ and â--posixâ. *Note Options::.
If the source code file is not found after the initial search, the
-path is searched again after adding the suffix '.awk' to the file name.
+path is searched again after adding the suffix â.awkâ to the file name.
- 'gawk''s path search mechanism is similar to the shell's. (See 'The
-Bourne-Again SHell manual' (https://www.gnu.org/software/bash/manual/).)
+ âgawkââs path search mechanism is similar to the shellâs. (See
âThe
+Bourne-Again SHell manualâ (https://www.gnu.org/software/bash/manual/).)
It treats a null entry in the path as indicating the current directory.
(A null entry is indicated by starting or ending the path with a colon
-or by placing two colons next to each other ['::'].)
+or by placing two colons next to each other [â::â].)
NOTE: To include the current directory in the path, either place
- '.' as an entry in the path or write a null entry in the path.
+ â.â as an entry in the path or write a null entry in the path.
- Different past versions of 'gawk' would also look explicitly in the
+ Different past versions of âgawkâ would also look explicitly in the
current directory, either before or after the path search. As of
version 4.1.2, this no longer happens; if you wish to look in the
- current directory, you must include '.' either as a separate entry
+ current directory, you must include â.â either as a separate entry
or as a null entry in the search path.
- The default value for 'AWKPATH' is '.:/usr/local/share/awk'.(2)
-Since '.' is included at the beginning, 'gawk' searches first in the
-current directory and then in '/usr/local/share/awk'. In practice, this
-means that you will rarely need to change the value of 'AWKPATH'.
+ The default value for âAWKPATHâ is â.:/usr/local/share/awkâ.(2)
+Since â.â is included at the beginning, âgawkâ searches first in the
+current directory and then in â/usr/local/share/awkâ. In practice, this
+means that you will rarely need to change the value of âAWKPATHâ.
*Note Shell Startup Files::, for information on functions that help
-to manipulate the 'AWKPATH' variable.
+to manipulate the âAWKPATHâ variable.
- 'gawk' places the value of the search path that it used into
-'ENVIRON["AWKPATH"]'. This provides access to the actual search path
-value from within an 'awk' program.
+ âgawkâ places the value of the search path that it used into
+âENVIRON["AWKPATH"]â. This provides access to the actual search path
+value from within an âawkâ program.
- Although you can change 'ENVIRON["AWKPATH"]' within your 'awk'
-program, this has no effect on the running program's behavior. This
-makes sense: the 'AWKPATH' environment variable is used to find the
+ Although you can change âENVIRON["AWKPATH"]â within your âawkâ
+program, this has no effect on the running programâs behavior. This
+makes sense: the âAWKPATHâ environment variable is used to find the
program source files. Once your program is running, all the files have
-been found, and 'gawk' no longer needs to use 'AWKPATH'.
+been found, and âgawkâ no longer needs to use âAWKPATHâ.
---------- Footnotes ----------
(1) Semicolons on MS-Windows.
- (2) Your version of 'gawk' may use a different directory; it will
-depend upon how 'gawk' was built and installed. The actual directory is
-the value of '$(pkgdatadir)' generated when 'gawk' was configured. (For
-more detail, see the 'INSTALL' file in the source distribution, and see
-*note Quick Installation::. You probably don't need to worry about
+ (2) Your version of âgawkâ may use a different directory; it will
+depend upon how âgawkâ was built and installed. The actual directory is
+the value of â$(pkgdatadir)â generated when âgawkâ was configured.
(For
+more detail, see the âINSTALLâ file in the source distribution, and see
+*note Quick Installation::. You probably donât need to worry about
this, though.)
File: gawk.info, Node: AWKLIBPATH Variable, Next: Other Environment
Variables, Prev: AWKPATH Variable, Up: Environment Variables
-2.5.2 The 'AWKLIBPATH' Environment Variable
+2.5.2 The âAWKLIBPATHâ Environment Variable
-------------------------------------------
-The 'AWKLIBPATH' environment variable is similar to the 'AWKPATH'
+The âAWKLIBPATHâ environment variable is similar to the âAWKPATHâ
variable, but it is used to search for loadable extensions (stored as
-system shared libraries) specified with the '-l' option rather than for
+system shared libraries) specified with the â-lâ option rather than for
source files. If the extension is not found, the path is searched again
after adding the appropriate shared library suffix for the platform.
-For example, on GNU/Linux systems, the suffix '.so' is used. The search
-path specified is also used for extensions loaded via the '@load'
+For example, on GNU/Linux systems, the suffix â.soâ is used. The search
+path specified is also used for extensions loaded via the â@loadâ
keyword (*note Loading Shared Libraries::).
- If 'AWKLIBPATH' does not exist in the environment, or if it has an
-empty value, 'gawk' uses a default path; this is typically
-'/usr/local/lib/gawk', although it can vary depending upon how 'gawk'
+ If âAWKLIBPATHâ does not exist in the environment, or if it has an
+empty value, âgawkâ uses a default path; this is typically
+â/usr/local/lib/gawkâ, although it can vary depending upon how âgawkâ
was built.(1)
*Note Shell Startup Files::, for information on functions that help
-to manipulate the 'AWKLIBPATH' variable.
+to manipulate the âAWKLIBPATHâ variable.
- 'gawk' places the value of the search path that it used into
-'ENVIRON["AWKLIBPATH"]'. This provides access to the actual search path
-value from within an 'awk' program.
+ âgawkâ places the value of the search path that it used into
+âENVIRON["AWKLIBPATH"]â. This provides access to the actual search path
+value from within an âawkâ program.
- Although you can change 'ENVIRON["AWKLIBPATH"]' within your 'awk'
-program, this has no effect on the running program's behavior. This
-makes sense: the 'AWKLIBPATH' environment variable is used to find any
+ Although you can change âENVIRON["AWKLIBPATH"]â within your âawkâ
+program, this has no effect on the running programâs behavior. This
+makes sense: the âAWKLIBPATHâ environment variable is used to find any
requested extensions, and they are loaded before the program starts to
run. Once your program is running, all the extensions have been found,
-and 'gawk' no longer needs to use 'AWKLIBPATH'.
+and âgawkâ no longer needs to use âAWKLIBPATHâ.
---------- Footnotes ----------
- (1) Your version of 'gawk' may use a different directory; it will
-depend upon how 'gawk' was built and installed. The actual directory is
-the value of '$(pkgextensiondir)' generated when 'gawk' was configured.
-(For more detail, see the 'INSTALL' file in the source distribution, and
-see *note Quick Installation::. You probably don't need to worry about
+ (1) Your version of âgawkâ may use a different directory; it will
+depend upon how âgawkâ was built and installed. The actual directory is
+the value of â$(pkgextensiondir)â generated when âgawkâ was configured.
+(For more detail, see the âINSTALLâ file in the source distribution, and
+see *note Quick Installation::. You probably donât need to worry about
this, though.)
@@ -3207,117 +3207,117 @@ File: gawk.info, Node: Other Environment Variables,
Prev: AWKLIBPATH Variable,
2.5.3 Other Environment Variables
---------------------------------
-A number of other environment variables affect 'gawk''s behavior, but
+A number of other environment variables affect âgawkââs behavior, but
they are more specialized. Those in the following list are meant to be
used by regular users:
-'GAWK_MSEC_SLEEP'
+âGAWK_MSEC_SLEEPâ
Specifies the interval between connection retries, in milliseconds.
- On systems that do not support the 'usleep()' system call, the
+ On systems that do not support the âusleep()â system call, the
value is rounded up to an integral number of seconds.
-'GAWK_PERSIST_FILE'
+âGAWK_PERSIST_FILEâ
Specifies the backing file to use for persistent storage of
- 'gawk''s variables and arrays. *Note Persistent Memory::.
+ âgawkââs variables and arrays. *Note Persistent Memory::.
-'GAWK_READ_TIMEOUT'
- Specifies the time, in milliseconds, for 'gawk' to wait for input
+âGAWK_READ_TIMEOUTâ
+ Specifies the time, in milliseconds, for âgawkâ to wait for input
before returning with an error. *Note Read Timeout::.
-'GAWK_SOCK_RETRIES'
- Controls the number of times 'gawk' attempts to retry a two-way
+âGAWK_SOCK_RETRIESâ
+ Controls the number of times âgawkâ attempts to retry a two-way
TCP/IP (socket) connection before giving up. *Note TCP/IP
Networking::. Note that when nonfatal I/O is enabled (*note
- Nonfatal::), 'gawk' only tries to open a TCP/IP socket once.
+ Nonfatal::), âgawkâ only tries to open a TCP/IP socket once.
-'PMA_VERBOSITY'
+âPMA_VERBOSITYâ
Controls the verbosity of the persistent memory allocator. *Note
Persistent Memory::.
-'POSIXLY_CORRECT'
- Causes 'gawk' to switch to POSIX-compatibility mode, disabling all
+âPOSIXLY_CORRECTâ
+ Causes âgawkâ to switch to POSIX-compatibility mode, disabling all
traditional and GNU extensions. *Note Options::.
The environment variables in the following list are meant for use by
-the 'gawk' developers for testing and tuning. They are subject to
+the âgawkâ developers for testing and tuning. They are subject to
change. The variables are:
-'AWKBUFSIZE'
- This variable only affects 'gawk' on POSIX-compliant systems. With
- a value of 'exact', 'gawk' uses the size of each input file as the
+âAWKBUFSIZEâ
+ This variable only affects âgawkâ on POSIX-compliant systems. With
+ a value of âexactâ, âgawkâ uses the size of each input file as the
size of the memory buffer to allocate for I/O. Otherwise, the value
- should be a number, and 'gawk' uses that number as the size of the
- buffer to allocate. (When this variable is not set, 'gawk' uses
- the smaller of the file's size and the "default" blocksize, which
- is usually the filesystem's I/O blocksize.)
+ should be a number, and âgawkâ uses that number as the size of the
+ buffer to allocate. (When this variable is not set, âgawkâ uses
+ the smaller of the fileâs size and the âdefaultâ blocksize, which
+ is usually the filesystemâs I/O blocksize.)
-'AWK_HASH'
- If this variable exists with a value of 'gst', 'gawk' switches to
+âAWK_HASHâ
+ If this variable exists with a value of âgstâ, âgawkâ switches to
using the hash function from GNU Smalltalk for managing arrays.
- With a value of 'fnv1a', 'gawk' uses the FNV1-A hash function
+ With a value of âfnv1aâ, âgawkâ uses the FNV1-A hash function
(http://www.isthe.com/chongo/tech/comp/fnv/index.html). These
functions may be marginally faster than the standard function.
-'AWKREADFUNC'
- If this variable exists, 'gawk' switches to reading source files
+âAWKREADFUNCâ
+ If this variable exists, âgawkâ switches to reading source files
one line at a time, instead of reading in blocks. This exists for
debugging problems on filesystems on non-POSIX operating systems
where I/O is performed in records, not in blocks.
-'GAWK_MSG_SRC'
- If this variable exists, 'gawk' includes the file name and line
- number within the 'gawk' source code from which warning and/or
+âGAWK_MSG_SRCâ
+ If this variable exists, âgawkâ includes the file name and line
+ number within the âgawkâ source code from which warning and/or
fatal messages are generated. Its purpose is to help isolate the
source of a message, as there are multiple places that produce the
same warning or error message.
-'GAWK_LOCALE_DIR'
- Specifies the location of compiled message object files for 'gawk'
- itself. This is passed to the 'bindtextdomain()' function when
- 'gawk' starts up.
+âGAWK_LOCALE_DIRâ
+ Specifies the location of compiled message object files for âgawkâ
+ itself. This is passed to the âbindtextdomain()â function when
+ âgawkâ starts up.
-'GAWK_NO_DFA'
- If this variable exists, 'gawk' does not use the DFA regexp matcher
- for "does it match" kinds of tests. This can cause 'gawk' to be
+âGAWK_NO_DFAâ
+ If this variable exists, âgawkâ does not use the DFA regexp matcher
+ for âdoes it matchâ kinds of tests. This can cause âgawkâ to be
slower. Its purpose is to help isolate differences between the two
- regexp matchers that 'gawk' uses internally. (There aren't
+ regexp matchers that âgawkâ uses internally. (There arenât
supposed to be differences, but occasionally theory and practice
- don't coordinate with each other.)
+ donât coordinate with each other.)
-'GAWK_STACKSIZE'
- This specifies the amount by which 'gawk' should grow its internal
+âGAWK_STACKSIZEâ
+ This specifies the amount by which âgawkâ should grow its internal
evaluation stack, when needed.
-'INT_CHAIN_MAX'
- This specifies intended maximum number of items 'gawk' will
+âINT_CHAIN_MAXâ
+ This specifies intended maximum number of items âgawkâ will
maintain on a hash chain for managing arrays indexed by integers.
-'STR_CHAIN_MAX'
- This specifies intended maximum number of items 'gawk' will
+âSTR_CHAIN_MAXâ
+ This specifies intended maximum number of items âgawkâ will
maintain on a hash chain for managing arrays indexed by strings.
-'TIDYMEM'
- If this variable exists, 'gawk' uses the 'mtrace()' library calls
+âTIDYMEMâ
+ If this variable exists, âgawkâ uses the âmtrace()â library calls
from the GNU C library to help track down possible memory leaks.
This cannot be used together with the persistent memory allocator.
File: gawk.info, Node: Exit Status, Next: Include Files, Prev: Environment
Variables, Up: Invoking Gawk
-2.6 'gawk''s Exit Status
+2.6 âgawkââs Exit Status
========================
-If the 'exit' statement is used with a value (*note Exit Statement::),
-then 'gawk' exits with the numeric value given to it.
+If the âexitâ statement is used with a value (*note Exit Statement::),
+then âgawkâ exits with the numeric value given to it.
- Otherwise, if there were no problems during execution, 'gawk' exits
-with the value of the C constant 'EXIT_SUCCESS'. This is usually zero.
+ Otherwise, if there were no problems during execution, âgawkâ exits
+with the value of the C constant âEXIT_SUCCESSâ. This is usually zero.
- If an error occurs, 'gawk' exits with the value of the C constant
-'EXIT_FAILURE'. This is usually one.
+ If an error occurs, âgawkâ exits with the value of the C constant
+âEXIT_FAILUREâ. This is usually one.
- If 'gawk' exits because of a fatal error, the exit status is two. On
-non-POSIX systems, this value may be mapped to 'EXIT_FAILURE'.
+ If âgawkâ exits because of a fatal error, the exit status is two. On
+non-POSIX systems, this value may be mapped to âEXIT_FAILUREâ.
File: gawk.info, Node: Include Files, Next: Loading Shared Libraries, Prev:
Exit Status, Up: Invoking Gawk
@@ -3325,41 +3325,41 @@ File: gawk.info, Node: Include Files, Next: Loading
Shared Libraries, Prev: E
2.7 Including Other Files into Your Program
===========================================
-This minor node describes a feature that is specific to 'gawk'.
+This minor node describes a feature that is specific to âgawkâ.
- The '@include' keyword can be used to read external 'awk' source
-files. This gives you the ability to split large 'awk' source files
+ The â@includeâ keyword can be used to read external âawkâ source
+files. This gives you the ability to split large âawkâ source files
into smaller, more manageable pieces, and also lets you reuse common
-'awk' code from various 'awk' scripts. In other words, you can group
-together 'awk' functions used to carry out specific tasks into external
+âawkâ code from various âawkâ scripts. In other words, you can group
+together âawkâ functions used to carry out specific tasks into external
files. These files can be used just like function libraries, using the
-'@include' keyword in conjunction with the 'AWKPATH' environment
-variable. Note that source files may also be included using the '-i'
+â@includeâ keyword in conjunction with the âAWKPATHâ environment
+variable. Note that source files may also be included using the â-iâ
option.
- Let's see an example. We'll start with two (trivial) 'awk' scripts,
-namely 'test1' and 'test2'. Here is the 'test1' script:
+ Letâs see an example. Weâll start with two (trivial) âawkâ scripts,
+namely âtest1â and âtest2â. Here is the âtest1â script:
BEGIN {
print "This is script test1."
}
-and here is 'test2':
+and here is âtest2â:
@include "test1"
BEGIN {
print "This is script test2."
}
- Running 'gawk' with 'test2' produces the following result:
+ Running âgawkâ with âtest2â produces the following result:
$ gawk -f test2
- -| This is script test1.
- -| This is script test2.
+ ⣠This is script test1.
+ ⣠This is script test2.
- 'gawk' runs the 'test2' script, which includes 'test1' using the
-'@include' keyword. So, to include external 'awk' source files, you
-just use '@include' followed by the name of the file to be included,
+ âgawkâ runs the âtest2â script, which includes âtest1â using the
+â@includeâ keyword. So, to include external âawkâ source files, you
+just use â@includeâ followed by the name of the file to be included,
enclosed in double quotes.
NOTE: Keep in mind that this is a language construct and the file
@@ -3367,19 +3367,19 @@ enclosed in double quotes.
constant in double quotes.
The files to be included may be nested; e.g., given a third script,
-namely 'test3':
+namely âtest3â:
@include "test2"
BEGIN {
print "This is script test3."
}
-Running 'gawk' with the 'test3' script produces the following results:
+Running âgawkâ with the âtest3â script produces the following results:
$ gawk -f test3
- -| This is script test1.
- -| This is script test2.
- -| This is script test3.
+ ⣠This is script test1.
+ ⣠This is script test2.
+ ⣠This is script test3.
The file name can, of course, be a pathname. For example:
@@ -3389,33 +3389,33 @@ and:
@include "/usr/awklib/network"
-are both valid. The 'AWKPATH' environment variable can be of great
-value when using '@include'. The same rules for the use of the
-'AWKPATH' variable in command-line file searches (*note AWKPATH
-Variable::) apply to '@include' also.
+are both valid. The âAWKPATHâ environment variable can be of great
+value when using â@includeâ. The same rules for the use of the
+âAWKPATHâ variable in command-line file searches (*note AWKPATH
+Variable::) apply to â@includeâ also.
- This is very helpful in constructing 'gawk' function libraries. If
-you have a large script with useful, general-purpose 'awk' functions,
+ This is very helpful in constructing âgawkâ function libraries. If
+you have a large script with useful, general-purpose âawkâ functions,
you can break it down into library files and put those files in a
-special directory. You can then include those "libraries," either by
-using the full pathnames of the files, or by setting the 'AWKPATH'
-environment variable accordingly and then using '@include' with just the
+special directory. You can then include those âlibraries,â either by
+using the full pathnames of the files, or by setting the âAWKPATHâ
+environment variable accordingly and then using â@includeâ with just the
file part of the full pathname. Of course, you can keep library files
in more than one directory; the more complex the working environment is,
the more directories you may need to organize the files to be included.
- Given the ability to specify multiple '-f' options, the '@include'
-mechanism is not strictly necessary. However, the '@include' keyword
-can help you in constructing self-contained 'gawk' programs, thus
+ Given the ability to specify multiple â-fâ options, the â@includeâ
+mechanism is not strictly necessary. However, the â@includeâ keyword
+can help you in constructing self-contained âgawkâ programs, thus
reducing the need for writing complex and tedious command lines. In
-particular, '@include' is very useful for writing CGI scripts to be run
+particular, â@includeâ is very useful for writing CGI scripts to be run
from web pages.
The rules for finding a source file described in *note AWKPATH
-Variable:: also apply to files loaded with '@include'.
+Variable:: also apply to files loaded with â@includeâ.
- Finally, files included with '@include' are treated as if they had
-'@namespace "awk"' at their beginning. *Note Changing The Namespace::,
+ Finally, files included with â@includeâ are treated as if they had
+â@namespace "awk"â at their beginning. *Note Changing The Namespace::,
for more information.
@@ -3424,35 +3424,35 @@ File: gawk.info, Node: Loading Shared Libraries,
Next: Obsolete, Prev: Includ
2.8 Loading Dynamic Extensions into Your Program
================================================
-This minor node describes a feature that is specific to 'gawk'.
+This minor node describes a feature that is specific to âgawkâ.
- The '@load' keyword can be used to read external 'awk' extensions
+ The â@loadâ keyword can be used to read external âawkâ extensions
(stored as system shared libraries). This allows you to link in
compiled code that may offer superior performance and/or give you access
-to extended capabilities not supported by the 'awk' language. The
-'AWKLIBPATH' variable is used to search for the extension. Using
-'@load' is completely equivalent to using the '-l' command-line option.
+to extended capabilities not supported by the âawkâ language. The
+âAWKLIBPATHâ variable is used to search for the extension. Using
+â@loadâ is completely equivalent to using the â-lâ command-line option.
- If the extension is not initially found in 'AWKLIBPATH', another
-search is conducted after appending the platform's default shared
+ If the extension is not initially found in âAWKLIBPATHâ, another
+search is conducted after appending the platformâs default shared
library suffix to the file name. For example, on GNU/Linux systems, the
-suffix '.so' is used:
+suffix â.soâ is used:
$ gawk '@load "ordchr"; BEGIN {print chr(65)}'
- -| A
+ ⣠A
This is equivalent to the following example:
$ gawk -lordchr 'BEGIN {print chr(65)}'
- -| A
+ ⣠A
-For command-line usage, the '-l' option is more convenient, but '@load'
-is useful for embedding inside an 'awk' source file that requires access
+For command-line usage, the â-lâ option is more convenient, but â@loadâ
+is useful for embedding inside an âawkâ source file that requires access
to an extension.
*note Dynamic Extensions::, describes how to write extensions (in C
-or C++) that can be loaded with either '@load' or the '-l' option. It
-also describes the 'ordchr' extension.
+or C++) that can be loaded with either â@loadâ or the â-lâ option. It
+also describes the âordchrâ extension.
File: gawk.info, Node: Obsolete, Next: Undocumented, Prev: Loading Shared
Libraries, Up: Invoking Gawk
@@ -3461,12 +3461,12 @@ File: gawk.info, Node: Obsolete, Next: Undocumented,
Prev: Loading Shared Lib
====================================
This minor node describes features and/or command-line options from
-previous releases of 'gawk' that either are not available in the current
+previous releases of âgawkâ that either are not available in the current
version or are still supported but deprecated (meaning that they will
_not_ be in a future release).
- The arbitrary precision arithmetic feature is deprecated as of 'gawk'
-version 5.2. Use of '-M'/'--bignum' produces a warning message. The
+ The arbitrary precision arithmetic feature is deprecated as of âgawkâ
+version 5.2. Use of â-Mâ/â--bignumâ produces a warning message. The
feature will be removed in the release of 2024.
@@ -3476,7 +3476,7 @@ File: gawk.info, Node: Undocumented, Next: Invoking
Summary, Prev: Obsolete,
======================================
Use the Source, Luke!
- -- _Obi-Wan_
+ â _Obi-Wan_
This minor node intentionally left blank.
@@ -3486,63 +3486,63 @@ File: gawk.info, Node: Invoking Summary, Prev:
Undocumented, Up: Invoking Gaw
2.11 Summary
============
- * 'gawk' parses arguments on the command line, left to right, to
+ ⢠âgawkâ parses arguments on the command line, left to right, to
determine if they should be treated as options or as non-option
arguments.
- * 'gawk' recognizes several options which control its operation, as
- described in *note Options::. All options begin with '-'.
+ ⢠âgawkâ recognizes several options which control its operation, as
+ described in *note Options::. All options begin with â-â.
- * Any argument that is not recognized as an option is treated as a
- non-option argument, even if it begins with '-'.
+ ⢠Any argument that is not recognized as an option is treated as a
+ non-option argument, even if it begins with â-â.
- - However, when an option itself requires an argument, and the
+ â However, when an option itself requires an argument, and the
option is separated from that argument on the command line by
at least one space, the space is ignored, and the argument is
considered to be related to the option. Thus, in the
- invocation, 'gawk -F x', the 'x' is treated as belonging to
- the '-F' option, not as a separate non-option argument.
+ invocation, âgawk -F xâ, the âxâ is treated as belonging to
+ the â-Fâ option, not as a separate non-option argument.
- * Once 'gawk' finds a non-option argument, it stops looking for
+ ⢠Once âgawkâ finds a non-option argument, it stops looking for
options. Therefore, all following arguments are also non-option
arguments, even if they resemble recognized options.
- * If no '-e' or '-f' options are present, 'gawk' expects the program
+ ⢠If no â-eâ or â-fâ options are present, âgawkâ expects the
program
text to be in the first non-option argument.
- * All non-option arguments, except program text provided in the first
- non-option argument, are placed in 'ARGV' as explained in *note
+ ⢠All non-option arguments, except program text provided in the first
+ non-option argument, are placed in âARGVâ as explained in *note
ARGC and ARGV::, and are processed as described in *note Other
- Arguments::. Adjusting 'ARGC' and 'ARGV' affects how 'awk'
+ Arguments::. Adjusting âARGCâ and âARGVâ affects how âawkâ
processes input.
- * The three standard options for all versions of 'awk' are '-f',
- '-F', and '-v'. 'gawk' supplies these and many others, as well as
+ ⢠The three standard options for all versions of âawkâ are â-fâ,
+ â-Fâ, and â-vâ. âgawkâ supplies these and many others, as
well as
corresponding GNU-style long options.
- * Nonoption command-line arguments are usually treated as file names,
- unless they have the form 'VAR=VALUE', in which case they are taken
+ ⢠Nonoption command-line arguments are usually treated as file names,
+ unless they have the form âVAR=VALUEâ, in which case they are taken
as variable assignments to be performed at that point in processing
the input.
- * You can use a single minus sign ('-') to refer to standard input on
- the command line. 'gawk' also lets you use the special file name
- '/dev/stdin'.
+ ⢠You can use a single minus sign (â-â) to refer to standard input on
+ the command line. âgawkâ also lets you use the special file name
+ â/dev/stdinâ.
- * 'gawk' pays attention to a number of environment variables.
- 'AWKPATH', 'AWKLIBPATH', and 'POSIXLY_CORRECT' are the most
+ ⢠âgawkâ pays attention to a number of environment variables.
+ âAWKPATHâ, âAWKLIBPATHâ, and âPOSIXLY_CORRECTâ are the most
important ones.
- * 'gawk''s exit status conveys information to the program that
- invoked it. Use the 'exit' statement from within an 'awk' program
+ ⢠âgawkââs exit status conveys information to the program that
+ invoked it. Use the âexitâ statement from within an âawkâ program
to set the exit status.
- * 'gawk' allows you to include other 'awk' source files into your
- program using the '@include' statement and/or the '-i' and '-f'
+ ⢠âgawkâ allows you to include other âawkâ source files into your
+ program using the â@includeâ statement and/or the â-iâ and
â-fâ
command-line options.
- * 'gawk' allows you to load additional functions written in C or C++
- using the '@load' statement and/or the '-l' option. (This advanced
+ ⢠âgawkâ allows you to load additional functions written in C or C++
+ using the â@loadâ statement and/or the â-lâ option. (This
advanced
feature is described later, in *note Dynamic Extensions::.)
@@ -3551,17 +3551,17 @@ File: gawk.info, Node: Regexp, Next: Reading Files,
Prev: Invoking Gawk, Up:
3 Regular Expressions
*********************
-A "regular expression", or "regexp", is a way of describing a set of
+A âregular expressionâ, or âregexpâ, is a way of describing a set of
strings. Because regular expressions are such a fundamental part of
-'awk' programming, their format and use deserve a separate major node.
+âawkâ programming, their format and use deserve a separate major node.
- A regular expression enclosed in slashes ('/') is an 'awk' pattern
+ A regular expression enclosed in slashes (â/â) is an âawkâ pattern
that matches every input record whose text belongs to that set. The
simplest regular expression is a sequence of letters, numbers, or both.
Such a regexp matches any string that contains that sequence. Thus, the
-regexp 'foo' matches any string containing 'foo'. Thus, the pattern
-'/foo/' matches any input record containing the three adjacent
-characters 'foo' _anywhere_ in the record. Other kinds of regexps let
+regexp âfooâ matches any string containing âfooâ. Thus, the pattern
+â/foo/â matches any input record containing the three adjacent
+characters âfooâ _anywhere_ in the record. Other kinds of regexps let
you specify more complicated classes of strings.
* Menu:
@@ -3569,7 +3569,7 @@ you specify more complicated classes of strings.
* Regexp Usage:: How to Use Regular Expressions.
* Escape Sequences:: How to write nonprinting characters.
* Regexp Operators:: Regular Expression Operators.
-* Bracket Expressions:: What can go between '[...]'.
+* Bracket Expressions:: What can go between â[...]â.
* Leftmost Longest:: How much text matches.
* Computed Regexps:: Using Dynamic Regexps.
* GNU Regexp Operators:: Operators specific to GNU software.
@@ -3586,33 +3586,33 @@ A regular expression can be used as a pattern by
enclosing it in
slashes. Then the regular expression is tested against the entire text
of each record. (Normally, it only needs to match some part of the text
in order to succeed.) For example, the following prints the second
-field of each record where the string 'li' appears anywhere in the
+field of each record where the string âliâ appears anywhere in the
record:
$ awk '/li/ { print $2 }' mail-list
- -| 555-5553
- -| 555-0542
- -| 555-6699
- -| 555-3430
+ ⣠555-5553
+ ⣠555-0542
+ ⣠555-6699
+ ⣠555-3430
Regular expressions can also be used in matching expressions. These
expressions allow you to specify the string to match against; it need
-not be the entire current input record. The two operators '~' and '!~'
+not be the entire current input record. The two operators â~â and â!~â
perform regular expression comparisons. Expressions using these
-operators can be used as patterns, or in 'if', 'while', 'for', and 'do'
+operators can be used as patterns, or in âifâ, âwhileâ, âforâ, and
âdoâ
statements. (*Note Statements::.) For example, the following is true
if the expression EXP (taken as a string) matches REGEXP:
EXP ~ /REGEXP/
This example matches, or selects, all input records with the uppercase
-letter 'J' somewhere in the first field:
+letter âJâ somewhere in the first field:
$ awk '$1 ~ /J/' inventory-shipped
- -| Jan 13 25 15 115
- -| Jun 31 42 75 492
- -| Jul 24 34 67 436
- -| Jan 21 36 64 620
+ ⣠Jan 13 25 15 115
+ ⣠Jun 31 42 75 492
+ ⣠Jul 24 34 67 436
+ ⣠Jan 21 36 64 620
So does this:
@@ -3624,17 +3624,17 @@ string) does _not_ match REGEXP:
EXP !~ /REGEXP/
The following example matches, or selects, all input records whose
-first field _does not_ contain the uppercase letter 'J':
+first field _does not_ contain the uppercase letter âJâ:
$ awk '$1 !~ /J/' inventory-shipped
- -| Feb 15 32 24 226
- -| Mar 15 24 34 228
- -| Apr 31 52 63 420
- -| May 16 34 29 208
+ ⣠Feb 15 32 24 226
+ ⣠Mar 15 24 34 228
+ ⣠Apr 31 52 63 420
+ ⣠May 16 34 29 208
...
- When a regexp is enclosed in slashes, such as '/foo/', we call it a
-"regexp constant", much like '5.27' is a numeric constant and '"foo"' is
+ When a regexp is enclosed in slashes, such as â/foo/â, we call it a
+âregexp constantâ, much like â5.27â is a numeric constant and
â"foo"â is
a string constant.
@@ -3644,101 +3644,101 @@ File: gawk.info, Node: Escape Sequences, Next:
Regexp Operators, Prev: Regexp
====================
Some characters cannot be included literally in string constants
-('"foo"') or regexp constants ('/foo/'). Instead, they should be
-represented with "escape sequences", which are character sequences
-beginning with a backslash ('\'). One use of an escape sequence is to
+(â"foo"â) or regexp constants (â/foo/â). Instead, they should be
+represented with âescape sequencesâ, which are character sequences
+beginning with a backslash (â\â). One use of an escape sequence is to
include a double-quote character in a string constant. Because a plain
-double quote ends the string, you must use '\"' to represent an actual
+double quote ends the string, you must use â\"â to represent an actual
double-quote character as a part of the string. For example:
$ awk 'BEGIN { print "He said \"hi!\" to her." }'
- -| He said "hi!" to her.
+ ⣠He said "hi!" to her.
The backslash character itself is another character that cannot be
-included normally; you must write '\\' to put one backslash in the
+included normally; you must write â\\â to put one backslash in the
string or regexp. Thus, the string whose contents are the two
-characters '"' and '\' must be written '"\"\\"'.
+characters â"â and â\â must be written â"\"\\"â.
Other escape sequences represent unprintable characters such as TAB
or newline. There is nothing to stop you from entering most unprintable
characters directly in a string constant or regexp constant, but they
may look ugly.
- The following list presents all the escape sequences used in 'awk'
+ The following list presents all the escape sequences used in âawkâ
and what they represent. Unless noted otherwise, all these escape
sequences apply to both string constants and regexp constants:
-'\\'
- A literal backslash, '\'.
+â\\â
+ A literal backslash, â\â.
-'\a'
- The "alert" character, 'Ctrl-g', ASCII code 7 (BEL). (This often
+â\aâ
+ The âalertâ character, âCtrl-gâ, ASCII code 7 (BEL). (This often
makes some sort of audible noise.)
-'\b'
- Backspace, 'Ctrl-h', ASCII code 8 (BS).
+â\bâ
+ Backspace, âCtrl-hâ, ASCII code 8 (BS).
-'\f'
- Formfeed, 'Ctrl-l', ASCII code 12 (FF).
+â\fâ
+ Formfeed, âCtrl-lâ, ASCII code 12 (FF).
-'\n'
- Newline, 'Ctrl-j', ASCII code 10 (LF).
+â\nâ
+ Newline, âCtrl-jâ, ASCII code 10 (LF).
-'\r'
- Carriage return, 'Ctrl-m', ASCII code 13 (CR).
+â\râ
+ Carriage return, âCtrl-mâ, ASCII code 13 (CR).
-'\t'
- Horizontal TAB, 'Ctrl-i', ASCII code 9 (HT).
+â\tâ
+ Horizontal TAB, âCtrl-iâ, ASCII code 9 (HT).
-'\v'
- Vertical TAB, 'Ctrl-k', ASCII code 11 (VT).
+â\vâ
+ Vertical TAB, âCtrl-kâ, ASCII code 11 (VT).
-'\NNN'
- The octal value NNN, where NNN stands for 1 to 3 digits between '0'
- and '7'. For example, the code for the ASCII ESC (escape)
- character is '\033'.
+â\NNNâ
+ The octal value NNN, where NNN stands for 1 to 3 digits between â0â
+ and â7â. For example, the code for the ASCII ESC (escape)
+ character is â\033â.
-'\xHH...'
+â\xHH...â
The hexadecimal value HH, where HH stands for a sequence of
- hexadecimal digits ('0'-'9', and either 'A'-'F' or 'a'-'f'). A
- maximum of two digits are allowed after the '\x'. Any further
+ hexadecimal digits (â0âââ9â, and either âAâââFâ or
âaâââfâ). A
+ maximum of two digits are allowed after the â\xâ. Any further
hexadecimal digits are treated as simple letters or numbers.
- (c.e.) (The '\x' escape sequence is not allowed in POSIX awk.)
+ (c.e.) (The â\xâ escape sequence is not allowed in POSIX awk.)
CAUTION: In ISO C, the escape sequence continues until the
- first nonhexadecimal digit is seen. For many years, 'gawk'
+ first nonhexadecimal digit is seen. For many years, âgawkâ
would continue incorporating hexadecimal digits into the value
until a non-hexadecimal digit or the end of the string was
encountered. However, using more than two hexadecimal digits
produced undefined results. As of version 4.2, only two
digits are processed.
-'\/'
+â\/â
A literal slash (should be used for regexp constants only). This
sequence is used when you want to write a regexp constant that
- contains a slash (such as '/.*:\/home\/[[:alnum:]]+:.*/'; the
- '[[:alnum:]]' notation is discussed in *note Bracket
+ contains a slash (such as â/.*:\/home\/[[:alnum:]]+:.*/â; the
+ â[[:alnum:]]â notation is discussed in *note Bracket
Expressions::). Because the regexp is delimited by slashes, you
need to escape any slash that is part of the pattern, in order to
- tell 'awk' to keep processing the rest of the regexp.
+ tell âawkâ to keep processing the rest of the regexp.
-'\"'
+â\"â
A literal double quote (should be used for string constants only).
This sequence is used when you want to write a string constant that
- contains a double quote (such as '"He said \"hi!\" to her."').
+ contains a double quote (such as â"He said \"hi!\" to her."â).
Because the string is delimited by double quotes, you need to
- escape any quote that is part of the string, in order to tell 'awk'
+ escape any quote that is part of the string, in order to tell âawkâ
to keep processing the rest of the string.
- In 'gawk', a number of additional two-character sequences that begin
+ In âgawkâ, a number of additional two-character sequences that begin
with a backslash have special meaning in regexps. *Note GNU Regexp
Operators::.
In a regexp, a backslash before any character that is not in the
previous list and not listed in *note GNU Regexp Operators:: means that
the next character should be taken literally, even if it would normally
-be a regexp operator. For example, '/a\+b/' matches the three
-characters 'a+b'.
+be a regexp operator. For example, â/a\+b/â matches the three
+characters âa+bâ.
For complete portability, do not use a backslash before any character
not shown in the previous list or that is not an operator.
@@ -3746,46 +3746,46 @@ not shown in the previous list or that is not an
operator.
Backslash Before Regular Characters
If you place a backslash in a string constant before something that
-is not one of the characters previously listed, POSIX 'awk' purposely
+is not one of the characters previously listed, POSIX âawkâ purposely
leaves what happens as undefined. There are two choices:
Strip the backslash out
- This is what BWK 'awk' and 'gawk' both do. For example, '"a\qc"'
- is the same as '"aqc"'. (Because this is such an easy bug both to
- introduce and to miss, 'gawk' warns you about it.) Consider 'FS =
- "[ \t]+\|[ \t]+"' to use vertical bars surrounded by whitespace as
+ This is what BWK âawkâ and âgawkâ both do. For example,
â"a\qc"â
+ is the same as â"aqc"â. (Because this is such an easy bug both to
+ introduce and to miss, âgawkâ warns you about it.) Consider âFS =
+ "[ \t]+\|[ \t]+"â to use vertical bars surrounded by whitespace as
the field separator. There should be two backslashes in the
- string: 'FS = "[ \t]+\\|[ \t]+"'.)
+ string: âFS = "[ \t]+\\|[ \t]+"â.)
Leave the backslash alone
- Some other 'awk' implementations do this. In such implementations,
- typing '"a\qc"' is the same as typing '"a\\qc"'.
+ Some other âawkâ implementations do this. In such implementations,
+ typing â"a\qc"â is the same as typing â"a\\qc"â.
To summarize:
- * The escape sequences in the preceding list are always processed
+ ⢠The escape sequences in the preceding list are always processed
first, for both string constants and regexp constants. This
- happens very early, as soon as 'awk' reads your program.
+ happens very early, as soon as âawkâ reads your program.
- * 'gawk' processes both regexp constants and dynamic regexps (*note
+ ⢠âgawkâ processes both regexp constants and dynamic regexps (*note
Computed Regexps::), for the special operators listed in *note GNU
Regexp Operators::.
- * A backslash before any other character means to treat that
+ ⢠A backslash before any other character means to treat that
character literally.
Escape Sequences for Metacharacters
Suppose you use an octal or hexadecimal escape to represent a regexp
-metacharacter. (See *note Regexp Operators::.) Does 'awk' treat the
+metacharacter. (See *note Regexp Operators::.) Does âawkâ treat the
character as a literal character or as a regexp operator?
Historically, such characters were taken literally. (d.c.) However,
the POSIX standard indicates that they should be treated as real
-metacharacters, which is what 'gawk' does. In compatibility mode (*note
-Options::), 'gawk' treats the characters represented by octal and
+metacharacters, which is what âgawkâ does. In compatibility mode (*note
+Options::), âgawkâ treats the characters represented by octal and
hexadecimal escape sequences literally when used in regexp constants.
-Thus, '/a\52b/' is equivalent to '/a\*b/'.
+Thus, â/a\52b/â is equivalent to â/a\*b/â.
File: gawk.info, Node: Regexp Operators, Next: Bracket Expressions, Prev:
Escape Sequences, Up: Regexp
@@ -3794,7 +3794,7 @@ File: gawk.info, Node: Regexp Operators, Next: Bracket
Expressions, Prev: Esc
================================
You can combine regular expressions with special characters, called
-"regular expression operators" or "metacharacters", to increase the
+âregular expression operatorsâ or âmetacharactersâ, to increase the
power and versatility of regular expressions.
* Menu:
@@ -3805,86 +3805,86 @@ power and versatility of regular expressions.
File: gawk.info, Node: Regexp Operator Details, Next: Interval Expressions,
Up: Regexp Operators
-3.3.1 Regexp Operators in 'awk'
+3.3.1 Regexp Operators in âawkâ
-------------------------------
The escape sequences described in *note Escape Sequences:: are valid
-inside a regexp. They are introduced by a '\' and are recognized and
+inside a regexp. They are introduced by a â\â and are recognized and
converted into corresponding real characters as the very first step in
processing regexps.
Here is a list of metacharacters. All characters that are not escape
sequences and that are not listed here stand for themselves:
-'\'
+â\â
This suppresses the special meaning of a character when matching.
- For example, '\$' matches the character '$'.
+ For example, â\$â matches the character â$â.
-'^'
- This matches the beginning of a string. '^@chapter' matches
- '@chapter' at the beginning of a string, for example, and can be
+â^â
+ This matches the beginning of a string. â^@chapterâ matches
+ â@chapterâ at the beginning of a string, for example, and can be
used to identify chapter beginnings in Texinfo source files. The
- '^' is known as an "anchor", because it anchors the pattern to
+ â^â is known as an âanchorâ, because it anchors the pattern to
match only at the beginning of the string.
- It is important to realize that '^' does not match the beginning of
- a line (the point right after a '\n' newline character) embedded in
+ It is important to realize that â^â does not match the beginning of
+ a line (the point right after a â\nâ newline character) embedded in
a string. The condition is not true in the following example:
if ("line1\nLINE 2" ~ /^L/) ...
-'$'
- This is similar to '^', but it matches only at the end of a string.
- For example, 'p$' matches a record that ends with a 'p'. The '$'
+â$â
+ This is similar to â^â, but it matches only at the end of a string.
+ For example, âp$â matches a record that ends with a âpâ. The
â$â
is an anchor and does not match the end of a line (the point right
- before a '\n' newline character) embedded in a string. The
+ before a â\nâ newline character) embedded in a string. The
condition in the following example is not true:
if ("line1\nLINE 2" ~ /1$/) ...
-'.' (period)
+â.â (period)
This matches any single character, _including_ the newline
- character. For example, '.P' matches any single character followed
- by a 'P' in a string. Using concatenation, we can make a regular
- expression such as 'U.A', which matches any three-character
- sequence that begins with 'U' and ends with 'A'.
+ character. For example, â.Pâ matches any single character followed
+ by a âPâ in a string. Using concatenation, we can make a regular
+ expression such as âU.Aâ, which matches any three-character
+ sequence that begins with âUâ and ends with âAâ.
- In strict POSIX mode (*note Options::), '.' does not match the NUL
+ In strict POSIX mode (*note Options::), â.â does not match the NUL
character, which is a character with all bits equal to zero.
- Otherwise, NUL is just another character. Other versions of 'awk'
+ Otherwise, NUL is just another character. Other versions of âawkâ
may not be able to match the NUL character.
-'['...']'
- This is called a "bracket expression".(1) It matches any _one_ of
+â[â...â]â
+ This is called a âbracket expressionâ.(1) It matches any _one_ of
the characters that are enclosed in the square brackets. For
- example, '[MVX]' matches any one of the characters 'M', 'V', or 'X'
+ example, â[MVX]â matches any one of the characters âMâ, âVâ,
or âXâ
in a string. A full discussion of what can be inside the square
brackets of a bracket expression is given in *note Bracket
Expressions::.
-'[^'...']'
- This is a "complemented bracket expression". The first character
- after the '[' _must_ be a '^'. It matches any characters _except_
- those in the square brackets. For example, '[^awk]' matches any
- character that is not an 'a', 'w', or 'k'.
-
-'|'
- This is the "alternation operator" and it is used to specify
- alternatives. The '|' has the lowest precedence of all the regular
- expression operators. For example, '^P|[aeiouy]' matches any
- string that matches either '^P' or '[aeiouy]'. This means it
- matches any string that starts with 'P' or contains (anywhere
+â[^â...â]â
+ This is a âcomplemented bracket expressionâ. The first character
+ after the â[â _must_ be a â^â. It matches any characters _except_
+ those in the square brackets. For example, â[^awk]â matches any
+ character that is not an âaâ, âwâ, or âkâ.
+
+â|â
+ This is the âalternation operatorâ and it is used to specify
+ alternatives. The â|â has the lowest precedence of all the regular
+ expression operators. For example, â^P|[aeiouy]â matches any
+ string that matches either â^Pâ or â[aeiouy]â. This means it
+ matches any string that starts with âPâ or contains (anywhere
within it) a lowercase English vowel.
The alternation applies to the largest possible regexps on either
side.
-'('...')'
+â(â...â)â
Parentheses are used for grouping in regular expressions, as in
arithmetic. They can be used to concatenate regular expressions
- containing the alternation operator, '|'. For example,
- '@(samp|code)\{[^}]+\}' matches both '@code{foo}' and '@samp{bar}'.
- (These are Texinfo formatting control sequences. The '+' is
+ containing the alternation operator, â|â. For example,
+ â@(samp|code)\{[^}]+\}â matches both â@code{foo}â and
â@samp{bar}â.
+ (These are Texinfo formatting control sequences. The â+â is
explained further on in this list.)
The left or opening parenthesis is always a metacharacter; to match
@@ -3893,75 +3893,75 @@ sequences and that are not listed here stand for
themselves:
parenthesis; an unpaired right parenthesis is (silently) treated as
a regular character.
-'*'
+â*â
This symbol means that the preceding regular expression should be
repeated as many times as necessary to find a match. For example,
- 'ph*' applies the '*' symbol to the preceding 'h' and looks for
- matches of one 'p' followed by any number of 'h's. This also
- matches just 'p' if no 'h's are present.
-
- There are two subtle points to understand about how '*' works.
- First, the '*' applies only to the single preceding regular
- expression component (e.g., in 'ph*', it applies just to the 'h').
- To cause '*' to apply to a larger subexpression, use parentheses:
- '(ph)*' matches 'ph', 'phph', 'phphph', and so on.
-
- Second, '*' finds as many repetitions as possible. If the text to
- be matched is 'phhhhhhhhhhhhhhooey', 'ph*' matches all of the 'h's.
-
-'+'
- This symbol is similar to '*', except that the preceding expression
- must be matched at least once. This means that 'wh+y' would match
- 'why' and 'whhy', but not 'wy', whereas 'wh*y' would match all
+ âph*â applies the â*â symbol to the preceding âhâ and looks
for
+ matches of one âpâ followed by any number of âhâs. This also
+ matches just âpâ if no âhâs are present.
+
+ There are two subtle points to understand about how â*â works.
+ First, the â*â applies only to the single preceding regular
+ expression component (e.g., in âph*â, it applies just to the âhâ).
+ To cause â*â to apply to a larger subexpression, use parentheses:
+ â(ph)*â matches âphâ, âphphâ, âphphphâ, and so on.
+
+ Second, â*â finds as many repetitions as possible. If the text to
+ be matched is âphhhhhhhhhhhhhhooeyâ, âph*â matches all of the
âhâs.
+
+â+â
+ This symbol is similar to â*â, except that the preceding expression
+ must be matched at least once. This means that âwh+yâ would match
+ âwhyâ and âwhhyâ, but not âwyâ, whereas âwh*yâ would
match all
three.
-'?'
- This symbol is similar to '*', except that the preceding expression
- can be matched either once or not at all. For example, 'fe?d'
- matches 'fed' and 'fd', but nothing else.
+â?â
+ This symbol is similar to â*â, except that the preceding expression
+ can be matched either once or not at all. For example, âfe?dâ
+ matches âfedâ and âfdâ, but nothing else.
-'{'N'}'
-'{'N',}'
-'{'N','M'}'
- One or two numbers inside braces denote an "interval expression".
+â{âNâ}â
+â{âNâ,}â
+â{âNâ,âMâ}â
+ One or two numbers inside braces denote an âinterval expressionâ.
If there is one number in the braces, the preceding regexp is
repeated N times. If there are two numbers separated by a comma,
the preceding regexp is repeated N to M times. If there is one
number followed by a comma, then the preceding regexp is repeated
at least N times:
- 'wh{3}y'
- Matches 'whhhy', but not 'why' or 'whhhhy'.
+ âwh{3}yâ
+ Matches âwhhhyâ, but not âwhyâ or âwhhhhyâ.
- 'wh{3,5}y'
- Matches 'whhhy', 'whhhhy', or 'whhhhhy' only.
+ âwh{3,5}yâ
+ Matches âwhhhyâ, âwhhhhyâ, or âwhhhhhyâ only.
- 'wh{2,}y'
- Matches 'whhy', 'whhhy', and so on.
+ âwh{2,}yâ
+ Matches âwhhyâ, âwhhhyâ, and so on.
- In regular expressions, the '*', '+', and '?' operators, as well as
-the braces '{' and '}', have the highest precedence, followed by
-concatenation, and finally by '|'. As in arithmetic, parentheses can
+ In regular expressions, the â*â, â+â, and â?â operators, as
well as
+the braces â{â and â}â, have the highest precedence, followed by
+concatenation, and finally by â|â. As in arithmetic, parentheses can
change how operators are grouped.
- In POSIX 'awk' and 'gawk', the '*', '+', and '?' operators stand for
+ In POSIX âawkâ and âgawkâ, the â*â, â+â, and â?â
operators stand for
themselves when there is nothing in the regexp that precedes them. For
-example, '/+/' matches a literal plus sign. However, many other
-versions of 'awk' treat such a usage as a syntax error.
+example, â/+/â matches a literal plus sign. However, many other
+versions of âawkâ treat such a usage as a syntax error.
What About The Empty Regexp?
We describe here an advanced regexp usage. Feel free to skip it upon
first reading.
- You can supply an empty regexp constant ('//') in all places where a
+ You can supply an empty regexp constant (â//â) in all places where a
regexp is expected. Is this useful? What does it match?
It is useful. It matches the (invisible) empty string at the start
and end of a string of characters, as well as the empty string between
-characters. This is best illustrated with the 'gsub()' function, which
+characters. This is best illustrated with the âgsub()â function, which
makes global substitutions in a string (*note String Functions::).
-Normal usage of 'gsub()' is like so:
+Normal usage of âgsub()â is like so:
$ awk '
> BEGIN {
@@ -3969,9 +3969,9 @@ Normal usage of 'gsub()' is like so:
> gsub(/B/, "bb", x)
> print x
> }'
- -| AbbC_CbbA
+ ⣠AbbC_CbbA
- We can use 'gsub()' to see where the empty strings are that match the
+ We can use âgsub()â to see where the empty strings are that match the
empty regexp:
$ awk '
@@ -3980,12 +3980,12 @@ empty regexp:
> gsub(//, "x", x)
> print x
> }'
- -| xAxBxCx
+ ⣠xAxBxCx
---------- Footnotes ----------
(1) In other literature, you may see a bracket expression referred to
-as either a "character set", a "character class", or a "character list".
+as either a âcharacter setâ, a âcharacter classâ, or a âcharacter
listâ.
File: gawk.info, Node: Interval Expressions, Prev: Regexp Operator Details,
Up: Regexp Operators
@@ -3993,52 +3993,52 @@ File: gawk.info, Node: Interval Expressions, Prev:
Regexp Operator Details, U
3.3.2 Some Notes On Interval Expressions
----------------------------------------
-Interval expressions were not traditionally available in 'awk'. They
-were added as part of the POSIX standard to make 'awk' and 'egrep'
+Interval expressions were not traditionally available in âawkâ. They
+were added as part of the POSIX standard to make âawkâ and âegrepâ
consistent with each other.
- Initially, because old programs may use '{' and '}' in regexp
-constants, 'gawk' did _not_ match interval expressions in regexps.
+ Initially, because old programs may use â{â and â}â in regexp
+constants, âgawkâ did _not_ match interval expressions in regexps.
- However, beginning with version 4.0, 'gawk' does match interval
+ However, beginning with version 4.0, âgawkâ does match interval
expressions by default. This is because compatibility with POSIX has
-become more important to most 'gawk' users than compatibility with old
+become more important to most âgawkâ users than compatibility with old
programs.
- For programs that use '{' and '}' in regexp constants, it is good
+ For programs that use â{â and â}â in regexp constants, it is good
practice to always escape them with a backslash. Then the regexp
constants are valid and work the way you want them to, using any version
-of 'awk'.(1)
+of âawkâ.(1)
- When '{' and '}' appear in regexp constants in a way that cannot be
-interpreted as an interval expression (such as '/q{a}/'), then they
+ When â{â and â}â appear in regexp constants in a way that cannot be
+interpreted as an interval expression (such as â/q{a}/â), then they
stand for themselves.
As mentioned, interval expressions were not traditionally available
-in 'awk'. In March of 2019, BWK 'awk' (finally) acquired them.
-Starting with version 5.2, 'gawk''s '--traditional' option no longer
+in âawkâ. In March of 2019, BWK âawkâ (finally) acquired them.
+Starting with version 5.2, âgawkââs â--traditionalâ option no longer
disables interval expressions in regular expressions.
POSIX says that interval expressions containing repetition counts
greater than 255 produce unspecified results.
- In the manual for GNU 'grep', Paul Eggert notes the following:
+ In the manual for GNU âgrepâ, Paul Eggert notes the following:
Interval expressions may be implemented internally via repetition.
- For example, '^(a|bc){2,4}$' might be implemented as
- '^(a|bc)(a|bc)((a|bc)(a|bc)?)?$'. A large repetition count may
+ For example, â^(a|bc){2,4}$â might be implemented as
+ â^(a|bc)(a|bc)((a|bc)(a|bc)?)?$â. A large repetition count may
exhaust memory or greatly slow matching. Even small counts can
- cause problems if cascaded; for example, 'grep -E
- ".*{10,}{10,}{10,}{10,}{10,}"' is likely to overflow a stack.
+ cause problems if cascaded; for example, âgrep -E
+ ".*{10,}{10,}{10,}{10,}{10,}"â is likely to overflow a stack.
Fortunately, regular expressions like these are typically
artificial, and cascaded repetitions do not conform to POSIX so
cannot be used in portable programs anyway.
-This same caveat applies to 'gawk'.
+This same caveat applies to âgawkâ.
---------- Footnotes ----------
- (1) Use two backslashes if you're using a string constant with a
+ (1) Use two backslashes if youâre using a string constant with a
regexp operator or function.
@@ -4050,38 +4050,38 @@ File: gawk.info, Node: Bracket Expressions, Next:
Leftmost Longest, Prev: Reg
As mentioned earlier, a bracket expression matches any character among
those listed between the opening and closing square brackets.
- Within a bracket expression, a "range expression" consists of two
+ Within a bracket expression, a ârange expressionâ consists of two
characters separated by a hyphen. It matches any single character that
-sorts between the two characters, based upon the system's native
-character set. For example, '[0-9]' is equivalent to '[0123456789]'.
+sorts between the two characters, based upon the systemâs native
+character set. For example, â[0-9]â is equivalent to â[0123456789]â.
(See *note Ranges and Locales:: for an explanation of how the POSIX
-standard and 'gawk' have changed over time. This is mainly of
+standard and âgawkâ have changed over time. This is mainly of
historical interest.)
With the increasing popularity of the Unicode character standard
(http://www.unicode.org), there is an additional wrinkle to consider.
Octal and hexadecimal escape sequences inside bracket expressions are
taken to represent only single-byte characters (characters whose values
-fit within the range 0-256). To match a range of characters where the
+fit within the range 0â256). To match a range of characters where the
endpoints of the range are larger than 256, enter the multibyte
encodings of the characters directly.
- To include one of the characters '\', ']', '-', or '^' in a bracket
-expression, put a '\' in front of it. For example:
+ To include one of the characters â\â, â]â, â-â, or â^â in a
bracket
+expression, put a â\â in front of it. For example:
[d\]]
-matches either 'd' or ']'. Additionally, if you place ']' right after
-the opening '[', the closing bracket is treated as one of the characters
+matches either âdâ or â]â. Additionally, if you place â]â right
after
+the opening â[â, the closing bracket is treated as one of the characters
to be matched.
- The treatment of '\' in bracket expressions is compatible with other
-'awk' implementations and is also mandated by POSIX. The regular
-expressions in 'awk' are a superset of the POSIX specification for
+ The treatment of â\â in bracket expressions is compatible with other
+âawkâ implementations and is also mandated by POSIX. The regular
+expressions in âawkâ are a superset of the POSIX specification for
Extended Regular Expressions (EREs). POSIX EREs are based on the
-regular expressions accepted by the traditional 'egrep' utility.
+regular expressions accepted by the traditional âegrepâ utility.
- "Character classes" are a feature introduced in the POSIX standard.
+ âCharacter classesâ are a feature introduced in the POSIX standard.
A character class is a special notation for describing lists of
characters that have a specific attribute, but the actual characters can
vary from country to country and/or from character set to character set.
@@ -4089,79 +4089,79 @@ For example, the notion of what is an alphabetic
character differs
between the United States and France.
A character class is only valid in a regexp _inside_ the brackets of
-a bracket expression. Character classes consist of '[:', a keyword
-denoting the class, and ':]'. *note Table 3.1: table-char-classes.
+a bracket expression. Character classes consist of â[:â, a keyword
+denoting the class, and â:]â. *note Table 3.1: table-char-classes.
lists the character classes defined by the POSIX standard.
Class Meaning
--------------------------------------------------------------------------
-'[:alnum:]' Alphanumeric characters
-'[:alpha:]' Alphabetic characters
-'[:blank:]' Space and TAB characters
-'[:cntrl:]' Control characters
-'[:digit:]' Numeric characters
-'[:graph:]' Characters that are both printable and visible (a space is
- printable but not visible, whereas an 'a' is both)
-'[:lower:]' Lowercase alphabetic characters
-'[:print:]' Printable characters (characters that are not control
+â[:alnum:]â Alphanumeric characters
+â[:alpha:]â Alphabetic characters
+â[:blank:]â Space and TAB characters
+â[:cntrl:]â Control characters
+â[:digit:]â Numeric characters
+â[:graph:]â Characters that are both printable and visible (a space is
+ printable but not visible, whereas an âaâ is both)
+â[:lower:]â Lowercase alphabetic characters
+â[:print:]â Printable characters (characters that are not control
characters)
-'[:punct:]' Punctuation characters (characters that are not letters,
+â[:punct:]â Punctuation characters (characters that are not letters,
digits, control characters, or space characters)
-'[:space:]' Space characters (these are: space, TAB, newline, carriage
+â[:space:]â Space characters (these are: space, TAB, newline, carriage
return, formfeed and vertical tab)
-'[:upper:]' Uppercase alphabetic characters
-'[:xdigit:]'Characters that are hexadecimal digits
+â[:upper:]â Uppercase alphabetic characters
+â[:xdigit:]âCharacters that are hexadecimal digits
Table 3.1: POSIX character classes
For example, before the POSIX standard, you had to write
-'/[A-Za-z0-9]/' to match alphanumeric characters. If your character set
+â/[A-Za-z0-9]/â to match alphanumeric characters. If your character set
had other alphabetic characters in it, this would not match them. With
-the POSIX character classes, you can write '/[[:alnum:]]/' to match the
+the POSIX character classes, you can write â/[[:alnum:]]/â to match the
alphabetic and numeric characters in your character set.
Some utilities that match regular expressions provide a nonstandard
-'[:ascii:]' character class; 'awk' does not. However, you can simulate
-such a construct using '[\x00-\x7F]'. This matches all values
+â[:ascii:]â character class; âawkâ does not. However, you can simulate
+such a construct using â[\x00-\x7F]â. This matches all values
numerically between zero and 127, which is the defined range of the
-ASCII character set. Use a complemented character list ('[^\x00-\x7F]')
+ASCII character set. Use a complemented character list (â[^\x00-\x7F]â)
to match any single-byte characters that are not in the ASCII range.
- NOTE: Some older versions of Unix 'awk' treat '[:blank:]' like
- '[:space:]', incorrectly matching more characters than they should.
+ NOTE: Some older versions of Unix âawkâ treat â[:blank:]â like
+ â[:space:]â, incorrectly matching more characters than they should.
Caveat Emptor.
Two additional special sequences can appear in bracket expressions.
These apply to non-ASCII character sets, which can have single symbols
-(called "collating elements") that are represented with more than one
+(called âcollating elementsâ) that are represented with more than one
character. They can also have several characters that are equivalent
-for "collating", or sorting, purposes. (For example, in French, a plain
-"e" and a grave-accented "è" are equivalent.) These sequences are:
+for âcollatingâ, or sorting, purposes. (For example, in French, a plain
+âeâ and a grave-accented âèâ are equivalent.) These sequences are:
Collating symbols
- Multicharacter collating elements enclosed between '[.' and '.]'.
- For example, if 'ch' is a collating element, then '[[.ch.]]' is a
- regexp that matches this collating element, whereas '[ch]' is a
- regexp that matches either 'c' or 'h'.
+ Multicharacter collating elements enclosed between â[.â and â.]â.
+ For example, if âchâ is a collating element, then â[[.ch.]]â is a
+ regexp that matches this collating element, whereas â[ch]â is a
+ regexp that matches either âcâ or âhâ.
Equivalence classes
Locale-specific names for a list of characters that are equal. The
- name is enclosed between '[=' and '=]'. For example, the name 'e'
- might be used to represent all of "e," "ê," "è," and "é." In this
- case, '[[=e=]]' is a regexp that matches any of 'e', 'ê', 'é', or
- 'è'.
+ name is enclosed between â[=â and â=]â. For example, the name
âeâ
+ might be used to represent all of âe,â âê,â âè,â and
âé.â In this
+ case, â[[=e=]]â is a regexp that matches any of âeâ, âêâ,
âéâ, or
+ âèâ.
These features are very valuable in non-English-speaking locales.
- CAUTION: The library functions that 'gawk' uses for regular
+ CAUTION: The library functions that âgawkâ uses for regular
expression matching currently recognize only POSIX character
classes; they do not recognize collating symbols or equivalence
classes.
- Inside a bracket expression, an opening bracket ('[') that does not
+ Inside a bracket expression, an opening bracket (â[â) that does not
start a character class, collating element or equivalence class is taken
-literally. This is also true of '.' and '*'.
+literally. This is also true of â.â and â*â.
File: gawk.info, Node: Leftmost Longest, Next: Computed Regexps, Prev:
Bracket Expressions, Up: Regexp
@@ -4173,23 +4173,23 @@ Consider the following:
echo aaaabcd | awk '{ sub(/a+/, "<A>"); print }'
- This example uses the 'sub()' function to make a change to the input
-record. ('sub()' replaces the first instance of any text matched by the
+ This example uses the âsub()â function to make a change to the input
+record. (âsub()â replaces the first instance of any text matched by the
first argument with the string provided as the second argument; *note
-String Functions::.) Here, the regexp '/a+/' indicates "one or more 'a'
-characters," and the replacement text is '<A>'.
+String Functions::.) Here, the regexp â/a+/â indicates âone or more
âaâ
+characters,â and the replacement text is â<A>â.
- The input contains four 'a' characters. 'awk' (and POSIX) regular
+ The input contains four âaâ characters. âawkâ (and POSIX) regular
expressions always match the leftmost, _longest_ sequence of input
-characters that can match. Thus, all four 'a' characters are replaced
-with '<A>' in this example:
+characters that can match. Thus, all four âaâ characters are replaced
+with â<A>â in this example:
$ echo aaaabcd | awk '{ sub(/a+/, "<A>"); print }'
- -| <A>bcd
+ ⣠<A>bcd
For simple match/no-match tests, this is not so important. But when
-doing text matching and substitutions with the 'match()', 'sub()',
-'gsub()', and 'gensub()' functions, it is very important. *Note String
+doing text matching and substitutions with the âmatch()â, âsub()â,
+âgsub()â, and âgensub()â functions, it is very important. *Note String
Functions::, for more information on these functions. Understanding
this principle is also important for regexp-based record and field
splitting (*note Records::, and also *note Field Separators::).
@@ -4200,28 +4200,28 @@ File: gawk.info, Node: Computed Regexps, Next: GNU
Regexp Operators, Prev: Le
3.6 Using Dynamic Regexps
=========================
-The righthand side of a '~' or '!~' operator need not be a regexp
+The righthand side of a â~â or â!~â operator need not be a regexp
constant (i.e., a string of characters between slashes). It may be any
expression. The expression is evaluated and converted to a string if
necessary; the contents of the string are then used as the regexp. A
-regexp computed in this way is called a "dynamic regexp" or a "computed
-regexp":
+regexp computed in this way is called a âdynamic regexpâ or a âcomputed
+regexpâ:
BEGIN { digits_regexp = "[[:digit:]]+" }
$0 ~ digits_regexp { print }
-This sets 'digits_regexp' to a regexp that describes one or more digits,
+This sets âdigits_regexpâ to a regexp that describes one or more digits,
and tests whether the input record matches this regexp.
- NOTE: When using the '~' and '!~' operators, be aware that there is
+ NOTE: When using the â~â and â!~â operators, be aware that there
is
a difference between a regexp constant enclosed in slashes and a
string constant enclosed in double quotes. If you are going to use
a string constant, you have to understand that the string is, in
- essence, scanned _twice_: the first time when 'awk' reads your
+ essence, scanned _twice_: the first time when âawkâ reads your
program, and the second time when it goes to match the string on
the lefthand side of the operator with the pattern on the right.
This is true of any string-valued expression (such as
- 'digits_regexp', shown in the previous example), not just string
+ âdigits_regexpâ, shown in the previous example), not just string
constants.
What difference does it make if the string is scanned twice? The
@@ -4229,144 +4229,144 @@ answer has to do with escape sequences, and
particularly with
backslashes. To get a backslash into a regular expression inside a
string, you have to type two backslashes.
- For example, '/\*/' is a regexp constant for a literal '*'. Only one
+ For example, â/\*/â is a regexp constant for a literal â*â. Only
one
backslash is needed. To do the same thing with a string, you have to
-type '"\\*"'. The first backslash escapes the second one so that the
-string actually contains the two characters '\' and '*'.
+type â"\\*"â. The first backslash escapes the second one so that the
+string actually contains the two characters â\â and â*â.
Given that you can use both regexp and string constants to describe
-regular expressions, which should you use? The answer is "regexp
-constants," for several reasons:
+regular expressions, which should you use? The answer is âregexp
+constants,â for several reasons:
- * String constants are more complicated to write and more difficult
+ ⢠String constants are more complicated to write and more difficult
to read. Using regexp constants makes your programs less
error-prone. Not understanding the difference between the two
kinds of constants is a common source of errors.
- * It is more efficient to use regexp constants. 'awk' can note that
+ ⢠It is more efficient to use regexp constants. âawkâ can note that
you have supplied a regexp and store it internally in a form that
makes pattern matching more efficient. When using a string
- constant, 'awk' must first convert the string into this internal
+ constant, âawkâ must first convert the string into this internal
form and then perform the pattern matching.
- * Using regexp constants is better form; it shows clearly that you
+ ⢠Using regexp constants is better form; it shows clearly that you
intend a regexp match.
- Using '\n' in Bracket Expressions of Dynamic Regexps
+ Using â\nâ in Bracket Expressions of Dynamic Regexps
- Some older versions of 'awk' do not allow the newline character to be
+ Some older versions of âawkâ do not allow the newline character to be
used inside a bracket expression for a dynamic regexp:
$ awk '$0 ~ "[ \t\n]"'
- error-> awk: newline in character class [
- error-> ]...
- error-> source line number 1
- error-> context is
- error-> $0 ~ "[ >>> \t\n]" <<<
+ errorâ awk: newline in character class [
+ errorâ ]...
+ errorâ source line number 1
+ errorâ context is
+ errorâ $0 ~ "[ >>> \t\n]" <<<
But a newline in a regexp constant works with no problem:
$ awk '$0 ~ /[ \t\n]/'
here is a sample line
- -| here is a sample line
+ ⣠here is a sample line
Ctrl-d
- 'gawk' does not have this problem, and it isn't likely to occur often
-in practice, but it's worth noting for future reference.
+ âgawkâ does not have this problem, and it isnât likely to occur often
+in practice, but itâs worth noting for future reference.
File: gawk.info, Node: GNU Regexp Operators, Next: Case-sensitivity, Prev:
Computed Regexps, Up: Regexp
-3.7 'gawk'-Specific Regexp Operators
+3.7 âgawkâ-Specific Regexp Operators
====================================
GNU software that deals with regular expressions provides a number of
additional regexp operators. These operators are described in this
-minor node and are specific to 'gawk'; they are not available in other
-'awk' implementations. Most of the additional operators deal with word
-matching. For our purposes, a "word" is a sequence of one or more
-letters, digits, or underscores ('_'):
+minor node and are specific to âgawkâ; they are not available in other
+âawkâ implementations. Most of the additional operators deal with word
+matching. For our purposes, a âwordâ is a sequence of one or more
+letters, digits, or underscores (â_â):
-'\s'
+â\sâ
Matches any space character as defined by the current locale.
- Think of it as shorthand for '[[:space:]]'.
+ Think of it as shorthand for â[[:space:]]â.
-'\S'
+â\Sâ
Matches any character that is not a space, as defined by the
- current locale. Think of it as shorthand for '[^[:space:]]'.
+ current locale. Think of it as shorthand for â[^[:space:]]â.
-'\w'
- Matches any word-constituent character--that is, it matches any
+â\wâ
+ Matches any word-constituent characterâthat is, it matches any
letter, digit, or underscore. Think of it as shorthand for
- '[[:alnum:]_]'.
+ â[[:alnum:]_]â.
-'\W'
+â\Wâ
Matches any character that is not word-constituent. Think of it as
- shorthand for '[^[:alnum:]_]'.
+ shorthand for â[^[:alnum:]_]â.
-'\<'
+â\<â
Matches the empty string at the beginning of a word. For example,
- '/\<away/' matches 'away' but not 'stowaway'.
+ â/\<away/â matches âawayâ but not âstowawayâ.
-'\>'
+â\>â
Matches the empty string at the end of a word. For example,
- '/stow\>/' matches 'stow' but not 'stowaway'.
+ â/stow\>/â matches âstowâ but not âstowawayâ.
-'\y'
+â\yâ
Matches the empty string at either the beginning or the end of a
- word (i.e., the word boundar*y*). For example, '\yballs?\y'
- matches either 'ball' or 'balls', as a separate word.
+ word (i.e., the word boundar*y*). For example, â\yballs?\yâ
+ matches either âballâ or âballsâ, as a separate word.
-'\B'
+â\Bâ
Matches the empty string that occurs between two word-constituent
- characters. For example, '/\Brat\B/' matches 'crate', but it does
- not match 'dirty rat'. '\B' is essentially the opposite of '\y'.
- Another way to think of this is that '\B' matches the empty string
- provided it's not at the edge of a word.
+ characters. For example, â/\Brat\B/â matches âcrateâ, but it does
+ not match âdirty ratâ. â\Bâ is essentially the opposite of
â\yâ.
+ Another way to think of this is that â\Bâ matches the empty string
+ provided itâs not at the edge of a word.
There are two other operators that work on buffers. In Emacs, a
-"buffer" is, naturally, an Emacs buffer. Other GNU programs, including
-'gawk', consider the entire string to match as the buffer. The
+âbufferâ is, naturally, an Emacs buffer. Other GNU programs, including
+âgawkâ, consider the entire string to match as the buffer. The
operators are:
-'\`'
+â\`â
Matches the empty string at the beginning of a buffer (string)
-'\''
+â\'â
Matches the empty string at the end of a buffer (string)
- Because '^' and '$' always work in terms of the beginning and end of
-strings, these operators don't add any new capabilities for 'awk'. They
+ Because â^â and â$â always work in terms of the beginning and end of
+strings, these operators donât add any new capabilities for âawkâ. They
are provided for compatibility with other GNU software.
- In other GNU software, the word-boundary operator is '\b'. However,
-that conflicts with the 'awk' language's definition of '\b' as
-backspace, so 'gawk' uses a different letter. An alternative method
+ In other GNU software, the word-boundary operator is â\bâ. However,
+that conflicts with the âawkâ languageâs definition of â\bâ as
+backspace, so âgawkâ uses a different letter. An alternative method
would have been to require two backslashes in the GNU operators, but
-this was deemed too confusing. The current method of using '\y' for the
-GNU '\b' appears to be the lesser of two evils.
+this was deemed too confusing. The current method of using â\yâ for the
+GNU â\bâ appears to be the lesser of two evils.
- The various command-line options (*note Options::) control how 'gawk'
+ The various command-line options (*note Options::) control how âgawkâ
interprets characters in regexps:
No options
- In the default case, 'gawk' provides all the facilities of POSIX
+ In the default case, âgawkâ provides all the facilities of POSIX
regexps and the GNU regexp operators described in *note Regexp
Operators::.
-'--posix'
+â--posixâ
Match only POSIX regexps; the GNU operators are not special (e.g.,
- '\w' matches a literal 'w'). Interval expressions are allowed.
+ â\wâ matches a literal âwâ). Interval expressions are allowed.
-'--traditional'
- Match traditional Unix 'awk' regexps. The GNU operators are not
- special. Because BWK 'awk' supports them, the POSIX character
- classes ('[[:alnum:]]', etc.) are available. So too, interval
+â--traditionalâ
+ Match traditional Unix âawkâ regexps. The GNU operators are not
+ special. Because BWK âawkâ supports them, the POSIX character
+ classes (â[[:alnum:]]â, etc.) are available. So too, interval
expressions are allowed. Characters described by octal and
hexadecimal escape sequences are treated literally, even if they
represent regexp metacharacters.
-'--re-interval'
+â--re-intervalâ
This option remains for backwards compatibility but no longer has
any real effect.
@@ -4378,32 +4378,32 @@ File: gawk.info, Node: Case-sensitivity, Next: Regexp
Summary, Prev: GNU Rege
Case is normally significant in regular expressions, both when matching
ordinary characters (i.e., not metacharacters) and inside bracket
-expressions. Thus, a 'w' in a regular expression matches only a
-lowercase 'w' and not an uppercase 'W'.
+expressions. Thus, a âwâ in a regular expression matches only a
+lowercase âwâ and not an uppercase âWâ.
The simplest way to do a case-independent match is to use a bracket
-expression--for example, '[Ww]'. However, this can be cumbersome if you
+expressionâfor example, â[Ww]â. However, this can be cumbersome if you
need to use it often, and it can make the regular expressions harder to
read. There are two alternatives that you might prefer.
One way to perform a case-insensitive match at a particular point in
the program is to convert the data to a single case, using the
-'tolower()' or 'toupper()' built-in string functions (which we haven't
+âtolower()â or âtoupper()â built-in string functions (which we
havenât
discussed yet; *note String Functions::). For example:
tolower($1) ~ /foo/ { ... }
converts the first field to lowercase before matching against it. This
-works in any POSIX-compliant 'awk'.
+works in any POSIX-compliant âawkâ.
- Another method, specific to 'gawk', is to set the variable
-'IGNORECASE' to a nonzero value (*note Built-in Variables::). When
-'IGNORECASE' is not zero, _all_ regexp and string operations ignore
+ Another method, specific to âgawkâ, is to set the variable
+âIGNORECASEâ to a nonzero value (*note Built-in Variables::). When
+âIGNORECASEâ is not zero, _all_ regexp and string operations ignore
case.
- Changing the value of 'IGNORECASE' dynamically controls the case
+ Changing the value of âIGNORECASEâ dynamically controls the case
sensitivity of the program as it runs. Case is significant by default
-because 'IGNORECASE' (like most variables) is initialized to zero:
+because âIGNORECASEâ (like most variables) is initialized to zero:
x = "aB"
if (x ~ /ab/) ... # this test will fail
@@ -4411,38 +4411,38 @@ because 'IGNORECASE' (like most variables) is
initialized to zero:
IGNORECASE = 1
if (x ~ /ab/) ... # now it will succeed
- In general, you cannot use 'IGNORECASE' to make certain rules case
+ In general, you cannot use âIGNORECASEâ to make certain rules case
insensitive and other rules case sensitive, as there is no
-straightforward way to set 'IGNORECASE' just for the pattern of a
+straightforward way to set âIGNORECASEâ just for the pattern of a
particular rule.(1) To do this, use either bracket expressions or
-'tolower()'. However, one thing you can do with 'IGNORECASE' only is
+âtolower()â. However, one thing you can do with âIGNORECASEâ only is
dynamically turn case sensitivity on or off for all the rules at once.
- 'IGNORECASE' can be set on the command line or in a 'BEGIN' rule
+ âIGNORECASEâ can be set on the command line or in a âBEGINâ rule
(*note Other Arguments::; also *note Using BEGIN/END::). Setting
-'IGNORECASE' from the command line is a way to make a program case
+âIGNORECASEâ from the command line is a way to make a program case
insensitive without having to edit it.
In multibyte locales, the equivalences between upper- and lowercase
-characters are tested based on the wide-character values of the locale's
+characters are tested based on the wide-character values of the localeâs
character set. Prior to version 5.0, single-byte characters were tested
based on the ISO-8859-1 (ISO Latin-1) character set. However, as of
version 5.0, single-byte characters are also tested based on the values
-of the locale's character set.(2)
+of the localeâs character set.(2)
- The value of 'IGNORECASE' has no effect if 'gawk' is in compatibility
+ The value of âIGNORECASEâ has no effect if âgawkâ is in
compatibility
mode (*note Options::). Case is always significant in compatibility
mode.
---------- Footnotes ----------
(1) Experienced C and C++ programmers will note that it is possible,
-using something like 'IGNORECASE = 1 && /foObAr/ { ... }' and
-'IGNORECASE = 0 || /foobar/ { ... }'. However, this is somewhat obscure
-and we don't recommend it.
+using something like âIGNORECASE = 1 && /foObAr/ { ... }â and
+âIGNORECASE = 0 || /foobar/ { ... }â. However, this is somewhat obscure
+and we donât recommend it.
- (2) If you don't understand this, don't worry about it; it just means
-that 'gawk' does the right thing.
+ (2) If you donât understand this, donât worry about it; it just means
+that âgawkâ does the right thing.
File: gawk.info, Node: Regexp Summary, Prev: Case-sensitivity, Up: Regexp
@@ -4450,36 +4450,36 @@ File: gawk.info, Node: Regexp Summary, Prev:
Case-sensitivity, Up: Regexp
3.9 Summary
===========
- * Regular expressions describe sets of strings to be matched. In
- 'awk', regular expression constants are written enclosed between
- slashes: '/'...'/'.
+ ⢠Regular expressions describe sets of strings to be matched. In
+ âawkâ, regular expression constants are written enclosed between
+ slashes: â/â...â/â.
- * Regexp constants may be used standalone in patterns and in
+ ⢠Regexp constants may be used standalone in patterns and in
conditional expressions, or as part of matching expressions using
- the '~' and '!~' operators.
+ the â~â and â!~â operators.
- * Escape sequences let you represent nonprintable characters and also
+ ⢠Escape sequences let you represent nonprintable characters and also
let you represent regexp metacharacters as literal characters to be
matched.
- * Regexp operators provide grouping, alternation, and repetition.
+ ⢠Regexp operators provide grouping, alternation, and repetition.
- * Bracket expressions give you a shorthand for specifying sets of
+ ⢠Bracket expressions give you a shorthand for specifying sets of
characters that can match at a particular point in a regexp.
Within bracket expressions, POSIX character classes let you specify
certain groups of characters in a locale-independent fashion.
- * Regular expressions match the leftmost longest text in the string
+ ⢠Regular expressions match the leftmost longest text in the string
being matched. This matters for cases where you need to know the
extent of the match, such as for text substitution and when the
record separator is a regexp.
- * Matching expressions may use dynamic regexps (i.e., string values
+ ⢠Matching expressions may use dynamic regexps (i.e., string values
treated as regular expressions).
- * 'gawk''s 'IGNORECASE' variable lets you control the case
- sensitivity of regexp matching. In other 'awk' versions, use
- 'tolower()' or 'toupper()'.
+ ⢠âgawkââs âIGNORECASEâ variable lets you control the case
+ sensitivity of regexp matching. In other âawkâ versions, use
+ âtolower()â or âtoupper()â.
File: gawk.info, Node: Reading Files, Next: Printing, Prev: Regexp, Up: Top
@@ -4487,24 +4487,24 @@ File: gawk.info, Node: Reading Files, Next: Printing,
Prev: Regexp, Up: Top
4 Reading Input Files
*********************
-In the typical 'awk' program, 'awk' reads all input either from the
+In the typical âawkâ program, âawkâ reads all input either from the
standard input (by default, this is the keyboard, but often it is a pipe
-from another command) or from files whose names you specify on the 'awk'
-command line. If you specify input files, 'awk' reads them in order,
+from another command) or from files whose names you specify on the âawkâ
+command line. If you specify input files, âawkâ reads them in order,
processing all the data from one before going on to the next. The name
of the current input file can be found in the predefined variable
-'FILENAME' (*note Built-in Variables::).
+âFILENAMEâ (*note Built-in Variables::).
- The input is read in units called "records", and is processed by the
+ The input is read in units called ârecordsâ, and is processed by the
rules of your program one record at a time. By default, each record is
one line. Each record is automatically split into chunks called
-"fields". This makes it more convenient for programs to work on the
+âfieldsâ. This makes it more convenient for programs to work on the
parts of a record.
- On rare occasions, you may need to use the 'getline' command. The
-'getline' command is valuable both because it can do explicit input from
+ On rare occasions, you may need to use the âgetlineâ command. The
+âgetlineâ command is valuable both because it can do explicit input from
any number of files, and because the files used with it do not have to
-be named on the 'awk' command line (*note Getline::).
+be named on the âawkâ command line (*note Getline::).
* Menu:
@@ -4515,11 +4515,11 @@ be named on the 'awk' command line (*note Getline::).
* Field Separators:: The field separator and how to change it.
* Constant Size:: Reading constant width data.
* Splitting By Content:: Defining Fields By Content
-* Testing field creation:: Checking how 'gawk' is splitting
+* Testing field creation:: Checking how âgawkâ is splitting
records.
* Multiple Line:: Reading multiline records.
* Getline:: Reading files under explicit program control
- using the 'getline' function.
+ using the âgetlineâ function.
* Read Timeout:: Reading input with a timeout.
* Retrying Input:: Retrying input after certain errors.
* Command-line directories:: What happens if you put a directory on the
@@ -4533,252 +4533,252 @@ File: gawk.info, Node: Records, Next: Fields, Up:
Reading Files
4.1 How Input Is Split into Records
===================================
-'awk' divides the input for your program into records and fields. It
+âawkâ divides the input for your program into records and fields. It
keeps track of the number of records that have been read so far from the
current input file. This value is stored in a predefined variable
-called 'FNR', which is reset to zero every time a new file is started.
-Another predefined variable, 'NR', records the total number of input
+called âFNRâ, which is reset to zero every time a new file is started.
+Another predefined variable, âNRâ, records the total number of input
records read so far from all data files. It starts at zero, but is
never automatically reset to zero.
Normally, records are separated by newline characters. You can
control how records are separated by assigning values to the built-in
-variable 'RS'. If 'RS' is any single character, that character
-separates records. Otherwise (in 'gawk'), 'RS' is treated as a regular
+variable âRSâ. If âRSâ is any single character, that character
+separates records. Otherwise (in âgawkâ), âRSâ is treated as a regular
expression. This mechanism is explained in greater detail shortly.
* Menu:
-* awk split records:: How standard 'awk' splits records.
-* gawk split records:: How 'gawk' splits records.
+* awk split records:: How standard âawkâ splits records.
+* gawk split records:: How âgawkâ splits records.
File: gawk.info, Node: awk split records, Next: gawk split records, Up:
Records
-4.1.1 Record Splitting with Standard 'awk'
+4.1.1 Record Splitting with Standard âawkâ
------------------------------------------
-Records are separated by a character called the "record separator". By
+Records are separated by a character called the ârecord separatorâ. By
default, the record separator is the newline character. This is why
records are, by default, single lines. To use a different character for
the record separator, simply assign that character to the predefined
-variable 'RS'.
+variable âRSâ.
- Like any other variable, the value of 'RS' can be changed in the
-'awk' program with the assignment operator, '=' (*note Assignment
+ Like any other variable, the value of âRSâ can be changed in the
+âawkâ program with the assignment operator, â=â (*note Assignment
Ops::). The new record-separator character should be enclosed in
quotation marks, which indicate a string constant. Often, the right
time to do this is at the beginning of execution, before any input is
processed, so that the very first record is read with the proper
-separator. To do this, use the special 'BEGIN' pattern (*note
+separator. To do this, use the special âBEGINâ pattern (*note
BEGIN/END::). For example:
awk 'BEGIN { RS = "u" }
{ print $0 }' mail-list
-changes the value of 'RS' to 'u', before reading any input. The new
-value is a string whose first character is the letter "u"; as a result,
-records are separated by the letter "u". Then the input file is read,
-and the second rule in the 'awk' program (the action with no pattern)
-prints each record. Because each 'print' statement adds a newline at
-the end of its output, this 'awk' program copies the input with each 'u'
+changes the value of âRSâ to âuâ, before reading any input. The new
+value is a string whose first character is the letter âuâ; as a result,
+records are separated by the letter âuâ. Then the input file is read,
+and the second rule in the âawkâ program (the action with no pattern)
+prints each record. Because each âprintâ statement adds a newline at
+the end of its output, this âawkâ program copies the input with each
âuâ
changed to a newline. Here are the results of running the program on
-'mail-list':
+âmail-listâ:
$ awk 'BEGIN { RS = "u" }
> { print $0 }' mail-list
- -| Amelia 555-5553 amelia.zodiac
- -| sq
- -| e@gmail.com F
- -| Anthony 555-3412 anthony.assert
- -| ro@hotmail.com A
- -| Becky 555-7685 becky.algebrar
- -| m@gmail.com A
- -| Bill 555-1675 bill.drowning@hotmail.com A
- -| Broderick 555-0542 broderick.aliq
- -| otiens@yahoo.com R
- -| Camilla 555-2912 camilla.inf
- -| sar
- -| m@skynet.be R
- -| Fabi
- -| s 555-1234 fabi
- -| s.
- -| ndevicesim
- -| s@
- -| cb.ed
- -| F
- -| J
- -| lie 555-6699 j
- -| lie.perscr
- -| tabor@skeeve.com F
- -| Martin 555-6480 martin.codicib
- -| s@hotmail.com A
- -| Sam
- -| el 555-3430 sam
- -| el.lanceolis@sh
- -| .ed
- -| A
- -| Jean-Pa
- -| l 555-2127 jeanpa
- -| l.campanor
- -| m@ny
- -| .ed
- -| R
- -|
-
-Note that the entry for the name 'Bill' is not split. In the original
+ ⣠Amelia 555-5553 amelia.zodiac
+ ⣠sq
+ ⣠e@gmail.com F
+ ⣠Anthony 555-3412 anthony.assert
+ ⣠ro@hotmail.com A
+ ⣠Becky 555-7685 becky.algebrar
+ ⣠m@gmail.com A
+ ⣠Bill 555-1675 bill.drowning@hotmail.com A
+ ⣠Broderick 555-0542 broderick.aliq
+ ⣠otiens@yahoo.com R
+ ⣠Camilla 555-2912 camilla.inf
+ ⣠sar
+ ⣠m@skynet.be R
+ ⣠Fabi
+ ⣠s 555-1234 fabi
+ ⣠s.
+ ⣠ndevicesim
+ ⣠s@
+ ⣠cb.ed
+ ⣠F
+ ⣠J
+ ⣠lie 555-6699 j
+ ⣠lie.perscr
+ ⣠tabor@skeeve.com F
+ ⣠Martin 555-6480 martin.codicib
+ ⣠s@hotmail.com A
+ ⣠Sam
+ ⣠el 555-3430 sam
+ ⣠el.lanceolis@sh
+ ⣠.ed
+ ⣠A
+ ⣠Jean-Pa
+ ⣠l 555-2127 jeanpa
+ ⣠l.campanor
+ ⣠m@ny
+ ⣠.ed
+ ⣠R
+ â£
+
+Note that the entry for the name âBillâ is not split. In the original
data file (*note Sample Data Files::), the line looks like this:
Bill 555-1675 bill.drowning@hotmail.com A
-It contains no 'u', so there is no reason to split the record, unlike
-the others, which each have one or more occurrences of the 'u'. In
+It contains no âuâ, so there is no reason to split the record, unlike
+the others, which each have one or more occurrences of the âuâ. In
fact, this record is treated as part of the previous record; the newline
separating them in the output is the original newline in the data file,
-not the one added by 'awk' when it printed the record!
+not the one added by âawkâ when it printed the record!
Another way to change the record separator is on the command line,
using the variable-assignment feature (*note Other Arguments::):
awk '{ print $0 }' RS="u" mail-list
-This sets 'RS' to 'u' before processing 'mail-list'.
+This sets âRSâ to âuâ before processing âmail-listâ.
- Using an alphabetic character such as 'u' for the record separator is
+ Using an alphabetic character such as âuâ for the record separator is
highly likely to produce strange results. Using an unusual character
-such as '/' is more likely to produce correct behavior in the majority
+such as â/â is more likely to produce correct behavior in the majority
of cases, but there are no guarantees. The moral is: Know Your Data.
- 'gawk' allows 'RS' to be a full regular expression (discussed
+ âgawkâ allows âRSâ to be a full regular expression (discussed
shortly; *note gawk split records::). Even so, using a regular
-expression metacharacter, such as '.' as the single character in the
-value of 'RS' has no special effect: it is treated literally. This is
-required for backwards compatibility with both Unix 'awk' and with
+expression metacharacter, such as â.â as the single character in the
+value of âRSâ has no special effect: it is treated literally. This is
+required for backwards compatibility with both Unix âawkâ and with
POSIX.
Reaching the end of an input file terminates the current input
record, even if the last character in the file is not the character in
-'RS'. (d.c.)
+âRSâ. (d.c.)
- The empty string '""' (a string without any characters) has a special
-meaning as the value of 'RS'. It means that records are separated by
+ The empty string â""â (a string without any characters) has a special
+meaning as the value of âRSâ. It means that records are separated by
one or more blank lines and nothing else. *Note Multiple Line:: for
more details.
- If you change the value of 'RS' in the middle of an 'awk' run, the
+ If you change the value of âRSâ in the middle of an âawkâ run, the
new value is used to delimit subsequent records, but the record
currently being processed, as well as records already processed, are not
affected.
- After the end of the record has been determined, 'gawk' sets the
-variable 'RT' to the text in the input that matched 'RS'.
+ After the end of the record has been determined, âgawkâ sets the
+variable âRTâ to the text in the input that matched âRSâ.
File: gawk.info, Node: gawk split records, Prev: awk split records, Up:
Records
-4.1.2 Record Splitting with 'gawk'
+4.1.2 Record Splitting with âgawkâ
----------------------------------
-When using 'gawk', the value of 'RS' is not limited to a one-character
+When using âgawkâ, the value of âRSâ is not limited to a one-character
string. If it contains more than one character, it is treated as a
regular expression (*note Regexp::). (c.e.) In general, each record
ends at the next string that matches the regular expression; the next
record starts at the end of the matching string. This general rule is
-actually at work in the usual case, where 'RS' contains just a newline:
+actually at work in the usual case, where âRSâ contains just a newline:
a record ends at the beginning of the next matching string (the next
newline in the input), and the following record starts just after the
end of this string (at the first character of the following line). The
-newline, because it matches 'RS', is not part of either record.
+newline, because it matches âRSâ, is not part of either record.
- When 'RS' is a single character, 'RT' contains the same single
-character. However, when 'RS' is a regular expression, 'RT' contains
+ When âRSâ is a single character, âRTâ contains the same single
+character. However, when âRSâ is a regular expression, âRTâ contains
the actual input text that matched the regular expression.
- If the input file ends without any text matching 'RS', 'gawk' sets
-'RT' to the null string.
+ If the input file ends without any text matching âRSâ, âgawkâ sets
+âRTâ to the null string.
The following example illustrates both of these features. It sets
-'RS' equal to a regular expression that matches either a newline or a
+âRSâ equal to a regular expression that matches either a newline or a
series of one or more uppercase letters with optional leading and/or
trailing whitespace:
$ echo record 1 AAAA record 2 BBBB record 3 |
> gawk 'BEGIN { RS = "\n|( *[[:upper:]]+ *)" }
> { print "Record =", $0,"and RT = [" RT "]" }'
- -| Record = record 1 and RT = [ AAAA ]
- -| Record = record 2 and RT = [ BBBB ]
- -| Record = record 3 and RT = [
- -| ]
-
-The square brackets delineate the contents of 'RT', letting you see the
-leading and trailing whitespace. The final value of 'RT' is a newline.
-*Note Simple Sed:: for a more useful example of 'RS' as a regexp and
-'RT'.
-
- If you set 'RS' to a regular expression that allows optional trailing
-text, such as 'RS = "abc(XYZ)?"', it is possible, due to implementation
-constraints, that 'gawk' may match the leading part of the regular
+ ⣠Record = record 1 and RT = [ AAAA ]
+ ⣠Record = record 2 and RT = [ BBBB ]
+ ⣠Record = record 3 and RT = [
+ ⣠]
+
+The square brackets delineate the contents of âRTâ, letting you see the
+leading and trailing whitespace. The final value of âRTâ is a newline.
+*Note Simple Sed:: for a more useful example of âRSâ as a regexp and
+âRTâ.
+
+ If you set âRSâ to a regular expression that allows optional trailing
+text, such as âRS = "abc(XYZ)?"â, it is possible, due to implementation
+constraints, that âgawkâ may match the leading part of the regular
expression, but not the trailing part, particularly if the input text
-that could match the trailing part is fairly long. 'gawk' attempts to
-avoid this problem, but currently, there's no guarantee that this will
+that could match the trailing part is fairly long. âgawkâ attempts to
+avoid this problem, but currently, thereâs no guarantee that this will
never happen.
- Caveats When Using Regular Expressions for 'RS'
+ Caveats When Using Regular Expressions for âRSâ
- Remember that in 'awk', the '^' and '$' anchor metacharacters match
+ Remember that in âawkâ, the â^â and â$â anchor metacharacters
match
the beginning and end of a _string_, and not the beginning and end of a
-_line_. As a result, something like 'RS = "^[[:upper:]]"' can only
-match at the beginning of a file. This is because 'gawk' views the
+_line_. As a result, something like âRS = "^[[:upper:]]"â can only
+match at the beginning of a file. This is because âgawkâ views the
input file as one long string that happens to contain newline
characters. It is thus best to avoid anchor metacharacters in the value
-of 'RS'.
+of âRSâ.
Record splitting with regular expressions works differently than
-regexp matching with the 'sub()', 'gsub()', and 'gensub()' (*note String
+regexp matching with the âsub()â, âgsub()â, and âgensub()â (*note
String
Functions::). Those functions allow a regexp to match the empty string;
-record splitting does not. Thus, for example 'RS = "()"' does _not_
+record splitting does not. Thus, for example âRS = "()"â does _not_
split records between characters.
- The use of 'RS' as a regular expression and the 'RT' variable are
-'gawk' extensions; they are not available in compatibility mode (*note
+ The use of âRSâ as a regular expression and the âRTâ variable are
+âgawkâ extensions; they are not available in compatibility mode (*note
Options::). In compatibility mode, only the first character of the
-value of 'RS' determines the end of the record.
+value of âRSâ determines the end of the record.
- 'mawk' has allowed 'RS' to be a regexp for decades. As of October,
-2019, BWK 'awk' also supports it. Neither version supplies 'RT',
+ âmawkâ has allowed âRSâ to be a regexp for decades. As of October,
+2019, BWK âawkâ also supports it. Neither version supplies âRTâ,
however.
- 'RS = "\0"' Is Not Portable
+ âRS = "\0"â Is Not Portable
There are times when you might want to treat an entire data file as a
-single record. The only way to make this happen is to give 'RS' a value
-that you know doesn't occur in the input file. This is hard to do in a
+single record. The only way to make this happen is to give âRSâ a value
+that you know doesnât occur in the input file. This is hard to do in a
general way, such that a program always works for arbitrary input files.
You might think that for text files, the NUL character, which
consists of a character with all bits equal to zero, is a good value to
-use for 'RS' in this case:
+use for âRSâ in this case:
BEGIN { RS = "\0" } # whole file becomes one record?
- 'gawk' in fact accepts this, and uses the NUL character for the
+ âgawkâ in fact accepts this, and uses the NUL character for the
record separator. This works for certain special files, such as
-'/proc/environ' on GNU/Linux systems, where the NUL character is in fact
+â/proc/environâ on GNU/Linux systems, where the NUL character is in fact
the record separator. However, this usage is _not_ portable to most
-other 'awk' implementations.
+other âawkâ implementations.
- Almost all other 'awk' implementations(1) store strings internally as
+ Almost all other âawkâ implementations(1) store strings internally as
C-style strings. C strings use the NUL character as the string
-terminator. In effect, this means that 'RS = "\0"' is the same as 'RS =
-""'. (d.c.)
+terminator. In effect, this means that âRS = "\0"â is the same as âRS =
+""â. (d.c.)
- It happens that recent versions of 'mawk' can use the NUL character
-as a record separator. However, this is a special case: 'mawk' does not
+ It happens that recent versions of âmawkâ can use the NUL character
+as a record separator. However, this is a special case: âmawkâ does not
allow embedded NUL characters in strings. (This may change in a future
-version of 'mawk'.)
+version of âmawkâ.)
*Note Readfile Function:: for an interesting way to read whole files.
-If you are using 'gawk', see *note Extension Sample Readfile:: for
+If you are using âgawkâ, see *note Extension Sample Readfile:: for
another option.
---------- Footnotes ----------
@@ -4791,61 +4791,61 @@ File: gawk.info, Node: Fields, Next: Nonconstant
Fields, Prev: Records, Up:
4.2 Examining Fields
====================
-When 'awk' reads an input record, the record is automatically "parsed"
-or separated by the 'awk' utility into chunks called "fields". By
-default, fields are separated by "whitespace", like words in a line.
-Whitespace in 'awk' means any string of one or more spaces, TABs, or
+When âawkâ reads an input record, the record is automatically âparsedâ
+or separated by the âawkâ utility into chunks called âfieldsâ. By
+default, fields are separated by âwhitespaceâ, like words in a line.
+Whitespace in âawkâ means any string of one or more spaces, TABs, or
newlines; other characters that are considered whitespace by other
languages (such as formfeed, vertical tab, etc.) are _not_ considered
-whitespace by 'awk'.
+whitespace by âawkâ.
The purpose of fields is to make it more convenient for you to refer
-to these pieces of the record. You don't have to use them--you can
-operate on the whole record if you want--but fields are what make simple
-'awk' programs so powerful.
-
- You use a dollar sign ('$') to refer to a field in an 'awk' program,
-followed by the number of the field you want. Thus, '$1' refers to the
-first field, '$2' to the second, and so on. (Unlike in the Unix shells,
-the field numbers are not limited to single digits. '$127' is the 127th
+to these pieces of the record. You donât have to use themâyou can
+operate on the whole record if you wantâbut fields are what make simple
+âawkâ programs so powerful.
+
+ You use a dollar sign (â$â) to refer to a field in an âawkâ program,
+followed by the number of the field you want. Thus, â$1â refers to the
+first field, â$2â to the second, and so on. (Unlike in the Unix shells,
+the field numbers are not limited to single digits. â$127â is the 127th
field in the record.) For example, suppose the following is a line of
input:
This seems like a pretty nice example.
-Here the first field, or '$1', is 'This', the second field, or '$2', is
-'seems', and so on. Note that the last field, '$7', is 'example.'.
-Because there is no space between the 'e' and the '.', the period is
+Here the first field, or â$1â, is âThisâ, the second field, or
â$2â, is
+âseemsâ, and so on. Note that the last field, â$7â, is âexample.â.
+Because there is no space between the âeâ and the â.â, the period is
considered part of the seventh field.
- 'NF' is a predefined variable whose value is the number of fields in
-the current record. 'awk' automatically updates the value of 'NF' each
+ âNFâ is a predefined variable whose value is the number of fields in
+the current record. âawkâ automatically updates the value of âNFâ each
time it reads a record. No matter how many fields there are, the last
-field in a record can be represented by '$NF'. So, '$NF' is the same as
-'$7', which is 'example.'. If you try to reference a field beyond the
-last one (such as '$8' when the record has only seven fields), you get
+field in a record can be represented by â$NFâ. So, â$NFâ is the same
as
+â$7â, which is âexample.â. If you try to reference a field beyond the
+last one (such as â$8â when the record has only seven fields), you get
the empty string. (If used in a numeric operation, you get zero.)
- The use of '$0', which looks like a reference to the "zeroth" field,
+ The use of â$0â, which looks like a reference to the âzerothâ field,
is a special case: it represents the whole input record. Use it when
you are not interested in specific fields. Here are some more examples:
$ awk '$1 ~ /li/ { print $0 }' mail-list
- -| Amelia 555-5553 amelia.zodiacusque@gmail.com F
- -| Julie 555-6699 julie.perscrutabor@skeeve.com F
+ ⣠Amelia 555-5553 amelia.zodiacusque@gmail.com F
+ ⣠Julie 555-6699 julie.perscrutabor@skeeve.com F
-This example prints each record in the file 'mail-list' whose first
-field contains the string 'li'.
+This example prints each record in the file âmail-listâ whose first
+field contains the string âliâ.
- By contrast, the following example looks for 'li' in _the entire
+ By contrast, the following example looks for âliâ in _the entire
record_ and prints the first and last fields for each matching input
record:
$ awk '/li/ { print $1, $NF }' mail-list
- -| Amelia F
- -| Broderick R
- -| Julie F
- -| Samuel A
+ ⣠Amelia F
+ ⣠Broderick R
+ ⣠Julie F
+ ⣠Samuel A
File: gawk.info, Node: Nonconstant Fields, Next: Changing Fields, Prev:
Fields, Up: Reading Files
@@ -4853,14 +4853,14 @@ File: gawk.info, Node: Nonconstant Fields, Next:
Changing Fields, Prev: Field
4.3 Nonconstant Field Numbers
=============================
-A field number need not be a constant. Any expression in the 'awk'
-language can be used after a '$' to refer to a field. The value of the
+A field number need not be a constant. Any expression in the âawkâ
+language can be used after a â$â to refer to a field. The value of the
expression specifies the field number. If the value is a string, rather
than a number, it is converted to a number. Consider this example:
awk '{ print $NR }'
-Recall that 'NR' is the number of records read so far: one in the first
+Recall that âNRâ is the number of records read so far: one in the first
record, two in the second, and so on. So this example prints the first
field of the first record, the second field of the second record, and so
on. For the twentieth record, field number 20 is printed; most likely,
@@ -4869,32 +4869,32 @@ is another example of using expressions as field
numbers:
awk '{ print $(2*2) }' mail-list
- 'awk' evaluates the expression '(2*2)' and uses its value as the
-number of the field to print. The '*' represents multiplication, so the
-expression '2*2' evaluates to four. The parentheses are used so that
-the multiplication is done before the '$' operation; they are necessary
+ âawkâ evaluates the expression â(2*2)â and uses its value as the
+number of the field to print. The â*â represents multiplication, so the
+expression â2*2â evaluates to four. The parentheses are used so that
+the multiplication is done before the â$â operation; they are necessary
whenever there is a binary operator(1) in the field-number expression.
This example, then, prints the type of relationship (the fourth field)
-for every line of the file 'mail-list'. (All of the 'awk' operators are
+for every line of the file âmail-listâ. (All of the âawkâ operators
are
listed, in order of decreasing precedence, in *note Precedence::.)
If the field number you compute is zero, you get the entire record.
-Thus, '$(2-2)' has the same value as '$0'. Negative field numbers are
+Thus, â$(2-2)â has the same value as â$0â. Negative field numbers are
not allowed; trying to reference one usually terminates the program.
(The POSIX standard does not define what happens when you reference a
-negative field number. 'gawk' notices this and terminates your program.
-Other 'awk' implementations may behave differently.)
+negative field number. âgawkâ notices this and terminates your program.
+Other âawkâ implementations may behave differently.)
- As mentioned in *note Fields::, 'awk' stores the current record's
-number of fields in the built-in variable 'NF' (also *note Built-in
-Variables::). Thus, the expression '$NF' is not a special feature--it
-is the direct consequence of evaluating 'NF' and using its value as a
-field number.
+ As mentioned in *note Fields::, âawkâ stores the current recordâs
+number of fields in the built-in variable âNFâ (also *note Built-in
+Variables::). Thus, the expression â$NFâ is not a special featureâit is
+the direct consequence of evaluating âNFâ and using its value as a field
+number.
---------- Footnotes ----------
- (1) A "binary operator", such as '*' for multiplication, is one that
-takes two operands. The distinction is required because 'awk' also has
+ (1) A âbinary operatorâ, such as â*â for multiplication, is one that
+takes two operands. The distinction is required because âawkâ also has
unary (one-operand) and ternary (three-operand) operators.
@@ -4903,41 +4903,41 @@ File: gawk.info, Node: Changing Fields, Next: Field
Separators, Prev: Noncons
4.4 Changing the Contents of a Field
====================================
-The contents of a field, as seen by 'awk', can be changed within an
-'awk' program; this changes what 'awk' perceives as the current input
-record. (The actual input is untouched; 'awk' _never_ modifies the
+The contents of a field, as seen by âawkâ, can be changed within an
+âawkâ program; this changes what âawkâ perceives as the current input
+record. (The actual input is untouched; âawkâ _never_ modifies the
input file.) Consider the following example and its output:
$ awk '{ nboxes = $3 ; $3 = $3 - 10
> print nboxes, $3 }' inventory-shipped
- -| 25 15
- -| 32 22
- -| 24 14
+ ⣠25 15
+ ⣠32 22
+ ⣠24 14
...
The program first saves the original value of field three in the
-variable 'nboxes'. The '-' sign represents subtraction, so this program
-reassigns field three, '$3', as the original value of field three minus
-ten: '$3 - 10'. (*Note Arithmetic Ops::.) Then it prints the original
+variable ânboxesâ. The â-â sign represents subtraction, so this
program
+reassigns field three, â$3â, as the original value of field three minus
+ten: â$3 - 10â. (*Note Arithmetic Ops::.) Then it prints the original
and new values for field three. (Someone in the warehouse made a
consistent mistake while inventorying the red boxes.)
- For this to work, the text in '$3' must make sense as a number; the
+ For this to work, the text in â$3â must make sense as a number; the
string of characters must be converted to a number for the computer to
do arithmetic on it. The number resulting from the subtraction is
converted back to a string of characters that then becomes field three.
*Note Conversion::.
- When the value of a field is changed (as perceived by 'awk'), the
+ When the value of a field is changed (as perceived by âawkâ), the
text of the input record is recalculated to contain the new field where
-the old one was. In other words, '$0' changes to reflect the altered
+the old one was. In other words, â$0â changes to reflect the altered
field. Thus, this program prints a copy of the input file, with 10
subtracted from the second field of each line:
$ awk '{ $2 = $2 - 10; print $0 }' inventory-shipped
- -| Jan 3 25 15 115
- -| Feb 5 32 24 226
- -| Mar 5 24 34 228
+ ⣠Jan 3 25 15 115
+ ⣠Feb 5 32 24 226
+ ⣠Mar 5 24 34 228
...
It is also possible to assign contents to fields that are out of
@@ -4945,31 +4945,31 @@ range. For example:
$ awk '{ $6 = ($5 + $4 + $3 + $2)
> print $6 }' inventory-shipped
- -| 168
- -| 297
- -| 301
+ ⣠168
+ ⣠297
+ ⣠301
...
-We've just created '$6', whose value is the sum of fields '$2', '$3',
-'$4', and '$5'. The '+' sign represents addition. For the file
-'inventory-shipped', '$6' represents the total number of parcels shipped
+Weâve just created â$6â, whose value is the sum of fields â$2â,
â$3â,
+â$4â, and â$5â. The â+â sign represents addition. For the file
+âinventory-shippedâ, â$6â represents the total number of parcels
shipped
for a particular month.
- Creating a new field changes 'awk''s internal copy of the current
-input record, which is the value of '$0'. Thus, if you do 'print $0'
+ Creating a new field changes âawkââs internal copy of the current
+input record, which is the value of â$0â. Thus, if you do âprint $0â
after adding a field, the record printed includes the new field, with
the appropriate number of field separators between it and the previously
existing fields.
- This recomputation affects and is affected by 'NF' (the number of
-fields; *note Fields::). For example, the value of 'NF' is set to the
-number of the highest field you create. The exact format of '$0' is
-also affected by a feature that has not been discussed yet: the "output
-field separator", 'OFS', used to separate the fields (*note Output
+ This recomputation affects and is affected by âNFâ (the number of
+fields; *note Fields::). For example, the value of âNFâ is set to the
+number of the highest field you create. The exact format of â$0â is
+also affected by a feature that has not been discussed yet: the âoutput
+field separatorâ, âOFSâ, used to separate the fields (*note Output
Separators::).
Note, however, that merely _referencing_ an out-of-range field does
-_not_ change the value of either '$0' or 'NF'. Referencing an
+_not_ change the value of either â$0â or âNFâ. Referencing an
out-of-range field only produces an empty string. For example:
if ($(NF+1) != "")
@@ -4977,75 +4977,75 @@ out-of-range field only produces an empty string. For
example:
else
print "everything is normal"
-should print 'everything is normal', because 'NF+1' is certain to be out
-of range. (*Note If Statement:: for more information about 'awk''s
-'if-else' statements. *Note Typing and Comparison:: for more
-information about the '!=' operator.)
+should print âeverything is normalâ, because âNF+1â is certain to be
out
+of range. (*Note If Statement:: for more information about âawkââs
+âif-elseâ statements. *Note Typing and Comparison:: for more
+information about the â!=â operator.)
It is important to note that making an assignment to an existing
-field changes the value of '$0' but does not change the value of 'NF',
+field changes the value of â$0â but does not change the value of âNFâ,
even when you assign the empty string to a field. For example:
$ echo a b c d | awk '{ OFS = ":"; $2 = ""
> print $0; print NF }'
- -| a::c:d
- -| 4
+ ⣠a::c:d
+ ⣠4
The field is still there; it just has an empty value, delimited by the
-two colons between 'a' and 'c'. This example shows what happens if you
+two colons between âaâ and âcâ. This example shows what happens if you
create a new field:
$ echo a b c d | awk '{ OFS = ":"; $2 = ""; $6 = "new"
> print $0; print NF }'
- -| a::c:d::new
- -| 6
+ ⣠a::c:d::new
+ ⣠6
-The intervening field, '$5', is created with an empty value (indicated
-by the second pair of adjacent colons), and 'NF' is updated with the
+The intervening field, â$5â, is created with an empty value (indicated
+by the second pair of adjacent colons), and âNFâ is updated with the
value six.
- Decrementing 'NF' throws away the values of the fields after the new
-value of 'NF' and recomputes '$0'. (d.c.) Here is an example:
+ Decrementing âNFâ throws away the values of the fields after the new
+value of âNFâ and recomputes â$0â. (d.c.) Here is an example:
$ echo a b c d e f | awk '{ print "NF =", NF;
> NF = 3; print $0 }'
- -| NF = 6
- -| a b c
+ ⣠NF = 6
+ ⣠a b c
- CAUTION: Some versions of 'awk' don't rebuild '$0' when 'NF' is
- decremented. Until August, 2018, this included BWK 'awk';
+ CAUTION: Some versions of âawkâ donât rebuild â$0â when
âNFâ is
+ decremented. Until August, 2018, this included BWK âawkâ;
fortunately his version now handles this correctly.
- Finally, there are times when it is convenient to force 'awk' to
+ Finally, there are times when it is convenient to force âawkâ to
rebuild the entire record, using the current values of the fields and
-'OFS'. To do this, use the seemingly innocuous assignment:
+âOFSâ. To do this, use the seemingly innocuous assignment:
$1 = $1 # force record to be reconstituted
print $0 # or whatever else with $0
-This forces 'awk' to rebuild the record. It does help to add a comment,
-as we've shown here.
+This forces âawkâ to rebuild the record. It does help to add a comment,
+as weâve shown here.
- There is a flip side to the relationship between '$0' and the fields.
-Any assignment to '$0' causes the record to be reparsed into fields
-using the _current_ value of 'FS'. This also applies to any built-in
-function that updates '$0', such as 'sub()' and 'gsub()' (*note String
+ There is a flip side to the relationship between â$0â and the fields.
+Any assignment to â$0â causes the record to be reparsed into fields
+using the _current_ value of âFSâ. This also applies to any built-in
+function that updates â$0â, such as âsub()â and âgsub()â (*note
String
Functions::).
- Understanding '$0'
+ Understanding â$0â
- It is important to remember that '$0' is the _full_ record, exactly
+ It is important to remember that â$0â is the _full_ record, exactly
as it was read from the input. This includes any leading or trailing
whitespace, and the exact whitespace (or other characters) that
separates the fields.
It is a common error to try to change the field separators in a
-record simply by setting 'FS' and 'OFS', and then expecting a plain
-'print' or 'print $0' to print the modified record.
+record simply by setting âFSâ and âOFSâ, and then expecting a plain
+âprintâ or âprint $0â to print the modified record.
But this does not work, because nothing was done to change the record
itself. Instead, you must force the record to be rebuilt, typically
-with a statement such as '$1 = $1', as described earlier.
+with a statement such as â$1 = $1â, as described earlier.
File: gawk.info, Node: Field Separators, Next: Constant Size, Prev:
Changing Fields, Up: Reading Files
@@ -5058,36 +5058,36 @@ File: gawk.info, Node: Field Separators, Next:
Constant Size, Prev: Changing
* Default Field Splitting:: How fields are normally separated.
* Regexp Field Splitting:: Using regexps as the field separator.
* Single Character Fields:: Making each character a separate field.
-* Command Line Field Separator:: Setting 'FS' from the command line.
+* Command Line Field Separator:: Setting âFSâ from the command line.
* Full Line Fields:: Making the full line be a single field.
* Field Splitting Summary:: Some final points and a summary table.
-The "field separator", which is either a single character or a regular
-expression, controls the way 'awk' splits an input record into fields.
-'awk' scans the input record for character sequences that match the
+The âfield separatorâ, which is either a single character or a regular
+expression, controls the way âawkâ splits an input record into fields.
+âawkâ scans the input record for character sequences that match the
separator; the fields themselves are the text between the matches.
- In the examples that follow, we use the bullet symbol (*) to
-represent spaces in the output. If the field separator is 'oo', then
+ In the examples that follow, we use the bullet symbol (â¢) to
+represent spaces in the output. If the field separator is âooâ, then
the following line:
moo goo gai pan
-is split into three fields: 'm', '*g', and '*gai*pan'. Note the leading
+is split into three fields: âmâ, ââ¢gâ, and ââ¢gaiâ¢panâ. Note
the leading
spaces in the values of the second and third fields.
- The field separator is represented by the predefined variable 'FS'.
-Shell programmers take note: 'awk' does _not_ use the name 'IFS' that is
-used by the POSIX-compliant shells (such as the Unix Bourne shell, 'sh',
+ The field separator is represented by the predefined variable âFSâ.
+Shell programmers take note: âawkâ does _not_ use the name âIFSâ that
is
+used by the POSIX-compliant shells (such as the Unix Bourne shell, âshâ,
or Bash).
- The value of 'FS' can be changed in the 'awk' program with the
-assignment operator, '=' (*note Assignment Ops::). Often, the right
+ The value of âFSâ can be changed in the âawkâ program with the
+assignment operator, â=â (*note Assignment Ops::). Often, the right
time to do this is at the beginning of execution before any input has
been processed, so that the very first record is read with the proper
-separator. To do this, use the special 'BEGIN' pattern (*note
-BEGIN/END::). For example, here we set the value of 'FS' to the string
-'","':
+separator. To do this, use the special âBEGINâ pattern (*note
+BEGIN/END::). For example, here we set the value of âFSâ to the string
+â","â:
awk 'BEGIN { FS = "," } ; { print $2 }'
@@ -5095,21 +5095,21 @@ Given the input line:
John Q. Smith, 29 Oak St., Walamazoo, MI 42139
-this 'awk' program extracts and prints the string '*29*Oak*St.'.
+this âawkâ program extracts and prints the string ââ¢29â¢Oakâ¢St.â.
- Sometimes the input data contains separator characters that don't
+ Sometimes the input data contains separator characters that donât
separate fields the way you thought they would. For instance, the
-person's name in the example we just used might have a title or suffix
+personâs name in the example we just used might have a title or suffix
attached, such as:
John Q. Smith, LXIX, 29 Oak St., Walamazoo, MI 42139
-The same program would extract '*LXIX' instead of '*29*Oak*St.'. If you
+The same program would extract ââ¢LXIXâ instead of
ââ¢29â¢Oakâ¢St.â. If you
were expecting the program to print the address, you would be surprised.
The moral is to choose your data layout and separator characters
carefully to prevent such problems. (If the data is not in a form that
is easy to process, perhaps you can massage it first with a separate
-'awk' program.)
+âawkâ program.)
File: gawk.info, Node: Default Field Splitting, Next: Regexp Field
Splitting, Up: Field Separators
@@ -5119,14 +5119,14 @@ File: gawk.info, Node: Default Field Splitting, Next:
Regexp Field Splitting,
Fields are normally separated by whitespace sequences (spaces, TABs, and
newlines), not by single spaces. Two spaces in a row do not delimit an
-empty field. The default value of the field separator 'FS' is a string
-containing a single space, '" "'. If 'awk' interpreted this value in
+empty field. The default value of the field separator âFSâ is a string
+containing a single space, â" "â. If âawkâ interpreted this value in
the usual way, each space character would separate fields, so two spaces
in a row would make an empty field between them. The reason this does
-not happen is that a single space as the value of 'FS' is a special
-case--it is taken to specify the default manner of delimiting fields.
+not happen is that a single space as the value of âFSâ is a special
+caseâit is taken to specify the default manner of delimiting fields.
- If 'FS' is any other single character, such as '","', then each
+ If âFSâ is any other single character, such as â","â, then each
occurrence of that character separates two fields. Two consecutive
occurrences delimit an empty field. If the character occurs at the
beginning or the end of the line, that too delimits an empty field. The
@@ -5140,7 +5140,7 @@ File: gawk.info, Node: Regexp Field Splitting, Next:
Single Character Fields,
--------------------------------------------------
The previous node discussed the use of single characters or simple
-strings as the value of 'FS'. More generally, the value of 'FS' may be
+strings as the value of âFSâ. More generally, the value of âFSâ may be
a string containing any regular expression. In this case, each match in
the record for the regular expression separates fields. For example,
the assignment:
@@ -5148,72 +5148,72 @@ the assignment:
FS = ", \t"
makes every area of an input line that consists of a comma followed by a
-space and a TAB into a field separator. ('\t' is an "escape sequence"
+space and a TAB into a field separator. (â\tâ is an âescape sequenceâ
that stands for a TAB; *note Escape Sequences::, for the complete list
of similar escape sequences.)
For a less trivial example of a regular expression, try using single
-spaces to separate fields the way single commas are used. 'FS' can be
-set to '"[ ]"' (left bracket, space, right bracket). This regular
+spaces to separate fields the way single commas are used. âFSâ can be
+set to â"[ ]"â (left bracket, space, right bracket). This regular
expression matches a single space and nothing else (*note Regexp::).
- There is an important difference between the two cases of 'FS = " "'
-(a single space) and 'FS = "[ \t\n]+"' (a regular expression matching
-one or more spaces, TABs, or newlines). For both values of 'FS', fields
-are separated by "runs" (multiple adjacent occurrences) of spaces, TABs,
-and/or newlines. However, when the value of 'FS' is '" "', 'awk' first
+ There is an important difference between the two cases of âFS = " "â
+(a single space) and âFS = "[ \t\n]+"â (a regular expression matching
+one or more spaces, TABs, or newlines). For both values of âFSâ, fields
+are separated by ârunsâ (multiple adjacent occurrences) of spaces, TABs,
+and/or newlines. However, when the value of âFSâ is â" "â, âawkâ
first
strips leading and trailing whitespace from the record and then decides
-where the fields are. For example, the following pipeline prints 'b':
+where the fields are. For example, the following pipeline prints âbâ:
$ echo ' a b c d ' | awk '{ print $2 }'
- -| b
+ ⣠b
-However, this pipeline prints 'a' (note the extra spaces around each
+However, this pipeline prints âaâ (note the extra spaces around each
letter):
$ echo ' a b c d ' | awk 'BEGIN { FS = "[ \t\n]+" }
> { print $2 }'
- -| a
+ ⣠a
In this case, the first field is null, or empty.
The stripping of leading and trailing whitespace also comes into play
-whenever '$0' is recomputed. For instance, study this pipeline:
+whenever â$0â is recomputed. For instance, study this pipeline:
$ echo ' a b c d' | awk '{ print; $2 = $2; print }'
- -| a b c d
- -| a b c d
+ ⣠a b c d
+ ⣠a b c d
-The first 'print' statement prints the record as it was read, with
-leading whitespace intact. The assignment to '$2' rebuilds '$0' by
-concatenating '$1' through '$NF' together, separated by the value of
-'OFS' (which is a space by default). Because the leading whitespace was
-ignored when finding '$1', it is not part of the new '$0'. Finally, the
-last 'print' statement prints the new '$0'.
+The first âprintâ statement prints the record as it was read, with
+leading whitespace intact. The assignment to â$2â rebuilds â$0â by
+concatenating â$1â through â$NFâ together, separated by the value of
+âOFSâ (which is a space by default). Because the leading whitespace was
+ignored when finding â$1â, it is not part of the new â$0â. Finally,
the
+last âprintâ statement prints the new â$0â.
There is an additional subtlety to be aware of when using regular
expressions for field splitting. It is not well specified in the POSIX
-standard, or anywhere else, what '^' means when splitting fields. Does
-the '^' match only at the beginning of the entire record? Or is each
-field separator a new string? It turns out that different 'awk'
+standard, or anywhere else, what â^â means when splitting fields. Does
+the â^â match only at the beginning of the entire record? Or is each
+field separator a new string? It turns out that different âawkâ
versions answer this question differently, and you should not rely on
any specific behavior in your programs. (d.c.)
- As a point of information, BWK 'awk' allows '^' to match only at the
-beginning of the record. 'gawk' also works this way. For example:
+ As a point of information, BWK âawkâ allows â^â to match only at the
+beginning of the record. âgawkâ also works this way. For example:
$ echo 'xxAA xxBxx C' |
> gawk -F '(^x+)|( +)' '{ for (i = 1; i <= NF; i++)
> printf "-->%s<--\n", $i }'
- -| --><--
- -| -->AA<--
- -| -->xxBxx<--
- -| -->C<--
+ ⣠--><--
+ ⣠-->AA<--
+ ⣠-->xxBxx<--
+ ⣠-->C<--
Finally, field splitting with regular expressions works differently
-than regexp matching with the 'sub()', 'gsub()', and 'gensub()' (*note
+than regexp matching with the âsub()â, âgsub()â, and âgensub()â
(*note
String Functions::). Those functions allow a regexp to match the empty
-string; field splitting does not. Thus, for example 'FS = "()"' does
+string; field splitting does not. Thus, for example âFS = "()"â does
_not_ split fields between characters.
@@ -5223,8 +5223,8 @@ File: gawk.info, Node: Single Character Fields, Next:
Command Line Field Separ
--------------------------------------------
There are times when you may want to examine each character of a record
-separately. This can be done in 'gawk' by simply assigning the null
-string ('""') to 'FS'. (c.e.) In this case, each individual character
+separately. This can be done in âgawkâ by simply assigning the null
+string (â""â) to âFSâ. (c.e.) In this case, each individual character
in the record becomes a separate field. For example:
$ echo a b | gawk 'BEGIN { FS = "" }
@@ -5232,75 +5232,75 @@ in the record becomes a separate field. For example:
> for (i = 1; i <= NF; i = i + 1)
> print "Field", i, "is", $i
> }'
- -| Field 1 is a
- -| Field 2 is
- -| Field 3 is b
+ ⣠Field 1 is a
+ ⣠Field 2 is
+ ⣠Field 3 is b
- Traditionally, the behavior of 'FS' equal to '""' was not defined.
-In this case, most versions of Unix 'awk' simply treat the entire record
+ Traditionally, the behavior of âFSâ equal to â""â was not defined.
+In this case, most versions of Unix âawkâ simply treat the entire record
as only having one field. (d.c.) In compatibility mode (*note
-Options::), if 'FS' is the null string, then 'gawk' also behaves this
+Options::), if âFSâ is the null string, then âgawkâ also behaves this
way.
File: gawk.info, Node: Command Line Field Separator, Next: Full Line Fields,
Prev: Single Character Fields, Up: Field Separators
-4.5.4 Setting 'FS' from the Command Line
+4.5.4 Setting âFSâ from the Command Line
----------------------------------------
-'FS' can be set on the command line. Use the '-F' option to do so. For
+âFSâ can be set on the command line. Use the â-Fâ option to do so.
For
example:
awk -F, 'PROGRAM' INPUT-FILES
-sets 'FS' to the ',' character. Notice that the option uses an
-uppercase 'F' instead of a lowercase 'f'. The latter option ('-f')
-specifies a file containing an 'awk' program.
+sets âFSâ to the â,â character. Notice that the option uses an
+uppercase âFâ instead of a lowercase âfâ. The latter option (â-fâ)
+specifies a file containing an âawkâ program.
- The value used for the argument to '-F' is processed in exactly the
-same way as assignments to the predefined variable 'FS'. Any special
+ The value used for the argument to â-Fâ is processed in exactly the
+same way as assignments to the predefined variable âFSâ. Any special
characters in the field separator must be escaped appropriately. For
-example, to use a '\' as the field separator on the command line, you
+example, to use a â\â as the field separator on the command line, you
would have to type:
# same as FS = "\\"
awk -F\\\\ '...' files ...
-Because '\' is used for quoting in the shell, 'awk' sees '-F\\'. Then
-'awk' processes the '\\' for escape characters (*note Escape
-Sequences::), finally yielding a single '\' to use for the field
+Because â\â is used for quoting in the shell, âawkâ sees â-F\\â.
Then
+âawkâ processes the â\\â for escape characters (*note Escape
+Sequences::), finally yielding a single â\â to use for the field
separator.
As a special case, in compatibility mode (*note Options::), if the
-argument to '-F' is 't', then 'FS' is set to the TAB character. If you
-type '-F\t' at the shell, without any quotes, the '\' gets deleted, so
-'awk' figures that you really want your fields to be separated with TABs
-and not 't's. Use '-v FS="t"' or '-F"[t]"' on the command line if you
-really do want to separate your fields with 't's. Use '-F '\t'' when
+argument to â-Fâ is âtâ, then âFSâ is set to the TAB character.
If you
+type â-F\tâ at the shell, without any quotes, the â\â gets deleted, so
+âawkâ figures that you really want your fields to be separated with TABs
+and not âtâs. Use â-v FS="t"â or â-F"[t]"â on the command line if
you
+really do want to separate your fields with âtâs. Use â-F '\t'â when
not in compatibility mode to specify that TABs separate fields.
- As an example, let's use an 'awk' program file called 'edu.awk' that
-contains the pattern '/edu/' and the action 'print $1':
+ As an example, letâs use an âawkâ program file called âedu.awkâ
that
+contains the pattern â/edu/â and the action âprint $1â:
/edu/ { print $1 }
- Let's also set 'FS' to be the '-' character and run the program on
-the file 'mail-list'. The following command prints a list of the names
+ Letâs also set âFSâ to be the â-â character and run the program on
+the file âmail-listâ. The following command prints a list of the names
of the people that work at or attend a university, and the first three
digits of their phone numbers:
$ awk -F- -f edu.awk mail-list
- -| Fabius 555
- -| Samuel 555
- -| Jean
+ ⣠Fabius 555
+ ⣠Samuel 555
+ ⣠Jean
Note the third line of output. The third line in the original file
looked like this:
Jean-Paul 555-2127 jeanpaul.campanorum@nyu.edu R
- The '-' as part of the person's name was used as the field separator,
-instead of the '-' in the phone number that was originally intended.
+ The â-â as part of the personâs name was used as the field separator,
+instead of the â-â in the phone number that was originally intended.
This demonstrates why you have to be careful in choosing your field and
record separators.
@@ -5308,9 +5308,9 @@ record separators.
separator occurs when processing the Unix system password file. On many
Unix systems, each user has a separate entry in the system password
file, with one line per user. The information in these lines is
-separated by colons. The first field is the user's login name and the
-second is the user's encrypted or shadow password. (A shadow password
-is indicated by the presence of a single 'x' in the second field.) A
+separated by colons. The first field is the userâs login name and the
+second is the userâs encrypted or shadow password. (A shadow password
+is indicated by the presence of a single âxâ in the second field.) A
password file entry might look like this:
arnold:x:2076:10:Arnold Robbins:/home/arnold:/bin/bash
@@ -5326,25 +5326,25 @@ File: gawk.info, Node: Full Line Fields, Next: Field
Splitting Summary, Prev:
4.5.5 Making the Full Line Be a Single Field
--------------------------------------------
-Occasionally, it's useful to treat the whole input line as a single
-field. This can be done easily and portably simply by setting 'FS' to
-'"\n"' (a newline):(1)
+Occasionally, itâs useful to treat the whole input line as a single
+field. This can be done easily and portably simply by setting âFSâ to
+â"\n"â (a newline):(1)
awk -F'\n' 'PROGRAM' FILES ...
-When you do this, '$1' is the same as '$0'.
+When you do this, â$1â is the same as â$0â.
- Changing 'FS' Does Not Affect the Fields
+ Changing âFSâ Does Not Affect the Fields
- According to the POSIX standard, 'awk' is supposed to behave as if
+ According to the POSIX standard, âawkâ is supposed to behave as if
each record is split into fields at the time it is read. In particular,
-this means that if you change the value of 'FS' after a record is read,
+this means that if you change the value of âFSâ after a record is read,
the values of the fields (i.e., how they were split) should reflect the
-old value of 'FS', not the new one.
+old value of âFSâ, not the new one.
- However, many older implementations of 'awk' do not work this way.
+ However, many older implementations of âawkâ do not work this way.
Instead, they defer splitting the fields until a field is actually
-referenced. The fields are split using the _current_ value of 'FS'!
+referenced. The fields are split using the _current_ value of âFSâ!
(d.c.) This behavior can be difficult to diagnose. The following
example illustrates the difference between the two methods:
@@ -5354,18 +5354,18 @@ which usually prints:
root
-on an incorrect implementation of 'awk', while 'gawk' prints the full
+on an incorrect implementation of âawkâ, while âgawkâ prints the full
first line of the file, something like:
root:x:0:0:Root:/:
- (The 'sed'(2) command prints just the first line of '/etc/passwd'.)
+ (The âsedâ(2) command prints just the first line of â/etc/passwdâ.)
---------- Footnotes ----------
(1) Thanks to Andrew Schorr for this tip.
- (2) The 'sed' utility is a "stream editor." Its behavior is also
+ (2) The âsedâ utility is a âstream editor.â Its behavior is also
defined by the POSIX standard.
@@ -5375,41 +5375,41 @@ File: gawk.info, Node: Field Splitting Summary, Prev:
Full Line Fields, Up: F
-----------------------------
It is important to remember that when you assign a string constant as
-the value of 'FS', it undergoes normal 'awk' string processing. For
-example, with Unix 'awk' and 'gawk', the assignment 'FS = "\.."' assigns
-the character string '".."' to 'FS' (the backslash is stripped). This
-creates a regexp meaning "fields are separated by occurrences of any two
-characters." If instead you want fields to be separated by a literal
-period followed by any single character, use 'FS = "\\.."'.
+the value of âFSâ, it undergoes normal âawkâ string processing. For
+example, with Unix âawkâ and âgawkâ, the assignment âFS = "\.."â
assigns
+the character string â".."â to âFSâ (the backslash is stripped). This
+creates a regexp meaning âfields are separated by occurrences of any two
+characters.â If instead you want fields to be separated by a literal
+period followed by any single character, use âFS = "\\.."â.
The following list summarizes how fields are split, based on the
-value of 'FS' ('==' means "is equal to"):
+value of âFSâ (â==â means âis equal toâ):
-'FS == " "'
+âFS == " "â
Fields are separated by runs of whitespace. Leading and trailing
whitespace are ignored. This is the default.
-'FS == ANY OTHER SINGLE CHARACTER'
+âFS == ANY OTHER SINGLE CHARACTERâ
Fields are separated by each occurrence of the character. Multiple
successive occurrences delimit empty fields, as do leading and
trailing occurrences. The character can even be a regexp
metacharacter; it does not need to be escaped.
-'FS == REGEXP'
+âFS == REGEXPâ
Fields are separated by occurrences of characters that match
REGEXP. Leading and trailing matches of REGEXP delimit empty
fields.
-'FS == ""'
+âFS == ""â
Each individual character in the record becomes a separate field.
(This is a common extension; it is not specified by the POSIX
standard.)
- 'FS' and 'IGNORECASE'
+ âFSâ and âIGNORECASEâ
- The 'IGNORECASE' variable (*note User-modified::) affects field
-splitting _only_ when the value of 'FS' is a regexp. It has no effect
-when 'FS' is a single character, even if that character is a letter.
+ The âIGNORECASEâ variable (*note User-modified::) affects field
+splitting _only_ when the value of âFSâ is a regexp. It has no effect
+when âFSâ is a single character, even if that character is a letter.
Thus, in the following code:
FS = "c"
@@ -5417,9 +5417,9 @@ Thus, in the following code:
$0 = "aCa"
print $1
-The output is 'aCa'. If you really want to split fields on an
+The output is âaCaâ. If you really want to split fields on an
alphabetic character while ignoring case, use a regexp that will do it
-for you (e.g., 'FS = "[c]"'). In this case, 'IGNORECASE' will take
+for you (e.g., âFS = "[c]"â). In this case, âIGNORECASEâ will take
effect.
@@ -5428,10 +5428,10 @@ File: gawk.info, Node: Constant Size, Next: Splitting
By Content, Prev: Field
4.6 Reading Fixed-Width Data
============================
-This minor node discusses an advanced feature of 'gawk'. If you are a
-novice 'awk' user, you might want to skip it on the first reading.
+This minor node discusses an advanced feature of âgawkâ. If you are a
+novice âawkâ user, you might want to skip it on the first reading.
- 'gawk' provides a facility for dealing with fixed-width fields with
+ âgawkâ provides a facility for dealing with fixed-width fields with
no distinctive field separator. We discuss this feature in the
following nodes.
@@ -5454,21 +5454,21 @@ did not anticipate the use of their output as input for
other programs.
An example of the latter is a table where all the columns are lined
up by the use of a variable number of spaces and _empty fields are just
-spaces_. Clearly, 'awk''s normal field splitting based on 'FS' does not
-work well in this case. Although a portable 'awk' program can use a
-series of 'substr()' calls on '$0' (*note String Functions::), this is
+spaces_. Clearly, âawkââs normal field splitting based on âFSâ does
not
+work well in this case. Although a portable âawkâ program can use a
+series of âsubstr()â calls on â$0â (*note String Functions::), this is
awkward and inefficient for a large number of fields.
The splitting of an input record into fixed-width fields is specified
by assigning a string containing space-separated numbers to the built-in
-variable 'FIELDWIDTHS'. Each number specifies the width of the field,
+variable âFIELDWIDTHSâ. Each number specifies the width of the field,
_including_ columns between fields. If you want to ignore the columns
between fields, you can specify the width as a separate field that is
subsequently ignored. It is a fatal error to supply a field width that
has a negative value.
- The following data is the output of the Unix 'w' utility. It is
-useful to illustrate the use of 'FIELDWIDTHS':
+ The following data is the output of the Unix âwâ utility. It is
+useful to illustrate the use of âFIELDWIDTHSâ:
10:06pm up 21 days, 14:04, 23 users
User tty login idle JCPU PCPU what
@@ -5501,8 +5501,8 @@ calculated idle time:
print $1, $2, idle
}
- NOTE: The preceding program uses a number of 'awk' features that
- haven't been introduced yet.
+ NOTE: The preceding program uses a number of âawkâ features that
+ havenât been introduced yet.
Running the program on the data produces the following results:
@@ -5521,8 +5521,8 @@ United States, voters mark their choices by punching
holes in computer
cards. These cards are then processed to count the votes for any
particular candidate or on any particular issue. Because a voter may
choose not to vote on some issue, any column on the card may be empty.
-An 'awk' program for processing such data could use the 'FIELDWIDTHS'
-feature to simplify reading the data. (Of course, getting 'gawk' to run
+An âawkâ program for processing such data could use the âFIELDWIDTHSâ
+feature to simplify reading the data. (Of course, getting âgawkâ to run
on a system with card readers is another story!)
@@ -5534,7 +5534,7 @@ File: gawk.info, Node: Skipping intervening, Next:
Allowing trailing data, Pr
Starting in version 4.2, each field width may optionally be preceded by
a colon-separated value specifying the number of characters to skip
before the field starts. Thus, the preceding program could be rewritten
-to specify 'FIELDWIDTHS' like so:
+to specify âFIELDWIDTHSâ like so:
BEGIN { FIELDWIDTHS = "8 1:5 4:7 6 1:6 1:6 2:33" }
@@ -5557,21 +5557,21 @@ File: gawk.info, Node: Allowing trailing data, Next:
Fields with fixed data,
There are times when fixed-width data may be followed by additional data
that has no fixed length. Such data may or may not be present, but if
-it is, it should be possible to get at it from an 'awk' program.
+it is, it should be possible to get at it from an âawkâ program.
- Starting with version 4.2, in order to provide a way to say "anything
-else in the record after the defined fields," 'gawk' allows you to add a
-final '*' character to the value of 'FIELDWIDTHS'. There can only be
+ Starting with version 4.2, in order to provide a way to say âanything
+else in the record after the defined fields,â âgawkâ allows you to add a
+final â*â character to the value of âFIELDWIDTHSâ. There can only be
one such character, and it must be the final non-whitespace character in
-'FIELDWIDTHS'. For example:
+âFIELDWIDTHSâ. For example:
$ cat fw.awk Show the program
- -| BEGIN { FIELDWIDTHS = "2 2 *" }
- -| { print NF, $1, $2, $3 }
+ ⣠BEGIN { FIELDWIDTHS = "2 2 *" }
+ ⣠{ print NF, $1, $2, $3 }
$ cat fw.in Show sample input
- -| 1234abcdefghi
+ ⣠1234abcdefghi
$ gawk -f fw.awk fw.in Run the program
- -| 3 12 34 abcdefghi
+ ⣠3 12 34 abcdefghi
File: gawk.info, Node: Fields with fixed data, Prev: Allowing trailing data,
Up: Constant Size
@@ -5579,35 +5579,35 @@ File: gawk.info, Node: Fields with fixed data, Prev:
Allowing trailing data,
4.6.4 Field Values With Fixed-Width Data
----------------------------------------
-So far, so good. But what happens if there isn't as much data as there
-should be based on the contents of 'FIELDWIDTHS'? Or, what happens if
+So far, so good. But what happens if there isnât as much data as there
+should be based on the contents of âFIELDWIDTHSâ? Or, what happens if
there is more data than expected?
For many years, what happens in these cases was not well defined.
Starting with version 4.2, the rules are as follows:
Enough data for some fields
- For example, if 'FIELDWIDTHS' is set to '"2 3 4"' and the input
- record is 'aabbb'. In this case, 'NF' is set to two.
+ For example, if âFIELDWIDTHSâ is set to â"2 3 4"â and the input
+ record is âaabbbâ. In this case, âNFâ is set to two.
Not enough data for a field
- For example, if 'FIELDWIDTHS' is set to '"2 3 4"' and the input
- record is 'aab'. In this case, 'NF' is set to two and '$2' has the
- value '"b"'. The idea is that even though there aren't as many
+ For example, if âFIELDWIDTHSâ is set to â"2 3 4"â and the input
+ record is âaabâ. In this case, âNFâ is set to two and â$2â
has the
+ value â"b"â. The idea is that even though there arenât as many
characters as were expected, there are some, so the data should be
made available to the program.
Too much data
- For example, if 'FIELDWIDTHS' is set to '"2 3 4"' and the input
- record is 'aabbbccccddd'. In this case, 'NF' is set to three and
- the extra characters ('ddd') are ignored. If you want 'gawk' to
- capture the extra characters, supply a final '*' in the value of
- 'FIELDWIDTHS'.
+ For example, if âFIELDWIDTHSâ is set to â"2 3 4"â and the input
+ record is âaabbbccccdddâ. In this case, âNFâ is set to three and
+ the extra characters (âdddâ) are ignored. If you want âgawkâ to
+ capture the extra characters, supply a final â*â in the value of
+ âFIELDWIDTHSâ.
-Too much data, but with '*' supplied
- For example, if 'FIELDWIDTHS' is set to '"2 3 4 *"' and the input
- record is 'aabbbccccddd'. In this case, 'NF' is set to four, and
- '$4' has the value '"ddd"'.
+Too much data, but with â*â supplied
+ For example, if âFIELDWIDTHSâ is set to â"2 3 4 *"â and the input
+ record is âaabbbccccdddâ. In this case, âNFâ is set to four, and
+ â$4â has the value â"ddd"â.
File: gawk.info, Node: Splitting By Content, Next: Testing field creation,
Prev: Constant Size, Up: Reading Files
@@ -5620,35 +5620,35 @@ File: gawk.info, Node: Splitting By Content, Next:
Testing field creation, Pr
* More CSV:: More on CSV files.
* FS versus FPAT:: A subtle difference.
-This minor node discusses an advanced feature of 'gawk'. If you are a
-novice 'awk' user, you might want to skip it on the first reading.
+This minor node discusses an advanced feature of âgawkâ. If you are a
+novice âawkâ user, you might want to skip it on the first reading.
- Normally, when using 'FS', 'gawk' defines the fields as the parts of
+ Normally, when using âFSâ, âgawkâ defines the fields as the parts of
the record that occur in between each field separator. In other words,
-'FS' defines what a field _is not_, instead of what a field _is_.
+âFSâ defines what a field _is not_, instead of what a field _is_.
However, there are times when you really want to define the fields by
what they are, and not by what they are not.
- The most notorious such case is so-called "comma-separated values"
+ The most notorious such case is so-called âcomma-separated valuesâ
(CSV) data. Many spreadsheet programs, for example, can export their
data into text files, where each record is terminated with a newline,
and fields are separated by commas. If commas only separated the data,
-there wouldn't be an issue. The problem comes when one of the fields
+there wouldnât be an issue. The problem comes when one of the fields
contains an _embedded_ comma. In such cases, most programs embed the
field in double quotes.(1) So, we might have data like this:
Robbins,Arnold,"1234 A Pretty Street, NE",MyTown,MyState,12345-6789,USA
- The 'FPAT' variable offers a solution for cases like this. The value
-of 'FPAT' should be a string that provides a regular expression. This
+ The âFPATâ variable offers a solution for cases like this. The value
+of âFPATâ should be a string that provides a regular expression. This
regular expression describes the contents of each field.
In the case of CSV data as presented here, each field is either
-"anything that is not a comma," or "a double quote, anything that is not
-a double quote, and a closing double quote." (There are more
-complicated definitions of CSV data, treated shortly.) If written as a
-regular expression constant (*note Regexp::), we would have
-'/([^,]+)|("[^"]+")/'. Writing this as a string requires us to escape
+âanything that is not a comma,â or âa double quote, anything that is not
+a double quote, and a closing double quote.â (There are more complicated
+definitions of CSV data, treated shortly.) If written as a regular
+expression constant (*note Regexp::), we would have
+â/([^,]+)|("[^"]+")/â. Writing this as a string requires us to escape
the double quotes, leading to:
FPAT = "([^,]+)|(\"[^\"]+\")"
@@ -5678,7 +5678,7 @@ the double quotes, leading to:
$6 = <12345-6789>
$7 = <USA>
- Note the embedded comma in the value of '$3'.
+ Note the embedded comma in the value of â$3â.
A straightforward improvement when processing CSV data of this sort
would be to remove the quotes when they occur, with something like this:
@@ -5689,25 +5689,25 @@ would be to remove the quotes when they occur, with
something like this:
}
NOTE: Some programs export CSV data that contains embedded newlines
- between the double quotes. 'gawk' provides no way to deal with
+ between the double quotes. âgawkâ provides no way to deal with
this. Even though a formal specification for CSV data exists,
- there isn't much more to be done; the 'FPAT' mechanism provides an
- elegant solution for the majority of cases, and the 'gawk'
+ there isnât much more to be done; the âFPATâ mechanism provides an
+ elegant solution for the majority of cases, and the âgawkâ
developers are satisfied with that.
- As written, the regexp used for 'FPAT' requires that each field
+ As written, the regexp used for âFPATâ requires that each field
contain at least one character. A straightforward modification
-(changing the first '+' to '*') allows fields to be empty:
+(changing the first â+â to â*â) allows fields to be empty:
FPAT = "([^,]*)|(\"[^\"]+\")"
- As with 'FS', the 'IGNORECASE' variable (*note User-modified::)
-affects field splitting with 'FPAT'.
+ As with âFSâ, the âIGNORECASEâ variable (*note User-modified::)
+affects field splitting with âFPATâ.
- Assigning a value to 'FPAT' overrides field splitting with 'FS' and
-with 'FIELDWIDTHS'.
+ Assigning a value to âFPATâ overrides field splitting with âFSâ and
+with âFIELDWIDTHSâ.
- Finally, the 'patsplit()' function makes the same functionality
+ Finally, the âpatsplit()â function makes the same functionality
available for splitting regular strings (*note String Functions::).
---------- Footnotes ----------
@@ -5725,9 +5725,9 @@ File: gawk.info, Node: More CSV, Next: FS versus FPAT,
Up: Splitting By Conte
Manuel Collado notes that in addition to commas, a CSV field can also
contains quotes, that have to be escaped by doubling them. The
previously described regexps fail to accept quoted fields with both
-commas and quotes inside. He suggests that the simplest 'FPAT'
+commas and quotes inside. He suggests that the simplest âFPATâ
expression that recognizes this kind of fields is
-'/([^,]*)|("([^"]|"")+")/'. He provides the following input data to
+â/([^,]*)|("([^"]|"")+")/â. He provides the following input data to
test these variants:
p,"q,r",s
@@ -5757,70 +5757,70 @@ And here is his test program:
When run on the third variant, it produces:
$ gawk -v fpat=2 -f test-csv.awk sample.csv
- -| <p,"q,r",s>
- -| NF = 3 <p><"q,r"><s>
- -| <p,"q""r",s>
- -| NF = 3 <p><"q""r"><s>
- -| <p,"q,""r",s>
- -| NF = 3 <p><"q,""r"><s>
- -| <p,"",s>
- -| NF = 3 <p><""><s>
- -| <p,,s>
- -| NF = 3 <p><><s>
-
- In general, using 'FPAT' to do your own CSV parsing is like having a
-bed with a blanket that's not quite big enough. There's always a corner
-that isn't covered. We recommend, instead, that you use Manuel
-Collado's 'CSVMODE' library for 'gawk' (http://mcollado.z15.es/xgawk/).
+ ⣠<p,"q,r",s>
+ ⣠NF = 3 <p><"q,r"><s>
+ ⣠<p,"q""r",s>
+ ⣠NF = 3 <p><"q""r"><s>
+ ⣠<p,"q,""r",s>
+ ⣠NF = 3 <p><"q,""r"><s>
+ ⣠<p,"",s>
+ ⣠NF = 3 <p><""><s>
+ ⣠<p,,s>
+ ⣠NF = 3 <p><><s>
+
+ In general, using âFPATâ to do your own CSV parsing is like having a
+bed with a blanket thatâs not quite big enough. Thereâs always a corner
+that isnât covered. We recommend, instead, that you use Manuel
+Colladoâs âCSVMODEâ library for âgawkâ
(http://mcollado.z15.es/xgawk/).
File: gawk.info, Node: FS versus FPAT, Prev: More CSV, Up: Splitting By
Content
-4.7.2 'FS' Versus 'FPAT': A Subtle Difference
+4.7.2 âFSâ Versus âFPATâ: A Subtle Difference
---------------------------------------------
-As we discussed earlier, 'FS' describes the data between fields ("what
-fields are not") and 'FPAT' describes the fields themselves ("what
-fields are"). This leads to a subtle difference in how fields are found
-when using regexps as the value for 'FS' or 'FPAT'.
+As we discussed earlier, âFSâ describes the data between fields (âwhat
+fields are notâ) and âFPATâ describes the fields themselves (âwhat
+fields areâ). This leads to a subtle difference in how fields are found
+when using regexps as the value for âFSâ or âFPATâ.
In order to distinguish one field from another, there must be a
non-empty separator between each field. This makes intuitive
-sense--otherwise one could not distinguish fields from separators.
+senseâotherwise one could not distinguish fields from separators.
Thus, regular expression matching as done when splitting fields with
-'FS' is not allowed to match the null string; it must always match at
+âFSâ is not allowed to match the null string; it must always match at
least one character, in order to be able to proceed through the entire
record.
- On the other hand, regular expression matching with 'FPAT' can match
+ On the other hand, regular expression matching with âFPATâ can match
the null string, and the non-matching intervening characters function as
the separators.
This same difference is reflected in how matching is done with the
-'split()' and 'patsplit()' functions (*note String Functions::).
+âsplit()â and âpatsplit()â functions (*note String Functions::).
File: gawk.info, Node: Testing field creation, Next: Multiple Line, Prev:
Splitting By Content, Up: Reading Files
-4.8 Checking How 'gawk' Is Splitting Records
+4.8 Checking How âgawkâ Is Splitting Records
============================================
-As we've seen, 'gawk' provides three independent methods to split input
+As weâve seen, âgawkâ provides three independent methods to split input
records into fields. The mechanism used is based on which of the three
-variables--'FS', 'FIELDWIDTHS', or 'FPAT'--was last assigned to. In
+variablesââFSâ, âFIELDWIDTHSâ, or âFPATââwas last assigned to.
In
addition, an API input parser may choose to override the record parsing
mechanism; please refer to *note Input Parsers:: for further information
about this feature.
- To restore normal field splitting after using 'FIELDWIDTHS' and/or
-'FPAT', simply assign a value to 'FS'. You can use 'FS = FS' to do
-this, without having to know the current value of 'FS'.
+ To restore normal field splitting after using âFIELDWIDTHSâ and/or
+âFPATâ, simply assign a value to âFSâ. You can use âFS = FSâ to do
+this, without having to know the current value of âFSâ.
In order to tell which kind of field splitting is in effect, use
-'PROCINFO["FS"]' (*note Auto-set::). The value is '"FS"' if regular
-field splitting is being used, '"FIELDWIDTHS"' if fixed-width field
-splitting is being used, or '"FPAT"' if content-based field splitting is
+âPROCINFO["FS"]â (*note Auto-set::). The value is â"FS"â if regular
+field splitting is being used, â"FIELDWIDTHS"â if fixed-width field
+splitting is being used, or â"FPAT"â if content-based field splitting is
being used:
if (PROCINFO["FS"] == "FS")
@@ -5833,7 +5833,7 @@ being used:
API INPUT PARSER FIELD SPLITTING ... (advanced feature)
This information is useful when writing a function that needs to
-temporarily change 'FS' or 'FIELDWIDTHS', read some records, and then
+temporarily change âFSâ or âFIELDWIDTHSâ, read some records, and then
restore the original settings (*note Passwd Functions:: for an example
of such a function).
@@ -5849,31 +5849,31 @@ The first step in doing this is to choose your data
format.
One technique is to use an unusual character or string to separate
records. For example, you could use the formfeed character (written
-'\f' in 'awk', as in C) to separate them, making each record a page of
-the file. To do this, just set the variable 'RS' to '"\f"' (a string
+â\fâ in âawkâ, as in C) to separate them, making each record a page of
+the file. To do this, just set the variable âRSâ to â"\f"â (a string
containing the formfeed character). Any other character could equally
-well be used, as long as it won't be part of the data in a record.
+well be used, as long as it wonât be part of the data in a record.
Another technique is to have blank lines separate records. By a
-special dispensation, an empty string as the value of 'RS' indicates
-that records are separated by one or more blank lines. When 'RS' is set
+special dispensation, an empty string as the value of âRSâ indicates
+that records are separated by one or more blank lines. When âRSâ is set
to the empty string, each record always ends at the first blank line
-encountered. The next record doesn't start until the first nonblank
+encountered. The next record doesnât start until the first nonblank
line that follows. No matter how many blank lines appear in a row, they
all act as one record separator. (Blank lines must be completely empty;
lines that contain only whitespace do not count.)
- You can achieve the same effect as 'RS = ""' by assigning the string
-'"\n\n+"' to 'RS'. This regexp matches the newline at the end of the
+ You can achieve the same effect as âRS = ""â by assigning the string
+â"\n\n+"â to âRSâ. This regexp matches the newline at the end of the
record and one or more blank lines after the record. In addition, a
regular expression always matches the longest possible sequence when
there is a choice (*note Leftmost Longest::). So, the next record
-doesn't start until the first nonblank line that follows--no matter how
+doesnât start until the first nonblank line that followsâno matter how
many blank lines appear in a row, they are considered one record
separator.
- However, there is an important difference between 'RS = ""' and 'RS =
-"\n\n+"'. In the first case, leading newlines in the input data file
+ However, there is an important difference between âRS = ""â and âRS =
+"\n\n+"â. In the first case, leading newlines in the input data file
are ignored, and if a file ends without extra blank lines after the last
record, the final newline is removed from the record. In the second
case, this special processing is not done. (d.c.)
@@ -5881,37 +5881,37 @@ case, this special processing is not done. (d.c.)
Now that the input is separated into records, the second step is to
separate the fields in the records. One way to do this is to divide
each of the lines into fields in the normal manner. This happens by
-default as the result of a special feature. When 'RS' is set to the
-empty string _and_ 'FS' is set to a single character, the newline
+default as the result of a special feature. When âRSâ is set to the
+empty string _and_ âFSâ is set to a single character, the newline
character _always_ acts as a field separator. This is in addition to
-whatever field separations result from 'FS'.
+whatever field separations result from âFSâ.
- NOTE: When 'FS' is the null string ('""') or a regexp, this special
- feature of 'RS' does not apply. It does apply to the default field
- separator of a single space: 'FS = " "'.
+ NOTE: When âFSâ is the null string (â""â) or a regexp, this
special
+ feature of âRSâ does not apply. It does apply to the default field
+ separator of a single space: âFS = " "â.
Note that language in the POSIX specification implies that this
- special feature should apply when 'FS' is a regexp. However, Unix
- 'awk' has never behaved that way, nor has 'gawk'. This is
+ special feature should apply when âFSâ is a regexp. However, Unix
+ âawkâ has never behaved that way, nor has âgawkâ. This is
essentially a bug in POSIX.
The original motivation for this special exception was probably to
-provide useful behavior in the default case (i.e., 'FS' is equal to
-'" "'). This feature can be a problem if you really don't want the
+provide useful behavior in the default case (i.e., âFSâ is equal to
+â" "â). This feature can be a problem if you really donât want the
newline character to separate fields, because there is no way to prevent
-it. However, you can work around this by using the 'split()' function
+it. However, you can work around this by using the âsplit()â function
to break up the record manually (*note String Functions::). If you have
a single-character field separator, you can work around the special
-feature in a different way, by making 'FS' into a regexp for that single
+feature in a different way, by making âFSâ into a regexp for that single
character. For example, if the field separator is a percent character,
-instead of 'FS = "%"', use 'FS = "[%]"'.
+instead of âFS = "%"â, use âFS = "[%]"â.
Another way to separate fields is to put each field on a separate
-line: to do this, just set the variable 'FS' to the string '"\n"'.
+line: to do this, just set the variable âFSâ to the string â"\n"â.
(This single-character separator matches a single newline.) A practical
example of a data file organized this way might be a mailing list, where
blank lines separate the entries. Consider a mailing list in a file
-named 'addresses', which looks like this:
+named âaddressesâ, which looks like this:
Jane Doe
123 Main Street
@@ -5940,107 +5940,107 @@ A simple program to process this file is as follows:
Running the program produces the following output:
$ awk -f addrs.awk addresses
- -| Name is: Jane Doe
- -| Address is: 123 Main Street
- -| City and State are: Anywhere, SE 12345-6789
- -|
- -| Name is: John Smith
- -| Address is: 456 Tree-lined Avenue
- -| City and State are: Smallville, MW 98765-4321
- -|
+ ⣠Name is: Jane Doe
+ ⣠Address is: 123 Main Street
+ ⣠City and State are: Anywhere, SE 12345-6789
+ â£
+ ⣠Name is: John Smith
+ ⣠Address is: 456 Tree-lined Avenue
+ ⣠City and State are: Smallville, MW 98765-4321
+ â£
...
*Note Labels Program:: for a more realistic program dealing with
address lists. The following list summarizes how records are split,
-based on the value of 'RS'. ('==' means "is equal to.")
+based on the value of âRSâ. (â==â means âis equal to.â)
-'RS == "\n"'
- Records are separated by the newline character ('\n'). In effect,
+âRS == "\n"â
+ Records are separated by the newline character (â\nâ). In effect,
every line in the data file is a separate record, including blank
lines. This is the default.
-'RS == ANY SINGLE CHARACTER'
+âRS == ANY SINGLE CHARACTERâ
Records are separated by each occurrence of the character.
Multiple successive occurrences delimit empty records.
-'RS == ""'
- Records are separated by runs of blank lines. When 'FS' is a
+âRS == ""â
+ Records are separated by runs of blank lines. When âFSâ is a
single character, then the newline character always serves as a
- field separator, in addition to whatever value 'FS' may have.
+ field separator, in addition to whatever value âFSâ may have.
Leading and trailing newlines in a file are ignored.
-'RS == REGEXP'
+âRS == REGEXPâ
Records are separated by occurrences of characters that match
REGEXP. Leading and trailing matches of REGEXP delimit empty
- records. (This is a 'gawk' extension; it is not specified by the
+ records. (This is a âgawkâ extension; it is not specified by the
POSIX standard.)
- If not in compatibility mode (*note Options::), 'gawk' sets 'RT' to
-the input text that matched the value specified by 'RS'. But if the
-input file ended without any text that matches 'RS', then 'gawk' sets
-'RT' to the null string.
+ If not in compatibility mode (*note Options::), âgawkâ sets âRTâ to
+the input text that matched the value specified by âRSâ. But if the
+input file ended without any text that matches âRSâ, then âgawkâ sets
+âRTâ to the null string.
File: gawk.info, Node: Getline, Next: Read Timeout, Prev: Multiple Line,
Up: Reading Files
-4.10 Explicit Input with 'getline'
+4.10 Explicit Input with âgetlineâ
==================================
-So far we have been getting our input data from 'awk''s main input
-stream--either the standard input (usually your keyboard, sometimes the
+So far we have been getting our input data from âawkââs main input
+streamâeither the standard input (usually your keyboard, sometimes the
output from another program) or the files specified on the command line.
-The 'awk' language has a special built-in command called 'getline' that
+The âawkâ language has a special built-in command called âgetlineâ that
can be used to read input under your explicit control.
- The 'getline' command is used in several different ways and should
+ The âgetlineâ command is used in several different ways and should
_not_ be used by beginners. The examples that follow the explanation of
-the 'getline' command include material that has not been covered yet.
-Therefore, come back and study the 'getline' command _after_ you have
+the âgetlineâ command include material that has not been covered yet.
+Therefore, come back and study the âgetlineâ command _after_ you have
reviewed the rest of this Info file and have a good knowledge of how
-'awk' works.
+âawkâ works.
- The 'getline' command returns 1 if it finds a record and 0 if it
+ The âgetlineâ command returns 1 if it finds a record and 0 if it
encounters the end of the file. If there is some error in getting a
-record, such as a file that cannot be opened, then 'getline' returns -1.
-In this case, 'gawk' sets the variable 'ERRNO' to a string describing
+record, such as a file that cannot be opened, then âgetlineâ returns â1.
+In this case, âgawkâ sets the variable âERRNOâ to a string describing
the error that occurred.
- If 'ERRNO' indicates that the I/O operation may be retried, and
-'PROCINFO["INPUT", "RETRY"]' is set, then 'getline' returns -2 instead
-of -1, and further calls to 'getline' may be attempted. *Note Retrying
+ If âERRNOâ indicates that the I/O operation may be retried, and
+âPROCINFO["INPUT", "RETRY"]â is set, then âgetlineâ returns â2
instead
+of â1, and further calls to âgetlineâ may be attempted. *Note Retrying
Input:: for further information about this feature.
In the following examples, COMMAND stands for a string value that
represents a shell command.
- NOTE: When '--sandbox' is specified (*note Options::), reading
+ NOTE: When â--sandboxâ is specified (*note Options::), reading
lines from files, pipes, and coprocesses is disabled.
* Menu:
-* Plain Getline:: Using 'getline' with no arguments.
-* Getline/Variable:: Using 'getline' into a variable.
-* Getline/File:: Using 'getline' from a file.
-* Getline/Variable/File:: Using 'getline' into a variable from a
+* Plain Getline:: Using âgetlineâ with no arguments.
+* Getline/Variable:: Using âgetlineâ into a variable.
+* Getline/File:: Using âgetlineâ from a file.
+* Getline/Variable/File:: Using âgetlineâ into a variable from a
file.
-* Getline/Pipe:: Using 'getline' from a pipe.
-* Getline/Variable/Pipe:: Using 'getline' into a variable from a
+* Getline/Pipe:: Using âgetlineâ from a pipe.
+* Getline/Variable/Pipe:: Using âgetlineâ into a variable from a
pipe.
-* Getline/Coprocess:: Using 'getline' from a coprocess.
-* Getline/Variable/Coprocess:: Using 'getline' into a variable from a
+* Getline/Coprocess:: Using âgetlineâ from a coprocess.
+* Getline/Variable/Coprocess:: Using âgetlineâ into a variable from a
coprocess.
-* Getline Notes:: Important things to know about 'getline'.
-* Getline Summary:: Summary of 'getline' Variants.
+* Getline Notes:: Important things to know about âgetlineâ.
+* Getline Summary:: Summary of âgetlineâ Variants.
File: gawk.info, Node: Plain Getline, Next: Getline/Variable, Up: Getline
-4.10.1 Using 'getline' with No Arguments
+4.10.1 Using âgetlineâ with No Arguments
----------------------------------------
-The 'getline' command can be used without arguments to read input from
+The âgetlineâ command can be used without arguments to read input from
the current input file. All it does in this case is read the next input
-record and split it up into fields. This is useful if you've finished
+record and split it up into fields. This is useful if youâve finished
processing the current record, but want to do some special processing on
the next record _right now_. For example:
@@ -6065,11 +6065,11 @@ the next record _right now_. For example:
print $0
}
- This 'awk' program deletes C-style comments ('/* ... */') from the
-input. It uses a number of features we haven't covered yet, including
-string concatenation (*note Concatenation::) and the 'index()' and
-'substr()' built-in functions (*note String Functions::). By replacing
-the 'print $0' with other statements, you could perform more complicated
+ This âawkâ program deletes C-style comments (â/* ... */â) from the
+input. It uses a number of features we havenât covered yet, including
+string concatenation (*note Concatenation::) and the âindex()â and
+âsubstr()â built-in functions (*note String Functions::). By replacing
+the âprint $0â with other statements, you could perform more complicated
processing on the decommented input, such as searching for matches of a
regular expression.
@@ -6085,18 +6085,18 @@ regular expression.
When run, the output is:
$ awk -f strip_comments.awk example_text
- -| monkey
- -| rabbit
- -| horse more text
- -| part 1 part 2 part 3
- -| no comment
-
- This form of the 'getline' command sets 'NF', 'NR', 'FNR', 'RT', and
-the value of '$0'.
-
- NOTE: The new value of '$0' is used to test the patterns of any
- subsequent rules. The original value of '$0' that triggered the
- rule that executed 'getline' is lost. By contrast, the 'next'
+ ⣠monkey
+ ⣠rabbit
+ ⣠horse more text
+ ⣠part 1 part 2 part 3
+ ⣠no comment
+
+ This form of the âgetlineâ command sets âNFâ, âNRâ, âFNRâ,
âRTâ, and
+the value of â$0â.
+
+ NOTE: The new value of â$0â is used to test the patterns of any
+ subsequent rules. The original value of â$0â that triggered the
+ rule that executed âgetlineâ is lost. By contrast, the ânextâ
statement reads a new record but immediately begins processing it
normally, starting with the first rule in the program. *Note Next
Statement::.
@@ -6104,15 +6104,15 @@ the value of '$0'.
File: gawk.info, Node: Getline/Variable, Next: Getline/File, Prev: Plain
Getline, Up: Getline
-4.10.2 Using 'getline' into a Variable
+4.10.2 Using âgetlineâ into a Variable
--------------------------------------
-You can use 'getline VAR' to read the next record from 'awk''s input
+You can use âgetline VARâ to read the next record from âawkââs input
into the variable VAR. No other processing is done. For example,
suppose the next line is a comment or a special string, and you want to
-read it without triggering any rules. This form of 'getline' allows you
+read it without triggering any rules. This form of âgetlineâ allows you
to read that line and store it in a variable so that the main
-read-a-line-and-check-each-rule loop of 'awk' never sees it. The
+read-a-line-and-check-each-rule loop of âawkâ never sees it. The
following example swaps every two lines of input:
{
@@ -6137,22 +6137,22 @@ and produces these results:
phore
free
- The 'getline' command used in this way sets only the variables 'NR',
-'FNR', and 'RT' (and, of course, VAR). The record is not split into
-fields, so the values of the fields (including '$0') and the value of
-'NF' do not change.
+ The âgetlineâ command used in this way sets only the variables âNRâ,
+âFNRâ, and âRTâ (and, of course, VAR). The record is not split into
+fields, so the values of the fields (including â$0â) and the value of
+âNFâ do not change.
File: gawk.info, Node: Getline/File, Next: Getline/Variable/File, Prev:
Getline/Variable, Up: Getline
-4.10.3 Using 'getline' from a File
+4.10.3 Using âgetlineâ from a File
----------------------------------
-Use 'getline < FILE' to read the next record from FILE. Here, FILE is a
-string-valued expression that specifies the file name. '< FILE' is
-called a "redirection" because it directs input to come from a different
+Use âgetline < FILEâ to read the next record from FILE. Here, FILE is a
+string-valued expression that specifies the file name. â< FILEâ is
+called a âredirectionâ because it directs input to come from a different
place. For example, the following program reads its input record from
-the file 'secondary.input' when it encounters a first field with a value
+the file âsecondary.inputâ when it encounters a first field with a value
equal to 10 in the current input file:
{
@@ -6163,33 +6163,33 @@ equal to 10 in the current input file:
print
}
- Because the main input stream is not used, the values of 'NR' and
-'FNR' are not changed. However, the record it reads is split into
-fields in the normal manner, so the values of '$0' and the other fields
-are changed, resulting in a new value of 'NF'. 'RT' is also set.
+ Because the main input stream is not used, the values of âNRâ and
+âFNRâ are not changed. However, the record it reads is split into
+fields in the normal manner, so the values of â$0â and the other fields
+are changed, resulting in a new value of âNFâ. âRTâ is also set.
- According to POSIX, 'getline < EXPRESSION' is ambiguous if EXPRESSION
-contains unparenthesized operators other than '$'; for example, 'getline
-< dir "/" file' is ambiguous because the concatenation operator (not
+ According to POSIX, âgetline < EXPRESSIONâ is ambiguous if EXPRESSION
+contains unparenthesized operators other than â$â; for example, âgetline
+< dir "/" fileâ is ambiguous because the concatenation operator (not
discussed yet; *note Concatenation::) is not parenthesized. You should
-write it as 'getline < (dir "/" file)' if you want your program to be
-portable to all 'awk' implementations.
+write it as âgetline < (dir "/" file)â if you want your program to be
+portable to all âawkâ implementations.
File: gawk.info, Node: Getline/Variable/File, Next: Getline/Pipe, Prev:
Getline/File, Up: Getline
-4.10.4 Using 'getline' into a Variable from a File
+4.10.4 Using âgetlineâ into a Variable from a File
--------------------------------------------------
-Use 'getline VAR < FILE' to read input from the file FILE, and put it in
+Use âgetline VAR < FILEâ to read input from the file FILE, and put it in
the variable VAR. As earlier, FILE is a string-valued expression that
specifies the file from which to read.
- In this version of 'getline', none of the predefined variables are
+ In this version of âgetlineâ, none of the predefined variables are
changed and the record is not split into fields. The only variable
changed is VAR.(1) For example, the following program copies all the
input files to the output, except for records that say
-'@include FILENAME'. Such a record is replaced by the contents of the
+â@include FILENAMEâ. Such a record is replaced by the contents of the
file FILENAME:
{
@@ -6203,38 +6203,38 @@ file FILENAME:
Note here how the name of the extra input file is not built into the
program; it is taken directly from the data, specifically from the
-second field on the '@include' line.
+second field on the â@includeâ line.
- The 'close()' function is called to ensure that if two identical
-'@include' lines appear in the input, the entire specified file is
+ The âclose()â function is called to ensure that if two identical
+â@includeâ lines appear in the input, the entire specified file is
included twice. *Note Close Files And Pipes::.
One deficiency of this program is that it does not process nested
-'@include' statements (i.e., '@include' statements in included files)
+â@includeâ statements (i.e., â@includeâ statements in included files)
the way a true macro preprocessor would. *Note Igawk Program:: for a
-program that does handle nested '@include' statements.
+program that does handle nested â@includeâ statements.
---------- Footnotes ----------
- (1) This is not quite true. 'RT' could be changed if 'RS' is a
+ (1) This is not quite true. âRTâ could be changed if âRSâ is a
regular expression.
File: gawk.info, Node: Getline/Pipe, Next: Getline/Variable/Pipe, Prev:
Getline/Variable/File, Up: Getline
-4.10.5 Using 'getline' from a Pipe
+4.10.5 Using âgetlineâ from a Pipe
----------------------------------
Omniscience has much to recommend it. Failing that, attention to
details would be useful.
- -- _Brian Kernighan_
+ â _Brian Kernighan_
- The output of a command can also be piped into 'getline', using
-'COMMAND | getline'. In this case, the string COMMAND is run as a shell
-command and its output is piped into 'awk' to be used as input. This
-form of 'getline' reads one record at a time from the pipe. For
+ The output of a command can also be piped into âgetlineâ, using
+âCOMMAND | getlineâ. In this case, the string COMMAND is run as a shell
+command and its output is piped into âawkâ to be used as input. This
+form of âgetlineâ reads one record at a time from the pipe. For
example, the following program copies its input to its output, except
-for lines that begin with '@execute', which are replaced by the output
+for lines that begin with â@executeâ, which are replaced by the output
produced by running the rest of the line as a shell command:
{
@@ -6247,8 +6247,8 @@ produced by running the rest of the line as a shell
command:
print
}
-The 'close()' function is called to ensure that if two identical
-'@execute' lines appear in the input, the command is run for each one.
+The âclose()â function is called to ensure that if two identical
+â@executeâ lines appear in the input, the command is run for each one.
*Note Close Files And Pipes::. Given the input:
foo
@@ -6267,38 +6267,38 @@ the program might produce:
bill ttyp1 Jul 13 14:23 (murphy:0)
bletch
-Notice that this program ran the command 'who' and printed the result.
+Notice that this program ran the command âwhoâ and printed the result.
(If you try this program yourself, you will of course get different
results, depending upon who is logged in on your system.)
- This variation of 'getline' splits the record into fields, sets the
-value of 'NF', and recomputes the value of '$0'. The values of 'NR' and
-'FNR' are not changed. 'RT' is set.
+ This variation of âgetlineâ splits the record into fields, sets the
+value of âNFâ, and recomputes the value of â$0â. The values of
âNRâ and
+âFNRâ are not changed. âRTâ is set.
- According to POSIX, 'EXPRESSION | getline' is ambiguous if EXPRESSION
-contains unparenthesized operators other than '$'--for example, '"echo "
-"date" | getline' is ambiguous because the concatenation operator is not
-parenthesized. You should write it as '("echo " "date") | getline' if
-you want your program to be portable to all 'awk' implementations.
+ According to POSIX, âEXPRESSION | getlineâ is ambiguous if EXPRESSION
+contains unparenthesized operators other than â$ââfor example, â"echo "
+"date" | getlineâ is ambiguous because the concatenation operator is not
+parenthesized. You should write it as â("echo " "date") | getlineâ if
+you want your program to be portable to all âawkâ implementations.
- NOTE: Unfortunately, 'gawk' has not been consistent in its
- treatment of a construct like '"echo " "date" | getline'. Most
- versions, including the current version, treat it as '("echo "
- "date") | getline'. (This is also how BWK 'awk' behaves.) Some
- versions instead treat it as '"echo " ("date" | getline)'. (This
- is how 'mawk' behaves.) In short, _always_ use explicit
- parentheses, and then you won't have to worry.
+ NOTE: Unfortunately, âgawkâ has not been consistent in its
+ treatment of a construct like â"echo " "date" | getlineâ. Most
+ versions, including the current version, treat it as â("echo "
+ "date") | getlineâ. (This is also how BWK âawkâ behaves.) Some
+ versions instead treat it as â"echo " ("date" | getline)â. (This
+ is how âmawkâ behaves.) In short, _always_ use explicit
+ parentheses, and then you wonât have to worry.
File: gawk.info, Node: Getline/Variable/Pipe, Next: Getline/Coprocess,
Prev: Getline/Pipe, Up: Getline
-4.10.6 Using 'getline' into a Variable from a Pipe
+4.10.6 Using âgetlineâ into a Variable from a Pipe
--------------------------------------------------
-When you use 'COMMAND | getline VAR', the output of COMMAND is sent
-through a pipe to 'getline' and into the variable VAR. For example, the
+When you use âCOMMAND | getline VARâ, the output of COMMAND is sent
+through a pipe to âgetlineâ and into the variable VAR. For example, the
following program reads the current date and time into the variable
-'current_time', using the 'date' utility, and then prints it:
+âcurrent_timeâ, using the âdateâ utility, and then prints it:
BEGIN {
"date" | getline current_time
@@ -6306,108 +6306,108 @@ following program reads the current date and time
into the variable
print "Report printed on " current_time
}
- In this version of 'getline', none of the predefined variables are
-changed and the record is not split into fields. However, 'RT' is set.
+ In this version of âgetlineâ, none of the predefined variables are
+changed and the record is not split into fields. However, âRTâ is set.
- According to POSIX, 'EXPRESSION | getline VAR' is ambiguous if
-EXPRESSION contains unparenthesized operators other than '$'; for
-example, '"echo " "date" | getline VAR' is ambiguous because the
+ According to POSIX, âEXPRESSION | getline VARâ is ambiguous if
+EXPRESSION contains unparenthesized operators other than â$â; for
+example, â"echo " "date" | getline VARâ is ambiguous because the
concatenation operator is not parenthesized. You should write it as
-'("echo " "date") | getline VAR' if you want your program to be portable
-to other 'awk' implementations.
+â("echo " "date") | getline VARâ if you want your program to be portable
+to other âawkâ implementations.
File: gawk.info, Node: Getline/Coprocess, Next: Getline/Variable/Coprocess,
Prev: Getline/Variable/Pipe, Up: Getline
-4.10.7 Using 'getline' from a Coprocess
+4.10.7 Using âgetlineâ from a Coprocess
---------------------------------------
-Reading input into 'getline' from a pipe is a one-way operation. The
-command that is started with 'COMMAND | getline' only sends data _to_
-your 'awk' program.
+Reading input into âgetlineâ from a pipe is a one-way operation. The
+command that is started with âCOMMAND | getlineâ only sends data _to_
+your âawkâ program.
On occasion, you might want to send data to another program for
-processing and then read the results back. 'gawk' allows you to start a
-"coprocess", with which two-way communications are possible. This is
-done with the '|&' operator. Typically, you write data to the coprocess
+processing and then read the results back. âgawkâ allows you to start a
+âcoprocessâ, with which two-way communications are possible. This is
+done with the â|&â operator. Typically, you write data to the coprocess
first and then read the results back, as shown in the following:
print "SOME QUERY" |& "db_server"
"db_server" |& getline
-which sends a query to 'db_server' and then reads the results.
+which sends a query to âdb_serverâ and then reads the results.
- The values of 'NR' and 'FNR' are not changed, because the main input
+ The values of âNRâ and âFNRâ are not changed, because the main input
stream is not used. However, the record is split into fields in the
-normal manner, thus changing the values of '$0', of the other fields,
-and of 'NF' and 'RT'.
+normal manner, thus changing the values of â$0â, of the other fields,
+and of âNFâ and âRTâ.
Coprocesses are an advanced feature. They are discussed here only
-because this is the minor node on 'getline'. *Note Two-way I/O::, where
+because this is the minor node on âgetlineâ. *Note Two-way I/O::, where
coprocesses are discussed in more detail.
File: gawk.info, Node: Getline/Variable/Coprocess, Next: Getline Notes,
Prev: Getline/Coprocess, Up: Getline
-4.10.8 Using 'getline' into a Variable from a Coprocess
+4.10.8 Using âgetlineâ into a Variable from a Coprocess
-------------------------------------------------------
-When you use 'COMMAND |& getline VAR', the output from the coprocess
-COMMAND is sent through a two-way pipe to 'getline' and into the
+When you use âCOMMAND |& getline VARâ, the output from the coprocess
+COMMAND is sent through a two-way pipe to âgetlineâ and into the
variable VAR.
- In this version of 'getline', none of the predefined variables are
+ In this version of âgetlineâ, none of the predefined variables are
changed and the record is not split into fields. The only variable
-changed is VAR. However, 'RT' is set.
+changed is VAR. However, âRTâ is set.
Coprocesses are an advanced feature. They are discussed here only
-because this is the minor node on 'getline'. *Note Two-way I/O::, where
+because this is the minor node on âgetlineâ. *Note Two-way I/O::, where
coprocesses are discussed in more detail.
File: gawk.info, Node: Getline Notes, Next: Getline Summary, Prev:
Getline/Variable/Coprocess, Up: Getline
-4.10.9 Points to Remember About 'getline'
+4.10.9 Points to Remember About âgetlineâ
-----------------------------------------
-Here are some miscellaneous points about 'getline' that you should bear
+Here are some miscellaneous points about âgetlineâ that you should bear
in mind:
- * When 'getline' changes the value of '$0' and 'NF', 'awk' does _not_
+ ⢠When âgetlineâ changes the value of â$0â and âNFâ,
âawkâ does _not_
automatically jump to the start of the program and start testing
the new record against every pattern. However, the new record is
tested against any subsequent rules.
- * Some very old 'awk' implementations limit the number of pipelines
- that an 'awk' program may have open to just one. In 'gawk', there
+ ⢠Some very old âawkâ implementations limit the number of pipelines
+ that an âawkâ program may have open to just one. In âgawkâ, there
is no such limit. You can open as many pipelines (and coprocesses)
as the underlying operating system permits.
- * An interesting side effect occurs if you use 'getline' without a
- redirection inside a 'BEGIN' rule. Because an unredirected
- 'getline' reads from the command-line data files, the first
- 'getline' command causes 'awk' to set the value of 'FILENAME'.
- Normally, 'FILENAME' does not have a value inside 'BEGIN' rules,
+ ⢠An interesting side effect occurs if you use âgetlineâ without a
+ redirection inside a âBEGINâ rule. Because an unredirected
+ âgetlineâ reads from the command-line data files, the first
+ âgetlineâ command causes âawkâ to set the value of âFILENAMEâ.
+ Normally, âFILENAMEâ does not have a value inside âBEGINâ rules,
because you have not yet started to process the command-line data
files. (d.c.) (See *note BEGIN/END::; also *note Auto-set::.)
- * Using 'FILENAME' with 'getline' ('getline < FILENAME') is likely to
- be a source of confusion. 'awk' opens a separate input stream from
- the current input file. However, by not using a variable, '$0' and
- 'NF' are still updated. If you're doing this, it's probably by
- accident, and you should reconsider what it is you're trying to
+ ⢠Using âFILENAMEâ with âgetlineâ (âgetline < FILENAMEâ) is
likely to
+ be a source of confusion. âawkâ opens a separate input stream from
+ the current input file. However, by not using a variable, â$0â and
+ âNFâ are still updated. If youâre doing this, itâs probably by
+ accident, and you should reconsider what it is youâre trying to
accomplish.
- * *note Getline Summary::, presents a table summarizing the 'getline'
+ ⢠*note Getline Summary::, presents a table summarizing the âgetlineâ
variants and which variables they can affect. It is worth noting
that those variants that do not use redirection can cause
- 'FILENAME' to be updated if they cause 'awk' to start reading a new
+ âFILENAMEâ to be updated if they cause âawkâ to start reading a
new
input file.
- * If the variable being assigned is an expression with side effects,
- different versions of 'awk' behave differently upon encountering
- end-of-file. Some versions don't evaluate the expression; many
- versions (including 'gawk') do. Here is an example, courtesy of
+ ⢠If the variable being assigned is an expression with side effects,
+ different versions of âawkâ behave differently upon encountering
+ end-of-file. Some versions donât evaluate the expression; many
+ versions (including âgawkâ) do. Here is an example, courtesy of
Duncan Moore:
BEGIN {
@@ -6416,42 +6416,42 @@ in mind:
print c
}
- Here, the side effect is the '++c'. Is 'c' incremented if
- end-of-file is encountered before the element in 'a' is assigned?
+ Here, the side effect is the â++câ. Is âcâ incremented if
+ end-of-file is encountered before the element in âaâ is assigned?
- 'gawk' treats 'getline' like a function call, and evaluates the
- expression 'a[++c]' before attempting to read from 'f'. However,
- some versions of 'awk' only evaluate the expression once they know
+ âgawkâ treats âgetlineâ like a function call, and evaluates the
+ expression âa[++c]â before attempting to read from âfâ. However,
+ some versions of âawkâ only evaluate the expression once they know
that there is a string value to be assigned.
File: gawk.info, Node: Getline Summary, Prev: Getline Notes, Up: Getline
-4.10.10 Summary of 'getline' Variants
+4.10.10 Summary of âgetlineâ Variants
-------------------------------------
*note Table 4.1: table-getline-variants. summarizes the eight variants
-of 'getline', listing which predefined variables are set by each one,
-and whether the variant is standard or a 'gawk' extension. Note: for
-each variant, 'gawk' sets the 'RT' predefined variable.
+of âgetlineâ, listing which predefined variables are set by each one,
+and whether the variant is standard or a âgawkâ extension. Note: for
+each variant, âgawkâ sets the âRTâ predefined variable.
-Variant Effect 'awk' / 'gawk'
+Variant Effect âawkâ / âgawkâ
-------------------------------------------------------------------------
-'getline' Sets '$0', 'NF', 'FNR', 'awk'
- 'NR', and 'RT'
-'getline' VAR Sets VAR, 'FNR', 'NR', 'awk'
- and 'RT'
-'getline <' FILE Sets '$0', 'NF', and 'RT' 'awk'
-'getline VAR < FILE' Sets VAR and 'RT' 'awk'
-COMMAND '| getline' Sets '$0', 'NF', and 'RT' 'awk'
-COMMAND '| getline' Sets VAR and 'RT' 'awk'
+âgetlineâ Sets â$0â, âNFâ, âFNRâ, âawkâ
+ âNRâ, and âRTâ
+âgetlineâ VAR Sets VAR, âFNRâ, âNRâ, âawkâ
+ and âRTâ
+âgetline <â FILE Sets â$0â, âNFâ, and âRTâ âawkâ
+âgetline VAR < FILEâ Sets VAR and âRTâ âawkâ
+COMMAND â| getlineâ Sets â$0â, âNFâ, and âRTâ âawkâ
+COMMAND â| getlineâ Sets VAR and âRTâ âawkâ
VAR
-COMMAND '|& getline' Sets '$0', 'NF', and 'RT' 'gawk'
-COMMAND '|& getline' Sets VAR and 'RT' 'gawk'
+COMMAND â|& getlineâ Sets â$0â, âNFâ, and âRTâ âgawkâ
+COMMAND â|& getlineâ Sets VAR and âRTâ âgawkâ
VAR
-Table 4.1: 'getline' variants and what they set
+Table 4.1: âgetlineâ variants and what they set
File: gawk.info, Node: Read Timeout, Next: Retrying Input, Prev: Getline,
Up: Reading Files
@@ -6459,16 +6459,16 @@ File: gawk.info, Node: Read Timeout, Next: Retrying
Input, Prev: Getline, Up
4.11 Reading Input with a Timeout
=================================
-This minor node describes a feature that is specific to 'gawk'.
+This minor node describes a feature that is specific to âgawkâ.
You may specify a timeout in milliseconds for reading input from the
keyboard, a pipe, or two-way communication, including TCP/IP sockets.
This can be done on a per-input, per-command, or per-connection basis,
-by setting a special element in the 'PROCINFO' array (*note Auto-set::):
+by setting a special element in the âPROCINFOâ array (*note Auto-set::):
PROCINFO["input_name", "READ_TIMEOUT"] = TIMEOUT IN MILLISECONDS
- When set, this causes 'gawk' to time out and return failure if no
+ When set, this causes âgawkâ to time out and return failure if no
data is available to read within the specified timeout period. For
example, a TCP client can decide to give up on receiving any response
from the server after a certain amount of time:
@@ -6487,8 +6487,8 @@ for more than five seconds:
while ((getline < "/dev/stdin") > 0)
print $0
- 'gawk' terminates the read operation if input does not arrive after
-waiting for the timeout period, returns failure, and sets 'ERRNO' to an
+ âgawkâ terminates the read operation if input does not arrive after
+waiting for the timeout period, returns failure, and sets âERRNOâ to an
appropriate string value. A negative or zero value for the timeout is
the same as specifying no timeout at all.
@@ -6499,12 +6499,12 @@ patterns, like so:
$ gawk 'BEGIN { PROCINFO["-", "READ_TIMEOUT"] = 5000 }
> { print "You entered: " $0 }'
gawk
- -| You entered: gawk
+ ⣠You entered: gawk
In this case, failure to respond within five seconds results in the
following error message:
- error-> gawk: cmd. line:2: (FILENAME=- FNR=1) fatal: error reading input
file `-': Connection timed out
+ errorâ gawk: cmd. line:2: (FILENAME=- FNR=1) fatal: error reading input
file `-': Connection timed out
The timeout can be set or changed at any time, and will take effect
on the next attempt to read from the input device. In the following
@@ -6520,24 +6520,24 @@ input to arrive:
NOTE: You should not assume that the read operation will block
exactly after the tenth record has been printed. It is possible
- that 'gawk' will read and buffer more than one record's worth of
+ that âgawkâ will read and buffer more than one recordâs worth of
data the first time. Because of this, changing the value of
timeout like in the preceding example is not very useful.
- If the 'PROCINFO' element is not present and the 'GAWK_READ_TIMEOUT'
-environment variable exists, 'gawk' uses its value to initialize the
+ If the âPROCINFOâ element is not present and the âGAWK_READ_TIMEOUTâ
+environment variable exists, âgawkâ uses its value to initialize the
timeout value. The exclusive use of the environment variable to specify
timeout has the disadvantage of not being able to control it on a
per-command or per-connection basis.
- 'gawk' considers a timeout event to be an error even though the
+ âgawkâ considers a timeout event to be an error even though the
attempt to read from the underlying device may succeed in a later
attempt. This is a limitation, and it also means that you cannot use
this to multiplex input from two or more sources. *Note Retrying
Input:: for a way to enable later I/O attempts to succeed.
Assigning a timeout value prevents read operations from being blocked
-indefinitely. But bear in mind that there are other ways 'gawk' can
+indefinitely. But bear in mind that there are other ways âgawkâ can
stall waiting for an input device to be ready. A network client can
sometimes take a long time to establish a connection before it can start
reading any data, or the attempt to open a FIFO special file for reading
@@ -6554,25 +6554,25 @@ File: gawk.info, Node: Retrying Input, Next:
Command-line directories, Prev:
4.12 Retrying Reads After Certain Input Errors
==============================================
-This minor node describes a feature that is specific to 'gawk'.
+This minor node describes a feature that is specific to âgawkâ.
- When 'gawk' encounters an error while reading input, by default
-'getline' returns -1, and subsequent attempts to read from that file
+ When âgawkâ encounters an error while reading input, by default
+âgetlineâ returns â1, and subsequent attempts to read from that file
result in an end-of-file indication. However, you may optionally
-instruct 'gawk' to allow I/O to be retried when certain errors are
-encountered by setting a special element in the 'PROCINFO' array (*note
+instruct âgawkâ to allow I/O to be retried when certain errors are
+encountered by setting a special element in the âPROCINFOâ array (*note
Auto-set::):
PROCINFO["INPUT_NAME", "RETRY"] = 1
- When this element exists, 'gawk' checks the value of the system (C
-language) 'errno' variable when an I/O error occurs. If 'errno'
-indicates a subsequent I/O attempt may succeed, 'getline' instead
-returns -2 and further calls to 'getline' may succeed. This applies to
-the 'errno' values 'EAGAIN', 'EWOULDBLOCK', 'EINTR', or 'ETIMEDOUT'.
+ When this element exists, âgawkâ checks the value of the system (C
+language) âerrnoâ variable when an I/O error occurs. If âerrnoâ
+indicates a subsequent I/O attempt may succeed, âgetlineâ instead
+returns â2 and further calls to âgetlineâ may succeed. This applies to
+the âerrnoâ values âEAGAINâ, âEWOULDBLOCKâ, âEINTRâ, or
âETIMEDOUTâ.
- This feature is useful in conjunction with 'PROCINFO["INPUT_NAME",
-"READ_TIMEOUT"]' or situations where a file descriptor has been
+ This feature is useful in conjunction with âPROCINFO["INPUT_NAME",
+"READ_TIMEOUT"]â or situations where a file descriptor has been
configured to behave in a non-blocking fashion.
@@ -6581,22 +6581,22 @@ File: gawk.info, Node: Command-line directories,
Next: Input Summary, Prev: R
4.13 Directories on the Command Line
====================================
-According to the POSIX standard, files named on the 'awk' command line
+According to the POSIX standard, files named on the âawkâ command line
must be text files; it is a fatal error if they are not. Most versions
-of 'awk' treat a directory on the command line as a fatal error.
+of âawkâ treat a directory on the command line as a fatal error.
- By default, 'gawk' produces a warning for a directory on the command
+ By default, âgawkâ produces a warning for a directory on the command
line, but otherwise ignores it. This makes it easier to use shell
-wildcards with your 'awk' program:
+wildcards with your âawkâ program:
$ gawk -f whizprog.awk * Directories could kill this program
- If either of the '--posix' or '--traditional' options is given, then
-'gawk' reverts to treating a directory on the command line as a fatal
+ If either of the â--posixâ or â--traditionalâ options is given, then
+âgawkâ reverts to treating a directory on the command line as a fatal
error.
*Note Extension Sample Readdir:: for a way to treat directories as
-usable data from an 'awk' program.
+usable data from an âawkâ program.
File: gawk.info, Node: Input Summary, Next: Input Exercises, Prev:
Command-line directories, Up: Reading Files
@@ -6604,71 +6604,71 @@ File: gawk.info, Node: Input Summary, Next: Input
Exercises, Prev: Command-li
4.14 Summary
============
- * Input is split into records based on the value of 'RS'. The
+ ⢠Input is split into records based on the value of âRSâ. The
possibilities are as follows:
- Value of 'RS' Records are split on 'awk' / 'gawk'
+ Value of âRSâ Records are split on âawkâ / âgawkâ
...
---------------------------------------------------------------------------
- Any single That character 'awk'
+ Any single That character âawkâ
character
- The empty string Runs of two or more 'awk'
- ('""') newlines
- A regexp Text that matches the 'gawk'
+ The empty string Runs of two or more âawkâ
+ (â""â) newlines
+ A regexp Text that matches the âgawkâ
regexp
- * 'FNR' indicates how many records have been read from the current
- input file; 'NR' indicates how many records have been read in
+ ⢠âFNRâ indicates how many records have been read from the current
+ input file; âNRâ indicates how many records have been read in
total.
- * 'gawk' sets 'RT' to the text matched by 'RS'.
+ ⢠âgawkâ sets âRTâ to the text matched by âRSâ.
- * After splitting the input into records, 'awk' further splits the
- records into individual fields, named '$1', '$2', and so on. '$0'
- is the whole record, and 'NF' indicates how many fields there are.
+ ⢠After splitting the input into records, âawkâ further splits the
+ records into individual fields, named â$1â, â$2â, and so on.
â$0â
+ is the whole record, and âNFâ indicates how many fields there are.
The default way to split fields is between whitespace characters.
- * Fields may be referenced using a variable, as in '$NF'. Fields may
- also be assigned values, which causes the value of '$0' to be
+ ⢠Fields may be referenced using a variable, as in â$NFâ. Fields may
+ also be assigned values, which causes the value of â$0â to be
recomputed when it is later referenced. Assigning to a field with
- a number greater than 'NF' creates the field and rebuilds the
- record, using 'OFS' to separate the fields. Incrementing 'NF' does
- the same thing. Decrementing 'NF' throws away fields and rebuilds
+ a number greater than âNFâ creates the field and rebuilds the
+ record, using âOFSâ to separate the fields. Incrementing âNFâ
does
+ the same thing. Decrementing âNFâ throws away fields and rebuilds
the record.
- * Field splitting is more complicated than record splitting:
+ ⢠Field splitting is more complicated than record splitting:
- Field separator value Fields are split ... 'awk' /
- 'gawk'
+ Field separator value Fields are split ... âawkâ /
+ âgawkâ
---------------------------------------------------------------------------
- 'FS == " "' On runs of whitespace 'awk'
- 'FS == ANY SINGLE On that character 'awk'
- CHARACTER'
- 'FS == REGEXP' On text matching the regexp 'awk'
- 'FS == ""' Such that each individual 'gawk'
+ âFS == " "â On runs of whitespace âawkâ
+ âFS == ANY SINGLE On that character âawkâ
+ CHARACTERâ
+ âFS == REGEXPâ On text matching the regexp âawkâ
+ âFS == ""â Such that each individual âgawkâ
character is a separate
field
- 'FIELDWIDTHS == LIST OF Based on character position 'gawk'
- COLUMNS'
- 'FPAT == REGEXP' On the text surrounding 'gawk'
+ âFIELDWIDTHS == LIST OF Based on character position âgawkâ
+ COLUMNSâ
+ âFPAT == REGEXPâ On the text surrounding âgawkâ
text matching the regexp
- * Using 'FS = "\n"' causes the entire record to be a single field
+ ⢠Using âFS = "\n"â causes the entire record to be a single field
(assuming that newlines separate records).
- * 'FS' may be set from the command line using the '-F' option. This
+ ⢠âFSâ may be set from the command line using the â-Fâ option.
This
can also be done using command-line variable assignment.
- * Use 'PROCINFO["FS"]' to see how fields are being split.
+ ⢠Use âPROCINFO["FS"]â to see how fields are being split.
- * Use 'getline' in its various forms to read additional records from
+ ⢠Use âgetlineâ in its various forms to read additional records from
the default input stream, from a file, or from a pipe or coprocess.
- * Use 'PROCINFO[FILE, "READ_TIMEOUT"]' to cause reads to time out for
+ ⢠Use âPROCINFO[FILE, "READ_TIMEOUT"]â to cause reads to time out for
FILE.
- * Directories on the command line are fatal for standard 'awk';
- 'gawk' ignores them if not in POSIX mode.
+ ⢠Directories on the command line are fatal for standard âawkâ;
+ âgawkâ ignores them if not in POSIX mode.
File: gawk.info, Node: Input Exercises, Prev: Input Summary, Up: Reading
Files
@@ -6676,9 +6676,9 @@ File: gawk.info, Node: Input Exercises, Prev: Input
Summary, Up: Reading File
4.15 Exercises
==============
- 1. Using the 'FIELDWIDTHS' variable (*note Constant Size::), write a
+ 1. Using the âFIELDWIDTHSâ variable (*note Constant Size::), write a
program to read election data, where each record represents one
- voter's votes. Come up with a way to define which columns are
+ voterâs votes. Come up with a way to define which columns are
associated with each ballot item, and print the total votes,
including abstentions, for each item.
@@ -6688,33 +6688,33 @@ File: gawk.info, Node: Printing, Next: Expressions,
Prev: Reading Files, Up:
5 Printing Output
*****************
-One of the most common programming actions is to "print", or output,
-some or all of the input. Use the 'print' statement for simple output,
-and the 'printf' statement for fancier formatting. The 'print'
+One of the most common programming actions is to âprintâ, or output,
+some or all of the input. Use the âprintâ statement for simple output,
+and the âprintfâ statement for fancier formatting. The âprintâ
statement is not limited when computing _which_ values to print.
-However, with two exceptions, you cannot specify _how_ to print
-them--how many columns, whether to use exponential notation or not, and
-so on. (For the exceptions, *note Output Separators:: and *note
-OFMT::.) For printing with specifications, you need the 'printf'
-statement (*note Printf::).
+However, with two exceptions, you cannot specify _how_ to print themâhow
+many columns, whether to use exponential notation or not, and so on.
+(For the exceptions, *note Output Separators:: and *note OFMT::.) For
+printing with specifications, you need the âprintfâ statement (*note
+Printf::).
Besides basic and formatted printing, this major node also covers I/O
redirections to files and pipes, introduces the special file names that
-'gawk' processes internally, and discusses the 'close()' built-in
+âgawkâ processes internally, and discusses the âclose()â built-in
function.
* Menu:
-* Print:: The 'print' statement.
-* Print Examples:: Simple examples of 'print' statements.
+* Print:: The âprintâ statement.
+* Print Examples:: Simple examples of âprintâ statements.
* Output Separators:: The output separators and how to change them.
-* OFMT:: Controlling Numeric Output With 'print'.
-* Printf:: The 'printf' statement.
+* OFMT:: Controlling Numeric Output With âprintâ.
+* Printf:: The âprintfâ statement.
* Redirection:: How to redirect output to multiple files and
pipes.
* Special FD:: Special files for I/O.
-* Special Files:: File name interpretation in 'gawk'.
- 'gawk' allows access to inherited file
+* Special Files:: File name interpretation in âgawkâ.
+ âgawkâ allows access to inherited file
descriptors.
* Close Files And Pipes:: Closing Input and Output Files and Pipes.
* Nonfatal:: Enabling Nonfatal Output.
@@ -6724,10 +6724,10 @@ function.
File: gawk.info, Node: Print, Next: Print Examples, Up: Printing
-5.1 The 'print' Statement
+5.1 The âprintâ Statement
=========================
-Use the 'print' statement to produce output with simple, standardized
+Use the âprintâ statement to produce output with simple, standardized
formatting. You specify only the strings or numbers to print, in a list
separated by commas. They are output, separated by single spaces,
followed by a newline. The statement looks like this:
@@ -6735,72 +6735,72 @@ followed by a newline. The statement looks like this:
print ITEM1, ITEM2, ...
The entire list of items may be optionally enclosed in parentheses. The
-parentheses are necessary if any of the item expressions uses the '>'
+parentheses are necessary if any of the item expressions uses the â>â
relational operator; otherwise it could be confused with an output
redirection (*note Redirection::).
The items to print can be constant strings or numbers, fields of the
-current record (such as '$1'), variables, or any 'awk' expression.
+current record (such as â$1â), variables, or any âawkâ expression.
Numeric values are converted to strings and then printed.
- The simple statement 'print' with no items is equivalent to 'print
-$0': it prints the entire current record. To print a blank line, use
-'print ""'. To print a fixed piece of text, use a string constant, such
-as '"Don't Panic"', as one item. If you forget to use the double-quote
-characters, your text is taken as an 'awk' expression, and you will
+ The simple statement âprintâ with no items is equivalent to âprint
+$0â: it prints the entire current record. To print a blank line, use
+âprint ""â. To print a fixed piece of text, use a string constant, such
+as â"Don't Panic"â, as one item. If you forget to use the double-quote
+characters, your text is taken as an âawkâ expression, and you will
probably get an error. Keep in mind that a space is printed between any
two items.
- Note that the 'print' statement is a statement and not an
-expression--you can't use it in the pattern part of a pattern-action
+ Note that the âprintâ statement is a statement and not an
+expressionâyou canât use it in the pattern part of a patternâaction
statement, for example.
File: gawk.info, Node: Print Examples, Next: Output Separators, Prev:
Print, Up: Printing
-5.2 'print' Statement Examples
+5.2 âprintâ Statement Examples
==============================
-Each 'print' statement makes at least one line of output. However, it
-isn't limited to only one line. If an item value is a string containing
+Each âprintâ statement makes at least one line of output. However, it
+isnât limited to only one line. If an item value is a string containing
a newline, the newline is output along with the rest of the string. A
-single 'print' statement can make any number of lines this way.
+single âprintâ statement can make any number of lines this way.
The following is an example of printing a string that contains
-embedded newlines (the '\n' is an escape sequence, used to represent the
+embedded newlines (the â\nâ is an escape sequence, used to represent the
newline character; *note Escape Sequences::):
$ awk 'BEGIN { print "line one\nline two\nline three" }'
- -| line one
- -| line two
- -| line three
+ ⣠line one
+ ⣠line two
+ ⣠line three
- The next example, which is run on the 'inventory-shipped' file,
+ The next example, which is run on the âinventory-shippedâ file,
prints the first two fields of each input record, with a space between
them:
$ awk '{ print $1, $2 }' inventory-shipped
- -| Jan 13
- -| Feb 15
- -| Mar 15
+ ⣠Jan 13
+ ⣠Feb 15
+ ⣠Mar 15
...
- A common mistake in using the 'print' statement is to omit the comma
+ A common mistake in using the âprintâ statement is to omit the comma
between two items. This often has the effect of making the items run
together in the output, with no space. The reason for this is that
-juxtaposing two string expressions in 'awk' means to concatenate them.
+juxtaposing two string expressions in âawkâ means to concatenate them.
Here is the same program, without the comma:
$ awk '{ print $1 $2 }' inventory-shipped
- -| Jan13
- -| Feb15
- -| Mar15
+ ⣠Jan13
+ ⣠Feb15
+ ⣠Mar15
...
- To someone unfamiliar with the 'inventory-shipped' file, neither
-example's output makes much sense. A heading line at the beginning
-would make it clearer. Let's add some headings to our table of months
-('$1') and green crates shipped ('$2'). We do this using a 'BEGIN' rule
+ To someone unfamiliar with the âinventory-shippedâ file, neither
+exampleâs output makes much sense. A heading line at the beginning
+would make it clearer. Letâs add some headings to our table of months
+(â$1â) and green crates shipped (â$2â). We do this using a
âBEGINâ rule
(*note BEGIN/END::) so that the headings are only printed once:
awk 'BEGIN { print "Month Crates"
@@ -6816,7 +6816,7 @@ When run, the program prints the following:
Mar 15
...
-The only problem, however, is that the headings and the table data don't
+The only problem, however, is that the headings and the table data donât
line up! We can fix this by printing some spaces between the two
fields:
@@ -6827,10 +6827,10 @@ fields:
Lining up columns this way can get pretty complicated when there are
many columns to fix. Counting spaces for two or three columns is
simple, but any more than this can take up a lot of time. This is why
-the 'printf' statement was created (*note Printf::); one of its
+the âprintfâ statement was created (*note Printf::); one of its
specialties is lining up columns of data.
- NOTE: You can continue either a 'print' or 'printf' statement
+ NOTE: You can continue either a âprintâ or âprintfâ statement
simply by putting a newline after any comma (*note
Statements/Lines::).
@@ -6840,102 +6840,102 @@ File: gawk.info, Node: Output Separators, Next:
OFMT, Prev: Print Examples,
5.3 Output Separators
=====================
-As mentioned previously, a 'print' statement contains a list of items
+As mentioned previously, a âprintâ statement contains a list of items
separated by commas. In the output, the items are normally separated by
-single spaces. However, this doesn't need to be the case; a single
+single spaces. However, this doesnât need to be the case; a single
space is simply the default. Any string of characters may be used as
-the "output field separator" by setting the predefined variable 'OFS'.
-The initial value of this variable is the string '" "' (i.e., a single
+the âoutput field separatorâ by setting the predefined variable âOFSâ.
+The initial value of this variable is the string â" "â (i.e., a single
space).
- The output from an entire 'print' statement is called an "output
-record". Each 'print' statement outputs one output record, and then
-outputs a string called the "output record separator" (or 'ORS'). The
-initial value of 'ORS' is the string '"\n"' (i.e., a newline character).
-Thus, each 'print' statement normally makes a separate line.
+ The output from an entire âprintâ statement is called an âoutput
+recordâ. Each âprintâ statement outputs one output record, and then
+outputs a string called the âoutput record separatorâ (or âORSâ). The
+initial value of âORSâ is the string â"\n"â (i.e., a newline
character).
+Thus, each âprintâ statement normally makes a separate line.
In order to change how output fields and records are separated,
-assign new values to the variables 'OFS' and 'ORS'. The usual place to
-do this is in the 'BEGIN' rule (*note BEGIN/END::), so that it happens
+assign new values to the variables âOFSâ and âORSâ. The usual place to
+do this is in the âBEGINâ rule (*note BEGIN/END::), so that it happens
before any input is processed. It can also be done with assignments on
-the command line, before the names of the input files, or using the '-v'
+the command line, before the names of the input files, or using the â-vâ
command-line option (*note Options::). The following example prints the
first and second fields of each input record, separated by a semicolon,
with a blank line added after each newline:
$ awk 'BEGIN { OFS = ";"; ORS = "\n\n" }
> { print $1, $2 }' mail-list
- -| Amelia;555-5553
- -|
- -| Anthony;555-3412
- -|
- -| Becky;555-7685
- -|
- -| Bill;555-1675
- -|
- -| Broderick;555-0542
- -|
- -| Camilla;555-2912
- -|
- -| Fabius;555-1234
- -|
- -| Julie;555-6699
- -|
- -| Martin;555-6480
- -|
- -| Samuel;555-3430
- -|
- -| Jean-Paul;555-2127
- -|
-
- If the value of 'ORS' does not contain a newline, the program's
+ ⣠Amelia;555-5553
+ â£
+ ⣠Anthony;555-3412
+ â£
+ ⣠Becky;555-7685
+ â£
+ ⣠Bill;555-1675
+ â£
+ ⣠Broderick;555-0542
+ â£
+ ⣠Camilla;555-2912
+ â£
+ ⣠Fabius;555-1234
+ â£
+ ⣠Julie;555-6699
+ â£
+ ⣠Martin;555-6480
+ â£
+ ⣠Samuel;555-3430
+ â£
+ ⣠Jean-Paul;555-2127
+ â£
+
+ If the value of âORSâ does not contain a newline, the programâs
output runs together on a single line.
File: gawk.info, Node: OFMT, Next: Printf, Prev: Output Separators, Up:
Printing
-5.4 Controlling Numeric Output with 'print'
+5.4 Controlling Numeric Output with âprintâ
===========================================
-When printing numeric values with the 'print' statement, 'awk'
+When printing numeric values with the âprintâ statement, âawkâ
internally converts each number to a string of characters and prints
-that string. 'awk' uses the 'sprintf()' function to do this conversion
+that string. âawkâ uses the âsprintf()â function to do this conversion
(*note String Functions::). For now, it suffices to say that the
-'sprintf()' function accepts a "format specification" that tells it how
+âsprintf()â function accepts a âformat specificationâ that tells it how
to format numbers (or strings), and that there are a number of different
ways in which numbers can be formatted. The different format
specifications are discussed more fully in *note Control Letters::.
- The predefined variable 'OFMT' contains the format specification that
-'print' uses with 'sprintf()' when it wants to convert a number to a
-string for printing. The default value of 'OFMT' is '"%.6g"'. The way
-'print' prints numbers can be changed by supplying a different format
-specification for the value of 'OFMT', as shown in the following
+ The predefined variable âOFMTâ contains the format specification that
+âprintâ uses with âsprintf()â when it wants to convert a number to a
+string for printing. The default value of âOFMTâ is â"%.6g"â. The way
+âprintâ prints numbers can be changed by supplying a different format
+specification for the value of âOFMTâ, as shown in the following
example:
$ awk 'BEGIN {
> OFMT = "%.0f" # print numbers as integers (rounds)
> print 17.23, 17.54 }'
- -| 17 18
+ ⣠17 18
-According to the POSIX standard, 'awk''s behavior is undefined if 'OFMT'
+According to the POSIX standard, âawkââs behavior is undefined if
âOFMTâ
contains anything but a floating-point conversion specification. (d.c.)
File: gawk.info, Node: Printf, Next: Redirection, Prev: OFMT, Up: Printing
-5.5 Using 'printf' Statements for Fancier Printing
+5.5 Using âprintfâ Statements for Fancier Printing
==================================================
For more precise control over the output format than what is provided by
-'print', use 'printf'. With 'printf' you can specify the width to use
+âprintâ, use âprintfâ. With âprintfâ you can specify the width to
use
for each item, as well as various formatting choices for numbers (such
as what output base to use, whether to print an exponent, whether to
print a sign, and how many digits to print after the decimal point).
* Menu:
-* Basic Printf:: Syntax of the 'printf' statement.
+* Basic Printf:: Syntax of the âprintfâ statement.
* Control Letters:: Format-control letters.
* Format Modifiers:: Format-specification modifiers.
* Printf Examples:: Several examples.
@@ -6943,33 +6943,33 @@ print a sign, and how many digits to print after the
decimal point).
File: gawk.info, Node: Basic Printf, Next: Control Letters, Up: Printf
-5.5.1 Introduction to the 'printf' Statement
+5.5.1 Introduction to the âprintfâ Statement
--------------------------------------------
-A simple 'printf' statement looks like this:
+A simple âprintfâ statement looks like this:
printf FORMAT, ITEM1, ITEM2, ...
-As for 'print', the entire list of arguments may optionally be enclosed
+As for âprintâ, the entire list of arguments may optionally be enclosed
in parentheses. Here too, the parentheses are necessary if any of the
-item expressions uses the '>' relational operator; otherwise, it can be
+item expressions uses the â>â relational operator; otherwise, it can be
confused with an output redirection (*note Redirection::).
- The difference between 'printf' and 'print' is the FORMAT argument.
+ The difference between âprintfâ and âprintâ is the FORMAT argument.
This is an expression whose value is taken as a string; it specifies how
-to output each of the other arguments. It is called the "format
-string".
+to output each of the other arguments. It is called the âformat
+stringâ.
The format string is very similar to that in the ISO C library
-function 'printf()'. Most of FORMAT is text to output verbatim.
-Scattered among this text are "format specifiers"--one per item. Each
+function âprintf()â. Most of FORMAT is text to output verbatim.
+Scattered among this text are âformat specifiersââone per item. Each
format specifier says to output the next item in the argument list at
that place in the format.
- The 'printf' statement does not automatically append a newline to its
+ The âprintfâ statement does not automatically append a newline to its
output. It outputs only what the format string specifies. So if a
newline is needed, you must include one in the format string. The
-output separator variables 'OFS' and 'ORS' have no effect on 'printf'
+output separator variables âOFSâ and âORSâ have no effect on
âprintfâ
statements. For example:
$ awk 'BEGIN {
@@ -6977,9 +6977,9 @@ statements. For example:
> msg = "Don\47t Panic!"
> printf "%s\n", msg
> }'
- -| Don't Panic!
+ ⣠Don't Panic!
-Here, neither the '+' nor the 'OUCH!' appears in the output message.
+Here, neither the â+â nor the âOUCH!â appears in the output message.
File: gawk.info, Node: Control Letters, Next: Format Modifiers, Prev: Basic
Printf, Up: Printf
@@ -6987,139 +6987,139 @@ File: gawk.info, Node: Control Letters, Next:
Format Modifiers, Prev: Basic P
5.5.2 Format-Control Letters
----------------------------
-A format specifier starts with the character '%' and ends with a
-"format-control letter"--it tells the 'printf' statement how to output
+A format specifier starts with the character â%â and ends with a
+âformat-control letterââit tells the âprintfâ statement how to output
one item. The format-control letter specifies what _kind_ of value to
print. The rest of the format specifier is made up of optional
-"modifiers" that control _how_ to print the value, such as the field
+âmodifiersâ that control _how_ to print the value, such as the field
width. Here is a list of the format-control letters:
-'%a', '%A'
- A floating point number of the form ['-']'0xH.HHHHp+-DD' (C99
- hexadecimal floating point format). For '%A', uppercase letters
+â%aâ, â%Aâ
+ A floating point number of the form [â-â]â0xH.HHHHp+-DDâ (C99
+ hexadecimal floating point format). For â%Aâ, uppercase letters
are used instead of lowercase ones.
- NOTE: The current POSIX standard requires support for '%a' and
- '%A' in 'awk'. As far as we know, besides 'gawk', the only
- other version of 'awk' that actually implements it is BWK
- 'awk'. It's use is thus highly nonportable!
+ NOTE: The current POSIX standard requires support for â%aâ and
+ â%Aâ in âawkâ. As far as we know, besides âgawkâ, the
only
+ other version of âawkâ that actually implements it is BWK
+ âawkâ. Itâs use is thus highly nonportable!
Furthermore, these formats are not available on any system
- where the underlying C library 'printf()' function does not
+ where the underlying C library âprintf()â function does not
support them. As of this writing, among current systems, only
OpenVMS is known to not support them.
-'%c'
- Print a number as a character; thus, 'printf "%c", 65' outputs the
- letter 'A'. The output for a string value is the first character
+â%câ
+ Print a number as a character; thus, âprintf "%c", 65â outputs the
+ letter âAâ. The output for a string value is the first character
of the string.
NOTE: The POSIX standard says the first character of a string
- is printed. In locales with multibyte characters, 'gawk'
+ is printed. In locales with multibyte characters, âgawkâ
attempts to convert the leading bytes of the string into a
valid wide character and then to print the multibyte encoding
of that character. Similarly, when printing a numeric value,
- 'gawk' allows the value to be within the numeric range of
+ âgawkâ allows the value to be within the numeric range of
values that can be held in a wide character. If the
- conversion to multibyte encoding fails, 'gawk' uses the low
+ conversion to multibyte encoding fails, âgawkâ uses the low
eight bits of the value as the character to print.
- Other 'awk' versions generally restrict themselves to printing
+ Other âawkâ versions generally restrict themselves to printing
the first byte of a string or to numeric values within the
- range of a single byte (0-255). (d.c.)
+ range of a single byte (0â255). (d.c.)
-'%d', '%i'
+â%dâ, â%iâ
Print a decimal integer. The two control letters are equivalent.
- (The '%i' specification is for compatibility with ISO C.)
+ (The â%iâ specification is for compatibility with ISO C.)
-'%e', '%E'
+â%eâ, â%Eâ
Print a number in scientific (exponential) notation. For example:
printf "%4.3e\n", 1950
- prints '1.950e+03', with a total of four significant figures, three
- of which follow the decimal point. (The '4.3' represents two
- modifiers, discussed in the next node.) '%E' uses 'E' instead of
- 'e' in the output.
+ prints â1.950e+03â, with a total of four significant figures, three
+ of which follow the decimal point. (The â4.3â represents two
+ modifiers, discussed in the next node.) â%Eâ uses âEâ instead of
+ âeâ in the output.
-'%f'
+â%fâ
Print a number in floating-point notation. For example:
printf "%4.3f", 1950
- prints '1950.000', with a minimum of four significant figures,
- three of which follow the decimal point. (The '4.3' represents two
+ prints â1950.000â, with a minimum of four significant figures,
+ three of which follow the decimal point. (The â4.3â represents two
modifiers, discussed in the next node.)
On systems supporting IEEE 754 floating-point format, values
- representing negative infinity are formatted as '-inf' or
- '-infinity', and positive infinity as 'inf' or 'infinity'. The
- special "not a number" value formats as '-nan' or 'nan' (*note
+ representing negative infinity are formatted as â-infâ or
+ â-infinityâ, and positive infinity as âinfâ or âinfinityâ.
The
+ special ânot a numberâ value formats as â-nanâ or ânanâ (*note
Strange values::).
-'%F'
- Like '%f', but the infinity and "not a number" values are spelled
+â%Fâ
+ Like â%fâ, but the infinity and ânot a numberâ values are spelled
using uppercase letters.
- The '%F' format is a POSIX extension to ISO C; not all systems
- support it. On those that don't, 'gawk' uses '%f' instead.
+ The â%Fâ format is a POSIX extension to ISO C; not all systems
+ support it. On those that donât, âgawkâ uses â%fâ instead.
-'%g', '%G'
+â%gâ, â%Gâ
Print a number in either scientific notation or in floating-point
notation, whichever uses fewer characters; if the result is printed
- in scientific notation, '%G' uses 'E' instead of 'e'.
+ in scientific notation, â%Gâ uses âEâ instead of âeâ.
-'%o'
+â%oâ
Print an unsigned octal integer (*note Nondecimal-numbers::).
-'%s'
+â%sâ
Print a string.
-'%u'
+â%uâ
Print an unsigned decimal integer. (This format is of marginal
- use, because all numbers in 'awk' are floating point; it is
+ use, because all numbers in âawkâ are floating point; it is
provided primarily for compatibility with C.)
-'%x', '%X'
- Print an unsigned hexadecimal integer; '%X' uses the letters 'A'
- through 'F' instead of 'a' through 'f' (*note
+â%xâ, â%Xâ
+ Print an unsigned hexadecimal integer; â%Xâ uses the letters âAâ
+ through âFâ instead of âaâ through âfâ (*note
Nondecimal-numbers::).
-'%%'
- Print a single '%'. This does not consume an argument and it
+â%%â
+ Print a single â%â. This does not consume an argument and it
ignores any modifiers.
NOTE: When using the integer format-control letters for values that
- are outside the range of the widest C integer type, 'gawk' switches
- to the '%g' format specifier. If '--lint' is provided on the
- command line (*note Options::), 'gawk' warns about this. Other
- versions of 'awk' may print invalid values or do something else
+ are outside the range of the widest C integer type, âgawkâ switches
+ to the â%gâ format specifier. If â--lintâ is provided on the
+ command line (*note Options::), âgawkâ warns about this. Other
+ versions of âawkâ may print invalid values or do something else
entirely. (d.c.)
NOTE: The IEEE 754 standard for floating-point arithmetic allows
- for special values that represent "infinity" (positive and
- negative) and values that are "not a number" (NaN).
+ for special values that represent âinfinityâ (positive and
+ negative) and values that are ânot a numberâ (NaN).
Input and output of these values occurs as text strings. This is
- somewhat problematic for the 'awk' language, which predates the
+ somewhat problematic for the âawkâ language, which predates the
IEEE standard. Further details are provided in *note POSIX
Floating Point Problems::; please see there.
File: gawk.info, Node: Format Modifiers, Next: Printf Examples, Prev:
Control Letters, Up: Printf
-5.5.3 Modifiers for 'printf' Formats
+5.5.3 Modifiers for âprintfâ Formats
------------------------------------
-A format specification can also include "modifiers" that can control how
-much of the item's value is printed, as well as how much space it gets.
-The modifiers come between the '%' and the format-control letter. We
-use the bullet symbol "*" in the following examples to represent spaces
+A format specification can also include âmodifiersâ that can control how
+much of the itemâs value is printed, as well as how much space it gets.
+The modifiers come between the â%â and the format-control letter. We
+use the bullet symbol ââ¢â in the following examples to represent spaces
in the output. Here are the possible modifiers, in the order in which
they may appear:
-'N$'
- An integer constant followed by a '$' is a "positional specifier".
+âN$â
+ An integer constant followed by a â$â is a âpositional specifierâ.
Normally, format specifications are applied to arguments in the
order given in the format string. With a positional specifier, the
format specification is applied to a specific argument, instead of
@@ -7131,12 +7131,12 @@ they may appear:
prints the famous friendly message twice.
- At first glance, this feature doesn't seem to be of much use. It
- is in fact a 'gawk' extension, intended for use in translating
+ At first glance, this feature doesnât seem to be of much use. It
+ is in fact a âgawkâ extension, intended for use in translating
messages at runtime. *Note Printf Ordering::, which describes how
and why to use positional specifiers. For now, we ignore them.
-'-' (Minus)
+â-â (Minus)
The minus sign, used before the width modifier (see later on in
this list), says to left-justify the argument within its specified
width. Normally, the argument is printed right-justified in the
@@ -7144,32 +7144,32 @@ they may appear:
printf "%-4s", "foo"
- prints 'foo*'.
+ prints âfooâ¢â.
SPACE
For numeric conversions, prefix positive values with a space and
negative values with a minus sign.
-'+'
+â+â
The plus sign, used before the width modifier (see later on in this
list), says to always supply a sign for numeric conversions, even
- if the data to format is positive. The '+' overrides the space
+ if the data to format is positive. The â+â overrides the space
modifier.
-'#'
- Use an "alternative form" for certain control letters. For '%o',
- supply a leading zero. For '%x' and '%X', supply a leading '0x' or
- '0X' for a nonzero result. For '%e', '%E', '%f', and '%F', the
- result always contains a decimal point. For '%g' and '%G',
+â#â
+ Use an âalternative formâ for certain control letters. For â%oâ,
+ supply a leading zero. For â%xâ and â%Xâ, supply a leading
â0xâ or
+ â0Xâ for a nonzero result. For â%eâ, â%Eâ, â%fâ, and
â%Fâ, the
+ result always contains a decimal point. For â%gâ and â%Gâ,
trailing zeros are not removed from the result.
-'0'
- A leading '0' (zero) acts as a flag indicating that output should
+â0â
+ A leading â0â (zero) acts as a flag indicating that output should
be padded with zeros instead of spaces. This applies only to the
numeric output formats. This flag only has an effect when the
field width is wider than the value to print.
-'''
+â'â
A single quote or apostrophe character is a POSIX extension to ISO
C. It indicates that the integer part of a floating-point value, or
the entire part of an integer decimal value, should have a
@@ -7177,29 +7177,29 @@ SPACE
that support such characters. For example:
$ cat thousands.awk Show source program
- -| BEGIN { printf "%'d\n", 1234567 }
+ ⣠BEGIN { printf "%'d\n", 1234567 }
$ LC_ALL=C gawk -f thousands.awk
- -| 1234567 Results in "C" locale
+ ⣠1234567 Results in "C" locale
$ LC_ALL=en_US.UTF-8 gawk -f thousands.awk
- -| 1,234,567 Results in US English UTF locale
+ ⣠1,234,567 Results in US English UTF locale
For more information about locales and internationalization issues,
see *note Locales::.
- NOTE: The ''' flag is a nice feature, but its use complicates
+ NOTE: The â'â flag is a nice feature, but its use complicates
things: it becomes difficult to use it in command-line
programs. For information on appropriate quoting tricks, see
*note Quoting::.
WIDTH
This is a number specifying the desired minimum width of a field.
- Inserting any number between the '%' sign and the format-control
+ Inserting any number between the â%â sign and the format-control
character forces the field to expand to this width. The default
way to do this is to pad with spaces on the left. For example:
printf "%4s", "foo"
- prints '*foo'.
+ prints ââ¢fooâ.
The value of WIDTH is a minimum width, not a maximum. If the item
value requires more than WIDTH characters, it can be as wide as
@@ -7207,26 +7207,26 @@ WIDTH
printf "%4s", "foobar"
- prints 'foobar'.
+ prints âfoobarâ.
Preceding the WIDTH with a minus sign causes the output to be
padded with spaces on the right, instead of on the left.
-'.PREC'
+â.PRECâ
A period followed by an integer constant specifies the precision to
use when printing. The meaning of the precision varies by control
letter:
- '%d', '%i', '%o', '%u', '%x', '%X'
+ â%dâ, â%iâ, â%oâ, â%uâ, â%xâ, â%Xâ
Minimum number of digits to print.
- '%e', '%E', '%f', '%F'
+ â%eâ, â%Eâ, â%fâ, â%Fâ
Number of digits to the right of the decimal point.
- '%g', '%G'
+ â%gâ, â%Gâ
Maximum number of significant digits.
- '%s'
+ â%sâ
Maximum number of characters from the string that should
print.
@@ -7234,10 +7234,10 @@ WIDTH
printf "%.4s", "foobar"
- prints 'foob'.
+ prints âfoobâ.
- The C library 'printf''s dynamic WIDTH and PREC capability (e.g.,
-'"%*.*s"') is supported. Instead of supplying explicit WIDTH and/or
+ The C library âprintfââs dynamic WIDTH and PREC capability (e.g.,
+â"%*.*s"â) is supported. Instead of supplying explicit WIDTH and/or
PREC values in the format string, they are passed in the argument list.
For example:
@@ -7251,7 +7251,7 @@ is exactly equivalent to:
s = "abcdefg"
printf "%5.3s\n", s
-Both programs output '**abc'. Earlier versions of 'awk' did not support
+Both programs output ââ¢â¢abcâ. Earlier versions of âawkâ did not
support
this capability. If you must use such a version, you may simulate this
feature by using concatenation to build up the format string, like so:
@@ -7262,61 +7262,61 @@ feature by using concatenation to build up the format
string, like so:
This is not particularly easy to read, but it does work.
- C programmers may be used to supplying additional modifiers ('h',
-'j', 'l', 'L', 't', and 'z') in 'printf' format strings. These are not
-valid in 'awk'. Most 'awk' implementations silently ignore them. If
-'--lint' is provided on the command line (*note Options::), 'gawk' warns
-about their use. If '--posix' is supplied, their use is a fatal error.
+ C programmers may be used to supplying additional modifiers (âhâ,
+âjâ, âlâ, âLâ, âtâ, and âzâ) in âprintfâ format
strings. These are not
+valid in âawkâ. Most âawkâ implementations silently ignore them. If
+â--lintâ is provided on the command line (*note Options::), âgawkâ
warns
+about their use. If â--posixâ is supplied, their use is a fatal error.
File: gawk.info, Node: Printf Examples, Prev: Format Modifiers, Up: Printf
-5.5.4 Examples Using 'printf'
+5.5.4 Examples Using âprintfâ
-----------------------------
-The following simple example shows how to use 'printf' to make an
+The following simple example shows how to use âprintfâ to make an
aligned table:
awk '{ printf "%-10s %s\n", $1, $2 }' mail-list
-This command prints the names of the people ('$1') in the file
-'mail-list' as a string of 10 characters that are left-justified. It
-also prints the phone numbers ('$2') next on the line. This produces an
+This command prints the names of the people (â$1â) in the file
+âmail-listâ as a string of 10 characters that are left-justified. It
+also prints the phone numbers (â$2â) next on the line. This produces an
aligned two-column table of names and phone numbers, as shown here:
$ awk '{ printf "%-10s %s\n", $1, $2 }' mail-list
- -| Amelia 555-5553
- -| Anthony 555-3412
- -| Becky 555-7685
- -| Bill 555-1675
- -| Broderick 555-0542
- -| Camilla 555-2912
- -| Fabius 555-1234
- -| Julie 555-6699
- -| Martin 555-6480
- -| Samuel 555-3430
- -| Jean-Paul 555-2127
+ ⣠Amelia 555-5553
+ ⣠Anthony 555-3412
+ ⣠Becky 555-7685
+ ⣠Bill 555-1675
+ ⣠Broderick 555-0542
+ ⣠Camilla 555-2912
+ ⣠Fabius 555-1234
+ ⣠Julie 555-6699
+ ⣠Martin 555-6480
+ ⣠Samuel 555-3430
+ ⣠Jean-Paul 555-2127
In this case, the phone numbers had to be printed as strings because
the numbers are separated by dashes. Printing the phone numbers as
-numbers would have produced just the first three digits: '555'. This
+numbers would have produced just the first three digits: â555â. This
would have been pretty confusing.
- It wasn't necessary to specify a width for the phone numbers because
-they are last on their lines. They don't need to have spaces after
+ It wasnât necessary to specify a width for the phone numbers because
+they are last on their lines. They donât need to have spaces after
them.
The table could be made to look even nicer by adding headings to the
-tops of the columns. This is done using a 'BEGIN' rule (*note
+tops of the columns. This is done using a âBEGINâ rule (*note
BEGIN/END::) so that the headers are only printed once, at the beginning
-of the 'awk' program:
+of the âawkâ program:
awk 'BEGIN { print "Name Number"
print "---- ------" }
{ printf "%-10s %s\n", $1, $2 }' mail-list
- The preceding example mixes 'print' and 'printf' statements in the
-same program. Using just 'printf' statements can produce the same
+ The preceding example mixes âprintâ and âprintfâ statements in the
+same program. Using just âprintfâ statements can produce the same
results:
awk 'BEGIN { printf "%-10s %s\n", "Name", "Number"
@@ -7338,26 +7338,26 @@ be emphasized by storing it in a variable, like this:
File: gawk.info, Node: Redirection, Next: Special FD, Prev: Printf, Up:
Printing
-5.6 Redirecting Output of 'print' and 'printf'
+5.6 Redirecting Output of âprintâ and âprintfâ
==============================================
-So far, the output from 'print' and 'printf' has gone to the standard
-output, usually the screen. Both 'print' and 'printf' can also send
-their output to other places. This is called "redirection".
+So far, the output from âprintâ and âprintfâ has gone to the standard
+output, usually the screen. Both âprintâ and âprintfâ can also send
+their output to other places. This is called âredirectionâ.
- NOTE: When '--sandbox' is specified (*note Options::), redirecting
+ NOTE: When â--sandboxâ is specified (*note Options::), redirecting
output to files, pipes, and coprocesses is disabled.
- A redirection appears after the 'print' or 'printf' statement.
-Redirections in 'awk' are written just like redirections in shell
-commands, except that they are written inside the 'awk' program.
+ A redirection appears after the âprintâ or âprintfâ statement.
+Redirections in âawkâ are written just like redirections in shell
+commands, except that they are written inside the âawkâ program.
There are four forms of output redirection: output to a file, output
appended to a file, output through a pipe to another command, and output
-to a coprocess. We show them all for the 'print' statement, but they
-work identically for 'printf':
+to a coprocess. We show them all for the âprintâ statement, but they
+work identically for âprintfâ:
-'print ITEMS > OUTPUT-FILE'
+âprint ITEMS > OUTPUT-FILEâ
This redirection prints the items into the output file named
OUTPUT-FILE. The file name OUTPUT-FILE can be any expression. Its
value is changed to a string and then used as a file name (*note
@@ -7368,40 +7368,40 @@ work identically for 'printf':
same OUTPUT-FILE do not erase OUTPUT-FILE, but append to it. (This
is different from how you use redirections in shell scripts.) If
OUTPUT-FILE does not exist, it is created. For example, here is
- how an 'awk' program can write a list of peoples' names to one file
- named 'name-list', and a list of phone numbers to another file
- named 'phone-list':
+ how an âawkâ program can write a list of peoplesâ names to one file
+ named âname-listâ, and a list of phone numbers to another file
+ named âphone-listâ:
$ awk '{ print $2 > "phone-list"
> print $1 > "name-list" }' mail-list
$ cat phone-list
- -| 555-5553
- -| 555-3412
+ ⣠555-5553
+ ⣠555-3412
...
$ cat name-list
- -| Amelia
- -| Anthony
+ ⣠Amelia
+ ⣠Anthony
...
Each output file contains one name or number per line.
-'print ITEMS >> OUTPUT-FILE'
+âprint ITEMS >> OUTPUT-FILEâ
This redirection prints the items into the preexisting output file
- named OUTPUT-FILE. The difference between this and the single-'>'
+ named OUTPUT-FILE. The difference between this and the single-â>â
redirection is that the old contents (if any) of OUTPUT-FILE are
- not erased. Instead, the 'awk' output is appended to the file. If
+ not erased. Instead, the âawkâ output is appended to the file. If
OUTPUT-FILE does not exist, then it is created.
-'print ITEMS | COMMAND'
+âprint ITEMS | COMMANDâ
It is possible to send output to another program through a pipe
instead of into a file. This redirection opens a pipe to COMMAND,
and writes the values of ITEMS through this pipe to another process
created to execute COMMAND.
- The redirection argument COMMAND is actually an 'awk' expression.
+ The redirection argument COMMAND is actually an âawkâ expression.
Its value is converted to a string whose contents give the shell
command to be run. For example, the following produces two files,
- one unsorted list of peoples' names, and one list sorted in reverse
+ one unsorted list of peoplesâ names, and one list sorted in reverse
alphabetical order:
awk '{ print $1 > "names.unsorted"
@@ -7409,11 +7409,11 @@ work identically for 'printf':
print $1 | command }' mail-list
The unsorted list is written with an ordinary redirection, while
- the sorted list is written by piping through the 'sort' utility.
+ the sorted list is written by piping through the âsortâ utility.
The next example uses redirection to mail a message to the mailing
- list 'bug-system'. This might be useful when trouble is
- encountered in an 'awk' script run periodically for system
+ list âbug-systemâ. This might be useful when trouble is
+ encountered in an âawkâ script run periodically for system
maintenance:
report = "mail bug-system"
@@ -7421,34 +7421,34 @@ work identically for 'printf':
print("at record number", FNR, "of", FILENAME) | report
close(report)
- The 'close()' function is called here because it's a good idea to
+ The âclose()â function is called here because itâs a good idea to
close the pipe as soon as all the intended output has been sent to
it. *Note Close Files And Pipes:: for more information.
This example also illustrates the use of a variable to represent a
- FILE or COMMAND--it is not necessary to always use a string
+ FILE or COMMANDâit is not necessary to always use a string
constant. Using a variable is generally a good idea, because (if
- you mean to refer to that same file or command) 'awk' requires that
+ you mean to refer to that same file or command) âawkâ requires that
the string value be written identically every time.
-'print ITEMS |& COMMAND'
+âprint ITEMS |& COMMANDâ
This redirection prints the items to the input of COMMAND. The
- difference between this and the single-'|' redirection is that the
- output from COMMAND can be read with 'getline'. Thus, COMMAND is a
- "coprocess", which works together with but is subsidiary to the
- 'awk' program.
+ difference between this and the single-â|â redirection is that the
+ output from COMMAND can be read with âgetlineâ. Thus, COMMAND is a
+ âcoprocessâ, which works together with but is subsidiary to the
+ âawkâ program.
- This feature is a 'gawk' extension, and is not available in POSIX
- 'awk'. *Note Getline/Coprocess::, for a brief discussion. *Note
+ This feature is a âgawkâ extension, and is not available in POSIX
+ âawkâ. *Note Getline/Coprocess::, for a brief discussion. *Note
Two-way I/O::, for a more complete discussion.
- Redirecting output using '>', '>>', '|', or '|&' asks the system to
+ Redirecting output using â>â, â>>â, â|â, or â|&â asks the
system to
open a file, pipe, or coprocess only if the particular FILE or COMMAND
you specify has not already been written to by your program or if it has
been closed since it was last written to.
- It is a common error to use '>' redirection for the first 'print' to
-a file, and then to use '>>' for subsequent output:
+ It is a common error to use â>â redirection for the first âprintâ to
+a file, and then to use â>>â for subsequent output:
# clear the file
print "Don't panic" > "guide.txt"
@@ -7457,22 +7457,22 @@ a file, and then to use '>>' for subsequent output:
print "Avoid improbability generators" >> "guide.txt"
This is indeed how redirections must be used from the shell. But in
-'awk', it isn't necessary. In this kind of case, a program should use
-'>' for all the 'print' statements, because the output file is only
-opened once. (It happens that if you mix '>' and '>>' output is
+âawkâ, it isnât necessary. In this kind of case, a program should use
+â>â for all the âprintâ statements, because the output file is only
+opened once. (It happens that if you mix â>â and â>>â output is
produced in the expected order. However, mixing the operators for the
same file is definitely poor style, and is confusing to readers of your
program.)
- Many older 'awk' implementations limit the number of pipelines that
-an 'awk' program may have open to just one! In 'gawk', there is no such
-limit. 'gawk' allows a program to open as many pipelines as the
+ Many older âawkâ implementations limit the number of pipelines that
+an âawkâ program may have open to just one! In âgawkâ, there is no
such
+limit. âgawkâ allows a program to open as many pipelines as the
underlying operating system permits.
- Piping into 'sh'
+ Piping into âshâ
A particularly powerful way to use redirection is to build command
-lines and pipe them into the shell, 'sh'. For example, suppose you have
+lines and pipe them into the shell, âshâ. For example, suppose you have
a list of files brought over from a system where all the file names are
stored in uppercase, and you wish to rename them to have names in all
lowercase. The following program is both simple and efficient:
@@ -7481,9 +7481,9 @@ lowercase. The following program is both simple and
efficient:
END { close("sh") }
- The 'tolower()' function returns its argument string with all
+ The âtolower()â function returns its argument string with all
uppercase characters converted to lowercase (*note String Functions::).
-The program builds up a list of command lines, using the 'mv' utility to
+The program builds up a list of command lines, using the âmvâ utility to
rename the files. It then sends the list to the shell for execution.
*Note Shell Quoting:: for a function that can help in generating
@@ -7497,53 +7497,53 @@ File: gawk.info, Node: Special FD, Next: Special
Files, Prev: Redirection, U
Running programs conventionally have three input and output streams
already available to them for reading and writing. These are known as
-the "standard input", "standard output", and "standard error output".
+the âstandard inputâ, âstandard outputâ, and âstandard error
outputâ.
These open streams (and any other open files or pipes) are often
-referred to by the technical term "file descriptors".
+referred to by the technical term âfile descriptorsâ.
These streams are, by default, connected to your keyboard and screen,
-but they are often redirected with the shell, via the '<', '<<', '>',
-'>>', '>&', and '|' operators. Standard error is typically used for
+but they are often redirected with the shell, via the â<â, â<<â,
â>â,
+â>>â, â>&â, and â|â operators. Standard error is typically used
for
writing error messages; the reason there are two separate streams,
standard output and standard error, is so that they can be redirected
separately.
- In traditional implementations of 'awk', the only way to write an
-error message to standard error in an 'awk' program is as follows:
+ In traditional implementations of âawkâ, the only way to write an
+error message to standard error in an âawkâ program is as follows:
print "Serious error detected!" | "cat 1>&2"
This works by opening a pipeline to a shell command that can access the
-standard error stream that it inherits from the 'awk' process. This is
+standard error stream that it inherits from the âawkâ process. This is
far from elegant, and it also requires a separate process. So people
-writing 'awk' programs often don't do this. Instead, they send the
+writing âawkâ programs often donât do this. Instead, they send the
error messages to the screen, like this:
print "Serious error detected!" > "/dev/tty"
-('/dev/tty' is a special file supplied by the operating system that is
-connected to your keyboard and screen. It represents the "terminal,"(1)
+(â/dev/ttyâ is a special file supplied by the operating system that is
+connected to your keyboard and screen. It represents the âterminal,â(1)
which on modern systems is a keyboard and screen, not a serial console.)
This generally has the same effect, but not always: although the
standard error stream is usually the screen, it can be redirected; when
-that happens, writing to the screen is not correct. In fact, if 'awk'
+that happens, writing to the screen is not correct. In fact, if âawkâ
is run from a background job, it may not have a terminal at all. Then
-opening '/dev/tty' fails.
+opening â/dev/ttyâ fails.
- 'gawk', BWK 'awk', and 'mawk' provide special file names for
+ âgawkâ, BWK âawkâ, and âmawkâ provide special file names for
accessing the three standard streams. If the file name matches one of
-these special names when 'gawk' (or one of the others) redirects input
+these special names when âgawkâ (or one of the others) redirects input
or output, then it directly uses the descriptor that the file name
stands for. These special file names work for all operating systems
-that 'gawk' has been ported to, not just those that are POSIX-compliant:
+that âgawkâ has been ported to, not just those that are POSIX-compliant:
-'/dev/stdin'
+â/dev/stdinâ
The standard input (file descriptor 0).
-'/dev/stdout'
+â/dev/stdoutâ
The standard output (file descriptor 1).
-'/dev/stderr'
+â/dev/stderrâ
The standard error output (file descriptor 2).
With these facilities, the proper way to write an error message then
@@ -7555,53 +7555,53 @@ becomes:
redirection, the value must be a string. It is a common error to omit
the quotes, which leads to confusing results.
- 'gawk' does not treat these file names as special when in
-POSIX-compatibility mode. However, because BWK 'awk' supports them,
-'gawk' does support them even when invoked with the '--traditional'
+ âgawkâ does not treat these file names as special when in
+POSIX-compatibility mode. However, because BWK âawkâ supports them,
+âgawkâ does support them even when invoked with the â--traditionalâ
option (*note Options::).
---------- Footnotes ----------
- (1) The "tty" in '/dev/tty' stands for "Teletype," a serial terminal.
+ (1) The âttyâ in â/dev/ttyâ stands for âTeletype,â a serial
terminal.
File: gawk.info, Node: Special Files, Next: Close Files And Pipes, Prev:
Special FD, Up: Printing
-5.8 Special File names in 'gawk'
+5.8 Special File names in âgawkâ
================================
Besides access to standard input, standard output, and standard error,
-'gawk' provides access to any open file descriptor. Additionally, there
+âgawkâ provides access to any open file descriptor. Additionally, there
are special file names reserved for TCP/IP networking.
* Menu:
* Other Inherited Files:: Accessing other open files with
- 'gawk'.
+ âgawkâ.
* Special Network:: Special files for network communications.
* Special Caveats:: Things to watch out for.
File: gawk.info, Node: Other Inherited Files, Next: Special Network, Up:
Special Files
-5.8.1 Accessing Other Open Files with 'gawk'
+5.8.1 Accessing Other Open Files with âgawkâ
--------------------------------------------
-Besides the '/dev/stdin', '/dev/stdout', and '/dev/stderr' special file
-names mentioned earlier, 'gawk' provides syntax for accessing any other
+Besides the â/dev/stdinâ, â/dev/stdoutâ, and â/dev/stderrâ special
file
+names mentioned earlier, âgawkâ provides syntax for accessing any other
inherited open file:
-'/dev/fd/N'
+â/dev/fd/Nâ
The file associated with file descriptor N. Such a file must be
- opened by the program initiating the 'awk' execution (typically the
+ opened by the program initiating the âawkâ execution (typically the
shell). Unless special pains are taken in the shell from which
- 'gawk' is invoked, only descriptors 0, 1, and 2 are available.
+ âgawkâ is invoked, only descriptors 0, 1, and 2 are available.
- The file names '/dev/stdin', '/dev/stdout', and '/dev/stderr' are
-essentially aliases for '/dev/fd/0', '/dev/fd/1', and '/dev/fd/2',
+ The file names â/dev/stdinâ, â/dev/stdoutâ, and â/dev/stderrâ
are
+essentially aliases for â/dev/fd/0â, â/dev/fd/1â, and â/dev/fd/2â,
respectively. However, those names are more self-explanatory.
- Note that using 'close()' on a file name of the form '"/dev/fd/N"',
+ Note that using âclose()â on a file name of the form â"/dev/fd/N"â,
for file descriptor numbers above two, does actually close the given
file descriptor.
@@ -7611,15 +7611,15 @@ File: gawk.info, Node: Special Network, Next: Special
Caveats, Prev: Other In
5.8.2 Special Files for Network Communications
----------------------------------------------
-'gawk' programs can open a two-way TCP/IP connection, acting as either a
+âgawkâ programs can open a two-way TCP/IP connection, acting as either a
client or a server. This is done using a special file name of the form:
/NET-TYPE/PROTOCOL/LOCAL-PORT/REMOTE-HOST/REMOTE-PORT
- The NET-TYPE is one of 'inet', 'inet4', or 'inet6'. The PROTOCOL is
-one of 'tcp' or 'udp', and the other fields represent the other
+ The NET-TYPE is one of âinetâ, âinet4â, or âinet6â. The
PROTOCOL is
+one of âtcpâ or âudpâ, and the other fields represent the other
essential pieces of information for making a networking connection.
-These file names are used with the '|&' operator for communicating with
+These file names are used with the â|&â operator for communicating with
a coprocess (*note Two-way I/O::). This is an advanced feature,
mentioned here only for completeness. Full discussion is delayed until
*note TCP/IP Networking::.
@@ -7631,18 +7631,18 @@ File: gawk.info, Node: Special Caveats, Prev: Special
Network, Up: Special Fi
-------------------------------
Here are some things to bear in mind when using the special file names
-that 'gawk' provides:
+that âgawkâ provides:
- * Recognition of the file names for the three standard preopened
+ ⢠Recognition of the file names for the three standard preopened
files is disabled only in POSIX mode.
- * Recognition of the other special file names is disabled if 'gawk'
- is in compatibility mode (either '--traditional' or '--posix';
+ ⢠Recognition of the other special file names is disabled if âgawkâ
+ is in compatibility mode (either â--traditionalâ or â--posixâ;
*note Options::).
- * 'gawk' _always_ interprets these special file names. For example,
- using '/dev/fd/4' for output actually writes on file descriptor 4,
- and not on a new file descriptor that is 'dup()'ed from file
+ ⢠âgawkâ _always_ interprets these special file names. For example,
+ using â/dev/fd/4â for output actually writes on file descriptor 4,
+ and not on a new file descriptor that is âdup()âed from file
descriptor 4. Most of the time this does not matter; however, it
is important to _not_ close any of the files related to file
descriptors 0, 1, and 2. Doing so results in unpredictable
@@ -7654,21 +7654,21 @@ File: gawk.info, Node: Close Files And Pipes, Next:
Nonfatal, Prev: Special F
5.9 Closing Input and Output Redirections
=========================================
-If the same file name or the same shell command is used with 'getline'
-more than once during the execution of an 'awk' program (*note
+If the same file name or the same shell command is used with âgetlineâ
+more than once during the execution of an âawkâ program (*note
Getline::), the file is opened (or the command is executed) the first
time only. At that time, the first record of input is read from that
file or command. The next time the same file or command is used with
-'getline', another record is read from it, and so on.
+âgetlineâ, another record is read from it, and so on.
- Similarly, when a file or pipe is opened for output, 'awk' remembers
+ Similarly, when a file or pipe is opened for output, âawkâ remembers
the file name or command associated with it, and subsequent writes to
the same file or command are appended to the previous writes. The file
-or pipe stays open until 'awk' exits.
+or pipe stays open until âawkâ exits.
This implies that special steps are necessary in order to read the
same file again from the beginning, or to rerun a shell command (rather
-than reading more output from the same command). The 'close()' function
+than reading more output from the same command). The âclose()â function
makes these things possible:
close(FILENAME)
@@ -7679,7 +7679,7 @@ or:
The argument FILENAME or COMMAND can be any expression. Its value
must _exactly_ match the string that was used to open the file or start
-the command (spaces and other "irrelevant" characters included). For
+the command (spaces and other âirrelevantâ characters included). For
example, if you open a pipe with this:
"sort -r names" | getline foo
@@ -7688,8 +7688,8 @@ then you must close it with this:
close("sort -r names")
- Once this function call is executed, the next 'getline' from that
-file or command, or the next 'print' or 'printf' to that file or
+ Once this function call is executed, the next âgetlineâ from that
+file or command, or the next âprintâ or âprintfâ to that file or
command, reopens the file or reruns the command. Because the expression
that you use to close a file or pipeline must exactly match the
expression used to open the file or run the command, it is good practice
@@ -7701,39 +7701,39 @@ example becomes the following:
...
close(sortcom)
-This helps avoid hard-to-find typographical errors in your 'awk'
+This helps avoid hard-to-find typographical errors in your âawkâ
programs. Here are some of the reasons for closing an output file:
- * To write a file and read it back later on in the same 'awk'
+ ⢠To write a file and read it back later on in the same âawkâ
program. Close the file after writing it, then begin reading it
- with 'getline'.
+ with âgetlineâ.
- * To write numerous files, successively, in the same 'awk' program.
- If the files aren't closed, eventually 'awk' may exceed a system
+ ⢠To write numerous files, successively, in the same âawkâ program.
+ If the files arenât closed, eventually âawkâ may exceed a system
limit on the number of open files in one process. It is best to
close each one when the program has finished writing it.
- * To make a command finish. When output is redirected through a
+ ⢠To make a command finish. When output is redirected through a
pipe, the command reading the pipe normally continues to try to
read input as long as the pipe is open. Often this means the
command cannot really do its work until the pipe is closed. For
- example, if output is redirected to the 'mail' program, the message
+ example, if output is redirected to the âmailâ program, the message
is not actually sent until the pipe is closed.
- * To run the same program a second time, with the same arguments.
+ ⢠To run the same program a second time, with the same arguments.
This is not the same thing as giving more input to the first run!
- For example, suppose a program pipes output to the 'mail' program.
+ For example, suppose a program pipes output to the âmailâ program.
If it outputs several lines redirected to this pipe without closing
it, they make a single message of several lines. By contrast, if
the program closes the pipe after each line of output, then each
line makes a separate message.
- If you use more files than the system allows you to have open, 'gawk'
+ If you use more files than the system allows you to have open, âgawkâ
attempts to multiplex the available open files among your data files.
-'gawk''s ability to do this depends upon the facilities of your
+âgawkââs ability to do this depends upon the facilities of your
operating system, so it may not always work. It is therefore both good
-practice and good portability advice to always use 'close()' on your
+practice and good portability advice to always use âclose()â on your
files when you are done with them. In fact, if you are using a lot of
pipes, it is essential that you close commands when done. For example,
consider something like this:
@@ -7748,85 +7748,85 @@ consider something like this:
}
This example creates a new pipeline based on data in _each_ record.
-Without the call to 'close()' indicated in the comment, 'awk' creates
+Without the call to âclose()â indicated in the comment, âawkâ creates
child processes to run the commands, until it eventually runs out of
file descriptors for more pipelines.
Even though each command has finished (as indicated by the
-end-of-file return status from 'getline'), the child process is not
+end-of-file return status from âgetlineâ), the child process is not
terminated;(1) more importantly, the file descriptor for the pipe is not
-closed and released until 'close()' is called or 'awk' exits.
+closed and released until âclose()â is called or âawkâ exits.
- 'close()' silently does nothing if given an argument that does not
+ âclose()â silently does nothing if given an argument that does not
represent a file, pipe, or coprocess that was opened with a redirection.
In such a case, it returns a negative value, indicating an error. In
-addition, 'gawk' sets 'ERRNO' to a string indicating the error.
+addition, âgawkâ sets âERRNOâ to a string indicating the error.
- Note also that 'close(FILENAME)' has no "magic" effects on the
+ Note also that âclose(FILENAME)â has no âmagicâ effects on the
implicit loop that reads through the files named on the command line.
It is, more likely, a close of a file that was never opened with a
-redirection, so 'awk' silently does nothing, except return a negative
+redirection, so âawkâ silently does nothing, except return a negative
value.
- When using the '|&' operator to communicate with a coprocess, it is
+ When using the â|&â operator to communicate with a coprocess, it is
occasionally useful to be able to close one end of the two-way pipe
without closing the other. This is done by supplying a second argument
-to 'close()'. As in any other call to 'close()', the first argument is
+to âclose()â. As in any other call to âclose()â, the first argument is
the name of the command or special file used to start the coprocess.
-The second argument should be a string, with either of the values '"to"'
-or '"from"'. Case does not matter. As this is an advanced feature,
+The second argument should be a string, with either of the values â"to"â
+or â"from"â. Case does not matter. As this is an advanced feature,
discussion is delayed until *note Two-way I/O::, which describes it in
more detail and gives an example.
- Using 'close()''s Return Value
+ Using âclose()ââs Return Value
- In many older versions of Unix 'awk', the 'close()' function is
+ In many older versions of Unix âawkâ, the âclose()â function is
actually a statement. (d.c.) It is a syntax error to try and use the
-return value from 'close()':
+return value from âclose()â:
command = "..."
command | getline info
retval = close(command) # syntax error in many Unix awks
- 'gawk' treats 'close()' as a function. The return value is -1 if the
+ âgawkâ treats âclose()â as a function. The return value is â1 if
the
argument names something that was never opened with a redirection, or if
there is a system problem closing the file or process. In these cases,
-'gawk' sets the predefined variable 'ERRNO' to a string describing the
+âgawkâ sets the predefined variable âERRNOâ to a string describing the
problem.
- In 'gawk', starting with version 4.2, when closing a pipe or
+ In âgawkâ, starting with version 4.2, when closing a pipe or
coprocess (input or output), the return value is the exit status of the
command, as described in *note Table 5.1:
table-close-pipe-return-values.(2) Otherwise, it is the return value
-from the system's 'close()' or 'fclose()' C functions when closing input
+from the systemâs âclose()â or âfclose()â C functions when closing
input
or output files, respectively. This value is zero if the close
-succeeds, or -1 if it fails.
+succeeds, or â1 if it fails.
-Situation Return value from 'close()'
+Situation Return value from âclose()â
--------------------------------------------------------------------------
-Normal exit of command Command's exit status
+Normal exit of command Commandâs exit status
Death by signal of command 256 + number of murderous signal
Death by signal of command with 512 + number of murderous signal
core dump
-Some kind of error -1
+Some kind of error â1
-Table 5.1: Return values from 'close()' of a pipe
+Table 5.1: Return values from âclose()â of a pipe
- The POSIX standard is very vague; it says that 'close()' returns zero
+ The POSIX standard is very vague; it says that âclose()â returns zero
on success and a nonzero value otherwise. In general, different
implementations vary in what they report when closing pipes; thus, the
return value cannot be used portably. (d.c.) In POSIX mode (*note
-Options::), 'gawk' just returns zero when closing a pipe.
+Options::), âgawkâ just returns zero when closing a pipe.
---------- Footnotes ----------
(1) The technical terminology is rather morbid. The finished child
-is called a "zombie," and cleaning up after it is referred to as
-"reaping."
+is called a âzombie,â and cleaning up after it is referred to as
+âreaping.â
(2) Prior to version 4.2, the return value from closing a pipe or
-co-process was the full 16-bit exit value as defined by the 'wait()'
+co-process was the full 16-bit exit value as defined by the âwait()â
system call.
@@ -7835,31 +7835,31 @@ File: gawk.info, Node: Nonfatal, Next: Output
Summary, Prev: Close Files And
5.10 Enabling Nonfatal Output
=============================
-This minor node describes a 'gawk'-specific feature.
+This minor node describes a âgawkâ-specific feature.
- In standard 'awk', output with 'print' or 'printf' to a nonexistent
+ In standard âawkâ, output with âprintâ or âprintfâ to a
nonexistent
file, or some other I/O error (such as filling up the disk) is a fatal
error.
$ gawk 'BEGIN { print "hi" > "/no/such/file" }'
- error-> gawk: cmd. line:1: fatal: can't redirect to `/no/such/file' (No
- error-> such file or directory)
+ errorâ gawk: cmd. line:1: fatal: can't redirect to `/no/such/file' (No
+ errorâ such file or directory)
- 'gawk' makes it possible to detect that an error has occurred,
+ âgawkâ makes it possible to detect that an error has occurred,
allowing you to possibly recover from the error, or at least print an
error message of your choosing before exiting. You can do this in one
of two ways:
- * For all output files, by assigning any value to
- 'PROCINFO["NONFATAL"]'.
+ ⢠For all output files, by assigning any value to
+ âPROCINFO["NONFATAL"]â.
- * On a per-file basis, by assigning any value to 'PROCINFO[FILENAME,
- "NONFATAL"]'. Here, FILENAME is the name of the file to which you
+ ⢠On a per-file basis, by assigning any value to âPROCINFO[FILENAME,
+ "NONFATAL"]â. Here, FILENAME is the name of the file to which you
wish output to be nonfatal.
- Once you have enabled nonfatal output, you must check 'ERRNO' after
-every relevant 'print' or 'printf' statement to see if something went
-wrong. It is also a good idea to initialize 'ERRNO' to zero before
+ Once you have enabled nonfatal output, you must check âERRNOâ after
+every relevant âprintâ or âprintfâ statement to see if something went
+wrong. It is also a good idea to initialize âERRNOâ to zero before
attempting the output. For example:
$ gawk '
@@ -7872,22 +7872,22 @@ attempting the output. For example:
> exit 1
> }
> }'
- error-> Output failed: No such file or directory
+ errorâ Output failed: No such file or directory
- Here, 'gawk' did not produce a fatal error; instead it let the 'awk'
+ Here, âgawkâ did not produce a fatal error; instead it let the âawkâ
program code detect the problem and handle it.
This mechanism works also for standard output and standard error.
-For standard output, you may use 'PROCINFO["-", "NONFATAL"]' or
-'PROCINFO["/dev/stdout", "NONFATAL"]'. For standard error, use
-'PROCINFO["/dev/stderr", "NONFATAL"]'.
+For standard output, you may use âPROCINFO["-", "NONFATAL"]â or
+âPROCINFO["/dev/stdout", "NONFATAL"]â. For standard error, use
+âPROCINFO["/dev/stderr", "NONFATAL"]â.
When attempting to open a TCP/IP socket (*note TCP/IP Networking::),
-'gawk' tries multiple times. The 'GAWK_SOCK_RETRIES' environment
+âgawkâ tries multiple times. The âGAWK_SOCK_RETRIESâ environment
variable (*note Other Environment Variables::) allows you to override
-'gawk''s builtin default number of attempts. However, once nonfatal I/O
-is enabled for a given socket, 'gawk' only retries once, relying on
-'awk'-level code to notice that there was a problem.
+âgawkââs builtin default number of attempts. However, once nonfatal I/O
+is enabled for a given socket, âgawkâ only retries once, relying on
+âawkâ-level code to notice that there was a problem.
File: gawk.info, Node: Output Summary, Next: Output Exercises, Prev:
Nonfatal, Up: Printing
@@ -7895,26 +7895,26 @@ File: gawk.info, Node: Output Summary, Next: Output
Exercises, Prev: Nonfatal
5.11 Summary
============
- * The 'print' statement prints comma-separated expressions. Each
- expression is separated by the value of 'OFS' and terminated by the
- value of 'ORS'. 'OFMT' provides the conversion format for numeric
- values for the 'print' statement.
+ ⢠The âprintâ statement prints comma-separated expressions. Each
+ expression is separated by the value of âOFSâ and terminated by the
+ value of âORSâ. âOFMTâ provides the conversion format for numeric
+ values for the âprintâ statement.
- * The 'printf' statement provides finer-grained control over output,
+ ⢠The âprintfâ statement provides finer-grained control over output,
with format-control letters for different data types and various
flags that modify the behavior of the format-control letters.
- * Output from both 'print' and 'printf' may be redirected to files,
+ ⢠Output from both âprintâ and âprintfâ may be redirected to
files,
pipes, and coprocesses.
- * 'gawk' provides special file names for access to standard input,
+ ⢠âgawkâ provides special file names for access to standard input,
output, and error, and for network communications.
- * Use 'close()' to close open file, pipe, and coprocess redirections.
+ ⢠Use âclose()â to close open file, pipe, and coprocess redirections.
For coprocesses, it is possible to close only one direction of the
communications.
- * Normally errors with 'print' or 'printf' are fatal. 'gawk' lets
+ ⢠Normally errors with âprintâ or âprintfâ are fatal. âgawkâ
lets
you make output errors be nonfatal either for all files or on a
per-file basis. You must then check for errors after every
relevant output statement.
@@ -7931,10 +7931,10 @@ File: gawk.info, Node: Output Exercises, Prev: Output
Summary, Up: Printing
print "----- ------" }
{ print $1, " ", $2 }' inventory-shipped
- from *note Output Separators::, by using a new value of 'OFS'.
+ from *note Output Separators::, by using a new value of âOFSâ.
- 2. Use the 'printf' statement to line up the headings and table data
- for the 'inventory-shipped' example that was covered in *note
+ 2. Use the âprintfâ statement to line up the headings and table data
+ for the âinventory-shippedâ example that was covered in *note
Print::.
3. What happens if you forget the double quotes when redirecting
@@ -7948,7 +7948,7 @@ File: gawk.info, Node: Expressions, Next: Patterns and
Actions, Prev: Printin
6 Expressions
*************
-Expressions are the basic building blocks of 'awk' patterns and actions.
+Expressions are the basic building blocks of âawkâ patterns and actions.
An expression evaluates to a value that you can print, test, or pass to
a function. Additionally, an expression can assign a new value to a
variable or a field by using an assignment operator.
@@ -7956,14 +7956,14 @@ variable or a field by using an assignment operator.
An expression can serve as a pattern or action statement on its own.
Most other kinds of statements contain one or more expressions that
specify the data on which to operate. As in other languages,
-expressions in 'awk' can include variables, array references, constants,
+expressions in âawkâ can include variables, array references, constants,
and function calls, as well as combinations of these with various
operators.
* Menu:
* Values:: Constants, Variables, and Regular Expressions.
-* All Operators:: 'gawk''s operators.
+* All Operators:: âgawkââs operators.
* Truth Values and Conditions:: Testing for true and false.
* Function Calls:: A function call is an expression.
* Precedence:: How various operators nest.
@@ -7994,12 +7994,12 @@ File: gawk.info, Node: Constants, Next: Using
Constant Regexps, Up: Values
6.1.1 Constant Expressions
--------------------------
-The simplest type of expression is the "constant", which always has the
+The simplest type of expression is the âconstantâ, which always has the
same value. There are three types of constants: numeric, string, and
regular expression.
Each is used in the appropriate context when you need a data value
-that isn't going to change. Numeric constants can have different forms,
+that isnât going to change. Numeric constants can have different forms,
but are internally stored in an identical manner.
* Menu:
@@ -8014,7 +8014,7 @@ File: gawk.info, Node: Scalar Constants, Next:
Nondecimal-numbers, Up: Consta
6.1.1.1 Numeric and String Constants
....................................
-A "numeric constant" stands for a number. This number can be an
+A ânumeric constantâ stands for a number. This number can be an
integer, a decimal fraction, or a number in scientific (exponential)
notation.(1) Here are some examples of numeric constants that all have
the same value:
@@ -8023,15 +8023,15 @@ the same value:
1.05e+2
1050e-1
- A "string constant" consists of a sequence of characters enclosed in
+ A âstring constantâ consists of a sequence of characters enclosed in
double quotation marks. For example:
"parrot"
-represents the string whose contents are 'parrot'. Strings in 'gawk'
+represents the string whose contents are âparrotâ. Strings in âgawkâ
can be of any length, and they can contain any of the possible eight-bit
ASCII characters, including ASCII NUL (character code zero). Other
-'awk' implementations may have difficulty with some character codes.
+âawkâ implementations may have difficulty with some character codes.
Some languages allow you to continue long strings across multiple
lines by ending the line with a backslash. For example in C:
@@ -8046,41 +8046,41 @@ lines by ending the line with a backslash. For example
in C:
}
In such a case, the C compiler removes both the backslash and the
-newline, producing a string as if it had been typed '"hello, world\n"'.
+newline, producing a string as if it had been typed â"hello, world\n"â.
This is useful when a single string needs to contain a large amount of
text.
The POSIX standard says explicitly that newlines are not allowed
-inside string constants. And indeed, all 'awk' implementations report
+inside string constants. And indeed, all âawkâ implementations report
an error if you try to do so. For example:
$ gawk 'BEGIN { print "hello,
> world" }'
- -| gawk: cmd. line:1: BEGIN { print "hello,
- -| gawk: cmd. line:1: ^ unterminated string
- -| gawk: cmd. line:1: BEGIN { print "hello,
- -| gawk: cmd. line:1: ^ syntax error
+ ⣠gawk: cmd. line:1: BEGIN { print "hello,
+ ⣠gawk: cmd. line:1: ^ unterminated string
+ ⣠gawk: cmd. line:1: BEGIN { print "hello,
+ ⣠gawk: cmd. line:1: ^ syntax error
- Although POSIX doesn't define what happens if you use an escaped
-newline, as in the previous C example, all known versions of 'awk' allow
+ Although POSIX doesnât define what happens if you use an escaped
+newline, as in the previous C example, all known versions of âawkâ allow
you to do so. Unfortunately, what each one does with such a string
-varies. (d.c.) 'gawk', 'mawk', and the OpenSolaris POSIX 'awk' (*note
+varies. (d.c.) âgawkâ, âmawkâ, and the OpenSolaris POSIX âawkâ
(*note
Other Versions::) elide the backslash and newline, as in C:
$ gawk 'BEGIN { print "hello, \
> world" }'
- -| hello, world
+ ⣠hello, world
- In POSIX mode (*note Options::), 'gawk' does not allow escaped
+ In POSIX mode (*note Options::), âgawkâ does not allow escaped
newlines. Otherwise, it behaves as just described.
- BWK 'awk' and BusyBox 'awk' remove the backslash but leave the
+ BWK âawkâ and BusyBox âawkâ remove the backslash but leave the
newline intact, as part of the string:
$ nawk 'BEGIN { print "hello, \
> world" }'
- -| hello,
- -| world
+ ⣠hello,
+ ⣠world
---------- Footnotes ----------
@@ -8095,72 +8095,72 @@ File: gawk.info, Node: Nondecimal-numbers, Next:
Regexp Constants, Prev: Scal
6.1.1.2 Octal and Hexadecimal Numbers
.....................................
-In 'awk', all numbers are in decimal (i.e., base 10). Many other
+In âawkâ, all numbers are in decimal (i.e., base 10). Many other
programming languages allow you to specify numbers in other bases, often
octal (base 8) and hexadecimal (base 16). In octal, the numbers go 0,
-1, 2, 3, 4, 5, 6, 7, 10, 11, 12, and so on. Just as '11' in decimal is
-1 times 10 plus 1, so '11' in octal is 1 times 8 plus 1. This equals 9
+1, 2, 3, 4, 5, 6, 7, 10, 11, 12, and so on. Just as â11â in decimal is
+1 times 10 plus 1, so â11â in octal is 1 times 8 plus 1. This equals 9
in decimal. In hexadecimal, there are 16 digits. Because the everyday
-decimal number system only has ten digits ('0'-'9'), the letters 'a'
-through 'f' represent the rest. (Case in the letters is usually
-irrelevant; hexadecimal 'a' and 'A' have the same value.) Thus, '11' in
+decimal number system only has ten digits (â0âââ9â), the letters
âaâ
+through âfâ represent the rest. (Case in the letters is usually
+irrelevant; hexadecimal âaâ and âAâ have the same value.) Thus,
â11â in
hexadecimal is 1 times 16 plus 1, which equals 17 in decimal.
- Just by looking at plain '11', you can't tell what base it's in. So,
+ Just by looking at plain â11â, you canât tell what base itâs in.
So,
in C, C++, and other languages derived from C, there is a special
-notation to signify the base. Octal numbers start with a leading '0',
-and hexadecimal numbers start with a leading '0x' or '0X':
+notation to signify the base. Octal numbers start with a leading â0â,
+and hexadecimal numbers start with a leading â0xâ or â0Xâ:
-'11'
+â11â
Decimal value 11
-'011'
+â011â
Octal 11, decimal value 9
-'0x11'
+â0x11â
Hexadecimal 11, decimal value 17
This example shows the difference:
$ gawk 'BEGIN { printf "%d, %d, %d\n", 011, 11, 0x11 }'
- -| 9, 11, 17
+ ⣠9, 11, 17
Being able to use octal and hexadecimal constants in your programs is
most useful when working with data that cannot be represented
conveniently as characters or as regular numbers, such as binary data of
various sorts.
- 'gawk' allows the use of octal and hexadecimal constants in your
+ âgawkâ allows the use of octal and hexadecimal constants in your
program text. However, such numbers in the input data are not treated
differently; doing so by default would break old programs. (If you
-really need to do this, use the '--non-decimal-data' command-line
+really need to do this, use the â--non-decimal-dataâ command-line
option; *note Nondecimal Data::.) If you have octal or hexadecimal
-data, you can use the 'strtonum()' function (*note String Functions::)
+data, you can use the âstrtonum()â function (*note String Functions::)
to convert the data into a number. Most of the time, you will want to
use octal or hexadecimal constants when working with the built-in
bit-manipulation functions; see *note Bitwise Functions:: for more
information.
- Unlike in some early C implementations, '8' and '9' are not valid in
-octal constants. For example, 'gawk' treats '018' as decimal 18:
+ Unlike in some early C implementations, â8â and â9â are not valid in
+octal constants. For example, âgawkâ treats â018â as decimal 18:
$ gawk 'BEGIN { print "021 is", 021 ; print 018 }'
- -| 021 is 17
- -| 18
+ ⣠021 is 17
+ ⣠18
- Octal and hexadecimal source code constants are a 'gawk' extension.
-If 'gawk' is in compatibility mode (*note Options::), they are not
+ Octal and hexadecimal source code constants are a âgawkâ extension.
+If âgawkâ is in compatibility mode (*note Options::), they are not
available.
- A Constant's Base Does Not Affect Its Value
+ A Constantâs Base Does Not Affect Its Value
Once a numeric constant has been converted internally into a number,
-'gawk' no longer remembers what the original form of the constant was;
+âgawkâ no longer remembers what the original form of the constant was;
the internal value is always used. This has particular consequences for
conversion of numbers to strings:
$ gawk 'BEGIN { printf "0x11 is <%s>\n", 0x11 }'
- -| 0x11 is <17>
+ ⣠0x11 is <17>
File: gawk.info, Node: Regexp Constants, Prev: Nondecimal-numbers, Up:
Constants
@@ -8168,9 +8168,9 @@ File: gawk.info, Node: Regexp Constants, Prev:
Nondecimal-numbers, Up: Consta
6.1.1.3 Regular Expression Constants
....................................
-A "regexp constant" is a regular expression description enclosed in
-slashes, such as '/^beginning and end$/'. Most regexps used in 'awk'
-programs are constant, but the '~' and '!~' matching operators can also
+A âregexp constantâ is a regular expression description enclosed in
+slashes, such as â/^beginning and end$/â. Most regexps used in âawkâ
+programs are constant, but the â~â and â!~â matching operators can also
match computed or dynamic regexps (which are typically just ordinary
strings or variables that contain a regexp, but could be more complex
expressions).
@@ -8182,14 +8182,14 @@ File: gawk.info, Node: Using Constant Regexps, Next:
Variables, Prev: Constan
----------------------------------------
Regular expression constants consist of text describing a regular
-expression enclosed in slashes (such as '/the +answer/'). This minor
-node describes how such constants work in POSIX 'awk' and 'gawk', and
-then goes on to describe "strongly typed regexp constants", which are a
-'gawk' extension.
+expression enclosed in slashes (such as â/the +answer/â). This minor
+node describes how such constants work in POSIX âawkâ and âgawkâ, and
+then goes on to describe âstrongly typed regexp constantsâ, which are a
+âgawkâ extension.
* Menu:
-* Standard Regexp Constants:: Regexp constants in standard 'awk'.
+* Standard Regexp Constants:: Regexp constants in standard âawkâ.
* Strong Regexp Constants:: Strongly typed regexp constants.
@@ -8198,11 +8198,11 @@ File: gawk.info, Node: Standard Regexp Constants,
Next: Strong Regexp Constant
6.1.2.1 Standard Regular Expression Constants
.............................................
-When used on the righthand side of the '~' or '!~' operators, a regexp
+When used on the righthand side of the â~â or â!~â operators, a regexp
constant merely stands for the regexp that is to be matched. However,
-regexp constants (such as '/foo/') may be used like simple expressions.
+regexp constants (such as â/foo/â) may be used like simple expressions.
When a regexp constant appears by itself, it has the same meaning as if
-it appeared in a pattern (i.e., '($0 ~ /foo/)'). (d.c.) *Note
+it appeared in a pattern (i.e., â($0 ~ /foo/)â). (d.c.) *Note
Expression Patterns::. This means that the following two code segments:
if ($0 ~ /barfly/ || $0 ~ /camelot/)
@@ -8220,27 +8220,27 @@ author probably intended:
# Note that /foo/ is on the left of the ~
if (/foo/ ~ $1) print "found foo"
-This code is "obviously" testing '$1' for a match against the regexp
-'/foo/'. But in fact, the expression '/foo/ ~ $1' really means '($0 ~
-/foo/) ~ $1'. In other words, first match the input record against the
-regexp '/foo/'. The result is either zero or one, depending upon the
+This code is âobviouslyâ testing â$1â for a match against the regexp
+â/foo/â. But in fact, the expression â/foo/ ~ $1â really means â($0
~
+/foo/) ~ $1â. In other words, first match the input record against the
+regexp â/foo/â. The result is either zero or one, depending upon the
success or failure of the match. That result is then matched against
the first field in the record. Because it is unlikely that you would
-ever really want to make this kind of test, 'gawk' issues a warning when
+ever really want to make this kind of test, âgawkâ issues a warning when
it sees this construct in a program. Another consequence of this rule
is that the assignment statement:
matches = /foo/
-assigns either zero or one to the variable 'matches', depending upon the
+assigns either zero or one to the variable âmatchesâ, depending upon the
contents of the current input record.
Constant regular expressions are also used as the first argument for
-the 'gensub()', 'sub()', and 'gsub()' functions, as the second argument
-of the 'match()' function, and as the third argument of the 'split()'
-and 'patsplit()' functions (*note String Functions::). Modern
-implementations of 'awk', including 'gawk', allow the third argument of
-'split()' to be a regexp constant, but some older implementations do
+the âgensub()â, âsub()â, and âgsub()â functions, as the second
argument
+of the âmatch()â function, and as the third argument of the âsplit()â
+and âpatsplit()â functions (*note String Functions::). Modern
+implementations of âawkâ, including âgawkâ, allow the third argument of
+âsplit()â to be a regexp constant, but some older implementations do
not. (d.c.) Because some built-in functions accept regexp constants as
arguments, confusion can arise when attempting to use regexp constants
as arguments to user-defined functions (*note User-defined::). For
@@ -8263,10 +8263,10 @@ example:
}
In this example, the programmer wants to pass a regexp constant to
-the user-defined function 'mysub()', which in turn passes it on to
-either 'sub()' or 'gsub()'. However, what really happens is that the
-'pat' parameter is assigned a value of either one or zero, depending
-upon whether or not '$0' matches '/hi/'. 'gawk' issues a warning when
+the user-defined function âmysub()â, which in turn passes it on to
+either âsub()â or âgsub()â. However, what really happens is that the
+âpatâ parameter is assigned a value of either one or zero, depending
+upon whether or not â$0â matches â/hi/â. âgawkâ issues a warning
when
it sees a regexp constant used as a parameter to a user-defined
function, because passing a truth value in this way is probably not what
was intended.
@@ -8277,14 +8277,14 @@ File: gawk.info, Node: Strong Regexp Constants, Prev:
Standard Regexp Constant
6.1.2.2 Strongly Typed Regexp Constants
.......................................
-This minor node describes a 'gawk'-specific feature.
+This minor node describes a âgawkâ-specific feature.
- As we saw in the previous minor node, regexp constants ('/.../') hold
-a strange position in the 'awk' language. In most contexts, they act
-like an expression: '$0 ~ /.../'. In other contexts, they denote only a
-regexp to be matched. In no case are they really a "first class
-citizen" of the language. That is, you cannot define a scalar variable
-whose type is "regexp" in the same sense that you can define a variable
+ As we saw in the previous minor node, regexp constants (â/.../â) hold
+a strange position in the âawkâ language. In most contexts, they act
+like an expression: â$0 ~ /.../â. In other contexts, they denote only a
+regexp to be matched. In no case are they really a âfirst class
+citizenâ of the language. That is, you cannot define a scalar variable
+whose type is âregexpâ in the same sense that you can define a variable
to be a number or a string:
num = 42 Numeric variable
@@ -8292,12 +8292,12 @@ to be a number or a string:
re = /foo/ Wrong! re is the result of $0 ~ /foo/
For a number of more advanced use cases, it would be nice to have
-regexp constants that are "strongly typed"; in other words, that denote
+regexp constants that are âstrongly typedâ; in other words, that denote
a regexp useful for matching, and not an expression.
- 'gawk' provides this feature. A strongly typed regexp constant looks
+ âgawkâ provides this feature. A strongly typed regexp constant looks
almost like a regular regexp constant, except that it is preceded by an
-'@' sign:
+â@â sign:
re = @/foo/ Regexp variable
@@ -8305,28 +8305,28 @@ almost like a regular regexp constant, except that it
is preceded by an
regular regexp constant can, because this would make the language even
more confusing. Instead, you may use them only in certain contexts:
- * On the righthand side of the '~' and '!~' operators: 'some_var ~
- @/foo/' (*note Regexp Usage::).
+ ⢠On the righthand side of the â~â and â!~â operators:
âsome_var ~
+ @/foo/â (*note Regexp Usage::).
- * In the 'case' part of a 'switch' statement (*note Switch
+ ⢠In the âcaseâ part of a âswitchâ statement (*note Switch
Statement::).
- * As an argument to one of the built-in functions that accept regexp
- constants: 'gensub()', 'gsub()', 'match()', 'patsplit()',
- 'split()', and 'sub()' (*note String Functions::).
+ ⢠As an argument to one of the built-in functions that accept regexp
+ constants: âgensub()â, âgsub()â, âmatch()â, âpatsplit()â,
+ âsplit()â, and âsub()â (*note String Functions::).
- * As a parameter in a call to a user-defined function (*note
+ ⢠As a parameter in a call to a user-defined function (*note
User-defined::).
- * As the return value of a user-defined function.
+ ⢠As the return value of a user-defined function.
- * On the righthand side of an assignment to a variable: 'some_var =
- @/foo/'. In this case, the type of 'some_var' is regexp.
- Additionally, 'some_var' can be used with '~' and '!~', passed to
+ ⢠On the righthand side of an assignment to a variable: âsome_var =
+ @/foo/â. In this case, the type of âsome_varâ is regexp.
+ Additionally, âsome_varâ can be used with â~â and â!~â,
passed to
one of the built-in functions listed above, or passed as a
parameter to a user-defined function.
- You may use the '-v' option (*note Options::) to assign a
+ You may use the â-vâ option (*note Options::) to assign a
strongly-typed regexp constant to a variable on the command line, like
so:
@@ -8335,7 +8335,7 @@ so:
You may also make such assignments as regular command-line arguments
(*note Other Arguments::).
- You may use the 'typeof()' built-in function (*note Type Functions::)
+ You may use the âtypeof()â built-in function (*note Type Functions::)
to determine if a variable or function parameter is a regexp variable.
The true power of this feature comes from the ability to create
@@ -8350,15 +8350,15 @@ convert to zero. When used in string conversions, they
convert to the
string value of the original regexp text.
There is an additional, interesting corner case. When used as the
-third argument to 'sub()' or 'gsub()', they retain their type. Thus, if
+third argument to âsub()â or âgsub()â, they retain their type. Thus,
if
you have something like this:
re = @/don't panic/
sub(/don't/, "do", re)
print typeof(re), re
-then 're' retains its type, but now attempts to match the string 'do
-panic'. This provides a (very indirect) way to create regexp-typed
+then âreâ retains its type, but now attempts to match the string âdo
+panicâ. This provides a (very indirect) way to create regexp-typed
variables at runtime.
@@ -8367,10 +8367,10 @@ File: gawk.info, Node: Variables, Next: Conversion,
Prev: Using Constant Rege
6.1.3 Variables
---------------
-"Variables" are ways of storing values at one point in your program for
+âVariablesâ are ways of storing values at one point in your program for
use later in another part of your program. They can be manipulated
entirely within the program text, and they can also be assigned values
-on the 'awk' command line.
+on the âawkâ command line.
* Menu:
@@ -8388,33 +8388,33 @@ File: gawk.info, Node: Using Variables, Next:
Assignment Options, Up: Variabl
Variables let you give names to values and refer to them later.
Variables have already been used in many of the examples. The name of a
variable must be a sequence of letters, digits, or underscores, and it
-may not begin with a digit. Here, a "letter" is any one of the 52
+may not begin with a digit. Here, a âletterâ is any one of the 52
upper- and lowercase English letters. Other characters that may be
defined as letters in non-English locales are not valid in variable
-names. Case is significant in variable names; 'a' and 'A' are distinct
+names. Case is significant in variable names; âaâ and âAâ are distinct
variables.
A variable name is a valid expression by itself; it represents the
-variable's current value. Variables are given new values with
-"assignment operators", "increment operators", and "decrement operators"
-(*note Assignment Ops::). In addition, the 'sub()' and 'gsub()'
-functions can change a variable's value, and the 'match()', 'split()',
-and 'patsplit()' functions can change the contents of their array
+variableâs current value. Variables are given new values with
+âassignment operatorsâ, âincrement operatorsâ, and âdecrement
operatorsâ
+(*note Assignment Ops::). In addition, the âsub()â and âgsub()â
+functions can change a variableâs value, and the âmatch()â,
âsplit()â,
+and âpatsplit()â functions can change the contents of their array
parameters (*note String Functions::).
- A few variables have special built-in meanings, such as 'FS' (the
-field separator) and 'NF' (the number of fields in the current input
+ A few variables have special built-in meanings, such as âFSâ (the
+field separator) and âNFâ (the number of fields in the current input
record). *Note Built-in Variables:: for a list of the predefined
variables. These predefined variables can be used and assigned just
like all other variables, but their values are also used or changed
-automatically by 'awk'. All predefined variables' names are entirely
+automatically by âawkâ. All predefined variablesâ names are entirely
uppercase.
- Variables in 'awk' can be assigned either numeric or string values.
+ Variables in âawkâ can be assigned either numeric or string values.
The kind of value a variable holds can change over the life of a
program. By default, variables are initialized to the empty string,
which is zero if converted to a number. There is no need to explicitly
-initialize a variable in 'awk', which is what you would do in C and in
+initialize a variable in âawkâ, which is what you would do in C and in
most other traditional languages.
@@ -8423,54 +8423,54 @@ File: gawk.info, Node: Assignment Options, Prev:
Using Variables, Up: Variabl
6.1.3.2 Assigning Variables on the Command Line
...............................................
-Any 'awk' variable can be set by including a "variable assignment" among
-the arguments on the command line when 'awk' is invoked (*note Other
+Any âawkâ variable can be set by including a âvariable assignmentâ
among
+the arguments on the command line when âawkâ is invoked (*note Other
Arguments::). Such an assignment has the following form:
VARIABLE=TEXT
-With it, a variable is set either at the beginning of the 'awk' run or
-in between input files. When the assignment is preceded with the '-v'
+With it, a variable is set either at the beginning of the âawkâ run or
+in between input files. When the assignment is preceded with the â-vâ
option, as in the following:
-v VARIABLE=TEXT
-the variable is set at the very beginning, even before the 'BEGIN' rules
-execute. The '-v' option and its assignment must precede all the file
+the variable is set at the very beginning, even before the âBEGINâ rules
+execute. The â-vâ option and its assignment must precede all the file
name arguments, as well as the program text. (*Note Options:: for more
-information about the '-v' option.) Otherwise, the variable assignment
+information about the â-vâ option.) Otherwise, the variable assignment
is performed at a time determined by its position among the input file
-arguments--after the processing of the preceding input file argument.
+argumentsâafter the processing of the preceding input file argument.
For example:
awk '{ print $n }' n=4 inventory-shipped n=2 mail-list
-prints the value of field number 'n' for all input records. Before the
-first file is read, the command line sets the variable 'n' equal to
+prints the value of field number ânâ for all input records. Before the
+first file is read, the command line sets the variable ânâ equal to
four. This causes the fourth field to be printed in lines from
-'inventory-shipped'. After the first file has finished, but before the
-second file is started, 'n' is set to two, so that the second field is
-printed in lines from 'mail-list':
+âinventory-shippedâ. After the first file has finished, but before the
+second file is started, ânâ is set to two, so that the second field is
+printed in lines from âmail-listâ:
$ awk '{ print $n }' n=4 inventory-shipped n=2 mail-list
- -| 15
- -| 24
+ ⣠15
+ ⣠24
...
- -| 555-5553
- -| 555-3412
+ ⣠555-5553
+ ⣠555-3412
...
Command-line arguments are made available for explicit examination by
-the 'awk' program in the 'ARGV' array (*note ARGC and ARGV::). 'awk'
+the âawkâ program in the âARGVâ array (*note ARGC and ARGV::).
âawkâ
processes the values of command-line assignments for escape sequences
(*note Escape Sequences::). (d.c.)
Normally, variables assigned on the command line (with or without the
-'-v' option) are treated as strings. When such variables are used as
-numbers, 'awk''s normal automatic conversion of strings to numbers takes
-place, and everything "just works."
+â-vâ option) are treated as strings. When such variables are used as
+numbers, âawkââs normal automatic conversion of strings to numbers takes
+place, and everything âjust works.â
- However, 'gawk' supports variables whose types are "regexp". You can
+ However, âgawkâ supports variables whose types are âregexpâ. You
can
assign variables of this type using the following syntax:
gawk -v 're1=@/foo|bar/' '...' /path/to/file1 're2=@/baz|quux/'
/path/to/file2
@@ -8486,23 +8486,23 @@ File: gawk.info, Node: Conversion, Prev: Variables,
Up: Values
Number-to-string and string-to-number conversion are generally
straightforward. There can be subtleties to be aware of; this minor
-node discusses this important facet of 'awk'.
+node discusses this important facet of âawkâ.
* Menu:
-* Strings And Numbers:: How 'awk' Converts Between Strings And
+* Strings And Numbers:: How âawkâ Converts Between Strings And
Numbers.
* Locale influences conversions:: How the locale may affect conversions.
File: gawk.info, Node: Strings And Numbers, Next: Locale influences
conversions, Up: Conversion
-6.1.4.1 How 'awk' Converts Between Strings and Numbers
+6.1.4.1 How âawkâ Converts Between Strings and Numbers
......................................................
Strings are converted to numbers and numbers are converted to strings,
-if the context of the 'awk' program demands it. For example, if the
-value of either 'foo' or 'bar' in the expression 'foo + bar' happens to
+if the context of the âawkâ program demands it. For example, if the
+value of either âfooâ or âbarâ in the expression âfoo + barâ
happens to
be a string, it is converted to a number before the addition is
performed. If numeric values appear in string concatenation, they are
converted to strings. Consider the following:
@@ -8511,53 +8511,53 @@ converted to strings. Consider the following:
print (two three) + 4
This prints the (numeric) value 27. The numeric values of the variables
-'two' and 'three' are converted to strings and concatenated together.
+âtwoâ and âthreeâ are converted to strings and concatenated together.
The resulting string is converted back to the number 23, to which 4 is
then added.
If, for some reason, you need to force a number to be converted to a
-string, concatenate that number with the empty string, '""'. To force a
+string, concatenate that number with the empty string, â""â. To force a
string to be converted to a number, add zero to that string. A string
is converted to a number by interpreting any numeric prefix of the
-string as numerals: '"2.5"' converts to 2.5, '"1e3"' converts to 1,000,
-and '"25fix"' has a numeric value of 25. Strings that can't be
+string as numerals: â"2.5"â converts to 2.5, â"1e3"â converts to 1,000,
+and â"25fix"â has a numeric value of 25. Strings that canât be
interpreted as valid numbers convert to zero.
The exact manner in which numbers are converted into strings is
-controlled by the 'awk' predefined variable 'CONVFMT' (*note Built-in
-Variables::). Numbers are converted using the 'sprintf()' function with
-'CONVFMT' as the format specifier (*note String Functions::).
+controlled by the âawkâ predefined variable âCONVFMTâ (*note Built-in
+Variables::). Numbers are converted using the âsprintf()â function with
+âCONVFMTâ as the format specifier (*note String Functions::).
- 'CONVFMT''s default value is '"%.6g"', which creates a value with at
+ âCONVFMTââs default value is â"%.6g"â, which creates a value with
at
most six significant digits. For some applications, you might want to
change it to specify more precision. On most modern machines, 17 digits
-is usually enough to capture a floating-point number's value exactly.(1)
+is usually enough to capture a floating-point numberâs value exactly.(1)
- Strange results can occur if you set 'CONVFMT' to a string that
-doesn't tell 'sprintf()' how to format floating-point numbers in a
-useful way. For example, if you forget the '%' in the format, 'awk'
+ Strange results can occur if you set âCONVFMTâ to a string that
+doesnât tell âsprintf()â how to format floating-point numbers in a
+useful way. For example, if you forget the â%â in the format, âawkâ
converts all numbers to the same constant string.
As a special case, if a number is an integer, then the result of
converting it to a string is _always_ an integer, no matter what the
-value of 'CONVFMT' may be. Given the following code fragment:
+value of âCONVFMTâ may be. Given the following code fragment:
CONVFMT = "%2.2f"
a = 12
b = a ""
-'b' has the value '"12"', not '"12.00"'. (d.c.)
+âbâ has the value â"12"â, not â"12.00"â. (d.c.)
- Pre-POSIX 'awk' Used 'OFMT' for String Conversion
+ Pre-POSIX âawkâ Used âOFMTâ for String Conversion
- Prior to the POSIX standard, 'awk' used the value of 'OFMT' for
-converting numbers to strings. 'OFMT' specifies the output format to
-use when printing numbers with 'print'. 'CONVFMT' was introduced in
+ Prior to the POSIX standard, âawkâ used the value of âOFMTâ for
+converting numbers to strings. âOFMTâ specifies the output format to
+use when printing numbers with âprintâ. âCONVFMTâ was introduced in
order to separate the semantics of conversion from the semantics of
-printing. Both 'CONVFMT' and 'OFMT' have the same default value:
-'"%.6g"'. In the vast majority of cases, old 'awk' programs do not
+printing. Both âCONVFMTâ and âOFMTâ have the same default value:
+â"%.6g"â. In the vast majority of cases, old âawkâ programs do not
change their behavior. *Note Print:: for more information on the
-'print' statement.
+âprintâ statement.
---------- Footnotes ----------
@@ -8571,20 +8571,20 @@ File: gawk.info, Node: Locale influences conversions,
Prev: Strings And Number
........................................
Where you are can matter when it comes to converting between numbers and
-strings. The local character set and language--the "locale"--can affect
-numeric formats. In particular, for 'awk' programs, it affects the
+strings. The local character set and languageâthe âlocaleââcan affect
+numeric formats. In particular, for âawkâ programs, it affects the
decimal point character and the thousands-separator character. The
-'"C"' locale, and most English-language locales, use the period
-character ('.') as the decimal point and don't have a thousands
+â"C"â locale, and most English-language locales, use the period
+character (â.â) as the decimal point and donât have a thousands
separator. However, many (if not most) European and non-English locales
-use the comma (',') as the decimal point character. European locales
+use the comma (â,â) as the decimal point character. European locales
often use either a space or a period as the thousands separator, if they
have one.
- The POSIX standard says that 'awk' always uses the period as the
-decimal point when reading the 'awk' program source code, and for
+ The POSIX standard says that âawkâ always uses the period as the
+decimal point when reading the âawkâ program source code, and for
command-line variable assignments (*note Other Arguments::). However,
-when interpreting input data, for 'print' and 'printf' output, and for
+when interpreting input data, for âprintâ and âprintfâ output, and for
number-to-string conversion, the local decimal point character is used.
(d.c.) In all cases, numbers in source code and in input data cannot
have a thousands separator. Here are some examples indicating the
@@ -8592,47 +8592,47 @@ difference in behavior, on a GNU/Linux system:
$ export POSIXLY_CORRECT=1 Force POSIX behavior
$ gawk 'BEGIN { printf "%g\n", 3.1415927 }'
- -| 3.14159
+ ⣠3.14159
$ LC_ALL=en_DK.utf-8 gawk 'BEGIN { printf "%g\n", 3.1415927 }'
- -| 3,14159
+ ⣠3,14159
$ echo 4,321 | gawk '{ print $1 + 1 }'
- -| 5
+ ⣠5
$ echo 4,321 | LC_ALL=en_DK.utf-8 gawk '{ print $1 + 1 }'
- -| 5,321
+ ⣠5,321
-The 'en_DK.utf-8' locale is for English in Denmark, where the comma acts
-as the decimal point separator. In the normal '"C"' locale, 'gawk'
-treats '4,321' as 4, while in the Danish locale, it's treated as the
+The âen_DK.utf-8â locale is for English in Denmark, where the comma acts
+as the decimal point separator. In the normal â"C"â locale, âgawkâ
+treats â4,321â as 4, while in the Danish locale, itâs treated as the
full number including the fractional part, 4.321.
- Some earlier versions of 'gawk' fully complied with this aspect of
+ Some earlier versions of âgawkâ fully complied with this aspect of
the standard. However, many users in non-English locales complained
about this behavior, because their data used a period as the decimal
point, so the default behavior was restored to use a period as the
-decimal point character. You can use the '--use-lc-numeric' option
-(*note Options::) to force 'gawk' to use the locale's decimal point
-character. ('gawk' also uses the locale's decimal point character when
-in POSIX mode, either via '--posix' or the 'POSIXLY_CORRECT' environment
+decimal point character. You can use the â--use-lc-numericâ option
+(*note Options::) to force âgawkâ to use the localeâs decimal point
+character. (âgawkâ also uses the localeâs decimal point character when
+in POSIX mode, either via â--posixâ or the âPOSIXLY_CORRECTâ
environment
variable, as shown previously.)
*note Table 6.1: table-locale-affects. describes the cases in which
-the locale's decimal point character is used and when a period is used.
+the localeâs decimal point character is used and when a period is used.
Some of these features have not been described yet.
-Feature Default '--posix' or
- '--use-lc-numeric'
+Feature Default â--posixâ or
+ â--use-lc-numericâ
------------------------------------------------------------
-'%'g' Use locale Use locale
-'%g' Use period Use locale
+â%'gâ Use locale Use locale
+â%gâ Use period Use locale
Input Use period Use locale
-'strtonum()'Use period Use locale
+âstrtonum()âUse period Use locale
Table 6.1: Locale decimal point versus a period
Finally, modern-day formal standards and the IEEE standard
floating-point representation can have an unusual but important effect
-on the way 'gawk' converts some special string values to numbers. The
+on the way âgawkâ converts some special string values to numbers. The
details are presented in *note POSIX Floating Point Problems::.
@@ -8641,12 +8641,12 @@ File: gawk.info, Node: All Operators, Next: Truth
Values and Conditions, Prev
6.2 Operators: Doing Something with Values
==========================================
-This minor node introduces the "operators" that make use of the values
+This minor node introduces the âoperatorsâ that make use of the values
provided by constants and variables.
* Menu:
-* Arithmetic Ops:: Arithmetic operations ('+', '-',
+* Arithmetic Ops:: Arithmetic operations (â+â, â-â,
etc.)
* Concatenation:: Concatenating strings.
* Assignment Ops:: Changing the value of a variable or a field.
@@ -8658,87 +8658,87 @@ File: gawk.info, Node: Arithmetic Ops, Next:
Concatenation, Up: All Operators
6.2.1 Arithmetic Operators
--------------------------
-The 'awk' language uses the common arithmetic operators when evaluating
+The âawkâ language uses the common arithmetic operators when evaluating
expressions. All of these arithmetic operators follow normal precedence
rules and work as you would expect them to.
- The following example uses a file named 'grades', which contains a
-list of student names as well as three test scores per student (it's a
+ The following example uses a file named âgradesâ, which contains a
+list of student names as well as three test scores per student (itâs a
small class):
Pat 100 97 58
Sandy 84 72 93
Chris 72 92 89
-This program takes the file 'grades' and prints the average of the
+This program takes the file âgradesâ and prints the average of the
scores:
$ awk '{ sum = $2 + $3 + $4 ; avg = sum / 3
> print $1, avg }' grades
- -| Pat 85
- -| Sandy 83
- -| Chris 84.3333
+ ⣠Pat 85
+ ⣠Sandy 83
+ ⣠Chris 84.3333
- The following list provides the arithmetic operators in 'awk', in
+ The following list provides the arithmetic operators in âawkâ, in
order from the highest precedence to the lowest:
-'X ^ Y'
-'X ** Y'
- Exponentiation; X raised to the Y power. '2 ^ 3' has the value
- eight; the character sequence '**' is equivalent to '^'. (c.e.)
+âX ^ Yâ
+âX ** Yâ
+ Exponentiation; X raised to the Y power. â2 ^ 3â has the value
+ eight; the character sequence â**â is equivalent to â^â. (c.e.)
-'- X'
+â- Xâ
Negation.
-'+ X'
+â+ Xâ
Unary plus; the expression is converted to a number.
-'X * Y'
+âX * Yâ
Multiplication.
-'X / Y'
- Division; because all numbers in 'awk' are floating-point numbers,
- the result is _not_ rounded to an integer--'3 / 4' has the value
+âX / Yâ
+ Division; because all numbers in âawkâ are floating-point numbers,
+ the result is _not_ rounded to an integerââ3 / 4â has the value
0.75. (It is a common mistake, especially for C programmers, to
- forget that _all_ numbers in 'awk' are floating point, and that
+ forget that _all_ numbers in âawkâ are floating point, and that
division of integer-looking constants produces a real number, not
an integer.)
-'X % Y'
+âX % Yâ
Remainder; further discussion is provided in the text, just after
this list.
-'X + Y'
+âX + Yâ
Addition.
-'X - Y'
+âX - Yâ
Subtraction.
Unary plus and minus have the same precedence, the multiplication
operators all have the same precedence, and addition and subtraction
have the same precedence.
- When computing the remainder of 'X % Y', the quotient is rounded
+ When computing the remainder of âX % Yâ, the quotient is rounded
toward zero to an integer and multiplied by Y. This result is
-subtracted from X; this operation is sometimes known as "trunc-mod."
-The following relation always holds:
+subtracted from X; this operation is sometimes known as âtrunc-mod.â The
+following relation always holds:
b * int(a / b) + (a % b) == a
One possibly undesirable effect of this definition of remainder is
-that 'X % Y' is negative if X is negative. Thus:
+that âX % Yâ is negative if X is negative. Thus:
-17 % 8 = -1
This definition is compliant with the POSIX standard, which says that
-the '%' operator produces results equivalent to using the standard C
-'fmod()' function, and that function in turn works as just described.
+the â%â operator produces results equivalent to using the standard C
+âfmod()â function, and that function in turn works as just described.
- In other 'awk' implementations, the signedness of the remainder may
+ In other âawkâ implementations, the signedness of the remainder may
be machine-dependent.
- NOTE: The POSIX standard only specifies the use of '^' for
- exponentiation. For maximum portability, do not use the '**'
+ NOTE: The POSIX standard only specifies the use of â^â for
+ exponentiation. For maximum portability, do not use the â**â
operator.
@@ -8748,7 +8748,7 @@ File: gawk.info, Node: Concatenation, Next: Assignment
Ops, Prev: Arithmetic
--------------------------
It seemed like a good idea at the time.
- -- _Brian Kernighan_
+ â _Brian Kernighan_
There is only one string operation: concatenation. It does not have
a specific operator to represent it. Instead, concatenation is
@@ -8756,75 +8756,75 @@ performed by writing expressions next to one another,
with no operator.
For example:
$ awk '{ print "Field number one: " $1 }' mail-list
- -| Field number one: Amelia
- -| Field number one: Anthony
+ ⣠Field number one: Amelia
+ ⣠Field number one: Anthony
...
- Without the space in the string constant after the ':', the line runs
+ Without the space in the string constant after the â:â, the line runs
together. For example:
$ awk '{ print "Field number one:" $1 }' mail-list
- -| Field number one:Amelia
- -| Field number one:Anthony
+ ⣠Field number one:Amelia
+ ⣠Field number one:Anthony
...
Because string concatenation does not have an explicit operator, it
is often necessary to ensure that it happens at the right time by using
parentheses to enclose the items to concatenate. For example, you might
-expect that the following code fragment concatenates 'file' and 'name':
+expect that the following code fragment concatenates âfileâ and ânameâ:
file = "file"
name = "name"
print "something meaningful" > file name
-This produces a syntax error with some versions of Unix 'awk'.(1) It is
+This produces a syntax error with some versions of Unix âawkâ.(1) It is
necessary to use the following:
print "something meaningful" > (file name)
Parentheses should be used around concatenation in all but the most
-common contexts, such as on the righthand side of '='. Be careful about
+common contexts, such as on the righthand side of â=â. Be careful about
the kinds of expressions used in string concatenation. In particular,
the order of evaluation of expressions used for concatenation is
-undefined in the 'awk' language. Consider this example:
+undefined in the âawkâ language. Consider this example:
BEGIN {
a = "don't"
print (a " " (a = "panic"))
}
-It is not defined whether the second assignment to 'a' happens before or
-after the value of 'a' is retrieved for producing the concatenated
-value. The result could be either 'don't panic', or 'panic panic'.
+It is not defined whether the second assignment to âaâ happens before or
+after the value of âaâ is retrieved for producing the concatenated
+value. The result could be either âdon't panicâ, or âpanic panicâ.
The precedence of concatenation, when mixed with other operators, is
often counter-intuitive. Consider this example:
$ awk 'BEGIN { print -12 " " -24 }'
- -| -12-24
+ ⣠-12-24
- This "obviously" is concatenating -12, a space, and -24. But where
+ This âobviouslyâ is concatenating â12, a space, and â24. But where
did the space disappear to? The answer lies in the combination of
-operator precedences and 'awk''s automatic conversion rules. To get the
+operator precedences and âawkââs automatic conversion rules. To get the
desired result, write the program this way:
$ awk 'BEGIN { print -12 " " (-24) }'
- -| -12 -24
+ ⣠-12 -24
- This forces 'awk' to treat the '-' on the '-24' as unary. Otherwise,
-it's parsed as follows:
+ This forces âawkâ to treat the â-â on the â-24â as unary.
Otherwise,
+itâs parsed as follows:
- -12 ('" "' - 24)
- => -12 (0 - 24)
- => -12 (-24)
- => -12-24
+ â12 (â" "â â 24)
+ â â12 (0 â 24)
+ â â12 (â24)
+ â â12â24
As mentioned earlier, when mixing concatenation with other operators,
-_parenthesize_. Otherwise, you're never quite sure what you'll get.
+_parenthesize_. Otherwise, youâre never quite sure what youâll get.
---------- Footnotes ----------
- (1) It happens that BWK 'awk', 'gawk', and 'mawk' all "get it right,"
+ (1) It happens that BWK âawkâ, âgawkâ, and âmawkâ all âget it
right,â
but you should not rely on this.
@@ -8833,42 +8833,42 @@ File: gawk.info, Node: Assignment Ops, Next:
Increment Ops, Prev: Concatenati
6.2.3 Assignment Expressions
----------------------------
-An "assignment" is an expression that stores a (usually different) value
-into a variable. For example, let's assign the value one to the
-variable 'z':
+An âassignmentâ is an expression that stores a (usually different) value
+into a variable. For example, letâs assign the value one to the
+variable âzâ:
z = 1
- After this expression is executed, the variable 'z' has the value
-one. Whatever old value 'z' had before the assignment is forgotten.
+ After this expression is executed, the variable âzâ has the value
+one. Whatever old value âzâ had before the assignment is forgotten.
Assignments can also store string values. For example, the following
-stores the value '"this food is good"' in the variable 'message':
+stores the value â"this food is good"â in the variable âmessageâ:
thing = "food"
predicate = "good"
message = "this " thing " is " predicate
-This also illustrates string concatenation. The '=' sign is called an
-"assignment operator". It is the simplest assignment operator because
+This also illustrates string concatenation. The â=â sign is called an
+âassignment operatorâ. It is the simplest assignment operator because
the value of the righthand operand is stored unchanged. Most operators
(addition, concatenation, and so on) have no effect except to compute a
-value. If the value isn't used, there's no reason to use the operator.
+value. If the value isnât used, thereâs no reason to use the operator.
An assignment operator is different; it does produce a value, but even
if you ignore it, the assignment still makes itself felt through the
-alteration of the variable. We call this a "side effect".
+alteration of the variable. We call this a âside effectâ.
The lefthand operand of an assignment need not be a variable (*note
Variables::); it can also be a field (*note Changing Fields::) or an
-array element (*note Arrays::). These are all called "lvalues", which
+array element (*note Arrays::). These are all called âlvaluesâ, which
means they can appear on the lefthand side of an assignment operator.
The righthand operand may be any expression; it produces the new value
that the assignment stores in the specified variable, field, or array
-element. (Such values are called "rvalues".)
+element. (Such values are called ârvaluesâ.)
It is important to note that variables do _not_ have permanent types.
-A variable's type is simply the type of whatever value was last assigned
-to it. In the following program fragment, the variable 'foo' has a
+A variableâs type is simply the type of whatever value was last assigned
+to it. In the following program fragment, the variable âfooâ has a
numeric value at first, and a string value later on:
foo = 1
@@ -8876,43 +8876,43 @@ numeric value at first, and a string value later on:
foo = "bar"
print foo
-When the second assignment gives 'foo' a string value, the fact that it
+When the second assignment gives âfooâ a string value, the fact that it
previously had a numeric value is forgotten.
String values that do not begin with a digit have a numeric value of
-zero. After executing the following code, the value of 'foo' is five:
+zero. After executing the following code, the value of âfooâ is five:
foo = "a string"
foo = foo + 5
NOTE: Using a variable as a number and then later as a string can
be confusing and is poor programming style. The previous two
- examples illustrate how 'awk' works, _not_ how you should write
+ examples illustrate how âawkâ works, _not_ how you should write
your programs!
- An assignment is an expression, so it has a value--the same value
-that is assigned. Thus, 'z = 1' is an expression with the value one.
-One consequence of this is that you can write multiple assignments
-together, such as:
+ An assignment is an expression, so it has a valueâthe same value that
+is assigned. Thus, âz = 1â is an expression with the value one. One
+consequence of this is that you can write multiple assignments together,
+such as:
x = y = z = 5
-This example stores the value five in all three variables ('x', 'y', and
-'z'). It does so because the value of 'z = 5', which is five, is stored
-into 'y' and then the value of 'y = z = 5', which is five, is stored
-into 'x'.
+This example stores the value five in all three variables (âxâ, âyâ,
and
+âzâ). It does so because the value of âz = 5â, which is five, is
stored
+into âyâ and then the value of ây = z = 5â, which is five, is stored
+into âxâ.
Assignments may be used anywhere an expression is called for. For
-example, it is valid to write 'x != (y = 1)' to set 'y' to one, and then
-test whether 'x' equals one. But this style tends to make programs hard
+example, it is valid to write âx != (y = 1)â to set âyâ to one, and
then
+test whether âxâ equals one. But this style tends to make programs hard
to read; such nesting of assignments should be avoided, except perhaps
in a one-shot program.
- Aside from '=', there are several other assignment operators that do
+ Aside from â=â, there are several other assignment operators that do
arithmetic with the old value of the variable. For example, the
-operator '+=' computes a new value by adding the righthand value to the
+operator â+=â computes a new value by adding the righthand value to the
old value of the variable. Thus, the following assignment adds five to
-the value of 'foo':
+the value of âfooâ:
foo += 5
@@ -8922,7 +8922,7 @@ This is equivalent to the following:
Use whichever makes the meaning of your program clearer.
- There are situations where using '+=' (or any assignment operator) is
+ There are situations where using â+=â (or any assignment operator) is
_not_ the same as simply repeating the lefthand operand in the righthand
expression. For example:
@@ -8937,9 +8937,9 @@ expression. For example:
print x, bar[x]
}
-The indices of 'bar' are practically guaranteed to be different, because
-'rand()' returns different values each time it is called. (Arrays and
-the 'rand()' function haven't been covered yet. *Note Arrays::, and
+The indices of âbarâ are practically guaranteed to be different, because
+ârand()â returns different values each time it is called. (Arrays and
+the ârand()â function havenât been covered yet. *Note Arrays::, and
*note Numeric Functions:: for more information.) This example
illustrates an important fact about assignment operators: the lefthand
expression is only evaluated _once_.
@@ -8950,7 +8950,7 @@ first, the lefthand or the righthand. Consider this
example:
i = 1
a[i += 2] = i + 1
-The value of 'a[3]' could be either two or four.
+The value of âa[3]â could be either two or four.
*note Table 6.2: table-assign-ops. lists the arithmetic assignment
operators. In each case, the righthand operand is an expression whose
@@ -8959,39 +8959,39 @@ value is converted to a number.
Operator Effect
--------------------------------------------------------------------------
-LVALUE '+=' Add INCREMENT to the value of LVALUE.
+LVALUE â+=â Add INCREMENT to the value of LVALUE.
INCREMENT
-LVALUE '-=' Subtract DECREMENT from the value of LVALUE.
+LVALUE â-=â Subtract DECREMENT from the value of LVALUE.
DECREMENT
-LVALUE '*=' Multiply the value of LVALUE by COEFFICIENT.
+LVALUE â*=â Multiply the value of LVALUE by COEFFICIENT.
COEFFICIENT
-LVALUE '/=' DIVISOR Divide the value of LVALUE by DIVISOR.
-LVALUE '%=' MODULUS Set LVALUE to its remainder by MODULUS.
-LVALUE '^=' POWER Raise LVALUE to the power POWER.
-LVALUE '**=' POWER Raise LVALUE to the power POWER. (c.e.)
+LVALUE â/=â DIVISOR Divide the value of LVALUE by DIVISOR.
+LVALUE â%=â MODULUS Set LVALUE to its remainder by MODULUS.
+LVALUE â^=â POWER Raise LVALUE to the power POWER.
+LVALUE â**=â POWER Raise LVALUE to the power POWER. (c.e.)
Table 6.2: Arithmetic assignment operators
- NOTE: Only the '^=' operator is specified by POSIX. For maximum
- portability, do not use the '**=' operator.
+ NOTE: Only the â^=â operator is specified by POSIX. For maximum
+ portability, do not use the â**=â operator.
- Syntactic Ambiguities Between '/=' and Regular Expressions
+ Syntactic Ambiguities Between â/=â and Regular Expressions
- There is a syntactic ambiguity between the '/=' assignment operator
-and regexp constants whose first character is an '='. (d.c.) This is
-most notable in some commercial 'awk' versions. For example:
+ There is a syntactic ambiguity between the â/=â assignment operator
+and regexp constants whose first character is an â=â. (d.c.) This is
+most notable in some commercial âawkâ versions. For example:
$ awk /==/ /dev/null
- error-> awk: syntax error at source line 1
- error-> context is
- error-> >>> /= <<<
- error-> awk: bailing out at source line 1
+ errorâ awk: syntax error at source line 1
+ errorâ context is
+ errorâ >>> /= <<<
+ errorâ awk: bailing out at source line 1
A workaround is:
awk '/[=]=/' /dev/null
- 'gawk' does not have this problem; BWK 'awk' and 'mawk' also do not.
+ âgawkâ does not have this problem; BWK âawkâ and âmawkâ also do
not.
File: gawk.info, Node: Increment Ops, Prev: Assignment Ops, Up: All
Operators
@@ -8999,63 +8999,63 @@ File: gawk.info, Node: Increment Ops, Prev:
Assignment Ops, Up: All Operators
6.2.4 Increment and Decrement Operators
---------------------------------------
-"Increment" and "decrement operators" increase or decrease the value of
+âIncrementâ and âdecrement operatorsâ increase or decrease the value of
a variable by one. An assignment operator can do the same thing, so the
-increment operators add no power to the 'awk' language; however, they
+increment operators add no power to the âawkâ language; however, they
are convenient abbreviations for very common operations.
- The operator used for adding one is written '++'. It can be used to
+ The operator used for adding one is written â++â. It can be used to
increment a variable either before or after taking its value. To
-"pre-increment" a variable 'v', write '++v'. This adds one to the value
-of 'v'--that new value is also the value of the expression. (The
-assignment expression 'v += 1' is completely equivalent.) Writing the
-'++' after the variable specifies "post-increment". This increments the
+âpre-incrementâ a variable âvâ, write â++vâ. This adds one to the
value
+of âvââthat new value is also the value of the expression. (The
+assignment expression âv += 1â is completely equivalent.) Writing the
+â++â after the variable specifies âpost-incrementâ. This increments
the
variable value just the same; the difference is that the value of the
-increment expression itself is the variable's _old_ value. Thus, if
-'foo' has the value four, then the expression 'foo++' has the value
-four, but it changes the value of 'foo' to five. In other words, the
+increment expression itself is the variableâs _old_ value. Thus, if
+âfooâ has the value four, then the expression âfoo++â has the value
+four, but it changes the value of âfooâ to five. In other words, the
operator returns the old value of the variable, but with the side effect
of incrementing it.
- The post-increment 'foo++' is nearly the same as writing '(foo += 1)
-- 1'. It is not perfectly equivalent because all numbers in 'awk' are
-floating point--in floating point, 'foo + 1 - 1' does not necessarily
-equal 'foo'. But the difference is minute as long as you stick to
+ The post-increment âfoo++â is nearly the same as writing â(foo += 1)
+- 1â. It is not perfectly equivalent because all numbers in âawkâ are
+floating pointâin floating point, âfoo + 1 - 1â does not necessarily
+equal âfooâ. But the difference is minute as long as you stick to
numbers that are fairly small (less than 10e12).
Fields and array elements are incremented just like variables. (Use
-'$(i++)' when you want to do a field reference and a variable increment
+â$(i++)â when you want to do a field reference and a variable increment
at the same time. The parentheses are necessary because of the
-precedence of the field reference operator '$'.)
+precedence of the field reference operator â$â.)
- The decrement operator '--' works just like '++', except that it
-subtracts one instead of adding it. As with '++', it can be used before
+ The decrement operator â--â works just like â++â, except that it
+subtracts one instead of adding it. As with â++â, it can be used before
the lvalue to pre-decrement or after it to post-decrement. Following is
a summary of increment and decrement expressions:
-'++LVALUE'
+â++LVALUEâ
Increment LVALUE, returning the new value as the value of the
expression.
-'LVALUE++'
+âLVALUE++â
Increment LVALUE, returning the _old_ value of LVALUE as the value
of the expression.
-'--LVALUE'
+â--LVALUEâ
Decrement LVALUE, returning the new value as the value of the
- expression. (This expression is like '++LVALUE', but instead of
+ expression. (This expression is like â++LVALUEâ, but instead of
adding, it subtracts.)
-'LVALUE--'
+âLVALUE--â
Decrement LVALUE, returning the _old_ value of LVALUE as the value
- of the expression. (This expression is like 'LVALUE++', but
+ of the expression. (This expression is like âLVALUE++â, but
instead of adding, it subtracts.)
Operator Evaluation Order
Doctor, it hurts when I do this!
- Then don't do that!
- -- _Groucho Marx_
+ Then donât do that!
+ â _Groucho Marx_
What happens for something like the following?
@@ -9069,9 +9069,9 @@ Or something even stranger?
print b
In other words, when do the various side effects prescribed by the
-postfix operators ('b++') take effect? When side effects happen is
-"implementation-defined". In other words, it is up to the particular
-version of 'awk'. The result for the first example may be 12 or 13, and
+postfix operators (âb++â) take effect? When side effects happen is
+âimplementation-definedâ. In other words, it is up to the particular
+version of âawkâ. The result for the first example may be 12 or 13, and
for the second, it may be 22 or 23.
In short, doing things like this is not recommended and definitely
@@ -9084,20 +9084,20 @@ File: gawk.info, Node: Truth Values and Conditions,
Next: Function Calls, Pre
6.3 Truth Values and Conditions
===============================
-In certain contexts, expression values also serve as "truth values";
+In certain contexts, expression values also serve as âtruth valuesâ;
i.e., they determine what should happen next as the program runs. This
-minor node describes how 'awk' defines "true" and "false" and how values
+minor node describes how âawkâ defines âtrueâ and âfalseâ and how
values
are compared.
* Menu:
-* Truth Values:: What is "true" and what is "false".
+* Truth Values:: What is âtrueâ and what is âfalseâ.
* Typing and Comparison:: How variables acquire types and how this
affects comparison of numbers and strings with
- '<', etc.
+ â<â, etc.
* Boolean Ops:: Combining comparison expressions using boolean
- operators '||' ("or"), '&&'
- ("and") and '!' ("not").
+ operators â||â (âorâ), â&&â
+ (âandâ) and â!â (ânotâ).
* Conditional Exp:: Conditional expressions select between two
subexpressions under control of a third
subexpression.
@@ -9105,16 +9105,16 @@ are compared.
File: gawk.info, Node: Truth Values, Next: Typing and Comparison, Up: Truth
Values and Conditions
-6.3.1 True and False in 'awk'
+6.3.1 True and False in âawkâ
-----------------------------
Many programming languages have a special representation for the
-concepts of "true" and "false." Such languages usually use the special
-constants 'true' and 'false', or perhaps their uppercase equivalents.
-However, 'awk' is different. It borrows a very simple concept of true
-and false from C. In 'awk', any nonzero numeric value _or_ any nonempty
-string value is true. Any other value (zero or the null string, '""')
-is false. The following program prints 'A strange truth value' three
+concepts of âtrueâ and âfalse.â Such languages usually use the special
+constants âtrueâ and âfalseâ, or perhaps their uppercase equivalents.
+However, âawkâ is different. It borrows a very simple concept of true
+and false from C. In âawkâ, any nonzero numeric value _or_ any nonempty
+string value is true. Any other value (zero or the null string, â""â)
+is false. The following program prints âA strange truth valueâ three
times:
BEGIN {
@@ -9126,8 +9126,8 @@ times:
print "A strange truth value"
}
- There is a surprising consequence of the "nonzero or non-null" rule:
-the string constant '"0"' is actually true, because it is non-null.
+ There is a surprising consequence of the ânonzero or non-nullâ rule:
+the string constant â"0"â is actually true, because it is non-null.
(d.c.)
@@ -9137,12 +9137,12 @@ File: gawk.info, Node: Typing and Comparison, Next:
Boolean Ops, Prev: Truth
------------------------------------------------
The Guide is definitive. Reality is frequently inaccurate.
- -- _Douglas Adams, 'The Hitchhiker's Guide to the Galaxy'_
+ â _Douglas Adams, âThe Hitchhikerâs Guide to the Galaxyâ_
- Unlike in other programming languages, in 'awk' variables do not have
+ Unlike in other programming languages, in âawkâ variables do not have
a fixed type. Instead, they can be either a number or a string,
depending upon the value that is assigned to them. We look now at how
-variables are typed, and how 'awk' compares variables.
+variables are typed, and how âawkâ compares variables.
* Menu:
@@ -9156,23 +9156,23 @@ File: gawk.info, Node: Variable Typing, Next:
Comparison Operators, Up: Typin
6.3.2.1 String Type versus Numeric Type
.......................................
-Scalar objects in 'awk' (variables, array elements, and fields) are
+Scalar objects in âawkâ (variables, array elements, and fields) are
_dynamically_ typed. This means their type can change as the program
-runs, from "untyped" before any use,(1) to string or number, and then
+runs, from âuntypedâ before any use,(1) to string or number, and then
from string to number or number to string, as the program progresses.
-('gawk' also provides regexp-typed scalars, but let's ignore that for
+(âgawkâ also provides regexp-typed scalars, but letâs ignore that for
now; *note Strong Regexp Constants::.)
- You can't do much with untyped variables, other than tell that they
-are untyped. The following program tests 'a' against '""' and '0'; the
-test succeeds when 'a' has never been assigned a value. It also uses
-the built-in 'typeof()' function (not presented yet; *note Type
-Functions::) to show 'a''s type:
+ You canât do much with untyped variables, other than tell that they
+are untyped. The following program tests âaâ against â""â and
â0â; the
+test succeeds when âaâ has never been assigned a value. It also uses
+the built-in âtypeof()â function (not presented yet; *note Type
+Functions::) to show âaââs type:
$ gawk 'BEGIN { print (a == "" && a == 0 ?
> "a is untyped" : "a has a type!") ; print typeof(a) }'
- -| a is untyped
- -| unassigned
+ ⣠a is untyped
+ ⣠unassigned
A scalar has numeric type when assigned a numeric value, such as from
a numeric constant, or from another scalar with numeric type:
@@ -9191,58 +9191,58 @@ such as from a string constant, or from another scalar
with string type:
string
So far, this is all simple and straightforward. What happens,
-though, when 'awk' has to process data from a user? Let's start with
+though, when âawkâ has to process data from a user? Letâs start with
field data. What should the following command produce as output?
echo hello | awk '{ printf("%s %s < 42\n", $1,
($1 < 42 ? "is" : "is not")) }'
-Since 'hello' is alphabetic data, 'awk' can only do a string comparison.
-Internally, it converts '42' into '"42"' and compares the two string
-values '"hello"' and '"42"'. Here's the result:
+Since âhelloâ is alphabetic data, âawkâ can only do a string
comparison.
+Internally, it converts â42â into â"42"â and compares the two string
+values â"hello"â and â"42"â. Hereâs the result:
$ echo hello | awk '{ printf("%s %s < 42\n", $1,
> ($1 < 42 ? "is" : "is not")) }'
- -| hello is not < 42
+ ⣠hello is not < 42
However, what happens when data from a user _looks like_ a number?
On the one hand, in reality, the input data consists of characters, not
binary numeric values. But, on the other hand, the data looks numeric,
-and 'awk' really ought to treat it as such. And indeed, it does:
+and âawkâ really ought to treat it as such. And indeed, it does:
$ echo 37 | awk '{ printf("%s %s < 42\n", $1,
> ($1 < 42 ? "is" : "is not")) }'
- -| 37 is < 42
+ ⣠37 is < 42
- Here are the rules for when 'awk' treats data as a number, and for
+ Here are the rules for when âawkâ treats data as a number, and for
when it treats data as a string.
- The POSIX standard uses the term "numeric string" for input data that
-looks numeric. The '37' in the previous example is a numeric string.
+ The POSIX standard uses the term ânumeric stringâ for input data that
+looks numeric. The â37â in the previous example is a numeric string.
So what is the type of a numeric string? Answer: numeric.
The type of a variable is important because the types of two
variables determine how they are compared. Variable typing follows
these definitions and rules:
- * A numeric constant or the result of a numeric operation has the
- "numeric" attribute.
+ ⢠A numeric constant or the result of a numeric operation has the
+ ânumericâ attribute.
- * A string constant or the result of a string operation has the
- "string" attribute.
+ ⢠A string constant or the result of a string operation has the
+ âstringâ attribute.
- * Fields, 'getline' input, 'FILENAME', 'ARGV' elements, 'ENVIRON'
- elements, and the elements of an array created by 'match()',
- 'split()', and 'patsplit()' that are numeric strings have the
- "strnum" attribute.(2) Otherwise, they have the "string"
- attribute. Uninitialized variables also have the "strnum"
+ ⢠Fields, âgetlineâ input, âFILENAMEâ, âARGVâ elements,
âENVIRONâ
+ elements, and the elements of an array created by âmatch()â,
+ âsplit()â, and âpatsplit()â that are numeric strings have the
+ âstrnumâ attribute.(2) Otherwise, they have the âstringâ
+ attribute. Uninitialized variables also have the âstrnumâ
attribute.
- * Attributes propagate across assignments but are not changed by any
+ ⢠Attributes propagate across assignments but are not changed by any
use.
The last rule is particularly important. In the following program,
-'a' has numeric type, even though it is later used in a string
+âaâ has numeric type, even though it is later used in a string
operation:
BEGIN {
@@ -9266,56 +9266,56 @@ NUMERIC | string numeric numeric
STRNUM | string numeric numeric
--------+----------------------------------------------
- The basic idea is that user input that looks numeric--and _only_ user
-input--should be treated as numeric, even though it is actually made of
+ The basic idea is that user input that looks numericâand _only_ user
+inputâshould be treated as numeric, even though it is actually made of
characters and is therefore also a string. Thus, for example, the
-string constant '" +3.14"', when it appears in program source code, is a
-string--even though it looks numeric--and is _never_ treated as a number
+string constant â" +3.14"â, when it appears in program source code, is a
+stringâeven though it looks numericâand is _never_ treated as a number
for comparison purposes.
- In short, when one operand is a "pure" string, such as a string
+ In short, when one operand is a âpureâ string, such as a string
constant, then a string comparison is performed. Otherwise, a numeric
comparison is performed. (The primary difference between a number and a
-strnum is that for strnums 'gawk' preserves the original string value
+strnum is that for strnums âgawkâ preserves the original string value
that the scalar had when it came in.)
This point bears additional emphasis: Input that looks numeric _is_
numeric. All other input is treated as strings.
- Thus, the six-character input string ' +3.14' receives the strnum
-attribute. In contrast, the eight characters '" +3.14"' appearing in
+ Thus, the six-character input string â +3.14â receives the strnum
+attribute. In contrast, the eight characters â" +3.14"â appearing in
program text comprise a string constant. The following examples print
-'1' when the comparison between the two different constants is true, and
-'0' otherwise:
+â1â when the comparison between the two different constants is true, and
+â0â otherwise:
$ echo ' +3.14' | awk '{ print($0 == " +3.14") }' True
- -| 1
+ ⣠1
$ echo ' +3.14' | awk '{ print($0 == "+3.14") }' False
- -| 0
+ ⣠0
$ echo ' +3.14' | awk '{ print($0 == "3.14") }' False
- -| 0
+ ⣠0
$ echo ' +3.14' | awk '{ print($0 == 3.14) }' True
- -| 1
+ ⣠1
$ echo ' +3.14' | awk '{ print($1 == " +3.14") }' False
- -| 0
+ ⣠0
$ echo ' +3.14' | awk '{ print($1 == "+3.14") }' True
- -| 1
+ ⣠1
$ echo ' +3.14' | awk '{ print($1 == "3.14") }' False
- -| 0
+ ⣠0
$ echo ' +3.14' | awk '{ print($1 == 3.14) }' True
- -| 1
+ ⣠1
You can see the type of an input field (or other user input) using
-'typeof()':
+âtypeof()â:
$ echo hello 37 | gawk '{ print typeof($1), typeof($2) }'
- -| string strnum
+ ⣠string strnum
---------- Footnotes ----------
- (1) 'gawk' calls this "unassigned", as the following example shows.
+ (1) âgawkâ calls this âunassignedâ, as the following example shows.
- (2) Thus, a POSIX numeric string and 'gawk''s strnum are the same
+ (2) Thus, a POSIX numeric string and âgawkââs strnum are the same
thing.
@@ -9324,40 +9324,40 @@ File: gawk.info, Node: Comparison Operators, Next:
POSIX String Comparison, P
6.3.2.2 Comparison Operators
............................
-"Comparison expressions" compare strings or numbers for relationships
-such as equality. They are written using "relational operators", which
+âComparison expressionsâ compare strings or numbers for relationships
+such as equality. They are written using ârelational operatorsâ, which
are a superset of those in C. *note Table 6.3: table-relational-ops.
describes them.
Expression Result
--------------------------------------------------------------------------
-X '<' Y True if X is less than Y
-X '<=' Y True if X is less than or equal to Y
-X '>' Y True if X is greater than Y
-X '>=' Y True if X is greater than or equal to Y
-X '==' Y True if X is equal to Y
-X '!=' Y True if X is not equal to Y
-X '~' Y True if the string X matches the regexp denoted by Y
-X '!~' Y True if the string X does not match the regexp
+X â<â Y True if X is less than Y
+X â<=â Y True if X is less than or equal to Y
+X â>â Y True if X is greater than Y
+X â>=â Y True if X is greater than or equal to Y
+X â==â Y True if X is equal to Y
+X â!=â Y True if X is not equal to Y
+X â~â Y True if the string X matches the regexp denoted by Y
+X â!~â Y True if the string X does not match the regexp
denoted by Y
-SUBSCRIPT 'in' True if the array ARRAY has an element with the
+SUBSCRIPT âinâ True if the array ARRAY has an element with the
ARRAY subscript SUBSCRIPT
Table 6.3: Relational operators
Comparison expressions have the value one if true and zero if false.
When comparing operands of mixed types, numeric operands are converted
-to strings using the value of 'CONVFMT' (*note Conversion::).
+to strings using the value of âCONVFMTâ (*note Conversion::).
Strings are compared by comparing the first character of each, then
-the second character of each, and so on. Thus, '"10"' is less than
-'"9"'. If there are two strings where one is a prefix of the other, the
-shorter string is less than the longer one. Thus, '"abc"' is less than
-'"abcd"'.
+the second character of each, and so on. Thus, â"10"â is less than
+â"9"â. If there are two strings where one is a prefix of the other, the
+shorter string is less than the longer one. Thus, â"abc"â is less than
+â"abcd"â.
- It is very easy to accidentally mistype the '==' operator and leave
-off one of the '=' characters. The result is still valid 'awk' code,
+ It is very easy to accidentally mistype the â==â operator and leave
+off one of the â=â characters. The result is still valid âawkâ code,
but the program does not do what is intended:
if (a = b) # oops! should be a == b
@@ -9365,71 +9365,71 @@ but the program does not do what is intended:
else
...
-Unless 'b' happens to be zero or the null string, the 'if' part of the
+Unless âbâ happens to be zero or the null string, the âifâ part of the
test always succeeds. Because the operators are so similar, this kind
of error is very difficult to spot when scanning the source code.
The following list of expressions illustrates the kinds of
-comparisons 'awk' performs, as well as what the result of each
+comparisons âawkâ performs, as well as what the result of each
comparison is:
-'1.5 <= 2.0'
+â1.5 <= 2.0â
Numeric comparison (true)
-'"abc" >= "xyz"'
+â"abc" >= "xyz"â
String comparison (false)
-'1.5 != " +2"'
+â1.5 != " +2"â
String comparison (true)
-'"1e2" < "3"'
+â"1e2" < "3"â
String comparison (true)
-'a = 2; b = "2"'
-'a == b'
+âa = 2; b = "2"â
+âa == bâ
String comparison (true)
-'a = 2; b = " +2"'
-'a == b'
+âa = 2; b = " +2"â
+âa == bâ
String comparison (false)
In this example:
$ echo 1e2 3 | awk '{ print ($1 < $2) ? "true" : "false" }'
- -| false
+ ⣠false
-the result is 'false' because both '$1' and '$2' are user input. They
-are numeric strings--therefore both have the strnum attribute, dictating
+the result is âfalseâ because both â$1â and â$2â are user input.
They
+are numeric stringsâtherefore both have the strnum attribute, dictating
a numeric comparison. The purpose of the comparison rules and the use
-of numeric strings is to attempt to produce the behavior that is "least
-surprising," while still "doing the right thing."
+of numeric strings is to attempt to produce the behavior that is âleast
+surprising,â while still âdoing the right thing.â
String comparisons and regular expression comparisons are very
different. For example:
x == "foo"
-has the value one, or is true if the variable 'x' is precisely 'foo'.
+has the value one, or is true if the variable âxâ is precisely âfooâ.
By contrast:
x ~ /foo/
-has the value one if 'x' contains 'foo', such as '"Oh, what a fool am
-I!"'.
+has the value one if âxâ contains âfooâ, such as â"Oh, what a fool am
+I!"â.
- The righthand operand of the '~' and '!~' operators may be either a
-regexp constant ('/'...'/') or an ordinary expression. In the latter
+ The righthand operand of the â~â and â!~â operators may be either a
+regexp constant (â/â...â/â) or an ordinary expression. In the latter
case, the value of the expression as a string is used as a dynamic
regexp (*note Regexp Usage::; also *note Computed Regexps::).
A constant regular expression in slashes by itself is also an
-expression. '/REGEXP/' is an abbreviation for the following comparison
+expression. â/REGEXP/â is an abbreviation for the following comparison
expression:
$0 ~ /REGEXP/
- One special place where '/foo/' is _not_ an abbreviation for '$0 ~
-/foo/' is when it is the righthand operand of '~' or '!~'. *Note Using
+ One special place where â/foo/â is _not_ an abbreviation for â$0 ~
+/foo/â is when it is the righthand operand of â~â or â!~â. *Note
Using
Constant Regexps::, where this is discussed in more detail.
@@ -9439,40 +9439,40 @@ File: gawk.info, Node: POSIX String Comparison, Prev:
Comparison Operators, U
.........................................................
The POSIX standard used to say that all string comparisons are performed
-based on the locale's "collating order". This is the order in which
+based on the localeâs âcollating orderâ. This is the order in which
characters sort, as defined by the locale (for more discussion, *note
Locales::). This order is usually very different from the results
obtained when doing straight byte-by-byte comparison.(1)
Because this behavior differs considerably from existing practice,
-'gawk' only implemented it when in POSIX mode (*note Options::). Here
-is an example to illustrate the difference, in an 'en_US.UTF-8' locale:
+âgawkâ only implemented it when in POSIX mode (*note Options::). Here
+is an example to illustrate the difference, in an âen_US.UTF-8â locale:
$ gawk 'BEGIN { printf("ABC < abc = %s\n",
> ("ABC" < "abc" ? "TRUE" : "FALSE")) }'
- -| ABC < abc = TRUE
+ ⣠ABC < abc = TRUE
$ gawk --posix 'BEGIN { printf("ABC < abc = %s\n",
> ("ABC" < "abc" ? "TRUE" : "FALSE")) }'
- -| ABC < abc = FALSE
+ ⣠ABC < abc = FALSE
Fortunately, as of August 2016, comparison based on locale collating
-order is no longer required for the '==' and '!=' operators.(2)
-However, comparison based on locales is still required for '<', '<=',
-'>', and '>='. POSIX thus recommends as follows:
+order is no longer required for the â==â and â!=â operators.(2)
+However, comparison based on locales is still required for â<â, â<=â,
+â>â, and â>=â. POSIX thus recommends as follows:
- Since the '==' operator checks whether strings are identical, not
+ Since the â==â operator checks whether strings are identical, not
whether they collate equally, applications needing to check whether
strings collate equally can use:
a <= b && a >= b
- As of version 4.2, 'gawk' continues to use locale collating order for
-'<', '<=', '>', and '>=' only in POSIX mode.
+ As of version 4.2, âgawkâ continues to use locale collating order for
+â<â, â<=â, â>â, and â>=â only in POSIX mode.
---------- Footnotes ----------
(1) Technically, string comparison is supposed to behave the same way
-as if the strings were compared with the C 'strcoll()' function.
+as if the strings were compared with the C âstrcoll()â function.
(2) See the Austin Group website
(http://austingroupbugs.net/view.php?id=1070).
@@ -9483,16 +9483,16 @@ File: gawk.info, Node: Boolean Ops, Next: Conditional
Exp, Prev: Typing and C
6.3.3 Boolean Expressions
-------------------------
-A "Boolean expression" is a combination of comparison expressions or
-matching expressions, using the Boolean operators "or" ('||'), "and"
-('&&'), and "not" ('!'), along with parentheses to control nesting. The
+A âBoolean expressionâ is a combination of comparison expressions or
+matching expressions, using the Boolean operators âorâ (â||â),
âandâ
+(â&&â), and ânotâ (â!â), along with parentheses to control
nesting. The
truth value of the Boolean expression is computed by combining the truth
values of the component expressions. Boolean expressions are also
-referred to as "logical expressions". The terms are equivalent.
+referred to as âlogical expressionsâ. The terms are equivalent.
Boolean expressions can be used wherever comparison and matching
-expressions can be used. They can be used in 'if', 'while', 'do', and
-'for' statements (*note Statements::). They have numeric values (one if
+expressions can be used. They can be used in âifâ, âwhileâ, âdoâ,
and
+âforâ statements (*note Statements::). They have numeric values (one if
true, zero if false) that come into play if the result of the Boolean
expression is stored in a variable or used in arithmetic.
@@ -9500,55 +9500,55 @@ expression is stored in a variable or used in
arithmetic.
can use one as a pattern to control the execution of rules. The Boolean
operators are:
-'BOOLEAN1 && BOOLEAN2'
+âBOOLEAN1 && BOOLEAN2â
True if both BOOLEAN1 and BOOLEAN2 are true. For example, the
following statement prints the current input record if it contains
- both 'edu' and 'li':
+ both âeduâ and âliâ:
if ($0 ~ /edu/ && $0 ~ /li/) print
The subexpression BOOLEAN2 is evaluated only if BOOLEAN1 is true.
This can make a difference when BOOLEAN2 contains expressions that
- have side effects. In the case of '$0 ~ /foo/ && ($2 == bar++)',
- the variable 'bar' is not incremented if there is no substring
- 'foo' in the record.
+ have side effects. In the case of â$0 ~ /foo/ && ($2 == bar++)â,
+ the variable âbarâ is not incremented if there is no substring
+ âfooâ in the record.
-'BOOLEAN1 || BOOLEAN2'
+âBOOLEAN1 || BOOLEAN2â
True if at least one of BOOLEAN1 or BOOLEAN2 is true. For example,
the following statement prints all records in the input that
- contain _either_ 'edu' or 'li':
+ contain _either_ âeduâ or âliâ:
if ($0 ~ /edu/ || $0 ~ /li/) print
The subexpression BOOLEAN2 is evaluated only if BOOLEAN1 is false.
This can make a difference when BOOLEAN2 contains expressions that
have side effects. (Thus, this test never really distinguishes
- records that contain both 'edu' and 'li'--as soon as 'edu' is
+ records that contain both âeduâ and âliââas soon as âeduâ is
matched, the full test succeeds.)
-'! BOOLEAN'
+â! BOOLEANâ
True if BOOLEAN is false. For example, the following program
- prints 'no home!' in the unusual event that the 'HOME' environment
+ prints âno home!â in the unusual event that the âHOMEâ environment
variable is not defined:
BEGIN { if (! ("HOME" in ENVIRON))
print "no home!" }
- (The 'in' operator is described in *note Reference to Elements::.)
+ (The âinâ operator is described in *note Reference to Elements::.)
- The '&&' and '||' operators are called "short-circuit" operators
+ The â&&â and â||â operators are called âshort-circuitâ operators
because of the way they work. Evaluation of the full expression is
-"short-circuited" if the result can be determined partway through its
+âshort-circuitedâ if the result can be determined partway through its
evaluation.
- Statements that end with '&&' or '||' can be continued simply by
+ Statements that end with â&&â or â||â can be continued simply by
putting a newline after them. But you cannot put a newline in front of
either of these operators without using backslash continuation (*note
Statements/Lines::).
- The actual value of an expression using the '!' operator is either
+ The actual value of an expression using the â!â operator is either
one or zero, depending upon the truth value of the expression it is
-applied to. The '!' operator is often useful for changing the sense of
+applied to. The â!â operator is often useful for changing the sense of
a flag variable from false to true and back again. For example, the
following program is one way to print lines in between special
bracketing lines:
@@ -9557,30 +9557,30 @@ bracketing lines:
interested { print }
$1 == "END" { interested = ! interested; next }
-The variable 'interested', as with all 'awk' variables, starts out
+The variable âinterestedâ, as with all âawkâ variables, starts out
initialized to zero, which is also false. When a line is seen whose
-first field is 'START', the value of 'interested' is toggled to true,
-using '!'. The next rule prints lines as long as 'interested' is true.
-When a line is seen whose first field is 'END', 'interested' is toggled
+first field is âSTARTâ, the value of âinterestedâ is toggled to true,
+using â!â. The next rule prints lines as long as âinterestedâ is true.
+When a line is seen whose first field is âENDâ, âinterestedâ is toggled
back to false.(1)
- Most commonly, the '!' operator is used in the conditions of 'if' and
-'while' statements, where it often makes more sense to phrase the logic
+ Most commonly, the â!â operator is used in the conditions of âifâ
and
+âwhileâ statements, where it often makes more sense to phrase the logic
in the negative:
if (! SOME CONDITION || SOME OTHER CONDITION) {
... DO WHATEVER PROCESSING ...
}
- NOTE: The 'next' statement is discussed in *note Next Statement::.
- 'next' tells 'awk' to skip the rest of the rules, get the next
+ NOTE: The ânextâ statement is discussed in *note Next Statement::.
+ ânextâ tells âawkâ to skip the rest of the rules, get the next
record, and start processing the rules over again at the top. The
- reason it's there is to avoid printing the bracketing 'START' and
- 'END' lines.
+ reason itâs there is to avoid printing the bracketing âSTARTâ and
+ âENDâ lines.
---------- Footnotes ----------
- (1) This program has a bug; it prints lines starting with 'END'. How
+ (1) This program has a bug; it prints lines starting with âENDâ. How
would you fix it?
@@ -9589,38 +9589,38 @@ File: gawk.info, Node: Conditional Exp, Prev: Boolean
Ops, Up: Truth Values a
6.3.4 Conditional Expressions
-----------------------------
-A "conditional expression" is a special kind of expression that has
-three operands. It allows you to use one expression's value to select
-one of two other expressions. The conditional expression in 'awk' is
+A âconditional expressionâ is a special kind of expression that has
+three operands. It allows you to use one expressionâs value to select
+one of two other expressions. The conditional expression in âawkâ is
the same as in the C language, as shown here:
SELECTOR ? IF-TRUE-EXP : IF-FALSE-EXP
There are three subexpressions. The first, SELECTOR, is always computed
-first. If it is "true" (not zero or not null), then IF-TRUE-EXP is
+first. If it is âtrueâ (not zero or not null), then IF-TRUE-EXP is
computed next, and its value becomes the value of the whole expression.
Otherwise, IF-FALSE-EXP is computed next, and its value becomes the
value of the whole expression. For example, the following expression
-produces the absolute value of 'x':
+produces the absolute value of âxâ:
x >= 0 ? x : -x
Each time the conditional expression is computed, only one of
IF-TRUE-EXP and IF-FALSE-EXP is used; the other is ignored. This is
important when the expressions have side effects. For example, this
-conditional expression examines element 'i' of either array 'a' or array
-'b', and increments 'i':
+conditional expression examines element âiâ of either array âaâ or
array
+âbâ, and increments âiâ:
x == y ? a[i++] : b[i++]
-This is guaranteed to increment 'i' exactly once, because each time only
+This is guaranteed to increment âiâ exactly once, because each time only
one of the two increment expressions is executed and the other is not.
*Note Arrays::, for more information about arrays.
- As a minor 'gawk' extension, a statement that uses '?:' can be
+ As a minor âgawkâ extension, a statement that uses â?:â can be
continued simply by putting a newline after either character. However,
putting a newline in front of either character does not work without
-using backslash continuation (*note Statements/Lines::). If '--posix'
+using backslash continuation (*note Statements/Lines::). If â--posixâ
is specified (*note Options::), this extension is disabled.
@@ -9629,24 +9629,24 @@ File: gawk.info, Node: Function Calls, Next:
Precedence, Prev: Truth Values a
6.4 Function Calls
==================
-A "function" is a name for a particular calculation. This enables you
+A âfunctionâ is a name for a particular calculation. This enables you
to ask for it by name at any point in the program. For example, the
-function 'sqrt()' computes the square root of a number.
+function âsqrt()â computes the square root of a number.
- A fixed set of functions are "built in", which means they are
-available in every 'awk' program. The 'sqrt()' function is one of
+ A fixed set of functions are âbuilt inâ, which means they are
+available in every âawkâ program. The âsqrt()â function is one of
these. *Note Built-in:: for a list of built-in functions and their
descriptions. In addition, you can define functions for use in your
program. *Note User-defined:: for instructions on how to do this.
-Finally, 'gawk' lets you write functions in C or C++ that may be called
+Finally, âgawkâ lets you write functions in C or C++ that may be called
from your program (*note Dynamic Extensions::).
- The way to use a function is with a "function call" expression, which
+ The way to use a function is with a âfunction callâ expression, which
consists of the function name followed immediately by a list of
-"arguments" in parentheses. The arguments are expressions that provide
-the raw materials for the function's calculations. When there is more
+âargumentsâ in parentheses. The arguments are expressions that provide
+the raw materials for the functionâs calculations. When there is more
than one argument, they are separated by commas. If there are no
-arguments, just write '()' after the function name. The following
+arguments, just write â()â after the function name. The following
examples show function calls with and without arguments:
sqrt(x^2 + y^2) one argument
@@ -9655,14 +9655,14 @@ examples show function calls with and without arguments:
CAUTION: Do not put any space between the function name and the
opening parenthesis! A user-defined function name looks just like
- the name of a variable--a space would make the expression look like
+ the name of a variableâa space would make the expression look like
concatenation of a variable with an expression inside parentheses.
With built-in functions, space before the parenthesis is harmless,
but it is best not to get into the habit of using space to avoid
mistakes with user-defined functions.
Each function expects a particular number of arguments. For example,
-the 'sqrt()' function must be called with a single argument, the number
+the âsqrt()â function must be called with a single argument, the number
of which to take the square root:
sqrt(ARGUMENT)
@@ -9675,31 +9675,31 @@ treated as local variables. Such local variables act
like the empty
string if referenced where a string value is required, and like zero if
referenced where a numeric value is required (*note User-defined::).
- As an advanced feature, 'gawk' provides indirect function calls,
+ As an advanced feature, âgawkâ provides indirect function calls,
which is a way to choose the function to call at runtime, instead of
when you write the source code to your program. We defer discussion of
this feature until later; see *note Indirect Calls::.
Like every other expression, the function call has a value, often
-called the "return value", which is computed by the function based on
+called the âreturn valueâ, which is computed by the function based on
the arguments you give it. In this example, the return value of
-'sqrt(ARGUMENT)' is the square root of ARGUMENT. The following program
+âsqrt(ARGUMENT)â is the square root of ARGUMENT. The following program
reads numbers, one number per line, and prints the square root of each
one:
$ awk '{ print "The square root of", $1, "is", sqrt($1) }'
1
- -| The square root of 1 is 1
+ ⣠The square root of 1 is 1
3
- -| The square root of 3 is 1.73205
+ ⣠The square root of 3 is 1.73205
5
- -| The square root of 5 is 2.23607
+ ⣠The square root of 5 is 2.23607
Ctrl-d
A function can also have side effects, such as assigning values to
-certain variables or doing I/O. This program shows how the 'match()'
-function (*note String Functions::) changes the variables 'RSTART' and
-'RLENGTH':
+certain variables or doing I/O. This program shows how the âmatch()â
+function (*note String Functions::) changes the variables âRSTARTâ and
+âRLENGTHâ:
{
if (match($1, $2))
@@ -9712,11 +9712,11 @@ Here is a sample run:
$ awk -f matchit.awk
aaccdd c+
- -| 3 2
+ ⣠3 2
foo bar
- -| no match
+ ⣠no match
abcdefg e
- -| 5 1
+ ⣠5 1
File: gawk.info, Node: Precedence, Next: Locales, Prev: Function Calls,
Up: Expressions
@@ -9724,10 +9724,10 @@ File: gawk.info, Node: Precedence, Next: Locales,
Prev: Function Calls, Up:
6.5 Operator Precedence (How Operators Nest)
============================================
-"Operator precedence" determines how operators are grouped when
-different operators appear close by in one expression. For example, '*'
-has higher precedence than '+'; thus, 'a + b * c' means to multiply 'b'
-and 'c', and then add 'a' to the product (i.e., 'a + (b * c)').
+âOperator precedenceâ determines how operators are grouped when
+different operators appear close by in one expression. For example, â*â
+has higher precedence than â+â; thus, âa + b * câ means to multiply
âbâ
+and âcâ, and then add âaâ to the product (i.e., âa + (b * c)â).
The normal precedence of the operators can be overruled by using
parentheses. Think of the precedence rules as saying where the
@@ -9740,82 +9740,82 @@ help prevent any such mistakes.
When operators of equal precedence are used together, the leftmost
operator groups first, except for the assignment, conditional, and
-exponentiation operators, which group in the opposite order. Thus, 'a -
-b + c' groups as '(a - b) + c' and 'a = b = c' groups as 'a = (b = c)'.
+exponentiation operators, which group in the opposite order. Thus, âa -
+b + câ groups as â(a - b) + câ and âa = b = câ groups as âa = (b =
c)â.
Normally the precedence of prefix unary operators does not matter,
because there is only one way to interpret them: innermost first. Thus,
-'$++i' means '$(++i)' and '++$x' means '++($x)'. However, when another
+â$++iâ means â$(++i)â and â++$xâ means â++($x)â. However,
when another
operator follows the operand, then the precedence of the unary operators
-can matter. '$x^2' means '($x)^2', but '-x^2' means '-(x^2)', because
-'-' has lower precedence than '^', whereas '$' has higher precedence.
+can matter. â$x^2â means â($x)^2â, but â-x^2â means â-(x^2)â,
because
+â-â has lower precedence than â^â, whereas â$â has higher
precedence.
Also, operators cannot be combined in a way that violates the precedence
-rules; for example, '$$0++--' is not a valid expression because the
-first '$' has higher precedence than the '++'; to avoid the problem the
-expression can be rewritten as '$($0++)--'.
+rules; for example, â$$0++--â is not a valid expression because the
+first â$â has higher precedence than the â++â; to avoid the problem the
+expression can be rewritten as â$($0++)--â.
- This list presents 'awk''s operators, in order of highest to lowest
+ This list presents âawkââs operators, in order of highest to lowest
precedence:
-'('...')'
+â(â...â)â
Grouping.
-'$'
+â$â
Field reference.
-'++ --'
+â++ --â
Increment, decrement.
-'^ **'
+â^ **â
Exponentiation. These operators group right to left.
-'+ - !'
- Unary plus, minus, logical "not."
+â+ - !â
+ Unary plus, minus, logical ânot.â
-'* / %'
+â* / %â
Multiplication, division, remainder.
-'+ -'
+â+ -â
Addition, subtraction.
String concatenation
There is no special symbol for concatenation. The operands are
simply written side by side (*note Concatenation::).
-'< <= == != > >= >> | |&'
+â< <= == != > >= >> | |&â
Relational and redirection. The relational operators and the
redirections have the same precedence level. Characters such as
- '>' serve both as relationals and as redirections; the context
+ â>â serve both as relationals and as redirections; the context
distinguishes between the two meanings.
- Note that the I/O redirection operators in 'print' and 'printf'
+ Note that the I/O redirection operators in âprintâ and âprintfâ
statements belong to the statement level, not to expressions. The
redirection does not produce an expression that could be the
operand of another operator. As a result, it does not make sense
to use a redirection operator near another operator of lower
- precedence without parentheses. Such combinations (e.g., 'print
- foo > a ? b : c') result in syntax errors. The correct way to
- write this statement is 'print foo > (a ? b : c)'.
+ precedence without parentheses. Such combinations (e.g., âprint
+ foo > a ? b : câ) result in syntax errors. The correct way to
+ write this statement is âprint foo > (a ? b : c)â.
-'~ !~'
+â~ !~â
Matching, nonmatching.
-'in'
+âinâ
Array membership.
-'&&'
- Logical "and."
+â&&â
+ Logical âand.â
-'||'
- Logical "or."
+â||â
+ Logical âor.â
-'?:'
+â?:â
Conditional. This operator groups right to left.
-'= += -= *= /= %= ^= **='
+â= += -= *= /= %= ^= **=â
Assignment. These operators group right to left.
- NOTE: The '|&', '**', and '**=' operators are not specified by
+ NOTE: The â|&â, â**â, and â**=â operators are not specified by
POSIX. For maximum portability, do not use them.
@@ -9824,34 +9824,34 @@ File: gawk.info, Node: Locales, Next: Expressions
Summary, Prev: Precedence,
6.6 Where You Are Makes a Difference
====================================
-Modern systems support the notion of "locales": a way to tell the system
+Modern systems support the notion of âlocalesâ: a way to tell the system
about the local character set and language. The ISO C standard defines
-a default '"C"' locale, which is an environment that is typical of what
+a default â"C"â locale, which is an environment that is typical of what
many C programmers are used to.
Once upon a time, the locale setting used to affect regexp matching,
but this is no longer true (*note Ranges and Locales::).
- Locales can affect record splitting. For the normal case of 'RS =
-"\n"', the locale is largely irrelevant. For other single-character
-record separators, setting 'LC_ALL=C' in the environment will give you
-much better performance when reading records. Otherwise, 'gawk' has to
+ Locales can affect record splitting. For the normal case of âRS =
+"\n"â, the locale is largely irrelevant. For other single-character
+record separators, setting âLC_ALL=Câ in the environment will give you
+much better performance when reading records. Otherwise, âgawkâ has to
make several function calls, _per input character_, to find the record
terminator.
Locales can affect how dates and times are formatted (*note Time
Functions::). For example, a common way to abbreviate the date
-September 4, 2015, in the United States is "9/4/15." In many countries
-in Europe, however, it is abbreviated "4.9.15." Thus, the '%x'
-specification in a '"US"' locale might produce '9/4/15', while in a
-'"EUROPE"' locale, it might produce '4.9.15'.
+September 4, 2015, in the United States is â9/4/15.â In many countries
+in Europe, however, it is abbreviated â4.9.15.â Thus, the â%xâ
+specification in a â"US"â locale might produce â9/4/15â, while in a
+â"EUROPE"â locale, it might produce â4.9.15â.
According to POSIX, string comparison is also affected by locales
(similar to regular expressions). The details are presented in *note
POSIX String Comparison::.
Finally, the locale affects the value of the decimal point character
-used when 'gawk' parses input data. This is discussed in detail in
+used when âgawkâ parses input data. This is discussed in detail in
*note Conversion::.
@@ -9860,54 +9860,54 @@ File: gawk.info, Node: Expressions Summary, Prev:
Locales, Up: Expressions
6.7 Summary
===========
- * Expressions are the basic elements of computation in programs.
+ ⢠Expressions are the basic elements of computation in programs.
They are built from constants, variables, function calls, and
combinations of the various kinds of values with operators.
- * 'awk' supplies three kinds of constants: numeric, string, and
- regexp. 'gawk' lets you specify numeric constants in octal and
+ ⢠âawkâ supplies three kinds of constants: numeric, string, and
+ regexp. âgawkâ lets you specify numeric constants in octal and
hexadecimal (bases 8 and 16) as well as decimal (base 10). In
- certain contexts, a standalone regexp constant such as '/foo/' has
- the same meaning as '$0 ~ /foo/'.
+ certain contexts, a standalone regexp constant such as â/foo/â has
+ the same meaning as â$0 ~ /foo/â.
- * Variables hold values between uses in computations. A number of
- built-in variables provide information to your 'awk' program, and a
- number of others let you control how 'awk' behaves.
+ ⢠Variables hold values between uses in computations. A number of
+ built-in variables provide information to your âawkâ program, and a
+ number of others let you control how âawkâ behaves.
- * Numbers are automatically converted to strings, and strings to
- numbers, as needed by 'awk'. Numeric values are converted as if
- they were formatted with 'sprintf()' using the format in 'CONVFMT'.
+ ⢠Numbers are automatically converted to strings, and strings to
+ numbers, as needed by âawkâ. Numeric values are converted as if
+ they were formatted with âsprintf()â using the format in
âCONVFMTâ.
Locales can influence the conversions.
- * 'awk' provides the usual arithmetic operators (addition,
+ ⢠âawkâ provides the usual arithmetic operators (addition,
subtraction, multiplication, division, modulus), and unary plus and
minus. It also provides comparison operators, Boolean operators,
an array membership testing operator, and regexp matching
operators. String concatenation is accomplished by placing two
expressions next to each other; there is no explicit operator. The
- three-operand '?:' operator provides an "if-else" test within
+ three-operand â?:â operator provides an âif-elseâ test within
expressions.
- * Assignment operators provide convenient shorthands for common
+ ⢠Assignment operators provide convenient shorthands for common
arithmetic operations.
- * In 'awk', a value is considered to be true if it is nonzero _or_
+ ⢠In âawkâ, a value is considered to be true if it is nonzero _or_
non-null. Otherwise, the value is false.
- * A variable's type is set upon each assignment and may change over
+ ⢠A variableâs type is set upon each assignment and may change over
its lifetime. The type determines how it behaves in comparisons
(string or numeric).
- * Function calls return a value that may be used as part of a larger
+ ⢠Function calls return a value that may be used as part of a larger
expression. Expressions used to pass parameter values are fully
- evaluated before the function is called. 'awk' provides built-in
+ evaluated before the function is called. âawkâ provides built-in
and user-defined functions; this is described in *note Functions::.
- * Operator precedence specifies the order in which operations are
- performed, unless explicitly overridden by parentheses. 'awk''s
+ ⢠Operator precedence specifies the order in which operations are
+ performed, unless explicitly overridden by parentheses. âawkââs
operator precedence is compatible with that of C.
- * Locales can affect the format of data as output by an 'awk'
+ ⢠Locales can affect the format of data as output by an âawkâ
program, and occasionally the format for data read as input.
@@ -9916,20 +9916,20 @@ File: gawk.info, Node: Patterns and Actions, Next:
Arrays, Prev: Expressions,
7 Patterns, Actions, and Variables
**********************************
-As you have already seen, each 'awk' statement consists of a pattern
+As you have already seen, each âawkâ statement consists of a pattern
with an associated action. This major node describes how you build
patterns and actions, what kinds of things you can do within actions,
-and 'awk''s predefined variables.
+and âawkââs predefined variables.
- The pattern-action rules and the statements available for use within
-actions form the core of 'awk' programming. In a sense, everything
+ The patternâaction rules and the statements available for use within
+actions form the core of âawkâ programming. In a sense, everything
covered up to here has been the foundation that programs are built on
-top of. Now it's time to start building something useful.
+top of. Now itâs time to start building something useful.
* Menu:
* Pattern Overview:: What goes into a pattern.
-* Using Shell Variables:: How to use shell variables with 'awk'.
+* Using Shell Variables:: How to use shell variables with âawkâ.
* Action Overview:: What goes into an action.
* Statements:: Describes the various control statements in
detail.
@@ -9951,34 +9951,34 @@ File: gawk.info, Node: Pattern Overview, Next: Using
Shell Variables, Up: Pat
* BEGINFILE/ENDFILE:: Two special patterns for advanced control.
* Empty:: The empty pattern, which matches every record.
-Patterns in 'awk' control the execution of rules--a rule is executed
-when its pattern matches the current input record. The following is a
-summary of the types of 'awk' patterns:
+Patterns in âawkâ control the execution of rulesâa rule is executed when
+its pattern matches the current input record. The following is a
+summary of the types of âawkâ patterns:
-'/REGULAR EXPRESSION/'
+â/REGULAR EXPRESSION/â
A regular expression. It matches when the text of the input record
fits the regular expression. (*Note Regexp::.)
-'EXPRESSION'
+âEXPRESSIONâ
A single expression. It matches when its value is nonzero (if a
number) or non-null (if a string). (*Note Expression Patterns::.)
-'BEGPAT, ENDPAT'
- A pair of patterns separated by a comma, specifying a "range" of
+âBEGPAT, ENDPATâ
+ A pair of patterns separated by a comma, specifying a ârangeâ of
records. The range includes both the initial record that matches
BEGPAT and the final record that matches ENDPAT. (*Note Ranges::.)
-'BEGIN'
-'END'
+âBEGINâ
+âENDâ
Special patterns for you to supply startup or cleanup actions for
- your 'awk' program. (*Note BEGIN/END::.)
+ your âawkâ program. (*Note BEGIN/END::.)
-'BEGINFILE'
-'ENDFILE'
+âBEGINFILEâ
+âENDFILEâ
Special patterns for you to supply startup or cleanup actions to be
done on a per-file basis. (*Note BEGINFILE/ENDFILE::.)
-'EMPTY'
+âEMPTYâ
The empty pattern matches every input record. (*Note Empty::.)
@@ -9989,7 +9989,7 @@ File: gawk.info, Node: Regexp Patterns, Next:
Expression Patterns, Up: Patter
Regular expressions are one of the first kinds of patterns presented in
this book. This kind of pattern is simply a regexp constant in the
-pattern part of a rule. Its meaning is '$0 ~ /PATTERN/'. The pattern
+pattern part of a rule. Its meaning is â$0 ~ /PATTERN/â. The pattern
matches when the input record matches the regexp. For example:
/foo|bar|baz/ { buzzwords++ }
@@ -10001,75 +10001,75 @@ File: gawk.info, Node: Expression Patterns, Next:
Ranges, Prev: Regexp Patter
7.1.2 Expressions as Patterns
-----------------------------
-Any 'awk' expression is valid as an 'awk' pattern. The pattern matches
-if the expression's value is nonzero (if a number) or non-null (if a
+Any âawkâ expression is valid as an âawkâ pattern. The pattern matches
+if the expressionâs value is nonzero (if a number) or non-null (if a
string). The expression is reevaluated each time the rule is tested
-against a new input record. If the expression uses fields such as '$1',
-the value depends directly on the new input record's text; otherwise, it
-depends on only what has happened so far in the execution of the 'awk'
+against a new input record. If the expression uses fields such as â$1â,
+the value depends directly on the new input recordâs text; otherwise, it
+depends on only what has happened so far in the execution of the âawkâ
program.
Comparison expressions, using the comparison operators described in
*note Typing and Comparison::, are a very common kind of pattern.
Regexp matching and nonmatching are also very common expressions. The
-left operand of the '~' and '!~' operators is a string. The right
+left operand of the â~â and â!~â operators is a string. The right
operand is either a constant regular expression enclosed in slashes
-('/REGEXP/'), or any expression whose string value is used as a dynamic
+(â/REGEXP/â), or any expression whose string value is used as a dynamic
regular expression (*note Computed Regexps::). The following example
prints the second field of each input record whose first field is
-precisely 'li':
+precisely âliâ:
$ awk '$1 == "li" { print $2 }' mail-list
(There is no output, because there is no person with the exact name
-'li'.) Contrast this with the following regular expression match, which
-accepts any record with a first field that contains 'li':
+âliâ.) Contrast this with the following regular expression match, which
+accepts any record with a first field that contains âliâ:
$ awk '$1 ~ /li/ { print $2 }' mail-list
- -| 555-5553
- -| 555-6699
+ ⣠555-5553
+ ⣠555-6699
A regexp constant as a pattern is also a special case of an
-expression pattern. The expression '/li/' has the value one if 'li'
-appears in the current input record. Thus, as a pattern, '/li/' matches
-any record containing 'li'.
+expression pattern. The expression â/li/â has the value one if âliâ
+appears in the current input record. Thus, as a pattern, â/li/â matches
+any record containing âliâ.
Boolean expressions are also commonly used as patterns. Whether the
pattern matches an input record depends on whether its subexpressions
match. For example, the following command prints all the records in
-'mail-list' that contain both 'edu' and 'li':
+âmail-listâ that contain both âeduâ and âliâ:
$ awk '/edu/ && /li/' mail-list
- -| Samuel 555-3430 samuel.lanceolis@shu.edu A
+ ⣠Samuel 555-3430 samuel.lanceolis@shu.edu A
- The following command prints all records in 'mail-list' that contain
-_either_ 'edu' or 'li' (or both, of course):
+ The following command prints all records in âmail-listâ that contain
+_either_ âeduâ or âliâ (or both, of course):
$ awk '/edu/ || /li/' mail-list
- -| Amelia 555-5553 amelia.zodiacusque@gmail.com F
- -| Broderick 555-0542 broderick.aliquotiens@yahoo.com R
- -| Fabius 555-1234 fabius.undevicesimus@ucb.edu F
- -| Julie 555-6699 julie.perscrutabor@skeeve.com F
- -| Samuel 555-3430 samuel.lanceolis@shu.edu A
- -| Jean-Paul 555-2127 jeanpaul.campanorum@nyu.edu R
+ ⣠Amelia 555-5553 amelia.zodiacusque@gmail.com F
+ ⣠Broderick 555-0542 broderick.aliquotiens@yahoo.com R
+ ⣠Fabius 555-1234 fabius.undevicesimus@ucb.edu F
+ ⣠Julie 555-6699 julie.perscrutabor@skeeve.com F
+ ⣠Samuel 555-3430 samuel.lanceolis@shu.edu A
+ ⣠Jean-Paul 555-2127 jeanpaul.campanorum@nyu.edu R
- The following command prints all records in 'mail-list' that do _not_
-contain the string 'li':
+ The following command prints all records in âmail-listâ that do _not_
+contain the string âliâ:
$ awk '! /li/' mail-list
- -| Anthony 555-3412 anthony.asserturo@hotmail.com A
- -| Becky 555-7685 becky.algebrarum@gmail.com A
- -| Bill 555-1675 bill.drowning@hotmail.com A
- -| Camilla 555-2912 camilla.infusarum@skynet.be R
- -| Fabius 555-1234 fabius.undevicesimus@ucb.edu F
- -| Martin 555-6480 martin.codicibus@hotmail.com A
- -| Jean-Paul 555-2127 jeanpaul.campanorum@nyu.edu R
+ ⣠Anthony 555-3412 anthony.asserturo@hotmail.com A
+ ⣠Becky 555-7685 becky.algebrarum@gmail.com A
+ ⣠Bill 555-1675 bill.drowning@hotmail.com A
+ ⣠Camilla 555-2912 camilla.infusarum@skynet.be R
+ ⣠Fabius 555-1234 fabius.undevicesimus@ucb.edu F
+ ⣠Martin 555-6480 martin.codicibus@hotmail.com A
+ ⣠Jean-Paul 555-2127 jeanpaul.campanorum@nyu.edu R
The subexpressions of a Boolean operator in a pattern can be constant
-regular expressions, comparisons, or any other 'awk' expressions. Range
+regular expressions, comparisons, or any other âawkâ expressions. Range
patterns are not expressions, so they cannot appear inside Boolean
-patterns. Likewise, the special patterns 'BEGIN', 'END', 'BEGINFILE',
-and 'ENDFILE', which never match any input record, are not expressions
+patterns. Likewise, the special patterns âBEGINâ, âENDâ,
âBEGINFILEâ,
+and âENDFILEâ, which never match any input record, are not expressions
and cannot appear inside Boolean patterns.
The precedence of the different operators that can appear in patterns
@@ -10081,63 +10081,63 @@ File: gawk.info, Node: Ranges, Next: BEGIN/END,
Prev: Expression Patterns, U
7.1.3 Specifying Record Ranges with Patterns
--------------------------------------------
-A "range pattern" is made of two patterns separated by a comma, in the
-form 'BEGPAT, ENDPAT'. It is used to match ranges of consecutive input
+A ârange patternâ is made of two patterns separated by a comma, in the
+form âBEGPAT, ENDPATâ. It is used to match ranges of consecutive input
records. The first pattern, BEGPAT, controls where the range begins,
while ENDPAT controls where the pattern ends. For example, the
following:
awk '$1 == "on", $1 == "off"' myfile
-prints every record in 'myfile' between 'on'/'off' pairs, inclusive.
+prints every record in âmyfileâ between âonâ/âoffâ pairs,
inclusive.
A range pattern starts out by matching BEGPAT against every input
-record. When a record matches BEGPAT, the range pattern is "turned on",
+record. When a record matches BEGPAT, the range pattern is âturned onâ,
and the range pattern matches this record as well. As long as the range
pattern stays turned on, it automatically matches every input record
read. The range pattern also matches ENDPAT against every input record;
-when this succeeds, the range pattern is "turned off" again for the
+when this succeeds, the range pattern is âturned offâ again for the
following record. Then the range pattern goes back to checking BEGPAT
against each record.
The record that turns on the range pattern and the one that turns it
-off both match the range pattern. If you don't want to operate on these
-records, you can write 'if' statements in the rule's action to
+off both match the range pattern. If you donât want to operate on these
+records, you can write âifâ statements in the ruleâs action to
distinguish them from the records you are interested in.
It is possible for a pattern to be turned on and off by the same
record. If the record satisfies both conditions, then the action is
executed for just that record. For example, suppose there is text
-between two identical markers (e.g., the '%' symbol), each on its own
+between two identical markers (e.g., the â%â symbol), each on its own
line, that should be ignored. A first attempt would be to combine a
-range pattern that describes the delimited text with the 'next'
+range pattern that describes the delimited text with the ânextâ
statement (not discussed yet, *note Next Statement::). This causes
-'awk' to skip any further processing of the current record and start
+âawkâ to skip any further processing of the current record and start
over again with the next input record. Such a program looks like this:
/^%$/,/^%$/ { next }
{ print }
This program fails because the range pattern is both turned on and
-turned off by the first line, which just has a '%' on it. To accomplish
+turned off by the first line, which just has a â%â on it. To accomplish
this task, write the program in the following manner, using a flag:
/^%$/ { skip = ! skip; next }
skip == 1 { next } # skip lines with `skip' set
- In a range pattern, the comma (',') has the lowest precedence of all
+ In a range pattern, the comma (â,â) has the lowest precedence of all
the operators (i.e., it is evaluated last). Thus, the following program
attempts to combine a range pattern with another, simpler test:
echo Yes | awk '/1/,/2/ || /Yes/'
- The intent of this program is '(/1/,/2/) || /Yes/'. However, 'awk'
-interprets this as '/1/, (/2/ || /Yes/)'. This cannot be changed or
+ The intent of this program is â(/1/,/2/) || /Yes/â. However, âawkâ
+interprets this as â/1/, (/2/ || /Yes/)â. This cannot be changed or
worked around; range patterns do not combine with other patterns:
$ echo Yes | gawk '(/1/,/2/) || /Yes/'
- error-> gawk: cmd. line:1: (/1/,/2/) || /Yes/
- error-> gawk: cmd. line:1: ^ syntax error
+ errorâ gawk: cmd. line:1: (/1/,/2/) || /Yes/
+ errorâ gawk: cmd. line:1: ^ syntax error
As a minor point of interest, although it is poor style, POSIX allows
you to put a newline after the comma in a range pattern. (d.c.)
@@ -10145,15 +10145,15 @@ you to put a newline after the comma in a range
pattern. (d.c.)
File: gawk.info, Node: BEGIN/END, Next: BEGINFILE/ENDFILE, Prev: Ranges,
Up: Pattern Overview
-7.1.4 The 'BEGIN' and 'END' Special Patterns
+7.1.4 The âBEGINâ and âENDâ Special Patterns
--------------------------------------------
All the patterns described so far are for matching input records. The
-'BEGIN' and 'END' special patterns are different. They supply startup
-and cleanup actions for 'awk' programs. 'BEGIN' and 'END' rules must
+âBEGINâ and âENDâ special patterns are different. They supply startup
+and cleanup actions for âawkâ programs. âBEGINâ and âENDâ rules
must
have actions; there is no default action for these rules because there
-is no current record when they run. 'BEGIN' and 'END' rules are often
-referred to as "'BEGIN' and 'END' blocks" by longtime 'awk' programmers.
+is no current record when they run. âBEGINâ and âENDâ rules are often
+referred to as ââBEGINâ and âENDâ blocksâ by longtime âawkâ
programmers.
* Menu:
@@ -10166,169 +10166,169 @@ File: gawk.info, Node: Using BEGIN/END, Next: I/O
And BEGIN/END, Up: BEGIN/EN
7.1.4.1 Startup and Cleanup Actions
...................................
-A 'BEGIN' rule is executed once only, before the first input record is
-read. Likewise, an 'END' rule is executed once only, after all the
+A âBEGINâ rule is executed once only, before the first input record is
+read. Likewise, an âENDâ rule is executed once only, after all the
input is read. For example:
$ awk '
> BEGIN { print "Analysis of \"li\"" }
> /li/ { ++n }
> END { print "\"li\" appears in", n, "records." }' mail-list
- -| Analysis of "li"
- -| "li" appears in 4 records.
+ ⣠Analysis of "li"
+ ⣠"li" appears in 4 records.
This program finds the number of records in the input file
-'mail-list' that contain the string 'li'. The 'BEGIN' rule prints a
-title for the report. There is no need to use the 'BEGIN' rule to
-initialize the counter 'n' to zero, as 'awk' does this automatically
-(*note Variables::). The second rule increments the variable 'n' every
-time a record containing the pattern 'li' is read. The 'END' rule
-prints the value of 'n' at the end of the run.
-
- The special patterns 'BEGIN' and 'END' cannot be used in ranges or
+âmail-listâ that contain the string âliâ. The âBEGINâ rule prints
a
+title for the report. There is no need to use the âBEGINâ rule to
+initialize the counter ânâ to zero, as âawkâ does this automatically
+(*note Variables::). The second rule increments the variable ânâ every
+time a record containing the pattern âliâ is read. The âENDâ rule
+prints the value of ânâ at the end of the run.
+
+ The special patterns âBEGINâ and âENDâ cannot be used in ranges or
with Boolean operators (indeed, they cannot be used with any operators).
-An 'awk' program may have multiple 'BEGIN' and/or 'END' rules. They are
-executed in the order in which they appear: all the 'BEGIN' rules at
-startup and all the 'END' rules at termination.
-
- 'BEGIN' and 'END' rules may be intermixed with other rules. This
-feature was added in the 1987 version of 'awk' and is included in the
-POSIX standard. The original (1978) version of 'awk' required the
-'BEGIN' rule to be placed at the beginning of the program, the 'END'
+An âawkâ program may have multiple âBEGINâ and/or âENDâ rules.
They are
+executed in the order in which they appear: all the âBEGINâ rules at
+startup and all the âENDâ rules at termination.
+
+ âBEGINâ and âENDâ rules may be intermixed with other rules. This
+feature was added in the 1987 version of âawkâ and is included in the
+POSIX standard. The original (1978) version of âawkâ required the
+âBEGINâ rule to be placed at the beginning of the program, the âENDâ
rule to be placed at the end, and only allowed one of each. This is no
longer required, but it is a good idea to follow this template in terms
of program organization and readability.
- Multiple 'BEGIN' and 'END' rules are useful for writing library
-functions, because each library file can have its own 'BEGIN' and/or
-'END' rule to do its own initialization and/or cleanup. The order in
+ Multiple âBEGINâ and âENDâ rules are useful for writing library
+functions, because each library file can have its own âBEGINâ and/or
+âENDâ rule to do its own initialization and/or cleanup. The order in
which library functions are named on the command line controls the order
-in which their 'BEGIN' and 'END' rules are executed. Therefore, you
+in which their âBEGINâ and âENDâ rules are executed. Therefore, you
have to be careful when writing such rules in library files so that the
-order in which they are executed doesn't matter. *Note Options:: for
+order in which they are executed doesnât matter. *Note Options:: for
more information on using library functions. *Note Library Functions::,
for a number of useful library functions.
- If an 'awk' program has only 'BEGIN' rules and no other rules, then
-the program exits after the 'BEGIN' rules are run.(1) However, if an
-'END' rule exists, then the input is read, even if there are no other
-rules in the program. This is necessary in case the 'END' rule checks
-the 'FNR' and 'NR' variables, or the fields.
+ If an âawkâ program has only âBEGINâ rules and no other rules, then
+the program exits after the âBEGINâ rules are run.(1) However, if an
+âENDâ rule exists, then the input is read, even if there are no other
+rules in the program. This is necessary in case the âENDâ rule checks
+the âFNRâ and âNRâ variables, or the fields.
---------- Footnotes ----------
- (1) The original version of 'awk' kept reading and ignoring input
+ (1) The original version of âawkâ kept reading and ignoring input
until the end of the file was seen.
File: gawk.info, Node: I/O And BEGIN/END, Prev: Using BEGIN/END, Up:
BEGIN/END
-7.1.4.2 Input/Output from 'BEGIN' and 'END' Rules
+7.1.4.2 Input/Output from âBEGINâ and âENDâ Rules
.................................................
There are several (sometimes subtle) points to be aware of when doing
-I/O from a 'BEGIN' or 'END' rule. The first has to do with the value of
-'$0' in a 'BEGIN' rule. Because 'BEGIN' rules are executed before any
+I/O from a âBEGINâ or âENDâ rule. The first has to do with the value
of
+â$0â in a âBEGINâ rule. Because âBEGINâ rules are executed before
any
input is read, there simply is no input record, and therefore no fields,
-when executing 'BEGIN' rules. References to '$0' and the fields yield a
-null string or zero, depending upon the context. One way to give '$0' a
-real value is to execute a 'getline' command without a variable (*note
-Getline::). Another way is simply to assign a value to '$0'.
+when executing âBEGINâ rules. References to â$0â and the fields yield
a
+null string or zero, depending upon the context. One way to give â$0â a
+real value is to execute a âgetlineâ command without a variable (*note
+Getline::). Another way is simply to assign a value to â$0â.
The second point is similar to the first, but from the other
-direction. Traditionally, due largely to implementation issues, '$0'
-and 'NF' were _undefined_ inside an 'END' rule. The POSIX standard
-specifies that 'NF' is available in an 'END' rule. It contains the
+direction. Traditionally, due largely to implementation issues, â$0â
+and âNFâ were _undefined_ inside an âENDâ rule. The POSIX standard
+specifies that âNFâ is available in an âENDâ rule. It contains the
number of fields from the last input record. Most probably due to an
-oversight, the standard does not say that '$0' is also preserved,
+oversight, the standard does not say that â$0â is also preserved,
although logically one would think that it should be. In fact, all of
-BWK 'awk', 'mawk', and 'gawk' preserve the value of '$0' for use in
-'END' rules. Be aware, however, that some other implementations and
-many older versions of Unix 'awk' do not.
-
- The third point follows from the first two. The meaning of 'print'
-inside a 'BEGIN' or 'END' rule is the same as always: 'print $0'. If
-'$0' is the null string, then this prints an empty record. Many
-longtime 'awk' programmers use an unadorned 'print' in 'BEGIN' and 'END'
-rules to mean 'print ""', relying on '$0' being null. Although one
-might generally get away with this in 'BEGIN' rules, it is a very bad
-idea in 'END' rules, at least in 'gawk'. It is also poor style, because
+BWK âawkâ, âmawkâ, and âgawkâ preserve the value of â$0â for
use in
+âENDâ rules. Be aware, however, that some other implementations and
+many older versions of Unix âawkâ do not.
+
+ The third point follows from the first two. The meaning of âprintâ
+inside a âBEGINâ or âENDâ rule is the same as always: âprint $0â.
If
+â$0â is the null string, then this prints an empty record. Many
+longtime âawkâ programmers use an unadorned âprintâ in âBEGINâ and
âENDâ
+rules to mean âprint ""â, relying on â$0â being null. Although one
+might generally get away with this in âBEGINâ rules, it is a very bad
+idea in âENDâ rules, at least in âgawkâ. It is also poor style,
because
if an empty line is needed in the output, the program should print one
explicitly.
- Finally, the 'next' and 'nextfile' statements are not allowed in a
-'BEGIN' rule, because the implicit
+ Finally, the ânextâ and ânextfileâ statements are not allowed in a
+âBEGINâ rule, because the implicit
read-a-record-and-match-against-the-rules loop has not started yet.
-Similarly, those statements are not valid in an 'END' rule, because all
+Similarly, those statements are not valid in an âENDâ rule, because all
the input has been read. (*Note Next Statement:: and *note Nextfile
Statement::.)
File: gawk.info, Node: BEGINFILE/ENDFILE, Next: Empty, Prev: BEGIN/END,
Up: Pattern Overview
-7.1.5 The 'BEGINFILE' and 'ENDFILE' Special Patterns
+7.1.5 The âBEGINFILEâ and âENDFILEâ Special Patterns
----------------------------------------------------
-This minor node describes a 'gawk'-specific feature.
+This minor node describes a âgawkâ-specific feature.
- Two special kinds of rule, 'BEGINFILE' and 'ENDFILE', give you
-"hooks" into 'gawk''s command-line file processing loop. As with the
-'BEGIN' and 'END' rules (*note BEGIN/END::), 'BEGINFILE' rules in a
-program execute in the order they are read by 'gawk'. Similarly, all
-'ENDFILE' rules also execute in the order they are read.
+ Two special kinds of rule, âBEGINFILEâ and âENDFILEâ, give you
+âhooksâ into âgawkââs command-line file processing loop. As with the
+âBEGINâ and âENDâ rules (*note BEGIN/END::), âBEGINFILEâ rules in a
+program execute in the order they are read by âgawkâ. Similarly, all
+âENDFILEâ rules also execute in the order they are read.
- The bodies of the 'BEGINFILE' rules execute just before 'gawk' reads
-the first record from a file. 'FILENAME' is set to the name of the
-current file, and 'FNR' is set to zero.
+ The bodies of the âBEGINFILEâ rules execute just before âgawkâ reads
+the first record from a file. âFILENAMEâ is set to the name of the
+current file, and âFNRâ is set to zero.
- Prior to version 5.1.1 of 'gawk', as an accident of the
-implementation, '$0' and the fields retained any previous values they
-had in 'BEGINFILE' rules. Starting with version 5.1.1, '$0' and the
+ Prior to version 5.1.1 of âgawkâ, as an accident of the
+implementation, â$0â and the fields retained any previous values they
+had in âBEGINFILEâ rules. Starting with version 5.1.1, â$0â and the
fields are cleared, since no record has been read yet from the file that
is about to be processed.
- The 'BEGINFILE' rule provides you the opportunity to accomplish two
+ The âBEGINFILEâ rule provides you the opportunity to accomplish two
tasks that would otherwise be difficult or impossible to perform:
- * You can test if the file is readable. Normally, it is a fatal
+ ⢠You can test if the file is readable. Normally, it is a fatal
error if a file named on the command line cannot be opened for
reading. However, you can bypass the fatal error and move on to
the next file on the command line.
- You do this by checking if the 'ERRNO' variable is not the empty
- string; if so, then 'gawk' was not able to open the file. In this
- case, your program can execute the 'nextfile' statement (*note
- Nextfile Statement::). This causes 'gawk' to skip the file
- entirely. Otherwise, 'gawk' exits with the usual fatal error.
+ You do this by checking if the âERRNOâ variable is not the empty
+ string; if so, then âgawkâ was not able to open the file. In this
+ case, your program can execute the ânextfileâ statement (*note
+ Nextfile Statement::). This causes âgawkâ to skip the file
+ entirely. Otherwise, âgawkâ exits with the usual fatal error.
- * If you have written extensions that modify the record handling (by
- inserting an "input parser"; *note Input Parsers::), you can invoke
- them at this point, before 'gawk' has started processing the file.
+ ⢠If you have written extensions that modify the record handling (by
+ inserting an âinput parserâ; *note Input Parsers::), you can invoke
+ them at this point, before âgawkâ has started processing the file.
(This is a _very_ advanced feature, currently used only by the
- 'gawkextlib' project
+ âgawkextlibâ project
(https://sourceforge.net/projects/gawkextlib).)
- The 'ENDFILE' rule is called when 'gawk' has finished processing the
+ The âENDFILEâ rule is called when âgawkâ has finished processing the
last record in an input file. For the last input file, it will be
-called before any 'END' rules. The 'ENDFILE' rule is executed even for
+called before any âENDâ rules. The âENDFILEâ rule is executed even for
empty input files.
Normally, when an error occurs when reading input in the normal
-input-processing loop, the error is fatal. However, if a 'BEGINFILE'
-rule is present, the error becomes non-fatal, and instead 'ERRNO' is
+input-processing loop, the error is fatal. However, if a âBEGINFILEâ
+rule is present, the error becomes non-fatal, and instead âERRNOâ is
set. This makes it possible to catch and process I/O errors at the
-level of the 'awk' program.
+level of the âawkâ program.
- The 'next' statement (*note Next Statement::) is not allowed inside
-either a 'BEGINFILE' or an 'ENDFILE' rule. The 'nextfile' statement is
-allowed only inside a 'BEGINFILE' rule, not inside an 'ENDFILE' rule.
+ The ânextâ statement (*note Next Statement::) is not allowed inside
+either a âBEGINFILEâ or an âENDFILEâ rule. The ânextfileâ
statement is
+allowed only inside a âBEGINFILEâ rule, not inside an âENDFILEâ rule.
- The 'getline' statement (*note Getline::) is restricted inside both
-'BEGINFILE' and 'ENDFILE': only redirected forms of 'getline' are
+ The âgetlineâ statement (*note Getline::) is restricted inside both
+âBEGINFILEâ and âENDFILEâ: only redirected forms of âgetlineâ are
allowed.
- 'BEGINFILE' and 'ENDFILE' are 'gawk' extensions. In most other 'awk'
-implementations, or if 'gawk' is in compatibility mode (*note
+ âBEGINFILEâ and âENDFILEâ are âgawkâ extensions. In most other
âawkâ
+implementations, or if âgawkâ is in compatibility mode (*note
Options::), they are not special.
@@ -10350,13 +10350,13 @@ File: gawk.info, Node: Using Shell Variables, Next:
Action Overview, Prev: Pa
7.2 Using Shell Variables in Programs
=====================================
-'awk' programs are often used as components in larger programs written
+âawkâ programs are often used as components in larger programs written
in shell. For example, it is very common to use a shell variable to
-hold a pattern that the 'awk' program searches for. There are two ways
-to get the value of the shell variable into the body of the 'awk'
+hold a pattern that the âawkâ program searches for. There are two ways
+to get the value of the shell variable into the body of the âawkâ
program.
- A common method is to use shell quoting to substitute the variable's
+ A common method is to use shell quoting to substitute the variableâs
value into the program inside the script. For example, consider the
following program:
@@ -10365,18 +10365,18 @@ following program:
awk "/$pattern/ "'{ nmatches++ }
END { print nmatches, "found" }' /path/to/data
-The 'awk' program consists of two pieces of quoted text that are
+The âawkâ program consists of two pieces of quoted text that are
concatenated together to form the program. The first part is
-double-quoted, which allows substitution of the 'pattern' shell variable
+double-quoted, which allows substitution of the âpatternâ shell variable
inside the quotes. The second part is single-quoted.
Variable substitution via quoting works, but can potentially be
-messy. It requires a good understanding of the shell's quoting rules
-(*note Quoting::), and it's often difficult to correctly match up the
+messy. It requires a good understanding of the shellâs quoting rules
+(*note Quoting::), and itâs often difficult to correctly match up the
quotes when reading the program.
- A better method is to use 'awk''s variable assignment feature (*note
-Assignment Options::) to assign the shell variable's value to an 'awk'
+ A better method is to use âawkââs variable assignment feature (*note
+Assignment Options::) to assign the shell variableâs value to an âawkâ
variable. Then use dynamic regexps to match the pattern (*note Computed
Regexps::). The following shows how to redo the previous example using
this technique:
@@ -10386,14 +10386,14 @@ this technique:
awk -v pat="$pattern" '$0 ~ pat { nmatches++ }
END { print nmatches, "found" }' /path/to/data
-Now, the 'awk' program is just one single-quoted string. The assignment
-'-v pat="$pattern"' still requires double quotes, in case there is
-whitespace in the value of '$pattern'. The 'awk' variable 'pat' could
-be named 'pattern' too, but that would be more confusing. Using a
+Now, the âawkâ program is just one single-quoted string. The assignment
+â-v pat="$pattern"â still requires double quotes, in case there is
+whitespace in the value of â$patternâ. The âawkâ variable âpatâ
could
+be named âpatternâ too, but that would be more confusing. Using a
variable also provides more flexibility, as the variable can be used
-anywhere inside the program--for printing, as an array subscript, or for
-any other use--without requiring the quoting tricks at every point in
-the program.
+anywhere inside the programâfor printing, as an array subscript, or for
+any other useâwithout requiring the quoting tricks at every point in the
+program.
File: gawk.info, Node: Action Overview, Next: Statements, Prev: Using Shell
Variables, Up: Patterns and Actions
@@ -10401,31 +10401,31 @@ File: gawk.info, Node: Action Overview, Next:
Statements, Prev: Using Shell V
7.3 Actions
===========
-An 'awk' program or script consists of a series of rules and function
+An âawkâ program or script consists of a series of rules and function
definitions interspersed. (Functions are described later. *Note
User-defined::.) A rule contains a pattern and an action, either of
-which (but not both) may be omitted. The purpose of the "action" is to
-tell 'awk' what to do once a match for the pattern is found. Thus, in
-outline, an 'awk' program generally looks like this:
+which (but not both) may be omitted. The purpose of the âactionâ is to
+tell âawkâ what to do once a match for the pattern is found. Thus, in
+outline, an âawkâ program generally looks like this:
- [PATTERN] '{ ACTION }'
- PATTERN ['{ ACTION }']
+ [PATTERN] â{ ACTION }â
+ PATTERN [â{ ACTION }â]
...
- 'function NAME(ARGS) { ... }'
+ âfunction NAME(ARGS) { ... }â
...
- An action consists of one or more 'awk' "statements", enclosed in
-braces ('{...}'). Each statement specifies one thing to do. The
+ An action consists of one or more âawkâ âstatementsâ, enclosed in
+braces (â{...}â). Each statement specifies one thing to do. The
statements are separated by newlines or semicolons. The braces around
an action must be used even if the action contains only one statement,
or if it contains no statements at all. However, if you omit the action
entirely, omit the braces as well. An omitted action is equivalent to
-'{ print $0 }':
+â{ print $0 }â:
- /foo/ { } match 'foo', do nothing -- empty action
- /foo/ match 'foo', print the record -- omitted action
+ /foo/ { } match foo, do nothing --- empty action
+ /foo/ match foo, print the record --- omitted action
- The following types of statements are supported in 'awk':
+ The following types of statements are supported in âawkâ:
Expressions
Call functions or assign values to variables (*note Expressions::).
@@ -10434,22 +10434,22 @@ Expressions
(*note Assignment Ops::).
Control statements
- Specify the control flow of 'awk' programs. The 'awk' language
- gives you C-like constructs ('if', 'for', 'while', and 'do') as
+ Specify the control flow of âawkâ programs. The âawkâ language
+ gives you C-like constructs (âifâ, âforâ, âwhileâ, and
âdoâ) as
well as a few special ones (*note Statements::).
Compound statements
Enclose one or more statements in braces. A compound statement is
used in order to put several statements together in the body of an
- 'if', 'while', 'do', or 'for' statement.
+ âifâ, âwhileâ, âdoâ, or âforâ statement.
Input statements
- Use the 'getline' command (*note Getline::). Also supplied in
- 'awk' are the 'next' statement (*note Next Statement::) and the
- 'nextfile' statement (*note Nextfile Statement::).
+ Use the âgetlineâ command (*note Getline::). Also supplied in
+ âawkâ are the ânextâ statement (*note Next Statement::) and the
+ ânextfileâ statement (*note Nextfile Statement::).
Output statements
- Such as 'print' and 'printf'. *Note Printing::.
+ Such as âprintâ and âprintfâ. *Note Printing::.
Deletion statements
For deleting array elements. *Note Delete::.
@@ -10460,21 +10460,21 @@ File: gawk.info, Node: Statements, Next: Built-in
Variables, Prev: Action Ove
7.4 Control Statements in Actions
=================================
-"Control statements", such as 'if', 'while', and so on, control the flow
-of execution in 'awk' programs. Most of 'awk''s control statements are
+âControl statementsâ, such as âifâ, âwhileâ, and so on, control
the flow
+of execution in âawkâ programs. Most of âawkââs control statements
are
patterned after similar statements in C.
- All the control statements start with special keywords, such as 'if'
-and 'while', to distinguish them from simple expressions. Many control
-statements contain other statements. For example, the 'if' statement
+ All the control statements start with special keywords, such as âifâ
+and âwhileâ, to distinguish them from simple expressions. Many control
+statements contain other statements. For example, the âifâ statement
contains another statement that may or may not be executed. The
-contained statement is called the "body". To include more than one
-statement in the body, group them into a single "compound statement"
+contained statement is called the âbodyâ. To include more than one
+statement in the body, group them into a single âcompound statementâ
with braces, separating them with newlines or semicolons.
* Menu:
-* If Statement:: Conditionally execute some 'awk'
+* If Statement:: Conditionally execute some âawkâ
statements.
* While Statement:: Loop until some condition is satisfied.
* Do Statement:: Do specified action while looping until some
@@ -10488,22 +10488,22 @@ with braces, separating them with newlines or
semicolons.
loop.
* Next Statement:: Stop processing the current input record.
* Nextfile Statement:: Stop processing the current file.
-* Exit Statement:: Stop execution of 'awk'.
+* Exit Statement:: Stop execution of âawkâ.
File: gawk.info, Node: If Statement, Next: While Statement, Up: Statements
-7.4.1 The 'if'-'else' Statement
+7.4.1 The âifâ-âelseâ Statement
-------------------------------
-The 'if'-'else' statement is 'awk''s decision-making statement. It
+The âifâ-âelseâ statement is âawkââs decision-making statement.
It
looks like this:
- 'if (CONDITION) THEN-BODY' ['else ELSE-BODY']
+ âif (CONDITION) THEN-BODYâ [âelse ELSE-BODYâ]
The CONDITION is an expression that controls what the rest of the
statement does. If the CONDITION is true, THEN-BODY is executed;
-otherwise, ELSE-BODY is executed. The 'else' part of the statement is
+otherwise, ELSE-BODY is executed. The âelseâ part of the statement is
optional. The condition is considered false if its value is zero or the
null string; otherwise, the condition is true. Refer to the following:
@@ -10512,45 +10512,45 @@ null string; otherwise, the condition is true. Refer
to the following:
else
print "x is odd"
- In this example, if the expression 'x % 2 == 0' is true (i.e., if the
-value of 'x' is evenly divisible by two), then the first 'print'
-statement is executed; otherwise, the second 'print' statement is
-executed. If the 'else' keyword appears on the same line as THEN-BODY
+ In this example, if the expression âx % 2 == 0â is true (i.e., if the
+value of âxâ is evenly divisible by two), then the first âprintâ
+statement is executed; otherwise, the second âprintâ statement is
+executed. If the âelseâ keyword appears on the same line as THEN-BODY
and THEN-BODY is not a compound statement (i.e., not surrounded by
-braces), then a semicolon must separate THEN-BODY from the 'else'. To
+braces), then a semicolon must separate THEN-BODY from the âelseâ. To
illustrate this, the previous example can be rewritten as:
if (x % 2 == 0) print "x is even"; else
print "x is odd"
-If the ';' is left out, 'awk' can't interpret the statement and it
-produces a syntax error. Don't actually write programs this way,
-because a human reader might fail to see the 'else' if it is not the
+If the â;â is left out, âawkâ canât interpret the statement and it
+produces a syntax error. Donât actually write programs this way,
+because a human reader might fail to see the âelseâ if it is not the
first thing on its line.
File: gawk.info, Node: While Statement, Next: Do Statement, Prev: If
Statement, Up: Statements
-7.4.2 The 'while' Statement
+7.4.2 The âwhileâ Statement
---------------------------
-In programming, a "loop" is a part of a program that can be executed two
-or more times in succession. The 'while' statement is the simplest
-looping statement in 'awk'. It repeatedly executes a statement as long
+In programming, a âloopâ is a part of a program that can be executed two
+or more times in succession. The âwhileâ statement is the simplest
+looping statement in âawkâ. It repeatedly executes a statement as long
as a condition is true. For example:
while (CONDITION)
BODY
-BODY is a statement called the "body" of the loop, and CONDITION is an
+BODY is a statement called the âbodyâ of the loop, and CONDITION is an
expression that controls how long the loop keeps running. The first
-thing the 'while' statement does is test the CONDITION. If the
+thing the âwhileâ statement does is test the CONDITION. If the
CONDITION is true, it executes the statement BODY. (The CONDITION is
true when the value is not zero and not a null string.) After BODY has
been executed, CONDITION is tested again, and if it is still true, BODY
executes again. This process repeats until the CONDITION is no longer
true. If the CONDITION is initially false, the body of the loop never
-executes and 'awk' continues with the statement following the loop.
+executes and âawkâ continues with the statement following the loop.
This example prints the first three fields of each record, one per line:
awk '
@@ -10564,10 +10564,10 @@ This example prints the first three fields of each
record, one per line:
The body of this loop is a compound statement enclosed in braces,
containing two statements. The loop works in the following manner:
-first, the value of 'i' is set to one. Then, the 'while' statement
-tests whether 'i' is less than or equal to three. This is true when 'i'
-equals one, so the 'i'th field is printed. Then the 'i++' increments
-the value of 'i' and the loop repeats. The loop terminates when 'i'
+first, the value of âiâ is set to one. Then, the âwhileâ statement
+tests whether âiâ is less than or equal to three. This is true when
âiâ
+equals one, so the âiâth field is printed. Then the âi++â increments
+the value of âiâ and the loop repeats. The loop terminates when âiâ
reaches four.
A newline is not required between the condition and the body;
@@ -10579,10 +10579,10 @@ program is harder to read without it.
File: gawk.info, Node: Do Statement, Next: For Statement, Prev: While
Statement, Up: Statements
-7.4.3 The 'do'-'while' Statement
+7.4.3 The âdoâ-âwhileâ Statement
--------------------------------
-The 'do' loop is a variation of the 'while' looping statement. The 'do'
+The âdoâ loop is a variation of the âwhileâ looping statement. The
âdoâ
loop executes the BODY once and then repeats the BODY as long as the
CONDITION is true. It looks like this:
@@ -10592,13 +10592,13 @@ CONDITION is true. It looks like this:
Even if the CONDITION is false at the start, the BODY executes at
least once (and only once, unless executing BODY makes CONDITION true).
-Contrast this with the corresponding 'while' statement:
+Contrast this with the corresponding âwhileâ statement:
while (CONDITION)
BODY
This statement does not execute the BODY even once if the CONDITION is
-false to begin with. The following is an example of a 'do' statement:
+false to begin with. The following is an example of a âdoâ statement:
{
i = 1
@@ -10608,27 +10608,27 @@ false to begin with. The following is an example of
a 'do' statement:
} while (i <= 10)
}
-This program prints each input record 10 times. However, it isn't a
-very realistic example, because in this case an ordinary 'while' would
+This program prints each input record 10 times. However, it isnât a
+very realistic example, because in this case an ordinary âwhileâ would
do just as well. This situation reflects actual experience; only
-occasionally is there a real use for a 'do' statement.
+occasionally is there a real use for a âdoâ statement.
File: gawk.info, Node: For Statement, Next: Switch Statement, Prev: Do
Statement, Up: Statements
-7.4.4 The 'for' Statement
+7.4.4 The âforâ Statement
-------------------------
-The 'for' statement makes it more convenient to count iterations of a
-loop. The general form of the 'for' statement looks like this:
+The âforâ statement makes it more convenient to count iterations of a
+loop. The general form of the âforâ statement looks like this:
for (INITIALIZATION; CONDITION; INCREMENT)
BODY
-The INITIALIZATION, CONDITION, and INCREMENT parts are arbitrary 'awk'
-expressions, and BODY stands for any 'awk' statement.
+The INITIALIZATION, CONDITION, and INCREMENT parts are arbitrary âawkâ
+expressions, and BODY stands for any âawkâ statement.
- The 'for' statement starts by executing INITIALIZATION. Then, as
+ The âforâ statement starts by executing INITIALIZATION. Then, as
long as the CONDITION is true, it repeatedly executes BODY and then
INCREMENT. Typically, INITIALIZATION sets a variable to either zero or
one, INCREMENT adds one to it, and CONDITION compares it against the
@@ -10645,17 +10645,17 @@ field per output line.
C and C++ programmers might expect to be able to use the comma
operator to set more than one variable in the INITIALIZATION part of the
-'for' loop, or to increment multiple variables in the INCREMENT part of
+âforâ loop, or to increment multiple variables in the INCREMENT part of
the loop, like so:
for (i = 0, j = length(a); i < j; i++, j--) ... C/C++, not awk!
-You cannot do this; the comma operator is not supported in 'awk'. There
+You cannot do this; the comma operator is not supported in âawkâ. There
are workarounds, but they are nonobvious and can lead to code that is
difficult to read and understand. It is best, therefore, to simply
write additional initializations as separate statements preceding the
-'for' loop and to place additional increment statements at the end of
-the loop's body.
+âforâ loop and to place additional increment statements at the end of
+the loopâs body.
Most often, INCREMENT is an increment expression, as in the earlier
example. But this is not required; it can be any expression whatsoever.
@@ -10666,12 +10666,12 @@ between 1 and 100:
print i
If there is nothing to be done, any of the three expressions in the
-parentheses following the 'for' keyword may be omitted. Thus,
-'for (; x > 0;)' is equivalent to 'while (x > 0)'. If the CONDITION is
-omitted, it is treated as true, effectively yielding an "infinite loop"
+parentheses following the âforâ keyword may be omitted. Thus,
+âfor (; x > 0;)â is equivalent to âwhile (x > 0)â. If the CONDITION is
+omitted, it is treated as true, effectively yielding an âinfinite loopâ
(i.e., a loop that never terminates).
- In most cases, a 'for' loop is an abbreviation for a 'while' loop, as
+ In most cases, a âforâ loop is an abbreviation for a âwhileâ loop,
as
shown here:
INITIALIZATION
@@ -10680,47 +10680,47 @@ shown here:
INCREMENT
}
-The only exception is when the 'continue' statement (*note Continue
-Statement::) is used inside the loop. Changing a 'for' statement to a
-'while' statement in this way can change the effect of the 'continue'
+The only exception is when the âcontinueâ statement (*note Continue
+Statement::) is used inside the loop. Changing a âforâ statement to a
+âwhileâ statement in this way can change the effect of the âcontinueâ
statement inside the loop.
- The 'awk' language has a 'for' statement in addition to a 'while'
-statement because a 'for' loop is often both less work to type and more
+ The âawkâ language has a âforâ statement in addition to a
âwhileâ
+statement because a âforâ loop is often both less work to type and more
natural to think of. Counting the number of iterations is very common
in loops. It can be easier to think of this counting as part of looping
rather than as something to do inside the loop.
- There is an alternative version of the 'for' loop, for iterating over
+ There is an alternative version of the âforâ loop, for iterating over
all the indices of an array:
for (i in array)
DO SOMETHING WITH array[i]
*Note Scanning an Array:: for more information on this version of the
-'for' loop.
+âforâ loop.
File: gawk.info, Node: Switch Statement, Next: Break Statement, Prev: For
Statement, Up: Statements
-7.4.5 The 'switch' Statement
+7.4.5 The âswitchâ Statement
----------------------------
-This minor node describes a 'gawk'-specific feature. If 'gawk' is in
+This minor node describes a âgawkâ-specific feature. If âgawkâ is in
compatibility mode (*note Options::), it is not available.
- The 'switch' statement allows the evaluation of an expression and the
-execution of statements based on a 'case' match. Case statements are
+ The âswitchâ statement allows the evaluation of an expression and the
+execution of statements based on a âcaseâ match. Case statements are
checked for a match in the order they are defined. If no suitable
-'case' is found, the 'default' section is executed, if supplied.
+âcaseâ is found, the âdefaultâ section is executed, if supplied.
- Each 'case' contains a single constant, be it numeric, string, or
-regexp. The 'switch' expression is evaluated, and then each 'case''s
+ Each âcaseâ contains a single constant, be it numeric, string, or
+regexp. The âswitchâ expression is evaluated, and then each âcaseââs
constant is compared against the result in turn. The type of constant
determines the comparison: numeric or string do the usual comparisons.
-A regexp constant (either regular, '/foo/', or strongly typed, '@/foo/')
+A regexp constant (either regular, â/foo/â, or strongly typed,
â@/foo/â)
does a regular expression match against the string value of the original
-expression. The general form of the 'switch' statement looks like this:
+expression. The general form of the âswitchâ statement looks like this:
switch (EXPRESSION) {
case VALUE OR REGULAR EXPRESSION:
@@ -10729,10 +10729,10 @@ expression. The general form of the 'switch'
statement looks like this:
DEFAULT-BODY
}
- Control flow in the 'switch' statement works as it does in C. Once a
+ Control flow in the âswitchâ statement works as it does in C. Once a
match to a given case is made, the case statement bodies execute until a
-'break', 'continue', 'next', 'nextfile', or 'exit' is encountered, or
-the end of the 'switch' statement itself. For example:
+âbreakâ, âcontinueâ, ânextâ, ânextfileâ, or âexitâ is
encountered, or
+the end of the âswitchâ statement itself. For example:
while ((c = getopt(ARGC, ARGV, "aksx")) != -1) {
switch (c) {
@@ -10759,19 +10759,19 @@ the end of the 'switch' statement itself. For
example:
}
Note that if none of the statements specified here halt execution of
-a matched 'case' statement, execution falls through to the next 'case'
-until execution halts. In this example, the 'case' for '"?"' falls
-through to the 'default' case, which is to call a function named
-'usage()'. (The 'getopt()' function being called here is described in
+a matched âcaseâ statement, execution falls through to the next âcaseâ
+until execution halts. In this example, the âcaseâ for â"?"â falls
+through to the âdefaultâ case, which is to call a function named
+âusage()â. (The âgetopt()â function being called here is described in
*note Getopt Function::.)
File: gawk.info, Node: Break Statement, Next: Continue Statement, Prev:
Switch Statement, Up: Statements
-7.4.6 The 'break' Statement
+7.4.6 The âbreakâ Statement
---------------------------
-The 'break' statement jumps out of the innermost 'for', 'while', or 'do'
+The âbreakâ statement jumps out of the innermost âforâ, âwhileâ,
or âdoâ
loop that encloses it. The following example finds the smallest divisor
of any integer, and also identifies prime numbers:
@@ -10788,15 +10788,15 @@ of any integer, and also identifies prime numbers:
printf "%d is prime\n", num
}
- When the remainder is zero in the first 'if' statement, 'awk'
-immediately "breaks out" of the containing 'for' loop. This means that
-'awk' proceeds immediately to the statement following the loop and
-continues processing. (This is very different from the 'exit'
-statement, which stops the entire 'awk' program. *Note Exit
+ When the remainder is zero in the first âifâ statement, âawkâ
+immediately âbreaks outâ of the containing âforâ loop. This means that
+âawkâ proceeds immediately to the statement following the loop and
+continues processing. (This is very different from the âexitâ
+statement, which stops the entire âawkâ program. *Note Exit
Statement::.)
- The following program illustrates how the CONDITION of a 'for' or
-'while' statement could be replaced with a 'break' inside an 'if':
+ The following program illustrates how the CONDITION of a âforâ or
+âwhileâ statement could be replaced with a âbreakâ inside an âifâ:
# find smallest divisor of num
{
@@ -10813,30 +10813,30 @@ Statement::.)
}
}
- The 'break' statement is also used to break out of the 'switch'
+ The âbreakâ statement is also used to break out of the âswitchâ
statement. This is discussed in *note Switch Statement::.
- The 'break' statement has no meaning when used outside the body of a
-loop or 'switch'. However, although it was never documented, historical
-implementations of 'awk' treated the 'break' statement outside of a loop
-as if it were a 'next' statement (*note Next Statement::). (d.c.)
-Recent versions of BWK 'awk' no longer allow this usage, nor does
-'gawk'.
+ The âbreakâ statement has no meaning when used outside the body of a
+loop or âswitchâ. However, although it was never documented, historical
+implementations of âawkâ treated the âbreakâ statement outside of a
loop
+as if it were a ânextâ statement (*note Next Statement::). (d.c.)
+Recent versions of BWK âawkâ no longer allow this usage, nor does
+âgawkâ.
File: gawk.info, Node: Continue Statement, Next: Next Statement, Prev:
Break Statement, Up: Statements
-7.4.7 The 'continue' Statement
+7.4.7 The âcontinueâ Statement
------------------------------
-Similar to 'break', the 'continue' statement is used only inside 'for',
-'while', and 'do' loops. It skips over the rest of the loop body,
+Similar to âbreakâ, the âcontinueâ statement is used only inside
âforâ,
+âwhileâ, and âdoâ loops. It skips over the rest of the loop body,
causing the next cycle around the loop to begin immediately. Contrast
-this with 'break', which jumps out of the loop altogether.
+this with âbreakâ, which jumps out of the loop altogether.
- The 'continue' statement in a 'for' loop directs 'awk' to skip the
+ The âcontinueâ statement in a âforâ loop directs âawkâ to skip
the
rest of the body of the loop and resume execution with the
-increment-expression of the 'for' statement. The following program
+increment-expression of the âforâ statement. The following program
illustrates this fact:
BEGIN {
@@ -10848,10 +10848,10 @@ illustrates this fact:
print ""
}
-This program prints all the numbers from 0 to 20--except for 5, for
-which the 'printf' is skipped. Because the increment 'x++' is not
-skipped, 'x' does not remain stuck at 5. Contrast the 'for' loop from
-the previous example with the following 'while' loop:
+This program prints all the numbers from 0 to 20âexcept for 5, for which
+the âprintfâ is skipped. Because the increment âx++â is not skipped,
+âxâ does not remain stuck at 5. Contrast the âforâ loop from the
+previous example with the following âwhileâ loop:
BEGIN {
x = 0
@@ -10864,43 +10864,43 @@ the previous example with the following 'while' loop:
print ""
}
-This program loops forever once 'x' reaches 5, because the increment
-('x++') is never reached.
+This program loops forever once âxâ reaches 5, because the increment
+(âx++â) is never reached.
- The 'continue' statement has no special meaning with respect to the
-'switch' statement, nor does it have any meaning when used outside the
-body of a loop. Historical versions of 'awk' treated a 'continue'
-statement outside a loop the same way they treated a 'break' statement
-outside a loop: as if it were a 'next' statement (*note Next
-Statement::). (d.c.) Recent versions of BWK 'awk' no longer work this
-way, nor does 'gawk'.
+ The âcontinueâ statement has no special meaning with respect to the
+âswitchâ statement, nor does it have any meaning when used outside the
+body of a loop. Historical versions of âawkâ treated a âcontinueâ
+statement outside a loop the same way they treated a âbreakâ statement
+outside a loop: as if it were a ânextâ statement (*note Next
+Statement::). (d.c.) Recent versions of BWK âawkâ no longer work this
+way, nor does âgawkâ.
File: gawk.info, Node: Next Statement, Next: Nextfile Statement, Prev:
Continue Statement, Up: Statements
-7.4.8 The 'next' Statement
+7.4.8 The ânextâ Statement
--------------------------
-The 'next' statement forces 'awk' to immediately stop processing the
+The ânextâ statement forces âawkâ to immediately stop processing the
current record and go on to the next record. This means that no further
rules are executed for the current record, and the rest of the current
-rule's action isn't executed.
+ruleâs action isnât executed.
- Contrast this with the effect of the 'getline' function (*note
-Getline::). That also causes 'awk' to read the next record immediately,
+ Contrast this with the effect of the âgetlineâ function (*note
+Getline::). That also causes âawkâ to read the next record immediately,
but it does not alter the flow of control in any way (i.e., the rest of
the current action executes with a new input record).
- At the highest level, 'awk' program execution is a loop that reads an
-input record and then tests each rule's pattern against it. If you
-think of this loop as a 'for' statement whose body contains the rules,
-then the 'next' statement is analogous to a 'continue' statement. It
+ At the highest level, âawkâ program execution is a loop that reads an
+input record and then tests each ruleâs pattern against it. If you
+think of this loop as a âforâ statement whose body contains the rules,
+then the ânextâ statement is analogous to a âcontinueâ statement. It
skips to the end of the body of this implicit loop and executes the
increment (which reads another record).
- For example, suppose an 'awk' program works only on records with four
-fields, and it shouldn't fail when given bad input. To avoid
-complicating the rest of the program, write a "weed out" rule near the
+ For example, suppose an âawkâ program works only on records with four
+fields, and it shouldnât fail when given bad input. To avoid
+complicating the rest of the program, write a âweed outâ rule near the
beginning, in the following manner:
NF != 4 {
@@ -10908,120 +10908,120 @@ beginning, in the following manner:
next
}
-Because of the 'next' statement, the program's subsequent rules won't
+Because of the ânextâ statement, the programâs subsequent rules wonât
see the bad record. The error message is redirected to the standard
error output stream, as error messages should be. For more detail, see
*note Special Files::.
- If the 'next' statement causes the end of the input to be reached,
-then the code in any 'END' rules is executed. *Note BEGIN/END::.
+ If the ânextâ statement causes the end of the input to be reached,
+then the code in any âENDâ rules is executed. *Note BEGIN/END::.
- The 'next' statement is not allowed inside 'BEGINFILE' and 'ENDFILE'
+ The ânextâ statement is not allowed inside âBEGINFILEâ and
âENDFILEâ
rules. *Note BEGINFILE/ENDFILE::.
According to the POSIX standard, the behavior is undefined if the
-'next' statement is used in a 'BEGIN' or 'END' rule. 'gawk' treats it
+ânextâ statement is used in a âBEGINâ or âENDâ rule. âgawkâ
treats it
as a syntax error. Although POSIX does not disallow it, most other
-'awk' implementations don't allow the 'next' statement inside function
-bodies (*note User-defined::). Just as with any other 'next' statement,
-a 'next' statement inside a function body reads the next record and
+âawkâ implementations donât allow the ânextâ statement inside
function
+bodies (*note User-defined::). Just as with any other ânextâ statement,
+a ânextâ statement inside a function body reads the next record and
starts processing it with the first rule in the program.
File: gawk.info, Node: Nextfile Statement, Next: Exit Statement, Prev: Next
Statement, Up: Statements
-7.4.9 The 'nextfile' Statement
+7.4.9 The ânextfileâ Statement
------------------------------
-The 'nextfile' statement is similar to the 'next' statement. However,
-instead of abandoning processing of the current record, the 'nextfile'
-statement instructs 'awk' to stop processing the current data file.
+The ânextfileâ statement is similar to the ânextâ statement. However,
+instead of abandoning processing of the current record, the ânextfileâ
+statement instructs âawkâ to stop processing the current data file.
- Upon execution of the 'nextfile' statement, 'FILENAME' is updated to
-the name of the next data file listed on the command line, 'FNR' is
+ Upon execution of the ânextfileâ statement, âFILENAMEâ is updated to
+the name of the next data file listed on the command line, âFNRâ is
reset to one, and processing starts over with the first rule in the
-program. If the 'nextfile' statement causes the end of the input to be
-reached, then the code in any 'END' rules is executed. An exception to
-this is when 'nextfile' is invoked during execution of any statement in
-an 'END' rule; in this case, it causes the program to stop immediately.
+program. If the ânextfileâ statement causes the end of the input to be
+reached, then the code in any âENDâ rules is executed. An exception to
+this is when ânextfileâ is invoked during execution of any statement in
+an âENDâ rule; in this case, it causes the program to stop immediately.
*Note BEGIN/END::.
- The 'nextfile' statement is useful when there are many data files to
-process but it isn't necessary to process every record in every file.
-Without 'nextfile', in order to move on to the next data file, a program
-would have to continue scanning the unwanted records. The 'nextfile'
+ The ânextfileâ statement is useful when there are many data files to
+process but it isnât necessary to process every record in every file.
+Without ânextfileâ, in order to move on to the next data file, a program
+would have to continue scanning the unwanted records. The ânextfileâ
statement accomplishes this much more efficiently.
- In 'gawk', execution of 'nextfile' causes additional things to
-happen: any 'ENDFILE' rules are executed if 'gawk' is not currently in
-an 'END' rule, 'ARGIND' is incremented, and any 'BEGINFILE' rules are
-executed. ('ARGIND' hasn't been introduced yet. *Note Built-in
+ In âgawkâ, execution of ânextfileâ causes additional things to
+happen: any âENDFILEâ rules are executed if âgawkâ is not currently in
+an âENDâ rule, âARGINDâ is incremented, and any âBEGINFILEâ rules
are
+executed. (âARGINDâ hasnât been introduced yet. *Note Built-in
Variables::.)
- There is an additional, special, use case with 'gawk'. 'nextfile' is
-useful inside a 'BEGINFILE' rule to skip over a file that would
-otherwise cause 'gawk' to exit with a fatal error. In this special
-case, 'ENDFILE' rules are not executed. *Note BEGINFILE/ENDFILE::.
+ There is an additional, special, use case with âgawkâ. ânextfileâ
is
+useful inside a âBEGINFILEâ rule to skip over a file that would
+otherwise cause âgawkâ to exit with a fatal error. In this special
+case, âENDFILEâ rules are not executed. *Note BEGINFILE/ENDFILE::.
- Although it might seem that 'close(FILENAME)' would accomplish the
-same as 'nextfile', this isn't true. 'close()' is reserved for closing
+ Although it might seem that âclose(FILENAME)â would accomplish the
+same as ânextfileâ, this isnât true. âclose()â is reserved for
closing
files, pipes, and coprocesses that are opened with redirections. It is
-not related to the main processing that 'awk' does with the files listed
-in 'ARGV'.
+not related to the main processing that âawkâ does with the files listed
+in âARGVâ.
- NOTE: For many years, 'nextfile' was a common extension. In
+ NOTE: For many years, ânextfileâ was a common extension. In
September 2012, it was accepted for inclusion into the POSIX
standard. See the Austin Group website
(http://austingroupbugs.net/view.php?id=607).
- The current version of BWK 'awk' and 'mawk' also support 'nextfile'.
-However, they don't allow the 'nextfile' statement inside function
-bodies (*note User-defined::). 'gawk' does; a 'nextfile' inside a
+ The current version of BWK âawkâ and âmawkâ also support
ânextfileâ.
+However, they donât allow the ânextfileâ statement inside function
+bodies (*note User-defined::). âgawkâ does; a ânextfileâ inside a
function body reads the first record from the next file and starts
processing it with the first rule in the program, just as any other
-'nextfile' statement.
+ânextfileâ statement.
File: gawk.info, Node: Exit Statement, Prev: Nextfile Statement, Up:
Statements
-7.4.10 The 'exit' Statement
+7.4.10 The âexitâ Statement
---------------------------
-The 'exit' statement causes 'awk' to immediately stop executing the
+The âexitâ statement causes âawkâ to immediately stop executing the
current rule and to stop processing input; any remaining input is
-ignored. The 'exit' statement is written as follows:
+ignored. The âexitâ statement is written as follows:
- 'exit' [RETURN CODE]
+ âexitâ [RETURN CODE]
- When an 'exit' statement is executed from a 'BEGIN' rule, the program
+ When an âexitâ statement is executed from a âBEGINâ rule, the
program
stops processing everything immediately. No input records are read.
-However, if an 'END' rule is present, as part of executing the 'exit'
-statement, the 'END' rule is executed (*note BEGIN/END::). If 'exit' is
-used in the body of an 'END' rule, it causes the program to stop
+However, if an âENDâ rule is present, as part of executing the âexitâ
+statement, the âENDâ rule is executed (*note BEGIN/END::). If âexitâ
is
+used in the body of an âENDâ rule, it causes the program to stop
immediately.
- An 'exit' statement that is not part of a 'BEGIN' or 'END' rule stops
+ An âexitâ statement that is not part of a âBEGINâ or âENDâ rule
stops
the execution of any further automatic rules for the current record,
-skips reading any remaining input records, and executes the 'END' rule
-if there is one. 'gawk' also skips any 'ENDFILE' rules; they do not
+skips reading any remaining input records, and executes the âENDâ rule
+if there is one. âgawkâ also skips any âENDFILEâ rules; they do not
execute.
- In such a case, if you don't want the 'END' rule to do its job, set a
-variable to a nonzero value before the 'exit' statement and check that
-variable in the 'END' rule. *Note Assert Function:: for an example that
+ In such a case, if you donât want the âENDâ rule to do its job, set a
+variable to a nonzero value before the âexitâ statement and check that
+variable in the âENDâ rule. *Note Assert Function:: for an example that
does this.
- If an argument is supplied to 'exit', its value is used as the exit
-status code for the 'awk' process. If no argument is supplied, 'exit'
-causes 'awk' to return a "success" status. In the case where an
-argument is supplied to a first 'exit' statement, and then 'exit' is
-called a second time from an 'END' rule with no argument, 'awk' uses the
+ If an argument is supplied to âexitâ, its value is used as the exit
+status code for the âawkâ process. If no argument is supplied, âexitâ
+causes âawkâ to return a âsuccessâ status. In the case where an
+argument is supplied to a first âexitâ statement, and then âexitâ is
+called a second time from an âENDâ rule with no argument, âawkâ uses
the
previously supplied exit value. (d.c.) *Note Exit Status:: for more
information.
For example, suppose an error condition occurs that is difficult or
impossible to handle. Conventionally, programs report this by exiting
-with a nonzero status. An 'awk' program can do this using an 'exit'
+with a nonzero status. An âawkâ program can do this using an âexitâ
statement with a nonzero argument, as shown in the following example:
BEGIN {
@@ -11043,162 +11043,162 @@ File: gawk.info, Node: Built-in Variables, Next:
Pattern Action Summary, Prev
7.5 Predefined Variables
========================
-Most 'awk' variables are available to use for your own purposes; they
+Most âawkâ variables are available to use for your own purposes; they
never change unless your program assigns values to them, and they never
affect anything unless your program examines them. However, a few
-variables in 'awk' have special built-in meanings. 'awk' examines some
-of these automatically, so that they enable you to tell 'awk' how to do
-certain things. Others are set automatically by 'awk', so that they
-carry information from the internal workings of 'awk' to your program.
+variables in âawkâ have special built-in meanings. âawkâ examines some
+of these automatically, so that they enable you to tell âawkâ how to do
+certain things. Others are set automatically by âawkâ, so that they
+carry information from the internal workings of âawkâ to your program.
- This minor node documents all of 'gawk''s predefined variables, most
+ This minor node documents all of âgawkââs predefined variables, most
of which are also documented in the major nodes describing their areas
of activity.
* Menu:
* User-modified:: Built-in variables that you change to control
- 'awk'.
-* Auto-set:: Built-in variables where 'awk' gives
+ âawkâ.
+* Auto-set:: Built-in variables where âawkâ gives
you information.
-* ARGC and ARGV:: Ways to use 'ARGC' and 'ARGV'.
+* ARGC and ARGV:: Ways to use âARGCâ and âARGVâ.
File: gawk.info, Node: User-modified, Next: Auto-set, Up: Built-in Variables
-7.5.1 Built-in Variables That Control 'awk'
+7.5.1 Built-in Variables That Control âawkâ
-------------------------------------------
The following is an alphabetical list of variables that you can change
-to control how 'awk' does certain things.
+to control how âawkâ does certain things.
- The variables that are specific to 'gawk' are marked with a pound
-sign ('#'). These variables are 'gawk' extensions. In other 'awk'
-implementations or if 'gawk' is in compatibility mode (*note Options::),
+ The variables that are specific to âgawkâ are marked with a pound
+sign (â#â). These variables are âgawkâ extensions. In other âawkâ
+implementations or if âgawkâ is in compatibility mode (*note Options::),
they are not special. (Any exceptions are noted in the description of
each variable.)
-'BINMODE #'
+âBINMODE #â
On non-POSIX systems, this variable specifies use of binary mode
for all I/O. Numeric values of one, two, or three specify that
input files, output files, or all files, respectively, should use
binary I/O. A numeric value less than zero is treated as zero, and
a numeric value greater than three is treated as three.
- Alternatively, string values of '"r"' or '"w"' specify that input
+ Alternatively, string values of â"r"â or â"w"â specify that input
files and output files, respectively, should use binary I/O. A
- string value of '"rw"' or '"wr"' indicates that all files should
+ string value of â"rw"â or â"wr"â indicates that all files should
use binary I/O. Any other string value is treated the same as
- '"rw"', but causes 'gawk' to generate a warning message. 'BINMODE'
- is described in more detail in *note PC Using::. 'mawk' (*note
+ â"rw"â, but causes âgawkâ to generate a warning message.
âBINMODEâ
+ is described in more detail in *note PC Using::. âmawkâ (*note
Other Versions::) also supports this variable, but only using
numeric values.
-'CONVFMT'
+âCONVFMTâ
A string that controls the conversion of numbers to strings (*note
Conversion::). It works by being passed, in effect, as the first
- argument to the 'sprintf()' function (*note String Functions::).
- Its default value is '"%.6g"'. 'CONVFMT' was introduced by the
+ argument to the âsprintf()â function (*note String Functions::).
+ Its default value is â"%.6g"â. âCONVFMTâ was introduced by the
POSIX standard.
-'FIELDWIDTHS #'
- A space-separated list of columns that tells 'gawk' how to split
+âFIELDWIDTHS #â
+ A space-separated list of columns that tells âgawkâ how to split
input with fixed columnar boundaries. Starting in version 4.2,
each field width may optionally be preceded by a colon-separated
value specifying the number of characters to skip before the field
- starts. Assigning a value to 'FIELDWIDTHS' overrides the use of
- 'FS' and 'FPAT' for field splitting. *Note Constant Size:: for
+ starts. Assigning a value to âFIELDWIDTHSâ overrides the use of
+ âFSâ and âFPATâ for field splitting. *Note Constant Size:: for
more information.
-'FPAT #'
- A regular expression (as a string) that tells 'gawk' to create the
+âFPAT #â
+ A regular expression (as a string) that tells âgawkâ to create the
fields based on text that matches the regular expression.
- Assigning a value to 'FPAT' overrides the use of 'FS' and
- 'FIELDWIDTHS' for field splitting. *Note Splitting By Content::
+ Assigning a value to âFPATâ overrides the use of âFSâ and
+ âFIELDWIDTHSâ for field splitting. *Note Splitting By Content::
for more information.
-'FS'
+âFSâ
The input field separator (*note Field Separators::). The value is
a single-character string or a multicharacter regular expression
that matches the separations between fields in an input record. If
- the value is the null string ('""'), then each character in the
- record becomes a separate field. (This behavior is a 'gawk'
- extension. POSIX 'awk' does not specify the behavior when 'FS' is
- the null string. Nonetheless, some other versions of 'awk' also
- treat '""' specially.)
+ the value is the null string (â""â), then each character in the
+ record becomes a separate field. (This behavior is a âgawkâ
+ extension. POSIX âawkâ does not specify the behavior when âFSâ is
+ the null string. Nonetheless, some other versions of âawkâ also
+ treat â""â specially.)
- The default value is '" "', a string consisting of a single space.
+ The default value is â" "â, a string consisting of a single space.
As a special exception, this value means that any sequence of
spaces, TABs, and/or newlines is a single separator. It also
causes spaces, TABs, and newlines at the beginning and end of a
record to be ignored.
- You can set the value of 'FS' on the command line using the '-F'
+ You can set the value of âFSâ on the command line using the â-Fâ
option:
awk -F, 'PROGRAM' INPUT-FILES
- If 'gawk' is using 'FIELDWIDTHS' or 'FPAT' for field splitting,
- assigning a value to 'FS' causes 'gawk' to return to the normal,
- 'FS'-based field splitting. An easy way to do this is to simply
- say 'FS = FS', perhaps with an explanatory comment.
+ If âgawkâ is using âFIELDWIDTHSâ or âFPATâ for field
splitting,
+ assigning a value to âFSâ causes âgawkâ to return to the normal,
+ âFSâ-based field splitting. An easy way to do this is to simply
+ say âFS = FSâ, perhaps with an explanatory comment.
-'IGNORECASE #'
- If 'IGNORECASE' is nonzero or non-null, then all string comparisons
+âIGNORECASE #â
+ If âIGNORECASEâ is nonzero or non-null, then all string comparisons
and all regular expression matching are case-independent. This
- applies to regexp matching with '~' and '!~', the 'gensub()',
- 'gsub()', 'index()', 'match()', 'patsplit()', 'split()', and
- 'sub()' functions, record termination with 'RS', and field
- splitting with 'FS' and 'FPAT'. However, the value of 'IGNORECASE'
+ applies to regexp matching with â~â and â!~â, the âgensub()â,
+ âgsub()â, âindex()â, âmatch()â, âpatsplit()â,
âsplit()â, and
+ âsub()â functions, record termination with âRSâ, and field
+ splitting with âFSâ and âFPATâ. However, the value of
âIGNORECASEâ
does _not_ affect array subscripting and it does not affect field
splitting when using a single-character field separator. *Note
Case-sensitivity::.
-'LINT #'
- When this variable is true (nonzero or non-null), 'gawk' behaves as
- if the '--lint' command-line option is in effect (*note Options::).
- With a value of '"fatal"', lint warnings become fatal errors. With
- a value of '"invalid"', only warnings about things that are
+âLINT #â
+ When this variable is true (nonzero or non-null), âgawkâ behaves as
+ if the â--lintâ command-line option is in effect (*note Options::).
+ With a value of â"fatal"â, lint warnings become fatal errors. With
+ a value of â"invalid"â, only warnings about things that are
actually invalid are issued. (This is not fully implemented yet.)
Any other true value prints nonfatal warnings. Assigning a false
- value to 'LINT' turns off the lint warnings.
+ value to âLINTâ turns off the lint warnings.
- This variable is a 'gawk' extension. It is not special in other
- 'awk' implementations. Unlike with the other special variables,
- changing 'LINT' does affect the production of lint warnings, even
- if 'gawk' is in compatibility mode. Much as the '--lint' and
- '--traditional' options independently control different aspects of
- 'gawk''s behavior, the control of lint warnings during program
- execution is independent of the flavor of 'awk' being executed.
+ This variable is a âgawkâ extension. It is not special in other
+ âawkâ implementations. Unlike with the other special variables,
+ changing âLINTâ does affect the production of lint warnings, even
+ if âgawkâ is in compatibility mode. Much as the â--lintâ and
+ â--traditionalâ options independently control different aspects of
+ âgawkââs behavior, the control of lint warnings during program
+ execution is independent of the flavor of âawkâ being executed.
-'OFMT'
+âOFMTâ
A string that controls conversion of numbers to strings (*note
- Conversion::) for printing with the 'print' statement. It works by
- being passed as the first argument to the 'sprintf()' function
- (*note String Functions::). Its default value is '"%.6g"'.
- Earlier versions of 'awk' used 'OFMT' to specify the format for
+ Conversion::) for printing with the âprintâ statement. It works by
+ being passed as the first argument to the âsprintf()â function
+ (*note String Functions::). Its default value is â"%.6g"â.
+ Earlier versions of âawkâ used âOFMTâ to specify the format for
converting numbers to strings in general expressions; this is now
- done by 'CONVFMT'.
+ done by âCONVFMTâ.
-'OFS'
+âOFSâ
The output field separator (*note Output Separators::). It is
- output between the fields printed by a 'print' statement. Its
- default value is '" "', a string consisting of a single space.
+ output between the fields printed by a âprintâ statement. Its
+ default value is â" "â, a string consisting of a single space.
-'ORS'
+âORSâ
The output record separator. It is output at the end of every
- 'print' statement. Its default value is '"\n"', the newline
+ âprintâ statement. Its default value is â"\n"â, the newline
character. (*Note Output Separators::.)
-'PREC #'
+âPREC #â
The working precision of arbitrary-precision floating-point
numbers, 53 bits by default (*note Setting precision::).
-'ROUNDMODE #'
+âROUNDMODE #â
The rounding mode to use for arbitrary-precision arithmetic on
- numbers, by default '"N"' ('roundTiesToEven' in the IEEE 754
+ numbers, by default â"N"â (âroundTiesToEvenâ in the IEEE 754
standard; *note Setting the rounding mode::).
-'RS'
+âRSâ
The input record separator. Its default value is a string
containing a single newline character, which means that an input
record consists of a single line of text. It can also be the null
@@ -11206,24 +11206,24 @@ each variable.)
If it is a regexp, records are separated by matches of the regexp
in the input text. (*Note Records::.)
- The ability for 'RS' to be a regular expression is a 'gawk'
- extension. In most other 'awk' implementations, or if 'gawk' is in
+ The ability for âRSâ to be a regular expression is a âgawkâ
+ extension. In most other âawkâ implementations, or if âgawkâ is
in
compatibility mode (*note Options::), just the first character of
- 'RS''s value is used.
+ âRSââs value is used.
-'SUBSEP'
- The subscript separator. It has the default value of '"\034"' and
+âSUBSEPâ
+ The subscript separator. It has the default value of â"\034"â and
is used to separate the parts of the indices of a multidimensional
- array. Thus, the expression 'foo["A", "B"]' really accesses
- 'foo["A\034B"]' (*note Multidimensional::).
+ array. Thus, the expression âfoo["A", "B"]â really accesses
+ âfoo["A\034B"]â (*note Multidimensional::).
-'TEXTDOMAIN #'
- Used for internationalization of programs at the 'awk' level. It
+âTEXTDOMAIN #â
+ Used for internationalization of programs at the âawkâ level. It
sets the default text domain for specially marked string constants
- in the source text, as well as for the 'dcgettext()',
- 'dcngettext()', and 'bindtextdomain()' functions (*note
- Internationalization::). The default value of 'TEXTDOMAIN' is
- '"messages"'.
+ in the source text, as well as for the âdcgettext()â,
+ âdcngettext()â, and âbindtextdomain()â functions (*note
+ Internationalization::). The default value of âTEXTDOMAINâ is
+ â"messages"â.
File: gawk.info, Node: Auto-set, Next: ARGC and ARGV, Prev: User-modified,
Up: Built-in Variables
@@ -11231,160 +11231,160 @@ File: gawk.info, Node: Auto-set, Next: ARGC and
ARGV, Prev: User-modified, U
7.5.2 Built-in Variables That Convey Information
------------------------------------------------
-The following is an alphabetical list of variables that 'awk' sets
+The following is an alphabetical list of variables that âawkâ sets
automatically on certain occasions in order to provide information to
your program.
- The variables that are specific to 'gawk' are marked with a pound
-sign ('#'). These variables are 'gawk' extensions. In other 'awk'
-implementations or if 'gawk' is in compatibility mode (*note Options::),
+ The variables that are specific to âgawkâ are marked with a pound
+sign (â#â). These variables are âgawkâ extensions. In other âawkâ
+implementations or if âgawkâ is in compatibility mode (*note Options::),
they are not special:
-'ARGC', 'ARGV'
- The command-line arguments available to 'awk' programs are stored
- in an array called 'ARGV'. 'ARGC' is the number of command-line
- arguments present. *Note Other Arguments::. Unlike most 'awk'
- arrays, 'ARGV' is indexed from 0 to 'ARGC' - 1. In the following
+âARGCâ, âARGVâ
+ The command-line arguments available to âawkâ programs are stored
+ in an array called âARGVâ. âARGCâ is the number of command-line
+ arguments present. *Note Other Arguments::. Unlike most âawkâ
+ arrays, âARGVâ is indexed from 0 to âARGCâ â 1. In the
following
example:
$ awk 'BEGIN {
> for (i = 0; i < ARGC; i++)
> print ARGV[i]
> }' inventory-shipped mail-list
- -| awk
- -| inventory-shipped
- -| mail-list
+ ⣠awk
+ ⣠inventory-shipped
+ ⣠mail-list
- 'ARGV[0]' contains 'awk', 'ARGV[1]' contains 'inventory-shipped',
- and 'ARGV[2]' contains 'mail-list'. The value of 'ARGC' is three,
- one more than the index of the last element in 'ARGV', because the
+ âARGV[0]â contains âawkâ, âARGV[1]â contains
âinventory-shippedâ,
+ and âARGV[2]â contains âmail-listâ. The value of âARGCâ is
three,
+ one more than the index of the last element in âARGVâ, because the
elements are numbered from zero.
- The names 'ARGC' and 'ARGV', as well as the convention of indexing
- the array from 0 to 'ARGC' - 1, are derived from the C language's
+ The names âARGCâ and âARGVâ, as well as the convention of indexing
+ the array from 0 to âARGCâ â 1, are derived from the C languageâs
method of accessing command-line arguments.
- The value of 'ARGV[0]' can vary from system to system. Also, you
- should note that the program text is _not_ included in 'ARGV', nor
- are any of 'awk''s command-line options. *Note ARGC and ARGV:: for
- information about how 'awk' uses these variables. (d.c.)
+ The value of âARGV[0]â can vary from system to system. Also, you
+ should note that the program text is _not_ included in âARGVâ, nor
+ are any of âawkââs command-line options. *Note ARGC and ARGV:: for
+ information about how âawkâ uses these variables. (d.c.)
-'ARGIND #'
- The index in 'ARGV' of the current file being processed. Every
- time 'gawk' opens a new data file for processing, it sets 'ARGIND'
- to the index in 'ARGV' of the file name. When 'gawk' is processing
- the input files, 'FILENAME == ARGV[ARGIND]' is always true.
+âARGIND #â
+ The index in âARGVâ of the current file being processed. Every
+ time âgawkâ opens a new data file for processing, it sets âARGINDâ
+ to the index in âARGVâ of the file name. When âgawkâ is
processing
+ the input files, âFILENAME == ARGV[ARGIND]â is always true.
This variable is useful in file processing; it allows you to tell
how far along you are in the list of data files as well as to
distinguish between successive instances of the same file name on
the command line.
- While you can change the value of 'ARGIND' within your 'awk'
- program, 'gawk' automatically sets it to a new value when it opens
+ While you can change the value of âARGINDâ within your âawkâ
+ program, âgawkâ automatically sets it to a new value when it opens
the next file.
-'ENVIRON'
+âENVIRONâ
An associative array containing the values of the environment. The
array indices are the environment variable names; the elements are
the values of the particular environment variables. For example,
- 'ENVIRON["HOME"]' might be '/home/arnold'.
+ âENVIRON["HOME"]â might be â/home/arnoldâ.
- For POSIX 'awk', changing this array does not affect the
- environment passed on to any programs that 'awk' may spawn via
- redirection or the 'system()' function.
+ For POSIX âawkâ, changing this array does not affect the
+ environment passed on to any programs that âawkâ may spawn via
+ redirection or the âsystem()â function.
However, beginning with version 4.2, if not in POSIX compatibility
- mode, 'gawk' does update its own environment when 'ENVIRON' is
+ mode, âgawkâ does update its own environment when âENVIRONâ is
changed, thus changing the environment seen by programs that it
creates. You should therefore be especially careful if you modify
- 'ENVIRON["PATH"]', which is the search path for finding executable
+ âENVIRON["PATH"]â, which is the search path for finding executable
programs.
- This can also affect the running 'gawk' program, since some of the
+ This can also affect the running âgawkâ program, since some of the
built-in functions may pay attention to certain environment
- variables. The most notable instance of this is 'mktime()' (*note
- Time Functions::), which pays attention the value of the 'TZ'
+ variables. The most notable instance of this is âmktime()â (*note
+ Time Functions::), which pays attention the value of the âTZâ
environment variable on many systems.
Some operating systems may not have environment variables. On such
- systems, the 'ENVIRON' array is empty (except for
- 'ENVIRON["AWKPATH"]' and 'ENVIRON["AWKLIBPATH"]'; *note AWKPATH
+ systems, the âENVIRONâ array is empty (except for
+ âENVIRON["AWKPATH"]â and âENVIRON["AWKLIBPATH"]â; *note AWKPATH
Variable:: and *note AWKLIBPATH Variable::).
-'ERRNO #'
- If a system error occurs during a redirection for 'getline', during
- a read for 'getline', or during a 'close()' operation, then 'ERRNO'
+âERRNO #â
+ If a system error occurs during a redirection for âgetlineâ, during
+ a read for âgetlineâ, or during a âclose()â operation, then
âERRNOâ
contains a string describing the error.
- In addition, 'gawk' clears 'ERRNO' before opening each command-line
+ In addition, âgawkâ clears âERRNOâ before opening each
command-line
input file. This enables checking if the file is readable inside a
- 'BEGINFILE' pattern (*note BEGINFILE/ENDFILE::).
+ âBEGINFILEâ pattern (*note BEGINFILE/ENDFILE::).
- Otherwise, 'ERRNO' works similarly to the C variable 'errno'.
- Except for the case just mentioned, 'gawk' _never_ clears it (sets
- it to zero or '""'). Thus, you should only expect its value to be
+ Otherwise, âERRNOâ works similarly to the C variable âerrnoâ.
+ Except for the case just mentioned, âgawkâ _never_ clears it (sets
+ it to zero or â""â). Thus, you should only expect its value to be
meaningful when an I/O operation returns a failure value, such as
- 'getline' returning -1. You are, of course, free to clear it
+ âgetlineâ returning â1. You are, of course, free to clear it
yourself before doing an I/O operation.
- If the value of 'ERRNO' corresponds to a system error in the C
- 'errno' variable, then 'PROCINFO["errno"]' will be set to the value
- of 'errno'. For non-system errors, 'PROCINFO["errno"]' will be
+ If the value of âERRNOâ corresponds to a system error in the C
+ âerrnoâ variable, then âPROCINFO["errno"]â will be set to the
value
+ of âerrnoâ. For non-system errors, âPROCINFO["errno"]â will be
zero.
-'FILENAME'
+âFILENAMEâ
The name of the current input file. When no data files are listed
- on the command line, 'awk' reads from the standard input and
- 'FILENAME' is set to '"-"'. 'FILENAME' changes each time a new
- file is read (*note Reading Files::). Inside a 'BEGIN' rule, the
- value of 'FILENAME' is '""', because there are no input files being
- processed yet.(1) (d.c.) Note, though, that using 'getline'
- (*note Getline::) inside a 'BEGIN' rule can give 'FILENAME' a
+ on the command line, âawkâ reads from the standard input and
+ âFILENAMEâ is set to â"-"â. âFILENAMEâ changes each time a
new
+ file is read (*note Reading Files::). Inside a âBEGINâ rule, the
+ value of âFILENAMEâ is â""â, because there are no input files
being
+ processed yet.(1) (d.c.) Note, though, that using âgetlineâ
+ (*note Getline::) inside a âBEGINâ rule can give âFILENAMEâ a
value.
-'FNR'
- The current record number in the current file. 'awk' increments
- 'FNR' each time it reads a new record (*note Records::). 'awk'
- resets 'FNR' to zero each time it starts a new input file.
+âFNRâ
+ The current record number in the current file. âawkâ increments
+ âFNRâ each time it reads a new record (*note Records::). âawkâ
+ resets âFNRâ to zero each time it starts a new input file.
-'NF'
- The number of fields in the current input record. 'NF' is set each
+âNFâ
+ The number of fields in the current input record. âNFâ is set each
time a new record is read, when a new field is created, or when
- '$0' changes (*note Fields::).
+ â$0â changes (*note Fields::).
Unlike most of the variables described in this node, assigning a
- value to 'NF' has the potential to affect 'awk''s internal
- workings. In particular, assignments to 'NF' can be used to create
+ value to âNFâ has the potential to affect âawkââs internal
+ workings. In particular, assignments to âNFâ can be used to create
fields in or remove fields from the current record. *Note Changing
Fields::.
-'FUNCTAB #'
+âFUNCTAB #â
An array whose indices and corresponding values are the names of
all the built-in, user-defined, and extension functions in the
program.
- NOTE: Attempting to use the 'delete' statement with the
- 'FUNCTAB' array causes a fatal error. Any attempt to assign
- to an element of 'FUNCTAB' also causes a fatal error.
+ NOTE: Attempting to use the âdeleteâ statement with the
+ âFUNCTABâ array causes a fatal error. Any attempt to assign
+ to an element of âFUNCTABâ also causes a fatal error.
-'NR'
- The number of input records 'awk' has processed since the beginning
- of the program's execution (*note Records::). 'awk' increments
- 'NR' each time it reads a new record.
+âNRâ
+ The number of input records âawkâ has processed since the beginning
+ of the programâs execution (*note Records::). âawkâ increments
+ âNRâ each time it reads a new record.
-'PROCINFO #'
+âPROCINFO #â
The elements of this array provide access to information about the
- running 'awk' program. The following elements (listed
+ running âawkâ program. The following elements (listed
alphabetically) are guaranteed to be available:
- 'PROCINFO["argv"]'
- The 'PROCINFO["argv"]' array contains all of the command-line
+ âPROCINFO["argv"]â
+ The âPROCINFO["argv"]â array contains all of the command-line
arguments (after glob expansion and redirection processing on
platforms where that must be done manually by the program)
- with subscripts ranging from 0 through 'argc' - 1. For
- example, 'PROCINFO["argv"][0]' will contain the name by which
- 'gawk' was invoked. Here is an example of how this feature
+ with subscripts ranging from 0 through âargcâ â 1. For
+ example, âPROCINFO["argv"][0]â will contain the name by which
+ âgawkâ was invoked. Here is an example of how this feature
may be used:
gawk '
@@ -11393,195 +11393,195 @@ they are not special:
print i, PROCINFO["argv"][i]
}'
- Please note that this differs from the standard 'ARGV' array
+ Please note that this differs from the standard âARGVâ array
which does not include command-line arguments that have
- already been processed by 'gawk' (*note ARGC and ARGV::).
+ already been processed by âgawkâ (*note ARGC and ARGV::).
- 'PROCINFO["egid"]'
- The value of the 'getegid()' system call.
+ âPROCINFO["egid"]â
+ The value of the âgetegid()â system call.
- 'PROCINFO["errno"]'
- The value of the C 'errno' variable when 'ERRNO' is set to the
+ âPROCINFO["errno"]â
+ The value of the C âerrnoâ variable when âERRNOâ is set to
the
associated error message.
- 'PROCINFO["euid"]'
- The value of the 'geteuid()' system call.
+ âPROCINFO["euid"]â
+ The value of the âgeteuid()â system call.
- 'PROCINFO["FS"]'
- This is '"FS"' if field splitting with 'FS' is in effect,
- '"FIELDWIDTHS"' if field splitting with 'FIELDWIDTHS' is in
- effect, '"FPAT"' if field matching with 'FPAT' is in effect,
- or '"API"' if field splitting is controlled by an API input
+ âPROCINFO["FS"]â
+ This is â"FS"â if field splitting with âFSâ is in effect,
+ â"FIELDWIDTHS"â if field splitting with âFIELDWIDTHSâ is in
+ effect, â"FPAT"â if field matching with âFPATâ is in effect,
+ or â"API"â if field splitting is controlled by an API input
parser.
- 'PROCINFO["gid"]'
- The value of the 'getgid()' system call.
+ âPROCINFO["gid"]â
+ The value of the âgetgid()â system call.
- 'PROCINFO["identifiers"]'
+ âPROCINFO["identifiers"]â
A subarray, indexed by the names of all identifiers used in
- the text of the 'awk' program. An "identifier" is simply the
+ the text of the âawkâ program. An âidentifierâ is simply the
name of a variable (be it scalar or array), built-in function,
user-defined function, or extension function. For each
identifier, the value of the element is one of the following:
- '"array"'
+ â"array"â
The identifier is an array.
- '"builtin"'
+ â"builtin"â
The identifier is a built-in function.
- '"extension"'
+ â"extension"â
The identifier is an extension function loaded via
- '@load' or '-l'.
+ â@loadâ or â-lâ.
- '"scalar"'
+ â"scalar"â
The identifier is a scalar.
- '"untyped"'
+ â"untyped"â
The identifier is untyped (could be used as a scalar or
- an array; 'gawk' doesn't know yet).
+ an array; âgawkâ doesnât know yet).
- '"user"'
+ â"user"â
The identifier is a user-defined function.
- The values indicate what 'gawk' knows about the identifiers
+ The values indicate what âgawkâ knows about the identifiers
after it has finished parsing the program; they are _not_
updated while the program runs.
- 'PROCINFO["platform"]'
+ âPROCINFO["platform"]â
This element gives a string indicating the platform for which
- 'gawk' was compiled. The value will be one of the following:
+ âgawkâ was compiled. The value will be one of the following:
- '"mingw"'
+ â"mingw"â
Microsoft Windows, using MinGW.
- '"os390"'
+ â"os390"â
OS/390 (also known as z/OS).
- '"posix"'
+ â"posix"â
GNU/Linux, Cygwin, macOS, and legacy Unix systems.
- '"vms"'
+ â"vms"â
OpenVMS.
- 'PROCINFO["pgrpid"]'
+ âPROCINFO["pgrpid"]â
The process group ID of the current process.
- 'PROCINFO["pid"]'
+ âPROCINFO["pid"]â
The process ID of the current process.
- 'PROCINFO["pma"]'
- The version of the PMA memory allocator compiled into 'gawk'.
+ âPROCINFO["pma"]â
+ The version of the PMA memory allocator compiled into âgawkâ.
This element will not be present if the PMA allocator is not
available for use. *Note Persistent Memory::.
- 'PROCINFO["ppid"]'
+ âPROCINFO["ppid"]â
The parent process ID of the current process.
- 'PROCINFO["strftime"]'
- The default time format string for 'strftime()'. Assigning a
+ âPROCINFO["strftime"]â
+ The default time format string for âstrftime()â. Assigning a
new value to this element changes the default. *Note Time
Functions::.
- 'PROCINFO["uid"]'
- The value of the 'getuid()' system call.
+ âPROCINFO["uid"]â
+ The value of the âgetuid()â system call.
- 'PROCINFO["version"]'
- The version of 'gawk'.
+ âPROCINFO["version"]â
+ The version of âgawkâ.
The following additional elements in the array are available to
provide information about the MPFR and GMP libraries if your
- version of 'gawk' supports arbitrary-precision arithmetic (*note
+ version of âgawkâ supports arbitrary-precision arithmetic (*note
Arbitrary Precision Arithmetic::):
- 'PROCINFO["gmp_version"]'
+ âPROCINFO["gmp_version"]â
The version of the GNU MP library.
- 'PROCINFO["mpfr_version"]'
+ âPROCINFO["mpfr_version"]â
The version of the GNU MPFR library.
- 'PROCINFO["prec_max"]'
+ âPROCINFO["prec_max"]â
The maximum precision supported by MPFR.
- 'PROCINFO["prec_min"]'
+ âPROCINFO["prec_min"]â
The minimum precision required by MPFR.
The following additional elements in the array are available to
provide information about the version of the extension API, if your
- version of 'gawk' supports dynamic loading of extension functions
+ version of âgawkâ supports dynamic loading of extension functions
(*note Dynamic Extensions::):
- 'PROCINFO["api_major"]'
+ âPROCINFO["api_major"]â
The major version of the extension API.
- 'PROCINFO["api_minor"]'
+ âPROCINFO["api_minor"]â
The minor version of the extension API.
- On some systems, there may be elements in the array, '"group1"'
- through '"groupN"' for some N. N is the number of supplementary
- groups that the process has. Use the 'in' operator to test for
+ On some systems, there may be elements in the array, â"group1"â
+ through â"groupN"â for some N. N is the number of supplementary
+ groups that the process has. Use the âinâ operator to test for
these elements (*note Reference to Elements::).
- The following elements allow you to change 'gawk''s behavior:
+ The following elements allow you to change âgawkââs behavior:
- 'PROCINFO["NONFATAL"]'
+ âPROCINFO["NONFATAL"]â
If this element exists, then I/O errors for all redirections
become nonfatal. *Note Nonfatal::.
- 'PROCINFO["NAME", "NONFATAL"]'
+ âPROCINFO["NAME", "NONFATAL"]â
Make I/O errors for NAME be nonfatal. *Note Nonfatal::.
- 'PROCINFO["COMMAND", "pty"]'
+ âPROCINFO["COMMAND", "pty"]â
For two-way communication to COMMAND, use a pseudo-tty instead
of setting up a two-way pipe. *Note Two-way I/O:: for more
information.
- 'PROCINFO["INPUT_NAME", "READ_TIMEOUT"]'
+ âPROCINFO["INPUT_NAME", "READ_TIMEOUT"]â
Set a timeout for reading from input redirection INPUT_NAME.
*Note Read Timeout:: for more information.
- 'PROCINFO["INPUT_NAME", "RETRY"]'
+ âPROCINFO["INPUT_NAME", "RETRY"]â
If an I/O error that may be retried occurs when reading data
- from INPUT_NAME, and this array entry exists, then 'getline'
- returns -2 instead of following the default behavior of
- returning -1 and configuring INPUT_NAME to return no further
- data. An I/O error that may be retried is one where 'errno'
- has the value 'EAGAIN', 'EWOULDBLOCK', 'EINTR', or
- 'ETIMEDOUT'. This may be useful in conjunction with
- 'PROCINFO["INPUT_NAME", "READ_TIMEOUT"]' or situations where a
+ from INPUT_NAME, and this array entry exists, then âgetlineâ
+ returns â2 instead of following the default behavior of
+ returning â1 and configuring INPUT_NAME to return no further
+ data. An I/O error that may be retried is one where âerrnoâ
+ has the value âEAGAINâ, âEWOULDBLOCKâ, âEINTRâ, or
+ âETIMEDOUTâ. This may be useful in conjunction with
+ âPROCINFO["INPUT_NAME", "READ_TIMEOUT"]â or situations where a
file descriptor has been configured to behave in a
non-blocking fashion. *Note Retrying Input:: for more
information.
- 'PROCINFO["sorted_in"]'
- If this element exists in 'PROCINFO', its value controls the
- order in which array indices will be processed by 'for (INDX
- in ARRAY)' loops. This is an advanced feature, so we defer
+ âPROCINFO["sorted_in"]â
+ If this element exists in âPROCINFOâ, its value controls the
+ order in which array indices will be processed by âfor (INDX
+ in ARRAY)â loops. This is an advanced feature, so we defer
the full description until later; see *note Controlling
Scanning::.
-'RLENGTH'
- The length of the substring matched by the 'match()' function
- (*note String Functions::). 'RLENGTH' is set by invoking the
- 'match()' function. Its value is the length of the matched string,
- or -1 if no match is found.
+âRLENGTHâ
+ The length of the substring matched by the âmatch()â function
+ (*note String Functions::). âRLENGTHâ is set by invoking the
+ âmatch()â function. Its value is the length of the matched string,
+ or â1 if no match is found.
-'RSTART'
+âRSTARTâ
The start index in characters of the substring that is matched by
- the 'match()' function (*note String Functions::). 'RSTART' is set
- by invoking the 'match()' function. Its value is the position of
+ the âmatch()â function (*note String Functions::). âRSTARTâ is
set
+ by invoking the âmatch()â function. Its value is the position of
the string where the matched substring starts, or zero if no match
was found.
-'RT #'
- The input text that matched the text denoted by 'RS', the record
+âRT #â
+ The input text that matched the text denoted by âRSâ, the record
separator. It is set every time a record is read.
-'SYMTAB #'
+âSYMTAB #â
An array whose indices are the names of all defined global
- variables and arrays in the program. 'SYMTAB' makes 'gawk''s
- symbol table visible to the 'awk' programmer. It is built as
- 'gawk' parses the program and is complete before the program starts
+ variables and arrays in the program. âSYMTABâ makes âgawkââs
+ symbol table visible to the âawkâ programmer. It is built as
+ âgawkâ parses the program and is complete before the program starts
to run.
The array may be used for indirect access to read or write the
@@ -11591,11 +11591,11 @@ they are not special:
SYMTAB["foo"] = 4
print foo # prints 4
- The 'isarray()' function (*note Type Functions::) may be used to
- test if an element in 'SYMTAB' is an array. Also, you may not use
- the 'delete' statement with the 'SYMTAB' array.
+ The âisarray()â function (*note Type Functions::) may be used to
+ test if an element in âSYMTABâ is an array. Also, you may not use
+ the âdeleteâ statement with the âSYMTABâ array.
- Prior to version 5.0 of 'gawk', you could use an index for 'SYMTAB'
+ Prior to version 5.0 of âgawkâ, you could use an index for
âSYMTABâ
that was not a predefined identifier:
SYMTAB["xxx"] = 5
@@ -11604,8 +11604,8 @@ they are not special:
This no longer works, instead producing a fatal error, as it led to
rampant confusion.
- The 'SYMTAB' array is more interesting than it looks. Andrew
- Schorr points out that it effectively gives 'awk' data pointers.
+ The âSYMTABâ array is more interesting than it looks. Andrew
+ Schorr points out that it effectively gives âawkâ data pointers.
Consider his example:
# Indirect multiply of any variable by amount, return result
@@ -11626,15 +11626,15 @@ they are not special:
When run, this produces:
$ gawk -f answer.awk
- -| The answer is 42
+ ⣠The answer is 42
NOTE: In order to avoid severe time-travel paradoxes,(2)
- neither 'FUNCTAB' nor 'SYMTAB' is available as an element
- within the 'SYMTAB' array.
+ neither âFUNCTABâ nor âSYMTABâ is available as an element
+ within the âSYMTABâ array.
- Changing 'NR' and 'FNR'
+ Changing âNRâ and âFNRâ
- 'awk' increments 'NR' and 'FNR' each time it reads a record, instead
+ âawkâ increments âNRâ and âFNRâ each time it reads a record,
instead
of setting them to the absolute value of the number of records read.
This means that a program can change these variables and their new
values are incremented for each record. (d.c.) The following example
@@ -11645,19 +11645,19 @@ shows this:
> 3
> 4' | awk 'NR == 2 { NR = 17 }
> { print NR }'
- -| 1
- -| 17
- -| 18
- -| 19
+ ⣠1
+ ⣠17
+ ⣠18
+ ⣠19
-Before 'FNR' was added to the 'awk' language (*note V7/SVR3.1::), many
-'awk' programs used this feature to track the number of records in a
-file by resetting 'NR' to zero when 'FILENAME' changed.
+Before âFNRâ was added to the âawkâ language (*note V7/SVR3.1::), many
+âawkâ programs used this feature to track the number of records in a
+file by resetting âNRâ to zero when âFILENAMEâ changed.
---------- Footnotes ----------
- (1) Some early implementations of Unix 'awk' initialized 'FILENAME'
-to '"-"', even if there were data files to be processed. This behavior
+ (1) Some early implementations of Unix âawkâ initialized âFILENAMEâ
+to â"-"â, even if there were data files to be processed. This behavior
was incorrect and should not be relied upon in your programs.
(2) Not to mention difficult implementation issues.
@@ -11665,28 +11665,28 @@ was incorrect and should not be relied upon in your
programs.
File: gawk.info, Node: ARGC and ARGV, Prev: Auto-set, Up: Built-in Variables
-7.5.3 Using 'ARGC' and 'ARGV'
+7.5.3 Using âARGCâ and âARGVâ
-----------------------------
*note Auto-set:: presented the following program describing the
-information contained in 'ARGC' and 'ARGV':
+information contained in âARGCâ and âARGVâ:
$ awk 'BEGIN {
> for (i = 0; i < ARGC; i++)
> print ARGV[i]
> }' inventory-shipped mail-list
- -| awk
- -| inventory-shipped
- -| mail-list
+ ⣠awk
+ ⣠inventory-shipped
+ ⣠mail-list
-In this example, 'ARGV[0]' contains 'awk', 'ARGV[1]' contains
-'inventory-shipped', and 'ARGV[2]' contains 'mail-list'. Notice that
-the 'awk' program is not entered in 'ARGV'. The other command-line
+In this example, âARGV[0]â contains âawkâ, âARGV[1]â contains
+âinventory-shippedâ, and âARGV[2]â contains âmail-listâ. Notice
that
+the âawkâ program is not entered in âARGVâ. The other command-line
options, with their arguments, are also not entered. This includes
-variable assignments done with the '-v' option (*note Options::).
+variable assignments done with the â-vâ option (*note Options::).
Normal variable assignments on the command line _are_ treated as
-arguments and do show up in the 'ARGV' array. Given the following
-program in a file named 'showargs.awk':
+arguments and do show up in the âARGVâ array. Given the following
+program in a file named âshowargs.awkâ:
BEGIN {
printf "A=%d, B=%d\n", A, B
@@ -11698,41 +11698,41 @@ program in a file named 'showargs.awk':
Running it produces the following:
$ awk -v A=1 -f showargs.awk B=2 /dev/null
- -| A=1, B=0
- -| ARGV[0] = awk
- -| ARGV[1] = B=2
- -| ARGV[2] = /dev/null
- -| A=1, B=2
-
- A program can alter 'ARGC' and the elements of 'ARGV'. Each time
-'awk' reaches the end of an input file, it uses the next element of
-'ARGV' as the name of the next input file. By storing a different
-string there, a program can change which files are read. Use '"-"' to
+ ⣠A=1, B=0
+ ⣠ARGV[0] = awk
+ ⣠ARGV[1] = B=2
+ ⣠ARGV[2] = /dev/null
+ ⣠A=1, B=2
+
+ A program can alter âARGCâ and the elements of âARGVâ. Each time
+âawkâ reaches the end of an input file, it uses the next element of
+âARGVâ as the name of the next input file. By storing a different
+string there, a program can change which files are read. Use â"-"â to
represent the standard input. Storing additional elements and
-incrementing 'ARGC' causes additional files to be read.
+incrementing âARGCâ causes additional files to be read.
- If the value of 'ARGC' is decreased, that eliminates input files from
-the end of the list. By recording the old value of 'ARGC' elsewhere, a
+ If the value of âARGCâ is decreased, that eliminates input files from
+the end of the list. By recording the old value of âARGCâ elsewhere, a
program can treat the eliminated arguments as something other than file
names.
To eliminate a file from the middle of the list, store the null
-string ('""') into 'ARGV' in place of the file's name. As a special
-feature, 'awk' ignores file names that have been replaced with the null
-string. Another option is to use the 'delete' statement to remove
-elements from 'ARGV' (*note Delete::).
+string (â""â) into âARGVâ in place of the fileâs name. As a special
+feature, âawkâ ignores file names that have been replaced with the null
+string. Another option is to use the âdeleteâ statement to remove
+elements from âARGVâ (*note Delete::).
- All of these actions are typically done in the 'BEGIN' rule, before
+ All of these actions are typically done in the âBEGINâ rule, before
actual processing of the input begins. *Note Split Program:: and *note
-Tee Program:: for examples of each way of removing elements from 'ARGV'.
+Tee Program:: for examples of each way of removing elements from âARGVâ.
- To actually get options into an 'awk' program, end the 'awk' options
-with '--' and then supply the 'awk' program's options, in the following
+ To actually get options into an âawkâ program, end the âawkâ options
+with â--â and then supply the âawkâ programâs options, in the
following
manner:
awk -f myprog.awk -- -v -q file1 file2 ...
- The following fragment processes 'ARGV' in order to examine, and then
+ The following fragment processes âARGVâ in order to examine, and then
remove, the previously mentioned command-line options:
BEGIN {
@@ -11751,23 +11751,23 @@ remove, the previously mentioned command-line options:
}
}
- Ending the 'awk' options with '--' isn't necessary in 'gawk'. Unless
-'--posix' has been specified, 'gawk' silently puts any unrecognized
-options into 'ARGV' for the 'awk' program to deal with. As soon as it
-sees an unknown option, 'gawk' stops looking for other options that it
-might otherwise recognize. The previous command line with 'gawk' would
+ Ending the âawkâ options with â--â isnât necessary in âgawkâ.
Unless
+â--posixâ has been specified, âgawkâ silently puts any unrecognized
+options into âARGVâ for the âawkâ program to deal with. As soon as it
+sees an unknown option, âgawkâ stops looking for other options that it
+might otherwise recognize. The previous command line with âgawkâ would
be:
gawk -f myprog.awk -q -v file1 file2 ...
-Because '-q' is not a valid 'gawk' option, it and the following '-v' are
-passed on to the 'awk' program. (*Note Getopt Function:: for an 'awk'
+Because â-qâ is not a valid âgawkâ option, it and the following
â-vâ are
+passed on to the âawkâ program. (*Note Getopt Function:: for an âawkâ
library function that parses command-line options.)
- When designing your program, you should choose options that don't
-conflict with 'gawk''s, because it will process any options that it
+ When designing your program, you should choose options that donât
+conflict with âgawkââs, because it will process any options that it
accepts before passing the rest of the command line on to your program.
-Using '#!' with the '-E' option may help (*note Executable Scripts:: and
+Using â#!â with the â-Eâ option may help (*note Executable Scripts::
and
*note Options::).
@@ -11776,80 +11776,80 @@ File: gawk.info, Node: Pattern Action Summary,
Prev: Built-in Variables, Up:
7.6 Summary
===========
- * Pattern-action pairs make up the basic elements of an 'awk'
+ ⢠Patternâaction pairs make up the basic elements of an âawkâ
program. Patterns are either normal expressions, range
expressions, or regexp constants; one of the special keywords
- 'BEGIN', 'END', 'BEGINFILE', or 'ENDFILE'; or empty. The action
+ âBEGINâ, âENDâ, âBEGINFILEâ, or âENDFILEâ; or empty. The
action
executes if the current record matches the pattern. Empty
(missing) patterns match all records.
- * I/O from 'BEGIN' and 'END' rules has certain constraints. This is
- also true, only more so, for 'BEGINFILE' and 'ENDFILE' rules. The
- latter two give you "hooks" into 'gawk''s file processing, allowing
+ ⢠I/O from âBEGINâ and âENDâ rules has certain constraints. This
is
+ also true, only more so, for âBEGINFILEâ and âENDFILEâ rules. The
+ latter two give you âhooksâ into âgawkââs file processing,
allowing
you to recover from a file that otherwise would cause a fatal error
(such as a file that cannot be opened).
- * Shell variables can be used in 'awk' programs by careful use of
- shell quoting. It is easier to pass a shell variable into 'awk' by
- using the '-v' option and an 'awk' variable.
+ ⢠Shell variables can be used in âawkâ programs by careful use of
+ shell quoting. It is easier to pass a shell variable into âawkâ by
+ using the â-vâ option and an âawkâ variable.
- * Actions consist of statements enclosed in curly braces. Statements
+ ⢠Actions consist of statements enclosed in curly braces. Statements
are built up from expressions, control statements, compound
statements, input and output statements, and deletion statements.
- * The control statements in 'awk' are 'if'-'else', 'while', 'for',
- and 'do'-'while'. 'gawk' adds the 'switch' statement. There are
- two flavors of 'for' statement: one for performing general looping,
+ ⢠The control statements in âawkâ are âifâ-âelseâ,
âwhileâ, âforâ,
+ and âdoâ-âwhileâ. âgawkâ adds the âswitchâ statement.
There are
+ two flavors of âforâ statement: one for performing general looping,
and the other for iterating through an array.
- * 'break' and 'continue' let you exit early or start the next
- iteration of a loop (or get out of a 'switch').
+ ⢠âbreakâ and âcontinueâ let you exit early or start the next
+ iteration of a loop (or get out of a âswitchâ).
- * 'next' and 'nextfile' let you read the next record and start over
+ ⢠ânextâ and ânextfileâ let you read the next record and start
over
at the top of your program or skip to the next input file and start
over, respectively.
- * The 'exit' statement terminates your program. When executed from
- an action (or function body), it transfers control to the 'END'
- statements. From an 'END' statement body, it exits immediately.
- You may pass an optional numeric value to be used as 'awk''s exit
+ ⢠The âexitâ statement terminates your program. When executed from
+ an action (or function body), it transfers control to the âENDâ
+ statements. From an âENDâ statement body, it exits immediately.
+ You may pass an optional numeric value to be used as âawkââs exit
status.
- * Some predefined variables provide control over 'awk', mainly for
- I/O. Other variables convey information from 'awk' to your program.
+ ⢠Some predefined variables provide control over âawkâ, mainly for
+ I/O. Other variables convey information from âawkâ to your program.
- * 'ARGC' and 'ARGV' make the command-line arguments available to your
- program. Manipulating them from a 'BEGIN' rule lets you control
- how 'awk' will process the provided data files.
+ ⢠âARGCâ and âARGVâ make the command-line arguments available to
your
+ program. Manipulating them from a âBEGINâ rule lets you control
+ how âawkâ will process the provided data files.
File: gawk.info, Node: Arrays, Next: Functions, Prev: Patterns and Actions,
Up: Top
-8 Arrays in 'awk'
+8 Arrays in âawkâ
*****************
-An "array" is a table of values called "elements". The elements of an
-array are distinguished by their "indices". Indices may be either
+An âarrayâ is a table of values called âelementsâ. The elements of an
+array are distinguished by their âindicesâ. Indices may be either
numbers or strings.
- This major node describes how arrays work in 'awk', how to use array
+ This major node describes how arrays work in âawkâ, how to use array
elements, how to scan through every element in an array, and how to
-remove array elements. It also describes how 'awk' simulates
+remove array elements. It also describes how âawkâ simulates
multidimensional arrays, as well as some of the less obvious points
-about array usage. The major node moves on to discuss 'gawk''s facility
-for sorting arrays, and ends with a brief description of 'gawk''s
+about array usage. The major node moves on to discuss âgawkââs facility
+for sorting arrays, and ends with a brief description of âgawkââs
ability to support true arrays of arrays.
* Menu:
* Array Basics:: The basics of arrays.
* Numeric Array Subscripts:: How to use numbers as subscripts in
- 'awk'.
+ âawkâ.
* Uninitialized Subscripts:: Using Uninitialized variables as subscripts.
-* Delete:: The 'delete' statement removes an element
+* Delete:: The âdeleteâ statement removes an element
from an array.
* Multidimensional:: Emulating multidimensional arrays in
- 'awk'.
+ âawkâ.
* Arrays of Arrays:: True multidimensional arrays.
* Arrays Summary:: Summary of arrays.
@@ -11868,8 +11868,8 @@ at a time, and traversing all of the elements in an
array.
* Reference to Elements:: How to examine one element of an array.
* Assigning Elements:: How to change an element of an array.
* Array Example:: Basic Example of an Array
-* Scanning an Array:: A variation of the 'for' statement. It
- loops through the indices of an array's
+* Scanning an Array:: A variation of the âforâ statement. It
+ loops through the indices of an arrayâs
existing elements.
* Controlling Scanning:: Controlling the order in which arrays are
scanned.
@@ -11882,21 +11882,21 @@ File: gawk.info, Node: Array Intro, Next: Reference
to Elements, Up: Array Ba
Doing linear scans over an associative array is like trying to club
someone to death with a loaded Uzi.
- -- _Larry Wall_
+ â _Larry Wall_
- The 'awk' language provides one-dimensional arrays for storing groups
-of related strings or numbers. Every 'awk' array must have a name.
+ The âawkâ language provides one-dimensional arrays for storing groups
+of related strings or numbers. Every âawkâ array must have a name.
Array names have the same syntax as variable names; any valid variable
name would also be a valid array name. But one name cannot be used in
-both ways (as an array and as a variable) in the same 'awk' program.
+both ways (as an array and as a variable) in the same âawkâ program.
- Arrays in 'awk' superficially resemble arrays in other programming
-languages, but there are fundamental differences. In 'awk', it isn't
+ Arrays in âawkâ superficially resemble arrays in other programming
+languages, but there are fundamental differences. In âawkâ, it isnât
necessary to specify the size of an array before starting to use it.
Additionally, any number or string, not just consecutive integers, may
be used as an array index.
- In most other languages, arrays must be "declared" before use,
+ In most other languages, arrays must be âdeclaredâ before use,
including a specification of how many elements or components they
contain. In such languages, the declaration causes a contiguous block
of memory to be allocated for that many elements. Usually, an index in
@@ -11906,13 +11906,13 @@ the beginning of the block of memory. Index one
specifies the second
element, which is stored in memory right after the first element, and so
on. It is impossible to add more elements to the array, because it has
room only for as many elements as given in the declaration. (Some
-languages allow arbitrary starting and ending indices--e.g., '15 ..
-27'--but the size of the array is still fixed when the array is
+languages allow arbitrary starting and ending indicesâe.g., â15 ..
+27ââbut the size of the array is still fixed when the array is
declared.)
A contiguous array of four elements might look like *note Figure 8.1:
figure-array-elements, conceptually, if the element values are eight,
-'"foo"', '""', and 30.
+â"foo"â, â""â, and 30.
[image src="array-elements.png" alt="A Contiguous Array"
text="+---------+---------+--------+---------+
@@ -11926,69 +11926,69 @@ Only the values are stored; the indices are implicit
from the order of
the values. Here, eight is the value at index zero, because eight
appears in the position with zero elements before it.
- Arrays in 'awk' are different--they are "associative". This means
-that each array is a collection of pairs--an index and its corresponding
+ Arrays in âawkâ are differentâthey are âassociativeâ. This means
+that each array is a collection of pairsâan index and its corresponding
array element value:
Index Value
------------------------
- '3' '30'
- '1' '"foo"'
- '0' '8'
- '2' '""'
+ â3â â30â
+ â1â â"foo"â
+ â0â â8â
+ â2â â""â
The pairs are shown in jumbled order because their order is
irrelevant.(1)
One advantage of associative arrays is that new pairs can be added at
any time. For example, suppose a tenth element is added to the array
-whose value is '"number ten"'. The result is:
+whose value is â"number ten"â. The result is:
Index Value
-------------------------------
- '10' '"number
- ten"'
- '3' '30'
- '1' '"foo"'
- '0' '8'
- '2' '""'
-
-Now the array is "sparse", which just means some indices are missing.
-It has elements 0-3 and 10, but doesn't have elements 4, 5, 6, 7, 8, or
+ â10â â"number
+ ten"â
+ â3â â30â
+ â1â â"foo"â
+ â0â â8â
+ â2â â""â
+
+Now the array is âsparseâ, which just means some indices are missing.
+It has elements 0â3 and 10, but doesnât have elements 4, 5, 6, 7, 8, or
9.
- Another consequence of associative arrays is that the indices don't
+ Another consequence of associative arrays is that the indices donât
have to be nonnegative integers. Any number, or even a string, can be
an index. For example, the following is an array that translates words
from English to French:
Index Value
------------------------
- '"dog"' '"chien"'
- '"cat"' '"chat"'
- '"one"' '"un"'
- '1' '"un"'
+ â"dog"â â"chien"â
+ â"cat"â â"chat"â
+ â"one"â â"un"â
+ â1â â"un"â
Here we decided to translate the number one in both spelled-out and
-numeric form--thus illustrating that a single array can have both
-numbers and strings as indices. (In fact, array subscripts are always
-strings. There are some subtleties to how numbers work when used as
-array subscripts; this is discussed in more detail in *note Numeric
-Array Subscripts::.) Here, the number '1' isn't double-quoted, because
-'awk' automatically converts it to a string.
-
- The value of 'IGNORECASE' has no effect upon array subscripting. The
+numeric formâthus illustrating that a single array can have both numbers
+and strings as indices. (In fact, array subscripts are always strings.
+There are some subtleties to how numbers work when used as array
+subscripts; this is discussed in more detail in *note Numeric Array
+Subscripts::.) Here, the number â1â isnât double-quoted, because
âawkâ
+automatically converts it to a string.
+
+ The value of âIGNORECASEâ has no effect upon array subscripting. The
identical string value used to store an array element must be used to
-retrieve it. When 'awk' creates an array (e.g., with the 'split()'
-built-in function), that array's indices are consecutive integers
+retrieve it. When âawkâ creates an array (e.g., with the âsplit()â
+built-in function), that arrayâs indices are consecutive integers
starting at one. (*Note String Functions::.)
- 'awk''s arrays are efficient--the time to access an element is
+ âawkââs arrays are efficientâthe time to access an element is
independent of the number of elements in the array.
---------- Footnotes ----------
- (1) The ordering will vary among 'awk' implementations, which
+ (1) The ordering will vary among âawkâ implementations, which
typically use hash tables to store array elements and values.
@@ -11998,7 +11998,7 @@ File: gawk.info, Node: Reference to Elements, Next:
Assigning Elements, Prev:
-----------------------------------
The principal way to use an array is to refer to one of its elements.
-An "array reference" is an expression as follows:
+An âarray referenceâ is an expression as follows:
ARRAY[INDEX-EXPRESSION]
@@ -12006,27 +12006,27 @@ Here, ARRAY is the name of an array. The expression
INDEX-EXPRESSION is
the index of the desired element of the array.
The value of the array reference is the current value of that array
-element. For example, 'foo[4.3]' is an expression referencing the
-element of array 'foo' at index '4.3'.
+element. For example, âfoo[4.3]â is an expression referencing the
+element of array âfooâ at index â4.3â.
A reference to an array element that has no recorded value yields a
-value of '""', the null string. This includes elements that have not
+value of â""â, the null string. This includes elements that have not
been assigned any value as well as elements that have been deleted
(*note Delete::).
NOTE: A reference to an element that does not exist _automatically_
creates that array element, with the null string as its value. (In
some cases, this is unfortunate, because it might waste memory
- inside 'awk'.)
+ inside âawkâ.)
- Novice 'awk' programmers often make the mistake of checking if an
+ Novice âawkâ programmers often make the mistake of checking if an
element exists by checking if the value is empty:
# Check if "foo" exists in a: Incorrect!
if (a["foo"] != "") ...
- This is incorrect for two reasons. First, it _creates_ 'a["foo"]'
- if it didn't exist before! Second, it is valid (if a bit unusual)
+ This is incorrect for two reasons. First, it _creates_ âa["foo"]â
+ if it didnât exist before! Second, it is valid (if a bit unusual)
to set an array element equal to the empty string.
To determine whether an element exists in an array at a certain
@@ -12036,18 +12036,18 @@ index, use the following expression:
This expression tests whether the particular index INDX exists, without
the side effect of creating that element if it is not present. The
-expression has the value one (true) if 'ARRAY[INDX]' exists and zero
-(false) if it does not exist. (We use INDX here, because 'index' is the
+expression has the value one (true) if âARRAY[INDX]â exists and zero
+(false) if it does not exist. (We use INDX here, because âindexâ is the
name of a built-in function.) For example, this statement tests whether
-the array 'frequencies' contains the index '2':
+the array âfrequenciesâ contains the index â2â:
if (2 in frequencies)
print "Subscript 2 is present."
- Note that this is _not_ a test of whether the array 'frequencies'
+ Note that this is _not_ a test of whether the array âfrequenciesâ
contains an element whose _value_ is two. There is no way to do that
except to scan all the elements. Also, this _does not_ create
-'frequencies[2]', while the following (incorrect) alternative does:
+âfrequencies[2]â, while the following (incorrect) alternative does:
if (frequencies[2] != "")
print "Subscript 2 is present."
@@ -12058,7 +12058,7 @@ File: gawk.info, Node: Assigning Elements, Next:
Array Example, Prev: Referen
8.1.3 Assigning Array Elements
------------------------------
-Array elements can be assigned values just like 'awk' variables:
+Array elements can be assigned values just like âawkâ variables:
ARRAY[INDEX-EXPRESSION] = VALUE
@@ -12074,11 +12074,11 @@ File: gawk.info, Node: Array Example, Next:
Scanning an Array, Prev: Assignin
The following program takes a list of lines, each beginning with a line
number, and prints them out in order of line number. The line numbers
-are not in order when they are first read--instead, they are scrambled.
+are not in order when they are first readâinstead, they are scrambled.
This program sorts the lines by making an array using the line numbers
as subscripts. The program then prints out the lines in sorted order of
their numbers. It is a very simple program and gets confused upon
-encountering repeated numbers, gaps, or lines that don't begin with a
+encountering repeated numbers, gaps, or lines that donât begin with a
number:
{
@@ -12093,8 +12093,8 @@ number:
}
The first rule keeps track of the largest line number seen so far; it
-also stores each line into the array 'arr', at an index that is the
-line's number. The second rule runs after all the input has been read,
+also stores each line into the array âarrâ, at an index that is the
+lineâs number. The second rule runs after all the input has been read,
to print out all the lines. When this program is run with the following
input:
@@ -12114,7 +12114,7 @@ Its output is:
If a line number is repeated, the last line with a given number
overrides the others. Gaps in the line numbers can be handled with an
-easy improvement to the program's 'END' rule, as follows:
+easy improvement to the programâs âENDâ rule, as follows:
END {
for (x = 1; x <= max; x++)
@@ -12136,9 +12136,9 @@ In programs that use arrays, it is often necessary to
use a loop that
executes once for each element of an array. In other languages, where
arrays are contiguous and indices are limited to nonnegative integers,
this is easy: all the valid indices can be found by counting from the
-lowest index up to the highest. This technique won't do the job in
-'awk', because any number or string can be an array index. So 'awk' has
-a special kind of 'for' statement for scanning an array:
+lowest index up to the highest. This technique wonât do the job in
+âawkâ, because any number or string can be an array index. So âawkâ
has
+a special kind of âforâ statement for scanning an array:
for (VAR in ARRAY)
BODY
@@ -12146,14 +12146,14 @@ a special kind of 'for' statement for scanning an
array:
This loop executes BODY once for each index in ARRAY that the program
has previously used, with the variable VAR set to that index.
- The following program uses this form of the 'for' statement. The
+ The following program uses this form of the âforâ statement. The
first rule scans the input records and notes which words appear (at
-least once) in the input, by storing a one into the array 'used' with
-the word as the index. The second rule scans the elements of 'used' to
+least once) in the input, by storing a one into the array âusedâ with
+the word as the index. The second rule scans the elements of âusedâ to
find all the distinct words that appear in the input. It prints each
word that is more than 10 characters long and also prints the number of
such words. *Note String Functions:: for more information on the
-built-in function 'length()'.
+built-in function âlength()â.
# Record a 1 for each word that is used at least once
{
@@ -12176,15 +12176,15 @@ built-in function 'length()'.
The order in which elements of the array are accessed by this
statement is determined by the internal arrangement of the array
-elements within 'awk' and in standard 'awk' cannot be controlled or
+elements within âawkâ and in standard âawkâ cannot be controlled or
changed. This can lead to problems if new elements are added to ARRAY
-by statements in the loop body; it is not predictable whether the 'for'
+by statements in the loop body; it is not predictable whether the âforâ
loop will reach them. Similarly, changing VAR inside the loop may
produce strange results. It is best to avoid such things.
- As a point of information, 'gawk' sets up the list of elements to be
+ As a point of information, âgawkâ sets up the list of elements to be
iterated over before the loop starts, and does not change it. But not
-all 'awk' versions do so. Consider this program, named 'loopcheck.awk':
+all âawkâ versions do so. Consider this program, named
âloopcheck.awkâ:
BEGIN {
a["here"] = "here"
@@ -12198,127 +12198,127 @@ all 'awk' versions do so. Consider this program,
named 'loopcheck.awk':
}
}
- Here is what happens when run with 'gawk' (and 'mawk'):
+ Here is what happens when run with âgawkâ (and âmawkâ):
$ gawk -f loopcheck.awk
- -| here
- -| loop
- -| a
- -| is
+ ⣠here
+ ⣠loop
+ ⣠a
+ ⣠is
- Contrast this to BWK 'awk':
+ Contrast this to BWK âawkâ:
$ nawk -f loopcheck.awk
- -| loop
- -| here
- -| is
- -| a
- -| 1
+ ⣠loop
+ ⣠here
+ ⣠is
+ ⣠a
+ ⣠1
File: gawk.info, Node: Controlling Scanning, Prev: Scanning an Array, Up:
Array Basics
-8.1.6 Using Predefined Array Scanning Orders with 'gawk'
+8.1.6 Using Predefined Array Scanning Orders with âgawkâ
--------------------------------------------------------
-This node describes a feature that is specific to 'gawk'.
+This node describes a feature that is specific to âgawkâ.
- By default, when a 'for' loop traverses an array, the order is
-undefined, meaning that the 'awk' implementation determines the order in
+ By default, when a âforâ loop traverses an array, the order is
+undefined, meaning that the âawkâ implementation determines the order in
which the array is traversed. This order is usually based on the
internal implementation of arrays and will vary from one version of
-'awk' to the next.
+âawkâ to the next.
- Often, though, you may wish to do something simple, such as "traverse
-the array by comparing the indices in ascending order," or "traverse the
-array by comparing the values in descending order." 'gawk' provides two
+ Often, though, you may wish to do something simple, such as âtraverse
+the array by comparing the indices in ascending order,â or âtraverse the
+array by comparing the values in descending order.â âgawkâ provides two
mechanisms that give you this control:
- * Set 'PROCINFO["sorted_in"]' to one of a set of predefined values.
+ ⢠Set âPROCINFO["sorted_in"]â to one of a set of predefined values.
We describe this now.
- * Set 'PROCINFO["sorted_in"]' to the name of a user-defined function
+ ⢠Set âPROCINFO["sorted_in"]â to the name of a user-defined function
to use for comparison of array elements. This advanced feature is
described later in *note Array Sorting::.
- The following special values for 'PROCINFO["sorted_in"]' are
+ The following special values for âPROCINFO["sorted_in"]â are
available:
-'"@unsorted"'
+â"@unsorted"â
Array elements are processed in arbitrary order, which is the
- default 'awk' behavior.
+ default âawkâ behavior.
-'"@ind_str_asc"'
+â"@ind_str_asc"â
Order by indices in ascending order compared as strings; this is
the most basic sort. (Internally, array indices are always
- strings, so with 'a[2*5] = 1' the index is '"10"' rather than
+ strings, so with âa[2*5] = 1â the index is â"10"â rather than
numeric 10.)
-'"@ind_num_asc"'
+â"@ind_num_asc"â
Order by indices in ascending order but force them to be treated as
numbers in the process. Any index with a non-numeric value will
end up positioned as if it were zero.
-'"@val_type_asc"'
+â"@val_type_asc"â
Order by element values in ascending order (rather than by
indices). Ordering is by the type assigned to the element (*note
Typing and Comparison::). All numeric values come before all
string values, which in turn come before all subarrays. (Subarrays
have not been described yet; *note Arrays of Arrays::.)
- If you choose to use this feature in traversing 'FUNCTAB' (*note
+ If you choose to use this feature in traversing âFUNCTABâ (*note
Auto-set::), then the order is built-in functions first (*note
Built-in::), then user-defined functions (*note User-defined::)
next, and finally functions loaded from an extension (*note Dynamic
Extensions::).
-'"@val_str_asc"'
+â"@val_str_asc"â
Order by element values in ascending order (rather than by
indices). Scalar values are compared as strings. If the string
values are identical, the index string values are compared instead.
- When comparing non-scalar values, '"@val_type_asc"' sort ordering
+ When comparing non-scalar values, â"@val_type_asc"â sort ordering
is used, so subarrays, if present, come out last.
-'"@val_num_asc"'
+â"@val_num_asc"â
Order by element values in ascending order (rather than by
indices). Scalar values are compared as numbers. Non-scalar
- values are compared using '"@val_type_asc"' sort ordering, so
+ values are compared using â"@val_type_asc"â sort ordering, so
subarrays, if present, come out last. When numeric values are
equal, the string values are used to provide an ordering: this
guarantees consistent results across different versions of the C
- 'qsort()' function,(1) which 'gawk' uses internally to perform the
+ âqsort()â function,(1) which âgawkâ uses internally to perform the
sorting. If the string values are also identical, the index string
values are compared instead.
-'"@ind_str_desc"'
- Like '"@ind_str_asc"', but the string indices are ordered from high
+â"@ind_str_desc"â
+ Like â"@ind_str_asc"â, but the string indices are ordered from high
to low.
-'"@ind_num_desc"'
- Like '"@ind_num_asc"', but the numeric indices are ordered from
+â"@ind_num_desc"â
+ Like â"@ind_num_asc"â, but the numeric indices are ordered from
high to low.
-'"@val_type_desc"'
- Like '"@val_type_asc"', but the element values, based on type, are
+â"@val_type_desc"â
+ Like â"@val_type_asc"â, but the element values, based on type, are
ordered from high to low. Subarrays, if present, come out first.
-'"@val_str_desc"'
- Like '"@val_str_asc"', but the element values, treated as strings,
+â"@val_str_desc"â
+ Like â"@val_str_asc"â, but the element values, treated as strings,
are ordered from high to low. If the string values are identical,
the index string values are compared instead. When comparing
- non-scalar values, '"@val_type_desc"' sort ordering is used, so
+ non-scalar values, â"@val_type_desc"â sort ordering is used, so
subarrays, if present, come out first.
-'"@val_num_desc"'
- Like '"@val_num_asc"', but the element values, treated as numbers,
+â"@val_num_desc"â
+ Like â"@val_num_asc"â, but the element values, treated as numbers,
are ordered from high to low. If the numeric values are equal, the
string values are compared instead. If they are also identical,
the index string values are compared instead. Non-scalar values
- are compared using '"@val_type_desc"' sort ordering, so subarrays,
+ are compared using â"@val_type_desc"â sort ordering, so subarrays,
if present, come out first.
- The array traversal order is determined before the 'for' loop starts
-to run. Changing 'PROCINFO["sorted_in"]' in the loop body does not
+ The array traversal order is determined before the âforâ loop starts
+to run. Changing âPROCINFO["sorted_in"]â in the loop body does not
affect the loop. For example:
$ gawk '
@@ -12328,8 +12328,8 @@ affect the loop. For example:
> for (i in a)
> print i, a[i]
> }'
- -| 4 4
- -| 3 3
+ ⣠4 4
+ ⣠3 3
$ gawk '
> BEGIN {
> PROCINFO["sorted_in"] = "@ind_str_asc"
@@ -12338,8 +12338,8 @@ affect the loop. For example:
> for (i in a)
> print i, a[i]
> }'
- -| 3 3
- -| 4 4
+ ⣠3 3
+ ⣠4 4
When sorting an array by element values, if a value happens to be a
subarray then it is considered to be greater than any string or numeric
@@ -12350,9 +12350,9 @@ relative to each other is determined by their index
strings.
Here are some additional things to bear in mind about sorted array
traversal:
- * The value of 'PROCINFO["sorted_in"]' is global. That is, it
- affects all array traversal 'for' loops. If you need to change it
- within your own code, you should see if it's defined and save and
+ ⢠The value of âPROCINFO["sorted_in"]â is global. That is, it
+ affects all array traversal âforâ loops. If you need to change it
+ within your own code, you should see if itâs defined and save and
restore the value:
...
@@ -12364,22 +12364,22 @@ traversal:
if (save_sorted)
PROCINFO["sorted_in"] = save_sorted
- * As already mentioned, the default array traversal order is
- represented by '"@unsorted"'. You can also get the default
- behavior by assigning the null string to 'PROCINFO["sorted_in"]' or
- by just deleting the '"sorted_in"' element from the 'PROCINFO'
- array with the 'delete' statement. (The 'delete' statement hasn't
+ ⢠As already mentioned, the default array traversal order is
+ represented by â"@unsorted"â. You can also get the default
+ behavior by assigning the null string to âPROCINFO["sorted_in"]â or
+ by just deleting the â"sorted_in"â element from the âPROCINFOâ
+ array with the âdeleteâ statement. (The âdeleteâ statement
hasnât
been described yet; *note Delete::.)
- In addition, 'gawk' provides built-in functions for sorting arrays;
+ In addition, âgawkâ provides built-in functions for sorting arrays;
see *note Array Sorting Functions::.
---------- Footnotes ----------
- (1) When two elements compare as equal, the C 'qsort()' function does
+ (1) When two elements compare as equal, the C âqsort()â function does
not guarantee that they will maintain their original relative order
after sorting. Using the string value to provide a unique ordering when
-the numeric values are equal ensures that 'gawk' behaves consistently
+the numeric values are equal ensures that âgawkâ behaves consistently
across different environments.
@@ -12392,7 +12392,7 @@ An important aspect to remember about arrays is that
_array subscripts
are always strings_. When a numeric value is used as a subscript, it is
converted to a string value before being used for subscripting (*note
Conversion::). This means that the value of the predefined variable
-'CONVFMT' can affect how your program accesses elements of an array.
+âCONVFMTâ can affect how your program accesses elements of an array.
For example:
xyz = 12.153
@@ -12403,32 +12403,32 @@ For example:
else
printf "%s is not in data\n", xyz
-This prints '12.15 is not in data'. The first statement gives 'xyz' a
-numeric value. Assigning to 'data[xyz]' subscripts 'data' with the
-string value '"12.153"' (using the default conversion value of
-'CONVFMT', '"%.6g"'). Thus, the array element 'data["12.153"]' is
+This prints â12.15 is not in dataâ. The first statement gives âxyzâ a
+numeric value. Assigning to âdata[xyz]â subscripts âdataâ with the
+string value â"12.153"â (using the default conversion value of
+âCONVFMTâ, â"%.6g"â). Thus, the array element âdata["12.153"]â is
assigned the value one. The program then changes the value of
-'CONVFMT'. The test '(xyz in data)' generates a new string value from
-'xyz'--this time '"12.15"'--because the value of 'CONVFMT' only allows
-two significant digits. This test fails, because '"12.15"' is different
-from '"12.153"'.
+âCONVFMTâ. The test â(xyz in data)â generates a new string value from
+âxyzââthis time â"12.15"ââbecause the value of âCONVFMTâ only
allows two
+significant digits. This test fails, because â"12.15"â is different
+from â"12.153"â.
According to the rules for conversions (*note Conversion::), integer
values always convert to strings as integers, no matter what the value
-of 'CONVFMT' may happen to be. So the usual case of the following
+of âCONVFMTâ may happen to be. So the usual case of the following
works:
for (i = 1; i <= maxsub; i++)
do something with array[i]
- The "integer values always convert to strings as integers" rule has
+ The âinteger values always convert to strings as integersâ rule has
an additional consequence for array indexing. Octal and hexadecimal
constants (*note Nondecimal-numbers::) are converted internally into
numbers, and their original form is forgotten. This means, for example,
-that 'array[17]', 'array[021]', and 'array[0x11]' all refer to the same
+that âarray[17]â, âarray[021]â, and âarray[0x11]â all refer to the
same
element!
- As with many things in 'awk', the majority of the time things work as
+ As with many things in âawkâ, the majority of the time things work as
you would expect them to. But it is useful to have a precise knowledge
of the actual rules, as they can sometimes have a subtle effect on your
programs.
@@ -12439,7 +12439,7 @@ File: gawk.info, Node: Uninitialized Subscripts,
Next: Delete, Prev: Numeric
8.3 Using Uninitialized Variables as Subscripts
===============================================
-Suppose it's necessary to write a program to print the input data in
+Suppose itâs necessary to write a program to print the input data in
reverse order. A reasonable attempt to do so (with some test data)
might look like this:
@@ -12450,20 +12450,20 @@ might look like this:
> for (i = lines - 1; i >= 0; i--)
> print l[i]
> }'
- -| line 3
- -| line 2
+ ⣠line 3
+ ⣠line 2
Unfortunately, the very first line of input data did not appear in
the output!
Upon first glance, we would think that this program should have
-worked. The variable 'lines' is uninitialized, and uninitialized
-variables have the numeric value zero. So, 'awk' should have printed
-the value of 'l[0]'.
+worked. The variable âlinesâ is uninitialized, and uninitialized
+variables have the numeric value zero. So, âawkâ should have printed
+the value of âl[0]â.
- The issue here is that subscripts for 'awk' arrays are _always_
+ The issue here is that subscripts for âawkâ arrays are _always_
strings. Uninitialized variables, when used as strings, have the value
-'""', not zero. Thus, 'line 1' ends up stored in 'l[""]'. The
+â""â, not zero. Thus, âline 1â ends up stored in âl[""]â. The
following version of the program works correctly:
{ l[lines++] = $0 }
@@ -12472,22 +12472,22 @@ following version of the program works correctly:
print l[i]
}
- Here, the '++' forces 'lines' to be numeric, thus making the "old
-value" numeric zero. This is then converted to '"0"' as the array
+ Here, the â++â forces âlinesâ to be numeric, thus making the âold
+valueâ numeric zero. This is then converted to â"0"â as the array
subscript.
- Even though it is somewhat unusual, the null string ('""') is a valid
-array subscript. (d.c.) 'gawk' warns about the use of the null string
-as a subscript if '--lint' is provided on the command line (*note
+ Even though it is somewhat unusual, the null string (â""â) is a valid
+array subscript. (d.c.) âgawkâ warns about the use of the null string
+as a subscript if â--lintâ is provided on the command line (*note
Options::).
File: gawk.info, Node: Delete, Next: Multidimensional, Prev: Uninitialized
Subscripts, Up: Arrays
-8.4 The 'delete' Statement
+8.4 The âdeleteâ Statement
==========================
-To remove an individual element of an array, use the 'delete' statement:
+To remove an individual element of an array, use the âdeleteâ statement:
delete ARRAY[INDEX-EXPRESSION]
@@ -12499,9 +12499,9 @@ deleting elements in an array:
for (i in frequencies)
delete frequencies[i]
-This example removes all the elements from the array 'frequencies'.
-Once an element is deleted, a subsequent 'for' statement to scan the
-array does not report that element and using the 'in' operator to check
+This example removes all the elements from the array âfrequenciesâ.
+Once an element is deleted, a subsequent âforâ statement to scan the
+array does not report that element and using the âinâ operator to check
for the presence of that element returns zero (i.e., false):
delete foo[4]
@@ -12509,30 +12509,30 @@ for the presence of that element returns zero (i.e.,
false):
print "This will never be printed"
It is important to note that deleting an element is _not_ the same as
-assigning it a null value (the empty string, '""'). For example:
+assigning it a null value (the empty string, â""â). For example:
foo[4] = ""
if (4 in foo)
print "This is printed, even though foo[4] is empty"
It is not an error to delete an element that does not exist.
-However, if '--lint' is provided on the command line (*note Options::),
-'gawk' issues a warning message when an element that is not in the array
+However, if â--lintâ is provided on the command line (*note Options::),
+âgawkâ issues a warning message when an element that is not in the array
is deleted.
All the elements of an array may be deleted with a single statement
-by leaving off the subscript in the 'delete' statement, as follows:
+by leaving off the subscript in the âdeleteâ statement, as follows:
delete ARRAY
- Using this version of the 'delete' statement is about three times
+ Using this version of the âdeleteâ statement is about three times
more efficient than the equivalent loop that deletes each element one at
a time.
- This form of the 'delete' statement is also supported by BWK 'awk'
-and 'mawk', as well as by a number of other implementations.
+ This form of the âdeleteâ statement is also supported by BWK âawkâ
+and âmawkâ, as well as by a number of other implementations.
- NOTE: For many years, using 'delete' without a subscript was a
+ NOTE: For many years, using âdeleteâ without a subscript was a
common extension. In September 2012, it was accepted for inclusion
into the POSIX standard. See the Austin Group website
(http://austingroupbugs.net/view.php?id=544).
@@ -12542,13 +12542,13 @@ clear out an array:(1)
split("", array)
- The 'split()' function (*note String Functions::) clears out the
+ The âsplit()â function (*note String Functions::) clears out the
target array first. This call asks it to split apart the null string.
Because there is no data to split out, the function simply clears the
array and then returns.
CAUTION: Deleting all the elements from an array does not change
- its type; you cannot clear an array and then use the array's name
+ its type; you cannot clear an array and then use the arrayâs name
as a scalar (i.e., a regular variable). For example, the following
does not work:
@@ -12570,39 +12570,39 @@ File: gawk.info, Node: Multidimensional, Next:
Arrays of Arrays, Prev: Delete
* Multiscanning:: Scanning multidimensional arrays.
-A "multidimensional array" is an array in which an element is identified
+A âmultidimensional arrayâ is an array in which an element is identified
by a sequence of indices instead of a single index. For example, a
two-dimensional array requires two indices. The usual way (in many
-languages, including 'awk') to refer to an element of a two-dimensional
-array named 'grid' is with 'grid[X,Y]'.
+languages, including âawkâ) to refer to an element of a two-dimensional
+array named âgridâ is with âgrid[X,Y]â.
- Multidimensional arrays are supported in 'awk' through concatenation
-of indices into one string. 'awk' converts the indices into strings
+ Multidimensional arrays are supported in âawkâ through concatenation
+of indices into one string. âawkâ converts the indices into strings
(*note Conversion::) and concatenates them together, with a separator
between them. This creates a single string that describes the values of
the separate indices. The combined string is used as a single index
into an ordinary, one-dimensional array. The separator used is the
-value of the built-in variable 'SUBSEP'.
+value of the built-in variable âSUBSEPâ.
- For example, suppose we evaluate the expression 'foo[5,12] = "value"'
-when the value of 'SUBSEP' is '"@"'. The numbers 5 and 12 are converted
-to strings and concatenated with an '@' between them, yielding '"5@12"';
-thus, the array element 'foo["5@12"]' is set to '"value"'.
+ For example, suppose we evaluate the expression âfoo[5,12] = "value"â
+when the value of âSUBSEPâ is â"@"â. The numbers 5 and 12 are
converted
+to strings and concatenated with an â@â between them, yielding
â"5@12"â;
+thus, the array element âfoo["5@12"]â is set to â"value"â.
- Once the element's value is stored, 'awk' has no record of whether it
+ Once the elementâs value is stored, âawkâ has no record of whether it
was stored with a single index or a sequence of indices. The two
-expressions 'foo[5,12]' and 'foo[5 SUBSEP 12]' are always equivalent.
+expressions âfoo[5,12]â and âfoo[5 SUBSEP 12]â are always equivalent.
- The default value of 'SUBSEP' is the string '"\034"', which contains
-a nonprinting character that is unlikely to appear in an 'awk' program
+ The default value of âSUBSEPâ is the string â"\034"â, which contains
+a nonprinting character that is unlikely to appear in an âawkâ program
or in most input data. The usefulness of choosing an unlikely character
comes from the fact that index values that contain a string matching
-'SUBSEP' can lead to combined strings that are ambiguous. Suppose that
-'SUBSEP' is '"@"'; then 'foo["a@b", "c"]' and 'foo["a", "b@c"]' are
-indistinguishable because both are actually stored as 'foo["a@b@c"]'.
+âSUBSEPâ can lead to combined strings that are ambiguous. Suppose that
+âSUBSEPâ is â"@"â; then âfoo["a@b", "c"]â and âfoo["a",
"b@c"]â are
+indistinguishable because both are actually stored as âfoo["a@b@c"]â.
To test whether a particular index sequence exists in a
-multidimensional array, use the same operator ('in') that is used for
+multidimensional array, use the same operator (âinâ) that is used for
single-dimensional arrays. Write the whole sequence of indices in
parentheses, separated by commas, as the left operand:
@@ -12651,15 +12651,15 @@ File: gawk.info, Node: Multiscanning, Up:
Multidimensional
8.5.1 Scanning Multidimensional Arrays
--------------------------------------
-There is no special 'for' statement for scanning a "multidimensional"
-array. There cannot be one, because, in truth, 'awk' does not have
-multidimensional arrays or elements--there is only a multidimensional
+There is no special âforâ statement for scanning a âmultidimensionalâ
+array. There cannot be one, because, in truth, âawkâ does not have
+multidimensional arrays or elementsâthere is only a multidimensional
_way of accessing_ an array.
However, if your program has an array that is always accessed as
multidimensional, you can get the effect of scanning it by combining the
-scanning 'for' statement (*note Scanning an Array::) with the built-in
-'split()' function (*note String Functions::). It works in the
+scanning âforâ statement (*note Scanning an Array::) with the built-in
+âsplit()â function (*note String Functions::). It works in the
following manner:
for (combined in array) {
@@ -12667,22 +12667,22 @@ following manner:
...
}
-This sets the variable 'combined' to each concatenated combined index in
+This sets the variable âcombinedâ to each concatenated combined index in
the array, and splits it into the individual indices by breaking it
-apart where the value of 'SUBSEP' appears. The individual indices then
-become the elements of the array 'separate'.
-
- Thus, if a value is previously stored in 'array[1, "foo"]', then an
-element with index '"1\034foo"' exists in 'array'. (Recall that the
-default value of 'SUBSEP' is the character with code 034.) Sooner or
-later, the 'for' statement finds that index and does an iteration with
-the variable 'combined' set to '"1\034foo"'. Then the 'split()'
+apart where the value of âSUBSEPâ appears. The individual indices then
+become the elements of the array âseparateâ.
+
+ Thus, if a value is previously stored in âarray[1, "foo"]â, then an
+element with index â"1\034foo"â exists in âarrayâ. (Recall that the
+default value of âSUBSEPâ is the character with code 034.) Sooner or
+later, the âforâ statement finds that index and does an iteration with
+the variable âcombinedâ set to â"1\034foo"â. Then the âsplit()â
function is called as follows:
split("1\034foo", separate, "\034")
-The result is to set 'separate[1]' to '"1"' and 'separate[2]' to
-'"foo"'. Presto! The original sequence of separate indices is
+The result is to set âseparate[1]â to â"1"â and âseparate[2]â to
+â"foo"â. Presto! The original sequence of separate indices is
recovered.
@@ -12691,11 +12691,11 @@ File: gawk.info, Node: Arrays of Arrays, Next:
Arrays Summary, Prev: Multidim
8.6 Arrays of Arrays
====================
-'gawk' goes beyond standard 'awk''s multidimensional array access and
+âgawkâ goes beyond standard âawkââs multidimensional array access and
provides true arrays of arrays. Elements of a subarray are referred to
by their own indices enclosed in square brackets, just like the elements
of the main array. For example, the following creates a two-element
-subarray at index '1' of the main array 'a':
+subarray at index â1â of the main array âaâ:
a[1][1] = 1
a[1][2] = 2
@@ -12703,9 +12703,9 @@ subarray at index '1' of the main array 'a':
This simulates a true two-dimensional array. Each subarray element
can contain another subarray as a value, which in turn can hold other
arrays as well. In this way, you can create arrays of three or more
-dimensions. The indices can be any 'awk' expressions, including scalars
-separated by commas (i.e., a regular 'awk' simulated multidimensional
-subscript). So the following is valid in 'gawk':
+dimensions. The indices can be any âawkâ expressions, including scalars
+separated by commas (i.e., a regular âawkâ simulated multidimensional
+subscript). So the following is valid in âgawkâ:
a[1][3][1, "name"] = "barney"
@@ -12713,49 +12713,49 @@ subscript). So the following is valid in 'gawk':
fact, the elements of an array or its subarray do not all have to have
the same type. This means that the main array and any of its subarrays
can be nonrectangular, or jagged in structure. You can assign a scalar
-value to the index '4' of the main array 'a', even though 'a[1]' is
+value to the index â4â of the main array âaâ, even though âa[1]â is
itself an array and not a scalar:
a[4] = "An element in a jagged array"
- The terms "dimension", "row", and "column" are meaningless when
-applied to such an array, but we will use "dimension" henceforth to
+ The terms âdimensionâ, ârowâ, and âcolumnâ are meaningless when
+applied to such an array, but we will use âdimensionâ henceforth to
imply the maximum number of indices needed to refer to an existing
element. The type of any element that has already been assigned cannot
be changed by assigning a value of a different type. You have to first
-delete the current element, which effectively makes 'gawk' forget about
+delete the current element, which effectively makes âgawkâ forget about
the element at that index:
delete a[4]
a[4][5][6][7] = "An element in a four-dimensional array"
-This removes the scalar value from index '4' and then inserts a
+This removes the scalar value from index â4â and then inserts a
three-level nested subarray containing a scalar. You can also delete an
entire subarray or subarray of subarrays:
delete a[4][5]
a[4][5] = "An element in subarray a[4]"
- But recall that you can not delete the main array 'a' and then use it
+ But recall that you can not delete the main array âaâ and then use it
as a scalar.
The built-in functions that take array arguments can also be used
with subarrays. For example, the following code fragment uses
-'length()' (*note String Functions::) to determine the number of
-elements in the main array 'a' and its subarrays:
+âlength()â (*note String Functions::) to determine the number of
+elements in the main array âaâ and its subarrays:
print length(a), length(a[1]), length(a[1][3])
-This results in the following output for our main array 'a':
+This results in the following output for our main array âaâ:
2, 3, 1
-The 'SUBSCRIPT in ARRAY' expression (*note Reference to Elements::)
-works similarly for both regular 'awk'-style arrays and arrays of
-arrays. For example, the tests '1 in a', '3 in a[1]', and '(1, "name")
-in a[1][3]' all evaluate to one (true) for our array 'a'.
+The âSUBSCRIPT in ARRAYâ expression (*note Reference to Elements::)
+works similarly for both regular âawkâ-style arrays and arrays of
+arrays. For example, the tests â1 in aâ, â3 in a[1]â, and â(1,
"name")
+in a[1][3]â all evaluate to one (true) for our array âaâ.
- The 'for (item in array)' statement (*note Scanning an Array::) can
+ The âfor (item in array)â statement (*note Scanning an Array::) can
be nested to scan all the elements of an array of arrays if it is
rectangular in structure. In order to print the contents (scalar
values) of a two-dimensional array of arrays (i.e., in which each
@@ -12766,7 +12766,7 @@ length), you could use the following code:
for (j in array[i])
print array[i][j]
- The 'isarray()' function (*note Type Functions::) lets you test if an
+ The âisarray()â function (*note Type Functions::) lets you test if an
array element is itself an array:
for (i in array) {
@@ -12781,7 +12781,7 @@ array element is itself an array:
If the structure of a jagged array of arrays is known in advance, you
can often devise workarounds using control statements. For example, the
-following code prints the elements of our main array 'a':
+following code prints the elements of our main array âaâ:
for (i in a) {
for (j in a[i]) {
@@ -12793,22 +12793,22 @@ following code prints the elements of our main array
'a':
}
}
-*Note Walking Arrays:: for a user-defined function that "walks" an
+*Note Walking Arrays:: for a user-defined function that âwalksâ an
arbitrarily dimensioned array of arrays.
Recall that a reference to an uninitialized array element yields a
-value of '""', the null string. This has one important implication when
+value of â""â, the null string. This has one important implication when
you intend to use a subarray as an argument to a function, as
illustrated by the following example:
$ gawk 'BEGIN { split("a b c d", b[1]); print b[1][1] }'
- error-> gawk: cmd. line:1: fatal: split: second argument is not an array
+ errorâ gawk: cmd. line:1: fatal: split: second argument is not an array
- The way to work around this is to first force 'b[1]' to be an array
+ The way to work around this is to first force âb[1]â to be an array
by creating an arbitrary index:
$ gawk 'BEGIN { b[1][1] = ""; split("a b c d", b[1]); print b[1][1] }'
- -| a
+ ⣠a
File: gawk.info, Node: Arrays Summary, Prev: Arrays of Arrays, Up: Arrays
@@ -12816,45 +12816,45 @@ File: gawk.info, Node: Arrays Summary, Prev: Arrays
of Arrays, Up: Arrays
8.7 Summary
===========
- * Standard 'awk' provides one-dimensional associative arrays (arrays
+ ⢠Standard âawkâ provides one-dimensional associative arrays (arrays
indexed by string values). All arrays are associative; numeric
indices are converted automatically to strings.
- * Array elements are referenced as 'ARRAY[INDX]'. Referencing an
+ ⢠Array elements are referenced as âARRAY[INDX]â. Referencing an
element creates it if it did not exist previously.
- * The proper way to see if an array has an element with a given index
- is to use the 'in' operator: 'INDX in ARRAY'.
+ ⢠The proper way to see if an array has an element with a given index
+ is to use the âinâ operator: âINDX in ARRAYâ.
- * Use 'for (INDX in ARRAY) ...' to scan through all the individual
+ ⢠Use âfor (INDX in ARRAY) ...â to scan through all the individual
elements of an array. In the body of the loop, INDX takes on the
- value of each element's index in turn.
+ value of each elementâs index in turn.
- * The order in which a 'for (INDX in ARRAY)' loop traverses an array
- is undefined in POSIX 'awk' and varies among implementations.
- 'gawk' lets you control the order by assigning special predefined
- values to 'PROCINFO["sorted_in"]'.
+ ⢠The order in which a âfor (INDX in ARRAY)â loop traverses an array
+ is undefined in POSIX âawkâ and varies among implementations.
+ âgawkâ lets you control the order by assigning special predefined
+ values to âPROCINFO["sorted_in"]â.
- * Use 'delete ARRAY[INDX]' to delete an individual element. To
- delete all of the elements in an array, use 'delete ARRAY'. This
+ ⢠Use âdelete ARRAY[INDX]â to delete an individual element. To
+ delete all of the elements in an array, use âdelete ARRAYâ. This
latter feature has been a common extension for many years and is
now standard, but may not be supported by all commercial versions
- of 'awk'.
+ of âawkâ.
- * Standard 'awk' simulates multidimensional arrays by separating
+ ⢠Standard âawkâ simulates multidimensional arrays by separating
subscript values with commas. The values are concatenated into a
- single string, separated by the value of 'SUBSEP'. The fact that
+ single string, separated by the value of âSUBSEPâ. The fact that
such a subscript was created in this way is not retained; thus,
- changing 'SUBSEP' may have unexpected consequences. You can use
- '(SUB1, SUB2, ...) in ARRAY' to see if such a multidimensional
+ changing âSUBSEPâ may have unexpected consequences. You can use
+ â(SUB1, SUB2, ...) in ARRAYâ to see if such a multidimensional
subscript exists in ARRAY.
- * 'gawk' provides true arrays of arrays. You use a separate set of
+ ⢠âgawkâ provides true arrays of arrays. You use a separate set of
square brackets for each dimension in such an array:
- 'data[row][col]', for example. Array elements may thus be either
+ âdata[row][col]â, for example. Array elements may thus be either
scalar values (number or string) or other arrays.
- * Use the 'isarray()' built-in function to determine if an array
+ ⢠Use the âisarray()â built-in function to determine if an array
element is itself a subarray.
@@ -12863,16 +12863,16 @@ File: gawk.info, Node: Functions, Next: Library
Functions, Prev: Arrays, Up:
9 Functions
***********
-This major node describes 'awk''s built-in functions, which fall into
-three categories: numeric, string, and I/O. 'gawk' provides additional
+This major node describes âawkââs built-in functions, which fall into
+three categories: numeric, string, and I/O. âgawkâ provides additional
groups of functions to work with values that represent time, do bit
manipulation, sort arrays, provide type information, and
internationalize and localize programs.
- Besides the built-in functions, 'awk' has provisions for writing new
+ Besides the built-in functions, âawkâ has provisions for writing new
functions that the rest of a program can use. The second half of this
-major node describes these "user-defined" functions. Finally, we
-explore indirect function calls, a 'gawk'-specific extension that lets
+major node describes these âuser-definedâ functions. Finally, we
+explore indirect function calls, a âgawkâ-specific extension that lets
you determine at runtime what function is to be called.
* Menu:
@@ -12888,8 +12888,8 @@ File: gawk.info, Node: Built-in, Next: User-defined,
Up: Functions
9.1 Built-in Functions
======================
-"Built-in" functions are always available for your 'awk' program to
-call. This minor node defines all the built-in functions in 'awk'; some
+âBuilt-inâ functions are always available for your âawkâ program to
+call. This minor node defines all the built-in functions in âawkâ; some
of these are mentioned in other minor nodes but are summarized here for
your convenience.
@@ -12898,10 +12898,10 @@ your convenience.
* Calling Built-in:: How to call built-in functions.
* Boolean Functions:: A function that returns Boolean values.
* Numeric Functions:: Functions that work with numbers, including
- 'int()', 'sin()' and 'rand()'.
+ âint()â, âsin()â and ârand()â.
* String Functions:: Functions for string manipulation, such as
- 'split()', 'match()' and
- 'sprintf()'.
+ âsplit()â, âmatch()â and
+ âsprintf()â.
* I/O Functions:: Functions for files and shell commands.
* Time Functions:: Functions for dealing with timestamps.
* Bitwise Functions:: Functions for bitwise operations.
@@ -12914,43 +12914,43 @@ File: gawk.info, Node: Calling Built-in, Next:
Boolean Functions, Up: Built-i
9.1.1 Calling Built-in Functions
--------------------------------
-To call one of 'awk''s built-in functions, write the name of the
-function followed by arguments in parentheses. For example, 'atan2(y +
-z, 1)' is a call to the function 'atan2()' and has two arguments.
+To call one of âawkââs built-in functions, write the name of the
+function followed by arguments in parentheses. For example, âatan2(y +
+z, 1)â is a call to the function âatan2()â and has two arguments.
Whitespace is ignored between the built-in function name and the
opening parenthesis, but nonetheless it is good practice to avoid using
whitespace there. User-defined functions do not permit whitespace in
this way, and it is easier to avoid mistakes by following a simple
-convention that always works--no whitespace after a function name.
+convention that always worksâno whitespace after a function name.
Each built-in function accepts a certain number of arguments. In
some cases, arguments can be omitted. The defaults for omitted
arguments vary from function to function and are described under the
-individual functions. In some 'awk' implementations, extra arguments
-given to built-in functions are ignored. However, in 'gawk', it is a
+individual functions. In some âawkâ implementations, extra arguments
+given to built-in functions are ignored. However, in âgawkâ, it is a
fatal error to give extra arguments to a built-in function.
- When a function is called, expressions that create the function's
+ When a function is called, expressions that create the functionâs
actual parameters are evaluated completely before the call is performed.
For example, in the following code fragment:
i = 4
j = sqrt(i++)
-the variable 'i' is incremented to the value five before 'sqrt()' is
+the variable âiâ is incremented to the value five before âsqrt()â is
called with a value of four for its actual parameter. The order of
-evaluation of the expressions used for the function's parameters is
+evaluation of the expressions used for the functionâs parameters is
undefined. Thus, avoid writing programs that assume that parameters are
evaluated from left to right or from right to left. For example:
i = 5
j = atan2(++i, i *= 2)
- If the order of evaluation is left to right, then 'i' first becomes
-six, and then 12, and 'atan2()' is called with the two arguments six and
-12. But if the order of evaluation is right to left, 'i' first becomes
-10, then 11, and 'atan2()' is called with the two arguments 11 and 10.
+ If the order of evaluation is left to right, then âiâ first becomes
+six, and then 12, and âatan2()â is called with the two arguments six and
+12. But if the order of evaluation is right to left, âiâ first becomes
+10, then 11, and âatan2()â is called with the two arguments 11 and 10.
File: gawk.info, Node: Boolean Functions, Next: Numeric Functions, Prev:
Calling Built-in, Up: Built-in
@@ -12958,13 +12958,13 @@ File: gawk.info, Node: Boolean Functions, Next:
Numeric Functions, Prev: Call
9.1.2 Generating Boolean Values
-------------------------------
-This function is specific to 'gawk'. It is not available in
+This function is specific to âgawkâ. It is not available in
compatibility mode (*note Options::):
-'mkbool(EXPRESSION)'
+âmkbool(EXPRESSION)â
Return a Boolean-typed value based on the regular Boolean value of
- EXPRESSION. Boolean "true" values have numeric value one. Boolean
- "false" values have numeric zero. This is discussed in more detail
+ EXPRESSION. Boolean âtrueâ values have numeric value one. Boolean
+ âfalseâ values have numeric zero. This is discussed in more detail
in *note Boolean Typed Values::.
@@ -12977,30 +12977,30 @@ The following list describes all of the built-in
functions that work
with numbers. Optional parameters are enclosed in square
brackets ([ ]):
-'atan2(Y, X)'
- Return the arctangent of 'Y / X' in radians. You can use 'pi =
- atan2(0, -1)' to retrieve the value of pi.
+âatan2(Y, X)â
+ Return the arctangent of âY / Xâ in radians. You can use âpi =
+ atan2(0, -1)â to retrieve the value of pi.
-'cos(X)'
+âcos(X)â
Return the cosine of X, with X in radians.
-'exp(X)'
- Return the exponential of X ('e ^ X') or report an error if X is
+âexp(X)â
+ Return the exponential of X (âe ^ Xâ) or report an error if X is
out of range. The range of values X can have depends on your
- machine's floating-point representation.
+ machineâs floating-point representation.
-'int(X)'
+âint(X)â
Return the nearest integer to X, located between X and zero and
- truncated toward zero. For example, 'int(3)' is 3, 'int(3.9)' is
- 3, 'int(-3.9)' is -3, and 'int(-3)' is -3 as well.
+ truncated toward zero. For example, âint(3)â is 3, âint(3.9)â is
+ 3, âint(-3.9)â is â3, and âint(-3)â is â3 as well.
-'log(X)'
+âlog(X)â
Return the natural logarithm of X, if X is positive; otherwise,
- return NaN ("not a number") on IEEE 754 systems. Additionally,
- 'gawk' prints a warning message when 'x' is negative.
+ return NaN (ânot a numberâ) on IEEE 754 systems. Additionally,
+ âgawkâ prints a warning message when âxâ is negative.
-'rand()'
- Return a random number. The values of 'rand()' are uniformly
+ârand()â
+ Return a random number. The values of ârand()â are uniformly
distributed between zero and one. The value could be zero but is
never one.(1)
@@ -13014,8 +13014,8 @@ brackets ([ ]):
}
The multiplication produces a random number greater than or equal
- to zero and less than 'n'. Using 'int()', this result is made into
- an integer between zero and 'n' - 1, inclusive.
+ to zero and less than ânâ. Using âint()â, this result is made
into
+ an integer between zero and ânâ â 1, inclusive.
The following example uses a similar function to produce random
integers between one and N. This program prints a new random
@@ -13030,24 +13030,24 @@ brackets ([ ]):
printf("%d points\n", roll(6) + roll(6) + roll(6))
}
- CAUTION: In most 'awk' implementations, including 'gawk',
- 'rand()' starts generating numbers from the same starting
- number, or "seed", each time you run 'awk'.(2) Thus, a
+ CAUTION: In most âawkâ implementations, including âgawkâ,
+ ârand()â starts generating numbers from the same starting
+ number, or âseedâ, each time you run âawkâ.(2) Thus, a
program generates the same results each time you run it. The
- numbers are random within one 'awk' run but predictable from
+ numbers are random within one âawkâ run but predictable from
run to run. This is convenient for debugging, but if you want
a program to do different things each time it is used, you
must change the seed to a value that is different in each run.
- To do this, use 'srand()'.
+ To do this, use âsrand()â.
-'sin(X)'
+âsin(X)â
Return the sine of X, with X in radians.
-'sqrt(X)'
- Return the positive square root of X. 'gawk' prints a warning
- message if X is negative. Thus, 'sqrt(4)' is 2.
+âsqrt(X)â
+ Return the positive square root of X. âgawkâ prints a warning
+ message if X is negative. Thus, âsqrt(4)â is 2.
-'srand('[X]')'
+âsrand(â[X]â)â
Set the starting point, or seed, for generating random numbers to
the value X.
@@ -13055,39 +13055,39 @@ brackets ([ ]):
numbers.(3) Thus, if the seed is set to the same value a second
time, the same sequence of random numbers is produced again.
- CAUTION: Different 'awk' implementations use different
- random-number generators internally. Don't expect the same
- 'awk' program to produce the same series of random numbers
- when executed by different versions of 'awk'.
+ CAUTION: Different âawkâ implementations use different
+ random-number generators internally. Donât expect the same
+ âawkâ program to produce the same series of random numbers
+ when executed by different versions of âawkâ.
- If the argument X is omitted, as in 'srand()', then the current
+ If the argument X is omitted, as in âsrand()â, then the current
date and time of day are used for a seed. This is the way to get
random numbers that are truly unpredictable.
- The return value of 'srand()' is the previous seed. This makes it
+ The return value of âsrand()â is the previous seed. This makes it
easy to keep track of the seeds in case you need to consistently
reproduce sequences of random numbers.
- POSIX does not specify the initial seed; it differs among 'awk'
+ POSIX does not specify the initial seed; it differs among âawkâ
implementations.
---------- Footnotes ----------
- (1) The C version of 'rand()' on many Unix systems is known to
+ (1) The C version of ârand()â on many Unix systems is known to
produce fairly poor sequences of random numbers. However, nothing
-requires that an 'awk' implementation use the C 'rand()' to implement
-the 'awk' version of 'rand()'. In fact, for many years, 'gawk' used the
-BSD 'random()' function, which is considerably better than 'rand()', to
+requires that an âawkâ implementation use the C ârand()â to implement
+the âawkâ version of ârand()â. In fact, for many years, âgawkâ
used the
+BSD ârandom()â function, which is considerably better than ârand()â, to
produce random numbers. From version 4.1.4, courtesy of Nelson H.F.
-Beebe, 'gawk' uses the Bayes-Durham shuffle buffer algorithm which
+Beebe, âgawkâ uses the Bayes-Durham shuffle buffer algorithm which
considerably extends the period of the random number generator, and
eliminates short-range and long-range correlations that might exist in
the original generator.
- (2) 'mawk' uses a different seed each time.
+ (2) âmawkâ uses a different seed each time.
(3) Computer-generated random numbers really are not truly random.
-They are technically known as "pseudorandom". This means that although
+They are technically known as âpseudorandomâ. This means that although
the numbers in a sequence appear to be random, you can in fact generate
the same sequence of random numbers over and over again.
@@ -13100,12 +13100,12 @@ File: gawk.info, Node: String Functions, Next: I/O
Functions, Prev: Numeric F
The functions in this minor node look at or change the text of one or
more strings.
- 'gawk' understands locales (*note Locales::) and does all string
+ âgawkâ understands locales (*note Locales::) and does all string
processing in terms of _characters_, not _bytes_. This distinction is
particularly important to understand for locales where one character may
-be represented by multiple bytes. Thus, for example, 'length()' returns
+be represented by multiple bytes. Thus, for example, âlength()â returns
the number of characters in a string, and not the number of bytes used
-to represent those characters. Similarly, 'index()' works with
+to represent those characters. Similarly, âindex()â works with
character indices, and not byte indices.
CAUTION: A number of functions deal with indices into strings. For
@@ -13117,21 +13117,21 @@ character indices, and not byte indices.
In the following list, optional parameters are enclosed in square
brackets ([ ]). Several functions perform string substitution; the full
-discussion is provided in the description of the 'sub()' function, which
+discussion is provided in the description of the âsub()â function, which
comes toward the end, because the list is presented alphabetically.
- Those functions that are specific to 'gawk' are marked with a pound
-sign ('#'). They are not available in compatibility mode (*note
+ Those functions that are specific to âgawkâ are marked with a pound
+sign (â#â). They are not available in compatibility mode (*note
Options::):
* Menu:
-* Gory Details:: More than you want to know about '\' and
- '&' with 'sub()', 'gsub()', and
- 'gensub()'.
+* Gory Details:: More than you want to know about â\â and
+ â&â with âsub()â, âgsub()â, and
+ âgensub()â.
-'asort('SOURCE [',' DEST [',' HOW ] ]') #'
-'asorti('SOURCE [',' DEST [',' HOW ] ]') #'
+âasort(âSOURCE [â,â DEST [â,â HOW ] ]â) #â
+âasorti(âSOURCE [â,â DEST [â,â HOW ] ]â) #â
These two functions are similar in behavior, so they are described
together.
@@ -13142,73 +13142,73 @@ Options::):
*note Array Sorting Functions:: for the full story.)
Both functions return the number of elements in the array SOURCE.
- For 'asort()', 'gawk' sorts the values of SOURCE and replaces the
+ For âasort()â, âgawkâ sorts the values of SOURCE and replaces the
indices of the sorted values of SOURCE with sequential integers
starting with one. If the optional array DEST is specified, then
SOURCE is duplicated into DEST. DEST is then sorted, leaving the
indices of SOURCE unchanged.
- When comparing strings, 'IGNORECASE' affects the sorting (*note
+ When comparing strings, âIGNORECASEâ affects the sorting (*note
Array Sorting Functions::). If the SOURCE array contains subarrays
as values (*note Arrays of Arrays::), they will come last, after
all scalar values. Subarrays are _not_ recursively sorted.
- For example, if the contents of 'a' are as follows:
+ For example, if the contents of âaâ are as follows:
a["last"] = "de"
a["first"] = "sac"
a["middle"] = "cul"
- A call to 'asort()':
+ A call to âasort()â:
asort(a)
- results in the following contents of 'a':
+ results in the following contents of âaâ:
a[1] = "cul"
a[2] = "de"
a[3] = "sac"
- The 'asorti()' function works similarly to 'asort()'; however, the
+ The âasorti()â function works similarly to âasort()â; however, the
_indices_ are sorted, instead of the values. Thus, in the previous
example, starting with the same initial set of indices and values
- in 'a', calling 'asorti(a)' would yield:
+ in âaâ, calling âasorti(a)â would yield:
a[1] = "first"
a[2] = "last"
a[3] = "middle"
- NOTE: You may not use either 'SYMTAB' or 'FUNCTAB' as the
+ NOTE: You may not use either âSYMTABâ or âFUNCTABâ as the
second argument to these functions. Attempting to do so
produces a fatal error. You may use them as the first
argument, but only if providing a second array to use for the
actual sorting.
You are allowed to use the same array for both the SOURCE and DEST
- arguments, but doing so only makes sense if you're also supplying
+ arguments, but doing so only makes sense if youâre also supplying
the third argument.
-'gensub(REGEXP, REPLACEMENT, HOW' [', TARGET']') #'
+âgensub(REGEXP, REPLACEMENT, HOWâ [â, TARGETâ]â) #â
Search the target string TARGET for matches of the regular
- expression REGEXP. If HOW is a string beginning with 'g' or 'G'
- (short for "global"), then replace all matches of REGEXP with
+ expression REGEXP. If HOW is a string beginning with âgâ or âGâ
+ (short for âglobalâ), then replace all matches of REGEXP with
REPLACEMENT. Otherwise, treat HOW as a number indicating which
match of REGEXP to replace. Treat numeric values less than one as
- if they were one. If no TARGET is supplied, use '$0'. Return the
+ if they were one. If no TARGET is supplied, use â$0â. Return the
modified string as the result of the function. The original target
string is _not_ changed.
The returned value is _always_ a string, even if the original
TARGET was a number or a regexp value.
- 'gensub()' is a general substitution function. Its purpose is to
- provide more features than the standard 'sub()' and 'gsub()'
+ âgensub()â is a general substitution function. Its purpose is to
+ provide more features than the standard âsub()â and âgsub()â
functions.
- 'gensub()' provides an additional feature that is not available in
- 'sub()' or 'gsub()': the ability to specify components of a regexp
+ âgensub()â provides an additional feature that is not available in
+ âsub()â or âgsub()â: the ability to specify components of a regexp
in the replacement text. This is done by using parentheses in the
- regexp to mark the components and then specifying '\N' in the
+ regexp to mark the components and then specifying â\Nâ in the
replacement text, where N is a digit from 1 to 9. For example:
$ gawk '
@@ -13217,125 +13217,125 @@ Options::):
> b = gensub(/(.+) (.+)/, "\\2 \\1", "g", a)
> print b
> }'
- -| def abc
+ ⣠def abc
- As with 'sub()', you must type two backslashes in order to get one
- into the string. In the replacement text, the sequence '\0'
- represents the entire matched text, as does the character '&'.
+ As with âsub()â, you must type two backslashes in order to get one
+ into the string. In the replacement text, the sequence â\0â
+ represents the entire matched text, as does the character â&â.
The following example shows how you can use the third argument to
control which match of the regexp should be changed:
$ echo a b c a b c |
> gawk '{ print gensub(/a/, "AA", 2) }'
- -| a b c AA b c
+ ⣠a b c AA b c
- In this case, '$0' is the default target string. 'gensub()'
+ In this case, â$0â is the default target string. âgensub()â
returns the new string as its result, which is passed directly to
- 'print' for printing.
+ âprintâ for printing.
- If the HOW argument is a string that does not begin with 'g' or
- 'G', or if it is a number that is less than or equal to zero, only
- one substitution is performed. If HOW is zero, 'gawk' issues a
+ If the HOW argument is a string that does not begin with âgâ or
+ âGâ, or if it is a number that is less than or equal to zero, only
+ one substitution is performed. If HOW is zero, âgawkâ issues a
warning message.
- If REGEXP does not match TARGET, 'gensub()''s return value is the
+ If REGEXP does not match TARGET, âgensub()ââs return value is the
original unchanged value of TARGET. Note that, as mentioned above,
the returned value is a string, even if TARGET was not.
-'gsub(REGEXP, REPLACEMENT' [', TARGET']')'
+âgsub(REGEXP, REPLACEMENTâ [â, TARGETâ]â)â
Search TARGET for _all_ of the longest, leftmost, _nonoverlapping_
matching substrings it can find and replace them with REPLACEMENT.
- The 'g' in 'gsub()' stands for "global," which means replace
+ The âgâ in âgsub()â stands for âglobal,â which means replace
everywhere. For example:
{ gsub(/Britain/, "United Kingdom"); print }
- replaces all occurrences of the string 'Britain' with 'United
- Kingdom' for all input records.
+ replaces all occurrences of the string âBritainâ with âUnited
+ Kingdomâ for all input records.
- The 'gsub()' function returns the number of substitutions made. If
+ The âgsub()â function returns the number of substitutions made. If
the variable to search and alter (TARGET) is omitted, then the
- entire input record ('$0') is used. As in 'sub()', the characters
- '&' and '\' are special, and the third argument must be assignable.
+ entire input record (â$0â) is used. As in âsub()â, the characters
+ â&â and â\â are special, and the third argument must be
assignable.
-'index(IN, FIND)'
+âindex(IN, FIND)â
Search the string IN for the first occurrence of the string FIND,
and return the position in characters where that occurrence begins
in the string IN. Consider the following example:
$ awk 'BEGIN { print index("peanut", "an") }'
- -| 3
+ ⣠3
- If FIND is not found, 'index()' returns zero.
+ If FIND is not found, âindex()â returns zero.
- With BWK 'awk' and 'gawk', it is a fatal error to use a regexp
+ With BWK âawkâ and âgawkâ, it is a fatal error to use a regexp
constant for FIND. Other implementations allow it, simply treating
- the regexp constant as an expression meaning '$0 ~ /regexp/'.
+ the regexp constant as an expression meaning â$0 ~ /regexp/â.
(d.c.)
-'length('[STRING]')'
+âlength(â[STRING]â)â
Return the number of characters in STRING. If STRING is a number,
the length of the digit string representing that number is
- returned. For example, 'length("abcde")' is five. By contrast,
- 'length(15 * 35)' works out to three. In this example, 15 * 35 =
- 525, and 525 is then converted to the string '"525"', which has
+ returned. For example, âlength("abcde")â is five. By contrast,
+ âlength(15 * 35)â works out to three. In this example, 15 * 35 =
+ 525, and 525 is then converted to the string â"525"â, which has
three characters.
- If no argument is supplied, 'length()' returns the length of '$0'.
+ If no argument is supplied, âlength()â returns the length of â$0â.
- NOTE: In older versions of 'awk', the 'length()' function
+ NOTE: In older versions of âawkâ, the âlength()â function
could be called without any parentheses. Doing so is
considered poor practice, although the 2008 POSIX standard
explicitly allows it, to support historical practice. For
programs to be maximally portable, always supply the
parentheses.
- If 'length()' is called with a variable that has not been used,
- 'gawk' forces the variable to be a scalar. Other implementations
- of 'awk' leave the variable without a type. (d.c.) Consider:
+ If âlength()â is called with a variable that has not been used,
+ âgawkâ forces the variable to be a scalar. Other implementations
+ of âawkâ leave the variable without a type. (d.c.) Consider:
$ gawk 'BEGIN { print length(x) ; x[1] = 1 }'
- -| 0
- error-> gawk: fatal: attempt to use scalar `x' as array
+ ⣠0
+ errorâ gawk: fatal: attempt to use scalar `x' as array
$ nawk 'BEGIN { print length(x) ; x[1] = 1 }'
- -| 0
+ ⣠0
- If '--lint' has been specified on the command line, 'gawk' issues a
+ If â--lintâ has been specified on the command line, âgawkâ issues
a
warning about this.
- With 'gawk' and several other 'awk' implementations, when given an
- array argument, the 'length()' function returns the number of
+ With âgawkâ and several other âawkâ implementations, when given an
+ array argument, the âlength()â function returns the number of
elements in the array. (c.e.) This is less useful than it might
seem at first, as the array is not guaranteed to be indexed from
- one to the number of elements in it. If '--lint' is provided on
- the command line (*note Options::), 'gawk' warns that passing an
- array argument is not portable. If '--posix' is supplied, using an
+ one to the number of elements in it. If â--lintâ is provided on
+ the command line (*note Options::), âgawkâ warns that passing an
+ array argument is not portable. If â--posixâ is supplied, using an
array argument is a fatal error (*note Arrays::).
-'match(STRING, REGEXP' [', ARRAY']')'
+âmatch(STRING, REGEXPâ [â, ARRAYâ]â)â
Search STRING for the longest, leftmost substring matched by the
regular expression REGEXP and return the character position (index)
at which that substring begins (one, if it starts at the beginning
of STRING). If no match is found, return zero.
- The REGEXP argument may be either a regexp constant ('/'...'/') or
- a string constant ('"'...'"'). In the latter case, the string is
+ The REGEXP argument may be either a regexp constant (â/â...â/â) or
+ a string constant (â"â...â"â). In the latter case, the string is
treated as a regexp to be matched. *Note Computed Regexps:: for a
discussion of the difference between the two forms, and the
implications for writing your program correctly.
The order of the first two arguments is the opposite of most other
string functions that work with regular expressions, such as
- 'sub()' and 'gsub()'. It might help to remember that for
- 'match()', the order is the same as for the '~' operator: 'STRING ~
- REGEXP'.
+ âsub()â and âgsub()â. It might help to remember that for
+ âmatch()â, the order is the same as for the â~â operator:
âSTRING ~
+ REGEXPâ.
- The 'match()' function sets the predefined variable 'RSTART' to the
- index. It also sets the predefined variable 'RLENGTH' to the
+ The âmatch()â function sets the predefined variable âRSTARTâ to
the
+ index. It also sets the predefined variable âRLENGTHâ to the
length in characters of the matched substring. If no match is
- found, 'RSTART' is set to zero, and 'RLENGTH' to -1.
+ found, âRSTARTâ is set to zero, and âRLENGTHâ to â1.
For example:
@@ -13350,8 +13350,8 @@ Options::):
}
This program looks for lines that match the regular expression
- stored in the variable 'regex'. This regular expression can be
- changed. If the first word on a line is 'FIND', 'regex' is changed
+ stored in the variable âregexâ. This regular expression can be
+ changed. If the first word on a line is âFINDâ, âregexâ is
changed
to be the second word on that line. Therefore, if given:
FIND ru+n
@@ -13362,7 +13362,7 @@ Options::):
This line is property of Reality Engineering Co.
Melvin was here.
- 'awk' prints:
+ âawkâ prints:
Match of ru+n found at 12 in My program runs
Match of Melvin found at 1 in Melvin was here.
@@ -13376,7 +13376,7 @@ Options::):
$ echo foooobazbarrrrr |
> gawk '{ match($0, /(fo+).+(bar*)/, arr)
> print arr[1], arr[2] }'
- -| foooo barrrrr
+ ⣠foooo barrrrr
In addition, multidimensional subscripts are available providing
the start index and length of each matched subexpression:
@@ -13387,75 +13387,75 @@ Options::):
> print arr[1, "start"], arr[1, "length"]
> print arr[2, "start"], arr[2, "length"]
> }'
- -| foooo barrrrr
- -| 1 5
- -| 9 7
+ ⣠foooo barrrrr
+ ⣠1 5
+ ⣠9 7
There may not be subscripts for the start and index for every
parenthesized subexpression, because they may not all have matched
- text; thus, they should be tested for with the 'in' operator (*note
+ text; thus, they should be tested for with the âinâ operator (*note
Reference to Elements::).
- The ARRAY argument to 'match()' is a 'gawk' extension. In
+ The ARRAY argument to âmatch()â is a âgawkâ extension. In
compatibility mode (*note Options::), using a third argument is a
fatal error.
-'patsplit(STRING, ARRAY' [', FIELDPAT' [', SEPS' ] ]') #'
- Divide STRING into pieces (or "fields") defined by FIELDPAT and
+âpatsplit(STRING, ARRAYâ [â, FIELDPATâ [â, SEPSâ ] ]â) #â
+ Divide STRING into pieces (or âfieldsâ) defined by FIELDPAT and
store the pieces in ARRAY and the separator strings in the SEPS
- array. The first piece is stored in 'ARRAY[1]', the second piece
- in 'ARRAY[2]', and so forth. The third argument, FIELDPAT, is a
- regexp describing the fields in STRING (just as 'FPAT' is a regexp
+ array. The first piece is stored in âARRAY[1]â, the second piece
+ in âARRAY[2]â, and so forth. The third argument, FIELDPAT, is a
+ regexp describing the fields in STRING (just as âFPATâ is a regexp
describing the fields in input records). It may be either a regexp
- constant or a string. If FIELDPAT is omitted, the value of 'FPAT'
- is used. 'patsplit()' returns the number of elements created.
- 'SEPS[I]' is the possibly null separator string after 'ARRAY[I]'.
- The possibly null leading separator will be in 'SEPS[0]'. So a
+ constant or a string. If FIELDPAT is omitted, the value of âFPATâ
+ is used. âpatsplit()â returns the number of elements created.
+ âSEPS[I]â is the possibly null separator string after âARRAY[I]â.
+ The possibly null leading separator will be in âSEPS[0]â. So a
non-null STRING with N fields will have N+1 separators. A null
STRING has no fields or separators.
- The 'patsplit()' function splits strings into pieces in a manner
- similar to the way input lines are split into fields using 'FPAT'
+ The âpatsplit()â function splits strings into pieces in a manner
+ similar to the way input lines are split into fields using âFPATâ
(*note Splitting By Content::).
- Before splitting the string, 'patsplit()' deletes any previously
+ Before splitting the string, âpatsplit()â deletes any previously
existing elements in the arrays ARRAY and SEPS.
-'split(STRING, ARRAY' [', FIELDSEP' [', SEPS' ] ]')'
+âsplit(STRING, ARRAYâ [â, FIELDSEPâ [â, SEPSâ ] ]â)â
Divide STRING into pieces separated by FIELDSEP and store the
pieces in ARRAY and the separator strings in the SEPS array. The
- first piece is stored in 'ARRAY[1]', the second piece in
- 'ARRAY[2]', and so forth. The string value of the third argument,
+ first piece is stored in âARRAY[1]â, the second piece in
+ âARRAY[2]â, and so forth. The string value of the third argument,
FIELDSEP, is a regexp describing where to split STRING (much as
- 'FS' can be a regexp describing where to split input records). If
- FIELDSEP is omitted, the value of 'FS' is used. 'split()' returns
- the number of elements created. SEPS is a 'gawk' extension, with
- 'SEPS[I]' being the separator string between 'ARRAY[I]' and
- 'ARRAY[I+1]'. If FIELDSEP is a single space, then any leading
- whitespace goes into 'SEPS[0]' and any trailing whitespace goes
- into 'SEPS[N]', where N is the return value of 'split()' (i.e., the
+ âFSâ can be a regexp describing where to split input records). If
+ FIELDSEP is omitted, the value of âFSâ is used. âsplit()â returns
+ the number of elements created. SEPS is a âgawkâ extension, with
+ âSEPS[I]â being the separator string between âARRAY[I]â and
+ âARRAY[I+1]â. If FIELDSEP is a single space, then any leading
+ whitespace goes into âSEPS[0]â and any trailing whitespace goes
+ into âSEPS[N]â, where N is the return value of âsplit()â (i.e.,
the
number of elements in ARRAY).
- The 'split()' function splits strings into pieces in the same way
+ The âsplit()â function splits strings into pieces in the same way
that input lines are split into fields. For example:
split("cul-de-sac", a, "-", seps)
- splits the string '"cul-de-sac"' into three fields using '-' as the
- separator. It sets the contents of the array 'a' as follows:
+ splits the string â"cul-de-sac"â into three fields using â-â as
the
+ separator. It sets the contents of the array âaâ as follows:
a[1] = "cul"
a[2] = "de"
a[3] = "sac"
- and sets the contents of the array 'seps' as follows:
+ and sets the contents of the array âsepsâ as follows:
seps[1] = "-"
seps[2] = "-"
- The value returned by this call to 'split()' is three.
+ The value returned by this call to âsplit()â is three.
- As with input field-splitting, when the value of FIELDSEP is '" "',
+ As with input field-splitting, when the value of FIELDSEP is â" "â,
leading and trailing whitespace is ignored in values assigned to
the elements of ARRAY but not in SEPS, and the elements are
separated by runs of whitespace. Also, as with input field
@@ -13465,19 +13465,19 @@ Options::):
that string acts as the separator, even if its value is a regular
expression metacharacter.
- Note, however, that 'RS' has no effect on the way 'split()' works.
- Even though 'RS = ""' causes the newline character to also be an
- input field separator, this does not affect how 'split()' splits
+ Note, however, that âRSâ has no effect on the way âsplit()â works.
+ Even though âRS = ""â causes the newline character to also be an
+ input field separator, this does not affect how âsplit()â splits
strings.
- Modern implementations of 'awk', including 'gawk', allow the third
- argument to be a regexp constant ('/'...'/') as well as a string.
+ Modern implementations of âawkâ, including âgawkâ, allow the third
+ argument to be a regexp constant (â/â...â/â) as well as a string.
(d.c.) The POSIX standard allows this as well. *Note Computed
Regexps:: for a discussion of the difference between using a string
constant or a regexp constant, and the implications for writing
your program correctly.
- Before splitting the string, 'split()' deletes any previously
+ Before splitting the string, âsplit()â deletes any previously
existing elements in the arrays ARRAY and SEPS.
If STRING is null, the array has no elements. (So this is a
@@ -13491,97 +13491,97 @@ Options::):
In POSIX mode (*note Options::), the fourth argument is not
allowed.
-'sprintf(FORMAT, EXPRESSION1, ...)'
- Return (without printing) the string that 'printf' would have
+âsprintf(FORMAT, EXPRESSION1, ...)â
+ Return (without printing) the string that âprintfâ would have
printed out with the same arguments (*note Printf::). For example:
pival = sprintf("pi = %.2f (approx.)", 22/7)
- assigns the string 'pi = 3.14 (approx.)' to the variable 'pival'.
+ assigns the string âpi = 3.14 (approx.)â to the variable âpivalâ.
-'strtonum(STR) #'
+âstrtonum(STR) #â
Examine STR and return its numeric value. If STR begins with a
- leading '0', 'strtonum()' assumes that STR is an octal number. If
- STR begins with a leading '0x' or '0X', 'strtonum()' assumes that
+ leading â0â, âstrtonum()â assumes that STR is an octal number. If
+ STR begins with a leading â0xâ or â0Xâ, âstrtonum()â assumes
that
STR is a hexadecimal number. For example:
$ echo 0x11 |
> gawk '{ printf "%d\n", strtonum($1) }'
- -| 17
+ ⣠17
- Using the 'strtonum()' function is _not_ the same as adding zero to
+ Using the âstrtonum()â function is _not_ the same as adding zero to
a string value; the automatic coercion of strings to numbers works
only for decimal data, not for octal or hexadecimal.(1)
- Note also that 'strtonum()' uses the current locale's decimal point
+ Note also that âstrtonum()â uses the current localeâs decimal point
for recognizing numbers (*note Locales::).
-'sub(REGEXP, REPLACEMENT' [', TARGET']')'
+âsub(REGEXP, REPLACEMENTâ [â, TARGETâ]â)â
Search TARGET, which is treated as a string, for the leftmost,
longest substring matched by the regular expression REGEXP. Modify
the entire string by replacing the matched text with REPLACEMENT.
The modified string becomes the new value of TARGET. Return the
number of substitutions made (zero or one).
- The REGEXP argument may be either a regexp constant ('/'...'/') or
- a string constant ('"'...'"'). In the latter case, the string is
+ The REGEXP argument may be either a regexp constant (â/â...â/â) or
+ a string constant (â"â...â"â). In the latter case, the string is
treated as a regexp to be matched. *Note Computed Regexps:: for a
discussion of the difference between the two forms, and the
implications for writing your program correctly.
This function is peculiar because TARGET is not simply used to
- compute a value, and not just any expression will do--it must be a
- variable, field, or array element so that 'sub()' can store a
+ compute a value, and not just any expression will doâit must be a
+ variable, field, or array element so that âsub()â can store a
modified value there. If this argument is omitted, then the
- default is to use and alter '$0'.(2) For example:
+ default is to use and alter â$0â.(2) For example:
str = "water, water, everywhere"
sub(/at/, "ith", str)
- sets 'str' to 'wither, water, everywhere', by replacing the
- leftmost longest occurrence of 'at' with 'ith'.
+ sets âstrâ to âwither, water, everywhereâ, by replacing the
+ leftmost longest occurrence of âatâ with âithâ.
- If the special character '&' appears in REPLACEMENT, it stands for
+ If the special character â&â appears in REPLACEMENT, it stands for
the precise substring that was matched by REGEXP. (If the regexp
can match more than one string, then this precise substring may
vary.) For example:
{ sub(/candidate/, "& and his wife"); print }
- changes the first occurrence of 'candidate' to 'candidate and his
- wife' on each input line. Here is another example:
+ changes the first occurrence of âcandidateâ to âcandidate and his
+ wifeâ on each input line. Here is another example:
$ awk 'BEGIN {
> str = "daabaaa"
> sub(/a+/, "C&C", str)
> print str
> }'
- -| dCaaCbaaa
+ ⣠dCaaCbaaa
- This shows how '&' can represent a nonconstant string and also
- illustrates the "leftmost, longest" rule in regexp matching (*note
+ This shows how â&â can represent a nonconstant string and also
+ illustrates the âleftmost, longestâ rule in regexp matching (*note
Leftmost Longest::).
- The effect of this special character ('&') can be turned off by
+ The effect of this special character (â&â) can be turned off by
putting a backslash before it in the string. As usual, to insert
one backslash in the string, you must write two backslashes.
- Therefore, write '\\&' in a string constant to include a literal
- '&' in the replacement. For example, the following shows how to
- replace the first '|' on each line with an '&':
+ Therefore, write â\\&â in a string constant to include a literal
+ â&â in the replacement. For example, the following shows how to
+ replace the first â|â on each line with an â&â:
{ sub(/\|/, "\\&"); print }
- As mentioned, the third argument to 'sub()' must be a variable,
- field, or array element. Some versions of 'awk' allow the third
+ As mentioned, the third argument to âsub()â must be a variable,
+ field, or array element. Some versions of âawkâ allow the third
argument to be an expression that is not an lvalue. In such a
- case, 'sub()' still searches for the pattern and returns zero or
+ case, âsub()â still searches for the pattern and returns zero or
one, but the result of the substitution (if any) is thrown away
- because there is no place to put it. Such versions of 'awk' accept
+ because there is no place to put it. Such versions of âawkâ accept
expressions like the following:
sub(/USA/, "United States", "the USA and Canada")
- For historical compatibility, 'gawk' accepts such erroneous code.
+ For historical compatibility, âgawkâ accepts such erroneous code.
However, using any other nonchangeable object as the third
parameter causes a fatal error and your program will not run.
@@ -13589,26 +13589,26 @@ Options::):
into a string, and then the value of that string is treated as the
regexp to match.
-'substr(STRING, START' [', LENGTH' ]')'
+âsubstr(STRING, STARTâ [â, LENGTHâ ]â)â
Return a LENGTH-character-long substring of STRING, starting at
character number START. The first character of a string is
- character number one.(3) For example, 'substr("washington", 5, 3)'
- returns '"ing"'.
+ character number one.(3) For example, âsubstr("washington", 5, 3)â
+ returns â"ing"â.
- If LENGTH is not present, 'substr()' returns the whole suffix of
+ If LENGTH is not present, âsubstr()â returns the whole suffix of
STRING that begins at character number START. For example,
- 'substr("washington", 5)' returns '"ington"'. The whole suffix is
+ âsubstr("washington", 5)â returns â"ington"â. The whole suffix is
also returned if LENGTH is greater than the number of characters
remaining in the string, counting from character START.
- If START is less than one, 'substr()' treats it as if it was one.
- (POSIX doesn't specify what to do in this case: BWK 'awk' acts this
- way, and therefore 'gawk' does too.) If START is greater than the
- number of characters in the string, 'substr()' returns the null
+ If START is less than one, âsubstr()â treats it as if it was one.
+ (POSIX doesnât specify what to do in this case: BWK âawkâ acts this
+ way, and therefore âgawkâ does too.) If START is greater than the
+ number of characters in the string, âsubstr()â returns the null
string. Similarly, if LENGTH is present but less than or equal to
zero, the null string is returned.
- The string returned by 'substr()' _cannot_ be assigned. Thus, it
+ The string returned by âsubstr()â _cannot_ be assigned. Thus, it
is a mistake to attempt to change a portion of a string, as shown
in the following example:
@@ -13616,62 +13616,62 @@ Options::):
# try to get "abCDEf", won't work
substr(string, 3, 3) = "CDE"
- It is also a mistake to use 'substr()' as the third argument of
- 'sub()' or 'gsub()':
+ It is also a mistake to use âsubstr()â as the third argument of
+ âsub()â or âgsub()â:
gsub(/xyz/, "pdq", substr($0, 5, 20)) # WRONG
- (Some commercial versions of 'awk' treat 'substr()' as assignable,
+ (Some commercial versions of âawkâ treat âsubstr()â as assignable,
but doing so is not portable.)
If you need to replace bits and pieces of a string, combine
- 'substr()' with string concatenation, in the following manner:
+ âsubstr()â with string concatenation, in the following manner:
string = "abcdef"
...
string = substr(string, 1, 2) "CDE" substr(string, 6)
-'tolower(STRING)'
+âtolower(STRING)â
Return a copy of STRING, with each uppercase character in the
string replaced with its corresponding lowercase character.
Nonalphabetic characters are left unchanged. For example,
- 'tolower("MiXeD cAsE 123")' returns '"mixed case 123"'.
+ âtolower("MiXeD cAsE 123")â returns â"mixed case 123"â.
-'toupper(STRING)'
+âtoupper(STRING)â
Return a copy of STRING, with each lowercase character in the
string replaced with its corresponding uppercase character.
Nonalphabetic characters are left unchanged. For example,
- 'toupper("MiXeD cAsE 123")' returns '"MIXED CASE 123"'.
+ âtoupper("MiXeD cAsE 123")â returns â"MIXED CASE 123"â.
- At first glance, the 'split()' and 'patsplit()' functions appear to
+ At first glance, the âsplit()â and âpatsplit()â functions appear to
be mirror images of each other. But there are differences:
- * 'split()' treats its third argument like 'FS', with all the special
- rules involved for 'FS'.
+ ⢠âsplit()â treats its third argument like âFSâ, with all the
special
+ rules involved for âFSâ.
- * Matching of null strings differs. This is discussed in *note FS
+ ⢠Matching of null strings differs. This is discussed in *note FS
versus FPAT::.
Matching the Null String
- In 'awk', the '*' operator can match the null string. This is
-particularly important for the 'sub()', 'gsub()', and 'gensub()'
+ In âawkâ, the â*â operator can match the null string. This is
+particularly important for the âsub()â, âgsub()â, and âgensub()â
functions. For example:
$ echo abc | awk '{ gsub(/m*/, "X"); print }'
- -| XaXbXcX
+ ⣠XaXbXcX
Although this makes a certain amount of sense, it can be surprising.
---------- Footnotes ----------
- (1) Unless you use the '--non-decimal-data' option, which isn't
+ (1) Unless you use the â--non-decimal-dataâ option, which isnât
recommended. *Note Nondecimal Data:: for more information.
(2) Note that this means that the record will first be regenerated
-using the value of 'OFS' if any fields have been changed, and that the
+using the value of âOFSâ if any fields have been changed, and that the
fields will be updated after the substitution, even if the operation is
-a "no-op" such as 'sub(/^/, "")'.
+a âno-opâ such as âsub(/^/, "")â.
(3) This is different from C and C++, in which the first character is
number zero.
@@ -13679,146 +13679,146 @@ number zero.
File: gawk.info, Node: Gory Details, Up: String Functions
-9.1.4.1 More about '\' and '&' with 'sub()', 'gsub()', and 'gensub()'
+9.1.4.1 More about â\â and â&â with âsub()â, âgsub()â, and
âgensub()â
.....................................................................
CAUTION: This subsubsection has been reported to cause headaches.
You might want to skip it upon first reading.
- When using 'sub()', 'gsub()', or 'gensub()', and trying to get
+ When using âsub()â, âgsub()â, or âgensub()â, and trying to get
literal backslashes and ampersands into the replacement text, you need
-to remember that there are several levels of "escape processing" going
+to remember that there are several levels of âescape processingâ going
on.
- First, there is the "lexical" level, which is when 'awk' reads your
+ First, there is the âlexicalâ level, which is when âawkâ reads your
program and builds an internal copy of it to execute. Then there is the
-runtime level, which is when 'awk' actually scans the replacement string
+runtime level, which is when âawkâ actually scans the replacement string
to determine what to generate.
- At both levels, 'awk' looks for a defined set of characters that can
+ At both levels, âawkâ looks for a defined set of characters that can
come after a backslash. At the lexical level, it looks for the escape
-sequences listed in *note Escape Sequences::. Thus, for every '\' that
-'awk' processes at the runtime level, you must type two backslashes at
+sequences listed in *note Escape Sequences::. Thus, for every â\â that
+âawkâ processes at the runtime level, you must type two backslashes at
the lexical level. When a character that is not valid for an escape
-sequence follows the '\', BWK 'awk' and 'gawk' both simply remove the
-initial '\' and put the next character into the string. Thus, for
-example, '"a\qb"' is treated as '"aqb"'.
-
- At the runtime level, the various functions handle sequences of '\'
-and '&' differently. The situation is (sadly) somewhat complex.
-Historically, the 'sub()' and 'gsub()' functions treated the
-two-character sequence '\&' specially; this sequence was replaced in the
-generated text with a single '&'. Any other '\' within the REPLACEMENT
-string that did not precede an '&' was passed through unchanged. This
+sequence follows the â\â, BWK âawkâ and âgawkâ both simply remove
the
+initial â\â and put the next character into the string. Thus, for
+example, â"a\qb"â is treated as â"aqb"â.
+
+ At the runtime level, the various functions handle sequences of â\â
+and â&â differently. The situation is (sadly) somewhat complex.
+Historically, the âsub()â and âgsub()â functions treated the
+two-character sequence â\&â specially; this sequence was replaced in the
+generated text with a single â&â. Any other â\â within the REPLACEMENT
+string that did not precede an â&â was passed through unchanged. This
is illustrated in *note Table 9.1: table-sub-escapes.
- You type 'sub()' sees 'sub()' generates
- ----- ------- ----------
- '\&' '&' The matched text
- '\\&' '\&' A literal '&'
- '\\\&' '\&' A literal '&'
- '\\\\&' '\\&' A literal '\&'
- '\\\\\&' '\\&' A literal '\&'
- '\\\\\\&' '\\\&' A literal '\\&'
- '\\q' '\q' A literal '\q'
+ You type âsub()â sees âsub()â generates
+ âââ âââ- âââââ
+ â\&â â&â The matched text
+ â\\&â â\&â A literal â&â
+ â\\\&â â\&â A literal â&â
+ â\\\\&â â\\&â A literal â\&â
+ â\\\\\&â â\\&â A literal â\&â
+ â\\\\\\&â â\\\&â A literal â\\&â
+ â\\qâ â\qâ A literal â\qâ
-Table 9.1: Historical escape sequence processing for 'sub()' and
-'gsub()'
+Table 9.1: Historical escape sequence processing for âsub()â and
+âgsub()â
This table shows the lexical-level processing, where an odd number of
backslashes becomes an even number at the runtime level, as well as the
-runtime processing done by 'sub()'. (For the sake of simplicity, the
+runtime processing done by âsub()â. (For the sake of simplicity, the
rest of the following tables only show the case of even numbers of
backslashes entered at the lexical level.)
The problem with the historical approach is that there is no way to
-get a literal '\' followed by the matched text.
+get a literal â\â followed by the matched text.
Several editions of the POSIX standard attempted to fix this problem
-but weren't successful. The details are irrelevant at this point in
+but werenât successful. The details are irrelevant at this point in
time.
- At one point, the 'gawk' maintainer submitted proposed text for a
+ At one point, the âgawkâ maintainer submitted proposed text for a
revised standard that reverts to rules that correspond more closely to
the original existing practice. The proposed rules have special cases
-that make it possible to produce a '\' preceding the matched text. This
+that make it possible to produce a â\â preceding the matched text. This
is shown in *note Table 9.2: table-sub-proposed.
- You type 'sub()' sees 'sub()' generates
- ----- ------- ----------
- '\\\\\\&' '\\\&' A literal '\&'
- '\\\\&' '\\&' A literal '\', followed by the
matched text
- '\\&' '\&' A literal '&'
- '\\q' '\q' A literal '\q'
- '\\\\' '\\' '\\'
+ You type âsub()â sees âsub()â generates
+ âââ âââ- âââââ
+ â\\\\\\&â â\\\&â A literal â\&â
+ â\\\\&â â\\&â A literal â\â, followed
by the matched text
+ â\\&â â\&â A literal â&â
+ â\\qâ â\qâ A literal â\qâ
+ â\\\\â â\\â â\\â
-Table 9.2: 'gawk' rules for 'sub()' and backslash
+Table 9.2: âgawkâ rules for âsub()â and backslash
In a nutshell, at the runtime level, there are now three special
-sequences of characters ('\\\&', '\\&', and '\&') whereas historically
-there was only one. However, as in the historical case, any '\' that is
+sequences of characters (â\\\&â, â\\&â, and â\&â) whereas
historically
+there was only one. However, as in the historical case, any â\â that is
not part of one of these three sequences is not special and appears in
the output literally.
- 'gawk' 3.0 and 3.1 follow these rules for 'sub()' and 'gsub()'. The
+ âgawkâ 3.0 and 3.1 follow these rules for âsub()â and âgsub()â.
The
POSIX standard took much longer to be revised than was expected. In
-addition, the 'gawk' maintainer's proposal was lost during the
+addition, the âgawkâ maintainerâs proposal was lost during the
standardization process. The final rules are somewhat simpler. The
results are similar except for one case.
- The POSIX rules state that '\&' in the replacement string produces a
-literal '&', '\\' produces a literal '\', and '\' followed by anything
-else is not special; the '\' is placed straight into the output. These
+ The POSIX rules state that â\&â in the replacement string produces a
+literal â&â, â\\â produces a literal â\â, and â\â followed by
anything
+else is not special; the â\â is placed straight into the output. These
rules are presented in *note Table 9.3: table-posix-sub.
- You type 'sub()' sees 'sub()' generates
- ----- ------- ----------
- '\\\\\\&' '\\\&' A literal '\&'
- '\\\\&' '\\&' A literal '\', followed by the
matched text
- '\\&' '\&' A literal '&'
- '\\q' '\q' A literal '\q'
- '\\\\' '\\' '\'
+ You type âsub()â sees âsub()â generates
+ âââ âââ- âââââ
+ â\\\\\\&â â\\\&â A literal â\&â
+ â\\\\&â â\\&â A literal â\â, followed
by the matched text
+ â\\&â â\&â A literal â&â
+ â\\qâ â\qâ A literal â\qâ
+ â\\\\â â\\â â\â
-Table 9.3: POSIX rules for 'sub()' and 'gsub()'
+Table 9.3: POSIX rules for âsub()â and âgsub()â
The only case where the difference is noticeable is the last one:
-'\\\\' is seen as '\\' and produces '\' instead of '\\'.
+â\\\\â is seen as â\\â and produces â\â instead of â\\â.
- Starting with version 3.1.4, 'gawk' followed the POSIX rules when
-'--posix' was specified (*note Options::). Otherwise, it continued to
+ Starting with version 3.1.4, âgawkâ followed the POSIX rules when
+â--posixâ was specified (*note Options::). Otherwise, it continued to
follow the proposed rules, as that had been its behavior for many years.
- When version 4.0.0 was released, the 'gawk' maintainer made the POSIX
-rules the default, breaking well over a decade's worth of backward
+ When version 4.0.0 was released, the âgawkâ maintainer made the POSIX
+rules the default, breaking well over a decadeâs worth of backward
compatibility.(1) Needless to say, this was a bad idea, and as of
-version 4.0.1, 'gawk' resumed its historical behavior, and only follows
-the POSIX rules when '--posix' is given.
+version 4.0.1, âgawkâ resumed its historical behavior, and only follows
+the POSIX rules when â--posixâ is given.
- The rules for 'gensub()' are considerably simpler. At the runtime
-level, whenever 'gawk' sees a '\', if the following character is a
+ The rules for âgensub()â are considerably simpler. At the runtime
+level, whenever âgawkâ sees a â\â, if the following character is a
digit, then the text that matched the corresponding parenthesized
subexpression is placed in the generated output. Otherwise, no matter
-what character follows the '\', it appears in the generated text and the
-'\' does not, as shown in *note Table 9.4: table-gensub-escapes.
+what character follows the â\â, it appears in the generated text and the
+â\â does not, as shown in *note Table 9.4: table-gensub-escapes.
- You type 'gensub()' sees 'gensub()' generates
- ----- --------- ------------
- '&' '&' The matched text
- '\\&' '\&' A literal '&'
- '\\\\' '\\' A literal '\'
- '\\\\&' '\\&' A literal '\', then the
matched text
- '\\\\\\&' '\\\&' A literal '\&'
- '\\q' '\q' A literal 'q'
+ You type âgensub()â sees âgensub()â generates
+ âââ ââââ- ââââââ
+ â&â â&â The matched text
+ â\\&â â\&â A literal â&â
+ â\\\\â â\\â A literal â\â
+ â\\\\&â â\\&â A literal â\â,
then the matched text
+ â\\\\\\&â â\\\&â A literal â\&â
+ â\\qâ â\qâ A literal âqâ
-Table 9.4: Escape sequence processing for 'gensub()'
+Table 9.4: Escape sequence processing for âgensub()â
Because of the complexity of the lexical- and runtime-level
-processing and the special cases for 'sub()' and 'gsub()', we recommend
-the use of 'gawk' and 'gensub()' when you have to do substitutions.
+processing and the special cases for âsub()â and âgsub()â, we recommend
+the use of âgawkâ and âgensub()â when you have to do substitutions.
---------- Footnotes ----------
@@ -13835,7 +13835,7 @@ File: gawk.info, Node: I/O Functions, Next: Time
Functions, Prev: String Func
The following functions relate to input/output (I/O). Optional
parameters are enclosed in square brackets ([ ]):
-'close('FILENAME [',' HOW]')'
+âclose(âFILENAME [â,â HOW]â)â
Close the file FILENAME for input or output. Alternatively, the
argument may be a shell command that was used for creating a
coprocess, or for redirecting to or from a pipe; then the coprocess
@@ -13844,77 +13844,77 @@ parameters are enclosed in square brackets ([ ]):
When closing a coprocess, it is occasionally useful to first close
one end of the two-way pipe and then to close the other. This is
- done by providing a second argument to 'close()'. This second
- argument (HOW) should be one of the two string values '"to"' or
- '"from"', indicating which end of the pipe to close. Case in the
+ done by providing a second argument to âclose()â. This second
+ argument (HOW) should be one of the two string values â"to"â or
+ â"from"â, indicating which end of the pipe to close. Case in the
string does not matter. *Note Two-way I/O::, which discusses this
feature in more detail and gives an example.
- Note that the second argument to 'close()' is a 'gawk' extension;
+ Note that the second argument to âclose()â is a âgawkâ extension;
it is not available in compatibility mode (*note Options::).
-'fflush('[FILENAME]')'
+âfflush(â[FILENAME]â)â
Flush any buffered output associated with FILENAME, which is either
a file opened for writing or a shell command for redirecting output
to a pipe or coprocess.
- Many utility programs "buffer" their output (i.e., they save
+ Many utility programs âbufferâ their output (i.e., they save
information to write to a disk file or the screen in memory until
there is enough for it to be worthwhile to send the data to the
output device). This is often more efficient than writing every
little bit of information as soon as it is ready. However,
- sometimes it is necessary to force a program to "flush" its buffers
+ sometimes it is necessary to force a program to âflushâ its buffers
(i.e., write the information to its destination, even if a buffer
- is not full). This is the purpose of the 'fflush()'
- function--'gawk' also buffers its output, and the 'fflush()'
- function forces 'gawk' to flush its buffers.
+ is not full). This is the purpose of the âfflush()â
+ functionââgawkâ also buffers its output, and the âfflush()â
+ function forces âgawkâ to flush its buffers.
- Brian Kernighan added 'fflush()' to his 'awk' in April 1992. For
+ Brian Kernighan added âfflush()â to his âawkâ in April 1992. For
two decades, it was a common extension. In December 2012, it was
accepted for inclusion into the POSIX standard. See the Austin
Group website (http://austingroupbugs.net/view.php?id=634).
- POSIX standardizes 'fflush()' as follows: if there is no argument,
- or if the argument is the null string ('""'), then 'awk' flushes
+ POSIX standardizes âfflush()â as follows: if there is no argument,
+ or if the argument is the null string (â""â), then âawkâ flushes
the buffers for _all_ open output files and pipes.
- NOTE: Prior to version 4.0.2, 'gawk' would flush only the
+ NOTE: Prior to version 4.0.2, âgawkâ would flush only the
standard output if there was no argument, and flush all output
files and pipes if the argument was the null string. This was
- changed in order to be compatible with BWK 'awk', in the hope
+ changed in order to be compatible with BWK âawkâ, in the hope
that standardizing this feature in POSIX would then be easier
(which indeed proved to be the case).
- With 'gawk', you can use 'fflush("/dev/stdout")' if you wish
+ With âgawkâ, you can use âfflush("/dev/stdout")â if you wish
to flush only the standard output.
- 'fflush()' returns zero if the buffer is successfully flushed;
- otherwise, it returns a nonzero value. ('gawk' returns -1.) In
+ âfflush()â returns zero if the buffer is successfully flushed;
+ otherwise, it returns a nonzero value. (âgawkâ returns â1.) In
the case where all buffers are flushed, the return value is zero
only if all buffers were flushed successfully. Otherwise, it is
- -1, and 'gawk' warns about the problem FILENAME.
+ â1, and âgawkâ warns about the problem FILENAME.
- 'gawk' also issues a warning message if you attempt to flush a file
- or pipe that was opened for reading (such as with 'getline'), or if
+ âgawkâ also issues a warning message if you attempt to flush a file
+ or pipe that was opened for reading (such as with âgetlineâ), or if
FILENAME is not an open file, pipe, or coprocess. In such a case,
- 'fflush()' returns -1, as well.
+ âfflush()â returns â1, as well.
Interactive Versus Noninteractive Buffering
As a side point, buffering issues can be even more confusing if your
-program is "interactive" (i.e., communicating with a user sitting at a
+program is âinteractiveâ (i.e., communicating with a user sitting at a
keyboard).(1)
- Interactive programs generally "line buffer" their output (i.e., they
+ Interactive programs generally âline bufferâ their output (i.e., they
write out every line). Noninteractive programs wait until they have a
full buffer, which may be many lines of output. Here is an example of
the difference:
$ awk '{ print $1 + $2 }'
1 1
- -| 2
+ ⣠2
2 3
- -| 5
+ ⣠5
Ctrl-d
Each line of output is printed immediately. Compare that behavior with
@@ -13924,27 +13924,27 @@ this example:
1 1
2 3
Ctrl-d
- -| 2
- -| 5
+ ⣠2
+ ⣠5
-Here, no output is printed until after the 'Ctrl-d' is typed, because it
-is all buffered and sent down the pipe to 'cat' in one shot.
+Here, no output is printed until after the âCtrl-dâ is typed, because it
+is all buffered and sent down the pipe to âcatâ in one shot.
-'system(COMMAND)'
+âsystem(COMMAND)â
Execute the operating system command COMMAND and then return to the
- 'awk' program. Return COMMAND's exit status (see further on).
+ âawkâ program. Return COMMANDâs exit status (see further on).
- For example, if the following fragment of code is put in your 'awk'
+ For example, if the following fragment of code is put in your âawkâ
program:
END {
system("date | mail -s 'awk run done' root")
}
- the system administrator is sent mail when the 'awk' program
+ the system administrator is sent mail when the âawkâ program
finishes processing input and begins its end-of-input processing.
- Note that redirecting 'print' or 'printf' into a pipe is often
+ Note that redirecting âprintâ or âprintfâ into a pipe is often
enough to accomplish your task. If you need to run many commands,
it is more efficient to simply print them down a pipeline to the
shell:
@@ -13953,66 +13953,66 @@ is all buffered and sent down the pipe to 'cat' in
one shot.
print COMMAND | "/bin/sh"
close("/bin/sh")
- However, if your 'awk' program is interactive, 'system()' is useful
+ However, if your âawkâ program is interactive, âsystem()â is
useful
for running large self-contained programs, such as a shell or an
- editor. Some operating systems cannot implement the 'system()'
- function. 'system()' causes a fatal error if it is not supported.
+ editor. Some operating systems cannot implement the âsystem()â
+ function. âsystem()â causes a fatal error if it is not supported.
- NOTE: When '--sandbox' is specified, the 'system()' function
+ NOTE: When â--sandboxâ is specified, the âsystem()â function
is disabled (*note Options::).
- On POSIX systems, a command's exit status is a 16-bit number. The
- exit value passed to the C 'exit()' function is held in the
+ On POSIX systems, a commandâs exit status is a 16-bit number. The
+ exit value passed to the C âexit()â function is held in the
high-order eight bits. The low-order bits indicate if the process
was killed by a signal (bit 7) and if so, the guilty signal number
- (bits 0-6).
+ (bits 0â6).
- Traditionally, 'awk''s 'system()' function has simply returned the
+ Traditionally, âawkââs âsystem()â function has simply returned
the
exit status value divided by 256. In the normal case this gives
the exit status but in the case of death-by-signal it yields a
- fractional floating-point value.(2) POSIX states that 'awk''s
- 'system()' should return the full 16-bit value.
+ fractional floating-point value.(2) POSIX states that âawkââs
+ âsystem()â should return the full 16-bit value.
- 'gawk' steers a middle ground. The return values are summarized in
+ âgawkâ steers a middle ground. The return values are summarized in
*note Table 9.5: table-system-return-values.
- Situation Return value from 'system()'
+ Situation Return value from âsystem()â
--------------------------------------------------------------------------
- '--traditional' C 'system()''s value divided by 256
- '--posix' C 'system()''s value
- Normal exit of command Command's exit status
+ â--traditionalâ C âsystem()ââs value divided by
256
+ â--posixâ C âsystem()ââs value
+ Normal exit of command Commandâs exit status
Death by signal of command 256 + number of murderous signal
Death by signal of command 512 + number of murderous signal
with core dump
- Some kind of error -1
+ Some kind of error â1
- Table 9.5: Return values from 'system()'
+ Table 9.5: Return values from âsystem()â
- As of August, 2018, BWK 'awk' now follows 'gawk''s behavior for the
-return value of 'system()'.
+ As of August, 2018, BWK âawkâ now follows âgawkââs behavior for
the
+return value of âsystem()â.
- Controlling Output Buffering with 'system()'
+ Controlling Output Buffering with âsystem()â
- The 'fflush()' function provides explicit control over output
+ The âfflush()â function provides explicit control over output
buffering for individual files and pipes. However, its use is not
-portable to many older 'awk' implementations. An alternative method to
-flush output buffers is to call 'system()' with a null string as its
+portable to many older âawkâ implementations. An alternative method to
+flush output buffers is to call âsystem()â with a null string as its
argument:
system("") # flush output
-'gawk' treats this use of the 'system()' function as a special case and
+âgawkâ treats this use of the âsystem()â function as a special case and
is smart enough not to run a shell (or other command interpreter) with
-the empty command. Therefore, with 'gawk', this idiom is not only
+the empty command. Therefore, with âgawkâ, this idiom is not only
useful, it is also efficient. Although this method should work with
-other 'awk' implementations, it does not necessarily avoid starting an
+other âawkâ implementations, it does not necessarily avoid starting an
unnecessary shell. (Other implementations may only flush the buffer
associated with the standard output and not necessarily all buffered
output.)
If you think about what a programmer expects, it makes sense that
-'system()' should flush any pending output. The following program:
+âsystem()â should flush any pending output. The following program:
BEGIN {
print "first print"
@@ -14032,7 +14032,7 @@ and not:
first print
second print
- If 'awk' did not flush its buffers before calling 'system()', you
+ If âawkâ did not flush its buffers before calling âsystem()â, you
would see the latter (undesirable) output.
---------- Footnotes ----------
@@ -14050,10 +14050,10 @@ File: gawk.info, Node: Time Functions, Next:
Bitwise Functions, Prev: I/O Fun
9.1.6 Time Functions
--------------------
-'awk' programs are commonly used to process log files containing
+âawkâ programs are commonly used to process log files containing
timestamp information, indicating when a particular log record was
written. Many programs log their timestamps in the form returned by the
-'time()' system call, which is the number of seconds since a particular
+âtime()â system call, which is the number of seconds since a particular
epoch. On POSIX-compliant systems, it is the number of seconds since
1970-01-01 00:00:00 UTC, not counting leap seconds.(1) All known
POSIX-compliant systems support timestamps from 0 through 2^31 - 1,
@@ -14062,254 +14062,254 @@ Many systems support a wider range of timestamps,
including negative
timestamps that represent times before the epoch.
In order to make it easier to process such log files and to produce
-useful reports, 'gawk' provides the following functions for working with
-timestamps. They are 'gawk' extensions; they are not specified in the
-POSIX standard.(2) However, recent versions of 'mawk' (*note Other
+useful reports, âgawkâ provides the following functions for working with
+timestamps. They are âgawkâ extensions; they are not specified in the
+POSIX standard.(2) However, recent versions of âmawkâ (*note Other
Versions::) also support these functions. Optional parameters are
enclosed in square brackets ([ ]):
-'mktime(DATESPEC' [', UTC-FLAG' ]')'
+âmktime(DATESPECâ [â, UTC-FLAGâ ]â)â
Turn DATESPEC into a timestamp in the same form as is returned by
- 'systime()'. It is similar to the function of the same name in ISO
+ âsystime()â. It is similar to the function of the same name in ISO
C. The argument, DATESPEC, is a string of the form
- '"YYYY MM DD HH MM SS [DST]"'. The string consists of six or seven
+ â"YYYY MM DD HH MM SS [DST]"â. The string consists of six or seven
numbers representing, respectively, the full year including
century, the month from 1 to 12, the day of the month from 1 to 31,
the hour of the day from 0 to 23, the minute from 0 to 59, the
second from 0 to 60,(3) and an optional daylight-savings flag.
The values of these numbers need not be within the ranges
- specified; for example, an hour of -1 means 1 hour before midnight.
+ specified; for example, an hour of â1 means 1 hour before midnight.
The origin-zero Gregorian calendar is assumed, with year 0
- preceding year 1 and year -1 preceding year 0. If UTC-FLAG is
+ preceding year 1 and year â1 preceding year 0. If UTC-FLAG is
present and is either nonzero or non-null, the time is assumed to
be in the UTC time zone; otherwise, the time is assumed to be in
the local time zone. If the DST daylight-savings flag is positive,
the time is assumed to be daylight savings time; if zero, the time
is assumed to be standard time; and if negative (the default),
- 'mktime()' attempts to determine whether daylight savings time is
+ âmktime()â attempts to determine whether daylight savings time is
in effect for the specified time.
If DATESPEC does not contain enough elements or if the resulting
- time is out of range, 'mktime()' returns -1.
+ time is out of range, âmktime()â returns â1.
-'strftime('[FORMAT [',' TIMESTAMP [',' UTC-FLAG] ] ]')'
+âstrftime(â[FORMAT [â,â TIMESTAMP [â,â UTC-FLAG] ] ]â)â
Format the time specified by TIMESTAMP based on the contents of the
FORMAT string and return the result. It is similar to the function
of the same name in ISO C. If UTC-FLAG is present and is either
nonzero or non-null, the value is formatted as UTC (Coordinated
Universal Time, formerly GMT or Greenwich Mean Time). Otherwise,
the value is formatted for the local time zone. The TIMESTAMP is
- in the same format as the value returned by the 'systime()'
- function. If no TIMESTAMP argument is supplied, 'gawk' uses the
+ in the same format as the value returned by the âsystime()â
+ function. If no TIMESTAMP argument is supplied, âgawkâ uses the
current time of day as the timestamp. Without a FORMAT argument,
- 'strftime()' uses the value of 'PROCINFO["strftime"]' as the format
+ âstrftime()â uses the value of âPROCINFO["strftime"]â as the
format
string (*note Built-in Variables::). The default string value is
- '"%a %b %e %H:%M:%S %Z %Y"'. This format string produces output
- that is equivalent to that of the 'date' utility. You can assign a
- new value to 'PROCINFO["strftime"]' to change the default format;
+ â"%a %b %e %H:%M:%S %Z %Y"â. This format string produces output
+ that is equivalent to that of the âdateâ utility. You can assign a
+ new value to âPROCINFO["strftime"]â to change the default format;
see the following list for the various format directives.
-'systime()'
+âsystime()â
Return the current time as the number of seconds since the system
epoch. On POSIX systems, this is the number of seconds since
1970-01-01 00:00:00 UTC, not counting leap seconds. It may be a
different number on other systems.
- The 'systime()' function allows you to compare a timestamp from a log
+ The âsystime()â function allows you to compare a timestamp from a log
file with the current time of day. In particular, it is easy to
determine how long ago a particular record was logged. It also allows
-you to produce log records using the "seconds since the epoch" format.
+you to produce log records using the âseconds since the epochâ format.
- The 'mktime()' function allows you to convert a textual
+ The âmktime()â function allows you to convert a textual
representation of a date and time into a timestamp. This makes it easy
to do before/after comparisons of dates and times, particularly when
dealing with date and time data coming from an external source, such as
a log file.
- The 'strftime()' function allows you to easily turn a timestamp into
-human-readable information. It is similar in nature to the 'sprintf()'
+ The âstrftime()â function allows you to easily turn a timestamp into
+human-readable information. It is similar in nature to the âsprintf()â
function (*note String Functions::), in that it copies nonformat
specification characters verbatim to the returned string, while
substituting date and time values for format specifications in the
FORMAT string.
- 'strftime()' is guaranteed by the 1999 ISO C standard(4) to support
+ âstrftime()â is guaranteed by the 1999 ISO C standard(4) to support
the following date format specifications:
-'%a'
- The locale's abbreviated weekday name.
+â%aâ
+ The localeâs abbreviated weekday name.
-'%A'
- The locale's full weekday name.
+â%Aâ
+ The localeâs full weekday name.
-'%b'
- The locale's abbreviated month name.
+â%bâ
+ The localeâs abbreviated month name.
-'%B'
- The locale's full month name.
+â%Bâ
+ The localeâs full month name.
-'%c'
- The locale's "appropriate" date and time representation. (This is
- '%A %B %d %T %Y' in the '"C"' locale.)
+â%câ
+ The localeâs âappropriateâ date and time representation. (This is
+ â%A %B %d %T %Yâ in the â"C"â locale.)
-'%C'
+â%Câ
The century part of the current year. This is the year divided by
100 and truncated to the next lower integer.
-'%d'
- The day of the month as a decimal number (01-31).
+â%dâ
+ The day of the month as a decimal number (01â31).
-'%D'
- Equivalent to specifying '%m/%d/%y'.
+â%Dâ
+ Equivalent to specifying â%m/%d/%yâ.
-'%e'
+â%eâ
The day of the month, padded with a space if it is only one digit.
-'%F'
- Equivalent to specifying '%Y-%m-%d'. This is the ISO 8601 date
+â%Fâ
+ Equivalent to specifying â%Y-%m-%dâ. This is the ISO 8601 date
format.
-'%g'
+â%gâ
The year modulo 100 of the ISO 8601 week number, as a decimal
- number (00-99). For example, January 1, 2012, is in week 53 of
+ number (00â99). For example, January 1, 2012, is in week 53 of
2011. Thus, the year of its ISO 8601 week number is 2011, even
though its year is 2012. Similarly, December 31, 2012, is in week
1 of 2013. Thus, the year of its ISO week number is 2013, even
though its year is 2012.
-'%G'
+â%Gâ
The full year of the ISO week number, as a decimal number.
-'%h'
- Equivalent to '%b'.
+â%hâ
+ Equivalent to â%bâ.
-'%H'
- The hour (24-hour clock) as a decimal number (00-23).
+â%Hâ
+ The hour (24-hour clock) as a decimal number (00â23).
-'%I'
- The hour (12-hour clock) as a decimal number (01-12).
+â%Iâ
+ The hour (12-hour clock) as a decimal number (01â12).
-'%j'
- The day of the year as a decimal number (001-366).
+â%jâ
+ The day of the year as a decimal number (001â366).
-'%m'
- The month as a decimal number (01-12).
+â%mâ
+ The month as a decimal number (01â12).
-'%M'
- The minute as a decimal number (00-59).
+â%Mâ
+ The minute as a decimal number (00â59).
-'%n'
+â%nâ
A newline character (ASCII LF).
-'%p'
- The locale's equivalent of the AM/PM designations associated with a
+â%pâ
+ The localeâs equivalent of the AM/PM designations associated with a
12-hour clock.
-'%r'
- The locale's 12-hour clock time. (This is '%I:%M:%S %p' in the
- '"C"' locale.)
+â%râ
+ The localeâs 12-hour clock time. (This is â%I:%M:%S %pâ in the
+ â"C"â locale.)
-'%R'
- Equivalent to specifying '%H:%M'.
+â%Râ
+ Equivalent to specifying â%H:%Mâ.
-'%S'
- The second as a decimal number (00-60).
+â%Sâ
+ The second as a decimal number (00â60).
-'%t'
+â%tâ
A TAB character.
-'%T'
- Equivalent to specifying '%H:%M:%S'.
+â%Tâ
+ Equivalent to specifying â%H:%M:%Sâ.
-'%u'
- The weekday as a decimal number (1-7). Monday is day one.
+â%uâ
+ The weekday as a decimal number (1â7). Monday is day one.
-'%U'
+â%Uâ
The week number of the year (with the first Sunday as the first day
- of week one) as a decimal number (00-53).
+ of week one) as a decimal number (00â53).
-'%V'
+â%Vâ
The week number of the year (with the first Monday as the first day
- of week one) as a decimal number (01-53). The method for
+ of week one) as a decimal number (01â53). The method for
determining the week number is as specified by ISO 8601. (To wit:
if the week containing January 1 has four or more days in the new
year, then it is week one; otherwise it is the last week [52 or 53]
of the previous year and the next week is week one.)
-'%w'
- The weekday as a decimal number (0-6). Sunday is day zero.
+â%wâ
+ The weekday as a decimal number (0â6). Sunday is day zero.
-'%W'
+â%Wâ
The week number of the year (with the first Monday as the first day
- of week one) as a decimal number (00-53).
+ of week one) as a decimal number (00â53).
-'%x'
- The locale's "appropriate" date representation. (This is '%A %B %d
- %Y' in the '"C"' locale.)
+â%xâ
+ The localeâs âappropriateâ date representation. (This is â%A %B
%d
+ %Yâ in the â"C"â locale.)
-'%X'
- The locale's "appropriate" time representation. (This is '%T' in
- the '"C"' locale.)
+â%Xâ
+ The localeâs âappropriateâ time representation. (This is â%Tâ
in
+ the â"C"â locale.)
-'%y'
- The year modulo 100 as a decimal number (00-99).
+â%yâ
+ The year modulo 100 as a decimal number (00â99).
-'%Y'
+â%Yâ
The full year as a decimal number (e.g., 2015).
-'%z'
- The time zone offset in a '+HHMM' format (e.g., the format
+â%zâ
+ The time zone offset in a â+HHMMâ format (e.g., the format
necessary to produce RFC 822/RFC 1036 date headers).
-'%Z'
+â%Zâ
The time zone name or abbreviation; no characters if no time zone
is determinable.
-'%Ec %EC %Ex %EX %Ey %EY %Od %Oe %OH'
-'%OI %Om %OM %OS %Ou %OU %OV %Ow %OW %Oy'
- "Alternative representations" for the specifications that use only
- the second letter ('%c', '%C', and so on).(5) (These facilitate
- compliance with the POSIX 'date' utility.)
+â%Ec %EC %Ex %EX %Ey %EY %Od %Oe %OHâ
+â%OI %Om %OM %OS %Ou %OU %OV %Ow %OW %Oyâ
+ âAlternative representationsâ for the specifications that use only
+ the second letter (â%câ, â%Câ, and so on).(5) (These facilitate
+ compliance with the POSIX âdateâ utility.)
-'%%'
- A literal '%'.
+â%%â
+ A literal â%â.
If a conversion specifier is not one of those just listed, the
behavior is undefined.(6)
- For systems that are not yet fully standards-compliant, 'gawk'
-supplies a copy of 'strftime()' from the GNU C Library. It supports all
+ For systems that are not yet fully standards-compliant, âgawkâ
+supplies a copy of âstrftime()â from the GNU C Library. It supports all
of the just-listed format specifications. If that version is used to
-compile 'gawk' (*note Installation::), then the following additional
+compile âgawkâ (*note Installation::), then the following additional
format specifications are available:
-'%k'
- The hour (24-hour clock) as a decimal number (0-23). Single-digit
+â%kâ
+ The hour (24-hour clock) as a decimal number (0â23). Single-digit
numbers are padded with a space.
-'%l'
- The hour (12-hour clock) as a decimal number (1-12). Single-digit
+â%lâ
+ The hour (12-hour clock) as a decimal number (1â12). Single-digit
numbers are padded with a space.
-'%s'
+â%sâ
The time as a decimal timestamp in seconds since the epoch.
Additionally, the alternative representations are recognized but
their normal representations are used.
- The following example is an 'awk' implementation of the POSIX 'date'
-utility. Normally, the 'date' utility prints the current date and time
+ The following example is an âawkâ implementation of the POSIX âdateâ
+utility. Normally, the âdateâ utility prints the current date and time
of day in a well-known format. However, if you provide an argument to
-it that begins with a '+', 'date' copies nonformat specifier characters
+it that begins with a â+â, âdateâ copies nonformat specifier characters
to the standard output and interprets the current time according to the
format specifiers in the string. For example:
$ date '+Today is %A, %B %d, %Y.'
- -| Today is Monday, September 22, 2014.
+ ⣠Today is Monday, September 22, 2014.
- Here is the 'gawk' version of the 'date' utility. It has a shell
-"wrapper" to handle the '-u' option, which requires that 'date' run as
+ Here is the âgawkâ version of the âdateâ utility. It has a shell
+âwrapperâ to handle the â-uâ option, which requires that âdateâ
run as
if the time zone is set to UTC:
#! /bin/sh
@@ -14339,26 +14339,26 @@ if the time zone is set to UTC:
---------- Footnotes ----------
- (1) *Note Glossary::, especially the entries "Epoch" and "UTC."
+ (1) *Note Glossary::, especially the entries âEpochâ and âUTC.â
- (2) The GNU 'date' utility can also do many of the things described
+ (2) The GNU âdateâ utility can also do many of the things described
here. Its use may be preferable for simple time-related operations in
shell scripts.
(3) Occasionally there are minutes in a year with a leap second,
which is why the seconds can go up to 60.
- (4) Unfortunately, not every system's 'strftime()' necessarily
+ (4) Unfortunately, not every systemâs âstrftime()â necessarily
supports all of the conversions listed here.
- (5) If you don't understand any of this, don't worry about it; these
-facilities are meant to make it easier to "internationalize" programs.
+ (5) If you donât understand any of this, donât worry about it; these
+facilities are meant to make it easier to âinternationalizeâ programs.
Other internationalization features are described in *note
Internationalization::.
(6) This is because ISO C leaves the behavior of the C version of
-'strftime()' undefined and 'gawk' uses the system's version of
-'strftime()' if it's there. Typically, the conversion specifier either
+âstrftime()â undefined and âgawkâ uses the systemâs version of
+âstrftime()â if itâs there. Typically, the conversion specifier either
does not appear in the returned string or appears literally.
@@ -14367,10 +14367,10 @@ File: gawk.info, Node: Bitwise Functions, Next:
Type Functions, Prev: Time Fu
9.1.7 Bit-Manipulation Functions
--------------------------------
- I can explain it for you, but I can't understand it for you.
- -- _Anonymous_
+ I can explain it for you, but I canât understand it for you.
+ â _Anonymous_
- Many languages provide the ability to perform "bitwise" operations on
+ Many languages provide the ability to perform âbitwiseâ operations on
two integer numbers. In other words, the operation is performed on each
successive pair of bits in the operands. Three common operations are
bitwise AND, OR, and XOR. The operations are described in *note Table
@@ -14390,43 +14390,43 @@ Table 9.6: Bitwise operations
As you can see, the result of an AND operation is 1 only when _both_
bits are 1. The result of an OR operation is 1 if _either_ bit is 1.
The result of an XOR operation is 1 if either bit is 1, but not both.
-The next operation is the "complement"; the complement of 1 is 0 and the
-complement of 0 is 1. Thus, this operation "flips" all the bits of a
+The next operation is the âcomplementâ; the complement of 1 is 0 and the
+complement of 0 is 1. Thus, this operation âflipsâ all the bits of a
given value.
Finally, two other common operations are to shift the bits left or
-right. For example, if you have a bit string '10111001' and you shift
-it right by three bits, you end up with '00010111'.(1) If you start
-over again with '10111001' and shift it left by three bits, you end up
-with '11001000'. The following list describes 'gawk''s built-in
+right. For example, if you have a bit string â10111001â and you shift
+it right by three bits, you end up with â00010111â.(1) If you start
+over again with â10111001â and shift it left by three bits, you end up
+with â11001000â. The following list describes âgawkââs built-in
functions that implement the bitwise operations. Optional parameters
are enclosed in square brackets ([ ]):
-'and('V1',' V2 [',' ...]')'
+âand(âV1â,â V2 [â,â ...]â)â
Return the bitwise AND of the arguments. There must be at least
two.
-'compl(VAL)'
+âcompl(VAL)â
Return the bitwise complement of VAL.
-'lshift(VAL, COUNT)'
+âlshift(VAL, COUNT)â
Return the value of VAL, shifted left by COUNT bits.
-'or('V1',' V2 [',' ...]')'
+âor(âV1â,â V2 [â,â ...]â)â
Return the bitwise OR of the arguments. There must be at least
two.
-'rshift(VAL, COUNT)'
+ârshift(VAL, COUNT)â
Return the value of VAL, shifted right by COUNT bits.
-'xor('V1',' V2 [',' ...]')'
+âxor(âV1â,â V2 [â,â ...]â)â
Return the bitwise XOR of the arguments. There must be at least
two.
- CAUTION: Beginning with 'gawk' version 4.2, negative operands are
+ CAUTION: Beginning with âgawkâ version 4.2, negative operands are
not allowed for any of these functions. A negative operand
- produces a fatal error. See the sidebar "Beware The Smoke and
- Mirrors!" for more information as to why.
+ produces a fatal error. See the sidebar âBeware The Smoke and
+ Mirrors!â for more information as to why.
Here is a user-defined function (*note User-defined::) that
illustrates the use of these functions:
@@ -14463,31 +14463,31 @@ illustrates the use of these functions:
This program produces the following output when run:
$ gawk -f testbits.awk
- -| 123 = 01111011
- -| 0123 = 01010011
- -| 0x99 = 10011001
- -| compl(0x99) = 0x3fffffffffff66 =
- -| 00111111111111111111111111111111111111111111111101100110
- -| lshift(0x99, 2) = 0x264 = 0000001001100100
- -| rshift(0x99, 2) = 0x26 = 00100110
-
- The 'bits2str()' function turns a binary number into a string.
-Initializing 'mask' to one creates a binary value where the rightmost
+ ⣠123 = 01111011
+ ⣠0123 = 01010011
+ ⣠0x99 = 10011001
+ ⣠compl(0x99) = 0x3fffffffffff66 =
+ ⣠00111111111111111111111111111111111111111111111101100110
+ ⣠lshift(0x99, 2) = 0x264 = 0000001001100100
+ ⣠rshift(0x99, 2) = 0x26 = 00100110
+
+ The âbits2str()â function turns a binary number into a string.
+Initializing âmaskâ to one creates a binary value where the rightmost
bit is set to one. Using this mask, the function repeatedly checks the
rightmost bit. ANDing the mask with the value indicates whether the
-rightmost bit is one or not. If so, a '"1"' is concatenated onto the
-front of the string. Otherwise, a '"0"' is added. The value is then
+rightmost bit is one or not. If so, a â"1"â is concatenated onto the
+front of the string. Otherwise, a â"0"â is added. The value is then
shifted right by one bit and the loop continues until there are no more
one bits.
- If the initial value is zero, it returns a simple '"0"'. Otherwise,
+ If the initial value is zero, it returns a simple â"0"â. Otherwise,
at the end, it pads the value with zeros to represent multiples of 8-bit
quantities. This is typical in modern computers.
- The main code in the 'BEGIN' rule shows the difference between the
+ The main code in the âBEGINâ rule shows the difference between the
decimal and octal values for the same numbers (*note
Nondecimal-numbers::), and then demonstrates the results of the
-'compl()', 'lshift()', and 'rshift()' functions.
+âcompl()â, âlshift()â, and ârshift()â functions.
Beware The Smoke and Mirrors!
@@ -14495,52 +14495,52 @@ Nondecimal-numbers::), and then demonstrates the
results of the
values, not floating-point values. As a general statement, such
operations work best when performed on unsigned integers.
- 'gawk' attempts to treat the arguments to the bitwise functions as
+ âgawkâ attempts to treat the arguments to the bitwise functions as
unsigned integers. For this reason, negative arguments produce a fatal
error.
In normal operation, for all of these functions, first the
double-precision floating-point value is converted to the widest C
unsigned integer type, then the bitwise operation is performed. If the
-result cannot be represented exactly as a C 'double', leading nonzero
+result cannot be represented exactly as a C âdoubleâ, leading nonzero
bits are removed one by one until it can be represented exactly. The
-result is then converted back into a C 'double'.(2)
+result is then converted back into a C âdoubleâ.(2)
- However, when using arbitrary precision arithmetic with the '-M'
+ However, when using arbitrary precision arithmetic with the â-Mâ
option (*note Arbitrary Precision Arithmetic::), the results may differ.
-This is particularly noticeable with the 'compl()' function:
+This is particularly noticeable with the âcompl()â function:
$ gawk 'BEGIN { print compl(42) }'
- -| 9007199254740949
+ ⣠9007199254740949
$ gawk -M 'BEGIN { print compl(42) }'
- -| -43
+ ⣠-43
- What's going on becomes clear when printing the results in
+ Whatâs going on becomes clear when printing the results in
hexadecimal:
$ gawk 'BEGIN { printf "%#x\n", compl(42) }'
- -| 0x1fffffffffffd5
+ ⣠0x1fffffffffffd5
$ gawk -M 'BEGIN { printf "%#x\n", compl(42) }'
- -| 0xffffffffffffffd5
+ ⣠0xffffffffffffffd5
- When using the '-M' option, under the hood, 'gawk' uses GNU MP
+ When using the â-Mâ option, under the hood, âgawkâ uses GNU MP
arbitrary precision integers which have at least 64 bits of precision.
-When not using '-M', 'gawk' stores integral values in regular
+When not using â-Mâ, âgawkâ stores integral values in regular
double-precision floating point, which only maintain 53 bits of
precision. Furthermore, the GNU MP library treats (or at least seems to
-treat) the leading bit as a sign bit; thus the result with '-M' in this
+treat) the leading bit as a sign bit; thus the result with â-Mâ in this
case is a negative number.
- In short, using 'gawk' for any but the simplest kind of bitwise
+ In short, using âgawkâ for any but the simplest kind of bitwise
operations is probably a bad idea; caveat emptor!
---------- Footnotes ----------
(1) This example shows that zeros come in on the left side. For
-'gawk', this is always true, but in some languages, it's possible to
+âgawkâ, this is always true, but in some languages, itâs possible to
have the left side fill with ones.
- (2) If you don't understand this paragraph, the upshot is that 'gawk'
+ (2) If you donât understand this paragraph, the upshot is that âgawkâ
can only store a particular range of integer values; numbers outside
that range are reduced to fit within the range.
@@ -14550,39 +14550,39 @@ File: gawk.info, Node: Type Functions, Next: I18N
Functions, Prev: Bitwise Fu
9.1.8 Getting Type Information
------------------------------
-'gawk' provides two functions that let you distinguish the type of a
+âgawkâ provides two functions that let you distinguish the type of a
variable. This is necessary for writing code that traverses every
element of an array of arrays (*note Arrays of Arrays::), and in other
contexts.
-'isarray(X)'
+âisarray(X)â
Return a true value if X is an array. Otherwise, return false.
-'typeof(X)'
+âtypeof(X)â
Return one of the following strings, depending upon the type of X:
- '"array"'
+ â"array"â
X is an array.
- '"regexp"'
+ â"regexp"â
X is a strongly typed regexp (*note Strong Regexp
Constants::).
- '"number"'
+ â"number"â
X is a number.
- '"number|bool"'
+ â"number|bool"â
X is a Boolean typed value (*note Boolean Typed Values::).
- '"string"'
+ â"string"â
X is a string.
- '"strnum"'
+ â"strnum"â
X is a number that started life as user input, such as a field
- or the result of calling 'split()'. (I.e., X has the strnum
+ or the result of calling âsplit()â. (I.e., X has the strnum
attribute; *note Variable Typing::.)
- '"unassigned"'
+ â"unassigned"â
X is a scalar variable that has not been assigned a value yet.
For example:
@@ -14592,7 +14592,7 @@ contexts.
print typeof(a[1]) # unassigned
}
- '"untyped"'
+ â"untyped"â
X has not yet been used yet at all; it can become a scalar or
an array. The typing could even conceivably differ from run
to run of the same program! For example:
@@ -14612,24 +14612,24 @@ contexts.
function make_array(p) { p[1] = 1 }
- 'isarray()' is meant for use in two circumstances. The first is when
+ âisarray()â is meant for use in two circumstances. The first is when
traversing a multidimensional array: you can test if an element is
itself an array or not. The second is inside the body of a user-defined
function (not discussed yet; *note User-defined::), to test if a
parameter is an array or not.
- NOTE: While you can use 'isarray()' at the global level to test
+ NOTE: While you can use âisarray()â at the global level to test
variables, doing so makes no sense. Because _you_ are the one
writing the program, _you_ are supposed to know if your variables
are arrays or not.
- The 'typeof()' function is general; it allows you to determine if a
+ The âtypeof()â function is general; it allows you to determine if a
variable or function parameter is a scalar (number, string, or strongly
typed regexp) or an array.
Normally, passing a variable that has never been used to a built-in
function causes it to become a scalar variable (unassigned). However,
-'isarray()' and 'typeof()' are different; they do not change their
+âisarray()â and âtypeof()â are different; they do not change their
arguments from untyped to unassigned.
This applies to both variables denoted by simple identifiers and
@@ -14637,18 +14637,18 @@ array elements that come into existence simply by
referencing them.
Consider:
$ gawk 'BEGIN { print typeof(x) }'
- -| untyped
+ ⣠untyped
$ gawk 'BEGIN { print typeof(x["foo"]) }'
- -| untyped
+ ⣠untyped
Note that prior to version 5.2, array elements that come into
existence simply by referencing them were different, they were
automatically forced to be scalars:
$ gawk-5.1.1 'BEGIN { print typeof(x) }'
- -| untyped
+ ⣠untyped
$ gawk-5.1.1 'BEGIN { print typeof(x["foo"]) }'
- -| unassigned
+ ⣠unassigned
File: gawk.info, Node: I18N Functions, Prev: Type Functions, Up: Built-in
@@ -14656,34 +14656,34 @@ File: gawk.info, Node: I18N Functions, Prev: Type
Functions, Up: Built-in
9.1.9 String-Translation Functions
----------------------------------
-'gawk' provides facilities for internationalizing 'awk' programs. These
+âgawkâ provides facilities for internationalizing âawkâ programs.
These
include the functions described in the following list. The descriptions
here are purposely brief. *Note Internationalization::, for the full
story. Optional parameters are enclosed in square brackets ([ ]):
-'bindtextdomain(DIRECTORY' [',' DOMAIN]')'
- Set the directory in which 'gawk' will look for message translation
- files, in case they will not or cannot be placed in the "standard"
+âbindtextdomain(DIRECTORYâ [â,â DOMAIN]â)â
+ Set the directory in which âgawkâ will look for message translation
+ files, in case they will not or cannot be placed in the âstandardâ
locations (e.g., during testing). It returns the directory in
- which DOMAIN is "bound."
+ which DOMAIN is âbound.â
- The default DOMAIN is the value of 'TEXTDOMAIN'. If DIRECTORY is
- the null string ('""'), then 'bindtextdomain()' returns the current
+ The default DOMAIN is the value of âTEXTDOMAINâ. If DIRECTORY is
+ the null string (â""â), then âbindtextdomain()â returns the
current
binding for the given DOMAIN.
-'dcgettext(STRING' [',' DOMAIN [',' CATEGORY] ]')'
+âdcgettext(STRINGâ [â,â DOMAIN [â,â CATEGORY] ]â)â
Return the translation of STRING in text domain DOMAIN for locale
category CATEGORY. The default value for DOMAIN is the current
- value of 'TEXTDOMAIN'. The default value for CATEGORY is
- '"LC_MESSAGES"'.
+ value of âTEXTDOMAINâ. The default value for CATEGORY is
+ â"LC_MESSAGES"â.
-'dcngettext(STRING1, STRING2, NUMBER' [',' DOMAIN [',' CATEGORY] ]')'
+âdcngettext(STRING1, STRING2, NUMBERâ [â,â DOMAIN [â,â CATEGORY]
]â)â
Return the plural form used for NUMBER of the translation of
STRING1 and STRING2 in text domain DOMAIN for locale category
CATEGORY. STRING1 is the English singular variant of a message,
and STRING2 is the English plural variant of the same message. The
- default value for DOMAIN is the current value of 'TEXTDOMAIN'. The
- default value for CATEGORY is '"LC_MESSAGES"'.
+ default value for DOMAIN is the current value of âTEXTDOMAINâ. The
+ default value for CATEGORY is â"LC_MESSAGES"â.
File: gawk.info, Node: User-defined, Next: Indirect Calls, Prev: Built-in,
Up: Functions
@@ -14691,10 +14691,10 @@ File: gawk.info, Node: User-defined, Next: Indirect
Calls, Prev: Built-in, U
9.2 User-Defined Functions
==========================
-Complicated 'awk' programs can often be simplified by defining your own
+Complicated âawkâ programs can often be simplified by defining your own
functions. User-defined functions can be called just like built-in ones
(*note Function Calls::), but it is up to you to define them (i.e., to
-tell 'awk' what they should do).
+tell âawkâ what they should do).
* Menu:
@@ -14711,32 +14711,32 @@ File: gawk.info, Node: Definition Syntax, Next:
Function Example, Up: User-de
9.2.1 Function Definition Syntax
--------------------------------
- It's entirely fair to say that the awk syntax for local variable
+ Itâs entirely fair to say that the awk syntax for local variable
definitions is appallingly awful.
- -- _Brian Kernighan_
+ â _Brian Kernighan_
Definitions of functions can appear anywhere between the rules of an
-'awk' program. Thus, the general form of an 'awk' program is extended
+âawkâ program. Thus, the general form of an âawkâ program is extended
to include sequences of rules _and_ user-defined function definitions.
There is no need to put the definition of a function before all uses of
-the function. This is because 'awk' reads the entire program before
+the function. This is because âawkâ reads the entire program before
starting to execute any of it.
The definition of a function named NAME looks like this:
- 'function' NAME'('[PARAMETER-LIST]')'
- '{'
+ âfunctionâ NAMEâ(â[PARAMETER-LIST]â)â
+ â{â
BODY-OF-FUNCTION
- '}'
+ â}â
Here, NAME is the name of the function to define. A valid function name
is like a valid variable name: a sequence of letters, digits, and
-underscores that doesn't start with a digit. Here too, only the 52
+underscores that doesnât start with a digit. Here too, only the 52
upper- and lowercase English letters may be used in a function name.
-Within a single 'awk' program, any particular name can only be used as a
+Within a single âawkâ program, any particular name can only be used as a
variable, array, or function.
- PARAMETER-LIST is an optional list of the function's arguments and
+ PARAMETER-LIST is an optional list of the functionâs arguments and
local variable names, separated by commas. When the function is called,
the argument names are used to hold the argument values given in the
call.
@@ -14749,8 +14749,8 @@ have a parameter with the same name as the function
itself.
variables (*note Built-in Variables::), nor may a function
parameter have the same name as another function.
- Not all versions of 'awk' enforce these restrictions. (d.c.)
- 'gawk' always enforces the first restriction. With '--posix'
+ Not all versions of âawkâ enforce these restrictions. (d.c.)
+ âgawkâ always enforces the first restriction. With â--posixâ
(*note Options::), it also enforces the second restriction.
Local variables act like the empty string if referenced where a
@@ -14759,7 +14759,7 @@ value is required. This is the same as the behavior of
regular
variables that have never been assigned a value. (There is more to
understand about local variables; *note Dynamic Typing::.)
- The BODY-OF-FUNCTION consists of 'awk' statements. It is the most
+ The BODY-OF-FUNCTION consists of âawkâ statements. It is the most
important part of the definition, because it says what the function
should actually _do_. The argument names exist to give the body a way
to talk about the arguments; local variables exist to give the body
@@ -14783,12 +14783,12 @@ the local variables, in order to document how your
function is supposed
to be used.
During execution of the function body, the arguments and local
-variable values hide, or "shadow", any variables of the same names used
+variable values hide, or âshadowâ, any variables of the same names used
in the rest of the program. The shadowed variables are not accessible
in the function definition, because there is no way to name them while
their names have been taken away for the arguments and local variables.
-All other variables used in the 'awk' program can be referenced or set
-normally in the function's body.
+All other variables used in the âawkâ program can be referenced or set
+normally in the functionâs body.
The arguments and local variables last only as long as the function
body is executing. Once the body finishes, you can once again access
@@ -14796,35 +14796,35 @@ the variables that were shadowed while the function
was running.
The function body can contain expressions that call functions. They
can even call this function, either directly or by way of another
-function. When this happens, we say the function is "recursive". The
-act of a function calling itself is called "recursion".
+function. When this happens, we say the function is ârecursiveâ. The
+act of a function calling itself is called ârecursionâ.
All the built-in functions return a value to their caller.
-User-defined functions can do so also, using the 'return' statement,
+User-defined functions can do so also, using the âreturnâ statement,
which is described in detail in *note Return Statement::. Many of the
-subsequent examples in this minor node use the 'return' statement.
+subsequent examples in this minor node use the âreturnâ statement.
- In many 'awk' implementations, including 'gawk', the keyword
-'function' may be abbreviated 'func'. (c.e.) However, POSIX only
-specifies the use of the keyword 'function'. This actually has some
-practical implications. If 'gawk' is in POSIX-compatibility mode (*note
+ In many âawkâ implementations, including âgawkâ, the keyword
+âfunctionâ may be abbreviated âfuncâ. (c.e.) However, POSIX only
+specifies the use of the keyword âfunctionâ. This actually has some
+practical implications. If âgawkâ is in POSIX-compatibility mode (*note
Options::), then the following statement does _not_ define a function:
func foo() { a = sqrt($1) ; print a }
Instead, it defines a rule that, for each record, concatenates the value
-of the variable 'func' with the return value of the function 'foo'. If
+of the variable âfuncâ with the return value of the function âfooâ. If
the resulting string is non-null, the action is executed. This is
-probably not what is desired. ('awk' accepts this input as
+probably not what is desired. (âawkâ accepts this input as
syntactically valid, because functions may be used before they are
-defined in 'awk' programs.(1))
+defined in âawkâ programs.(1))
- To ensure that your 'awk' programs are portable, always use the
-keyword 'function' when defining a function.
+ To ensure that your âawkâ programs are portable, always use the
+keyword âfunctionâ when defining a function.
---------- Footnotes ----------
- (1) This program won't actually run, because 'foo()' is undefined.
+ (1) This program wonât actually run, because âfoo()â is undefined.
File: gawk.info, Node: Function Example, Next: Function Calling, Prev:
Definition Syntax, Up: User-defined
@@ -14832,7 +14832,7 @@ File: gawk.info, Node: Function Example, Next:
Function Calling, Prev: Defini
9.2.2 Function Definition Examples
----------------------------------
-Here is an example of a user-defined function, called 'myprint()', that
+Here is an example of a user-defined function, called âmyprint()â, that
takes a number and prints it in a specific format:
function myprint(num)
@@ -14840,7 +14840,7 @@ takes a number and prints it in a specific format:
printf "%6.3g\n", num
}
-To illustrate, here is an 'awk' rule that uses our 'myprint()' function:
+To illustrate, here is an âawkâ rule that uses our âmyprint()â
function:
$3 > 0 { myprint($3) }
@@ -14869,8 +14869,8 @@ extra whitespace signifies the start of the local
variable list):
When working with arrays, it is often necessary to delete all the
elements in an array and start over with a new list of elements (*note
Delete::). Instead of having to repeat this loop everywhere that you
-need to clear out an array, your program can just call 'delarray()'.
-(This guarantees portability. The use of 'delete ARRAY' to delete the
+need to clear out an array, your program can just call âdelarray()â.
+(This guarantees portability. The use of âdelete ARRAYâ to delete the
contents of an entire array is a relatively recent(1) addition to the
POSIX standard.)
@@ -14888,17 +14888,17 @@ empty:
return (rev(substr(str, 2)) substr(str, 1, 1))
}
- If this function is in a file named 'rev.awk', it can be tested this
+ If this function is in a file named ârev.awkâ, it can be tested this
way:
$ echo "Don't Panic!" |
> gawk -e '{ print rev($0) }' -f rev.awk
- -| !cinaP t'noD
+ ⣠!cinaP t'noD
- The C 'ctime()' function takes a timestamp and returns it as a
+ The C âctime()â function takes a timestamp and returns it as a
string, formatted in a well-known fashion. The following example uses
-the built-in 'strftime()' function (*note Time Functions::) to create an
-'awk' version of 'ctime()':
+the built-in âstrftime()â function (*note Time Functions::) to create an
+âawkâ version of âctime()â:
# ctime.awk
#
@@ -14913,10 +14913,10 @@ the built-in 'strftime()' function (*note Time
Functions::) to create an
return strftime(format, ts)
}
- You might think that 'ctime()' could use 'PROCINFO["strftime"]' for
-its format string. That would be a mistake, because 'ctime()' is
+ You might think that âctime()â could use âPROCINFO["strftime"]â for
+its format string. That would be a mistake, because âctime()â is
supposed to return the time formatted in a standard fashion, and
-user-level code could have changed 'PROCINFO["strftime"]'.
+user-level code could have changed âPROCINFO["strftime"]â.
---------- Footnotes ----------
@@ -14928,13 +14928,13 @@ File: gawk.info, Node: Function Calling, Next:
Return Statement, Prev: Functi
9.2.3 Calling User-Defined Functions
------------------------------------
-"Calling a function" means causing the function to run and do its job.
+âCalling a functionâ means causing the function to run and do its job.
A function call is an expression and its value is the value returned by
the function.
* Menu:
-* Calling A Function:: Don't use spaces.
+* Calling A Function:: Donât use spaces.
* Variable Scope:: Controlling variable scope.
* Pass By Value/Reference:: Passing parameters.
* Function Caveats:: Other points to know about functions.
@@ -14946,17 +14946,17 @@ File: gawk.info, Node: Calling A Function, Next:
Variable Scope, Up: Function
...............................
A function call consists of the function name followed by the arguments
-in parentheses. 'awk' expressions are what you write in the call for
+in parentheses. âawkâ expressions are what you write in the call for
the arguments. Each time the call is executed, these expressions are
evaluated, and the values become the actual arguments. For example,
-here is a call to 'foo()' with three arguments (the first being a string
+here is a call to âfoo()â with three arguments (the first being a string
concatenation):
foo(x y, "lose", 4 * z)
CAUTION: Whitespace characters (spaces and TABs) are not allowed
between the function name and the opening parenthesis of the
- argument list. If you write whitespace by mistake, 'awk' might
+ argument list. If you write whitespace by mistake, âawkâ might
think that you mean to concatenate a variable with an expression in
parentheses. However, it notices that you used a function name and
not a variable name, and reports an error.
@@ -14968,14 +14968,14 @@ File: gawk.info, Node: Variable Scope, Next: Pass
By Value/Reference, Prev: C
..................................
Unlike in many languages, there is no way to make a variable local to a
-'{' ... '}' block in 'awk', but you can make a variable local to a
+â{â ... â}â block in âawkâ, but you can make a variable local to a
function. It is good practice to do so whenever a variable is needed
only in that function.
To make a variable local to a function, simply declare the variable
as an argument after the actual function arguments (*note Definition
-Syntax::). Look at the following example, where variable 'i' is a
-global variable used by both functions 'foo()' and 'bar()':
+Syntax::). Look at the following example, where variable âiâ is a
+global variable used by both functions âfoo()â and âbar()â:
function bar()
{
@@ -14998,8 +14998,8 @@ global variable used by both functions 'foo()' and
'bar()':
print "top's i=" i
}
- Running this script produces the following, because the 'i' in
-functions 'foo()' and 'bar()' and at the top level refer to the same
+ Running this script produces the following, because the âiâ in
+functions âfoo()â and âbar()â and at the top level refer to the same
variable instance:
top's i=10
@@ -15010,9 +15010,9 @@ variable instance:
foo's i=3
top's i=3
- If you want 'i' to be local to both 'foo()' and 'bar()', do as
-follows (the extra space before 'i' is a coding convention to indicate
-that 'i' is a local variable, not an argument):
+ If you want âiâ to be local to both âfoo()â and âbar()â, do as
+follows (the extra space before âiâ is a coding convention to indicate
+that âiâ is a local variable, not an argument):
function bar( i)
{
@@ -15046,7 +15046,7 @@ that 'i' is a local variable, not an argument):
top's i=10
Besides scalar values (strings and numbers), you may also have local
-arrays. By using a parameter name as an array, 'awk' treats it as an
+arrays. By using a parameter name as an array, âawkâ treats it as an
array, and it is local to the function. In addition, recursive calls
create new arrays. Consider this example:
@@ -15087,9 +15087,9 @@ File: gawk.info, Node: Pass By Value/Reference, Next:
Function Caveats, Prev:
9.2.3.3 Passing Function Arguments by Value Or by Reference
...........................................................
-In 'awk', when you declare a function, there is no way to declare
-explicitly whether the arguments are passed "by value" or "by
-reference".
+In âawkâ, when you declare a function, there is no way to declare
+explicitly whether the arguments are passed âby valueâ or âby
+referenceâ.
Instead, the passing convention is determined at runtime when the
function is called, according to the following rule: if the argument is
@@ -15099,17 +15099,17 @@ argument is passed by value.
Passing an argument by value means that when a function is called, it
is given a _copy_ of the value of this argument. The caller may use a
variable as the expression for the argument, but the called function
-does not know this--it only knows what value the argument had. For
+does not know thisâit only knows what value the argument had. For
example, if you write the following code:
foo = "bar"
z = myfunc(foo)
-then you should not think of the argument to 'myfunc()' as being "the
-variable 'foo'." Instead, think of the argument as the string value
-'"bar"'. If the function 'myfunc()' alters the values of its local
+then you should not think of the argument to âmyfunc()â as being âthe
+variable âfooâ.â Instead, think of the argument as the string value
+â"bar"â. If the function âmyfunc()â alters the values of its local
variables, this has no effect on any other variables. Thus, if
-'myfunc()' does this:
+âmyfunc()â does this:
function myfunc(str)
{
@@ -15118,17 +15118,17 @@ variables, this has no effect on any other variables.
Thus, if
print str
}
-to change its first argument variable 'str', it does _not_ change the
-value of 'foo' in the caller. The role of 'foo' in calling 'myfunc()'
-ended when its value ('"bar"') was computed. If 'str' also exists
-outside of 'myfunc()', the function body cannot alter this outer value,
-because it is shadowed during the execution of 'myfunc()' and cannot be
+to change its first argument variable âstrâ, it does _not_ change the
+value of âfooâ in the caller. The role of âfooâ in calling
âmyfunc()â
+ended when its value (â"bar"â) was computed. If âstrâ also exists
+outside of âmyfunc()â, the function body cannot alter this outer value,
+because it is shadowed during the execution of âmyfunc()â and cannot be
seen or changed from there.
However, when arrays are the parameters to functions, they are _not_
copied. Instead, the array itself is made available for direct
-manipulation by the function. This is usually termed "call by
-reference". Changes made to an array parameter inside the body of a
+manipulation by the function. This is usually termed âcall by
+referenceâ. Changes made to an array parameter inside the body of a
function _are_ visible outside that function.
NOTE: Changing an array parameter inside a function can be very
@@ -15146,8 +15146,8 @@ function _are_ visible outside that function.
a[1], a[2], a[3]
}
- prints 'a[1] = 1, a[2] = two, a[3] = 3', because 'changeit()'
- stores '"two"' in the second element of 'a'.
+ prints âa[1] = 1, a[2] = two, a[3] = 3â, because âchangeit()â
+ stores â"two"â in the second element of âaâ.
File: gawk.info, Node: Function Caveats, Prev: Pass By Value/Reference, Up:
Function Calling
@@ -15155,7 +15155,7 @@ File: gawk.info, Node: Function Caveats, Prev: Pass
By Value/Reference, Up: F
9.2.3.4 Other Points About Calling Functions
............................................
-Some 'awk' implementations allow you to call a function that has not
+Some âawkâ implementations allow you to call a function that has not
been defined. They only report a problem at runtime, when the program
actually tries to call the function. For example:
@@ -15168,17 +15168,17 @@ actually tries to call the function. For example:
function bar() { ... }
# note that `foo' is not defined
-Because the 'if' statement will never be true, it is not really a
-problem that 'foo()' has not been defined. Usually, though, it is a
+Because the âifâ statement will never be true, it is not really a
+problem that âfoo()â has not been defined. Usually, though, it is a
problem if a program calls an undefined function.
- If '--lint' is specified (*note Options::), 'gawk' reports calls to
+ If â--lintâ is specified (*note Options::), âgawkâ reports calls to
undefined functions.
- Some 'awk' implementations generate a runtime error if you use either
-the 'next' statement or the 'nextfile' statement (*note Next
+ Some âawkâ implementations generate a runtime error if you use either
+the ânextâ statement or the ânextfileâ statement (*note Next
Statement::, and *note Nextfile Statement::) inside a user-defined
-function. 'gawk' does not have this limitation.
+function. âgawkâ does not have this limitation.
You can call a function and pass it more parameters than it was
declared with, like so:
@@ -15193,7 +15193,7 @@ declared with, like so:
}
Doing so is bad practice, however. The called function cannot do
-anything with the additional values being passed to it, so 'awk'
+anything with the additional values being passed to it, so âawkâ
evaluates the expressions but then just throws them away.
More importantly, such a call is confusing for whoever will next read
@@ -15202,44 +15202,44 @@ influence the computation performed by the function.
Calling a function
with more parameters than it accepts gives the false impression that
those values are important to the function, when in fact they are not.
- Because this is such a bad practice, 'gawk' _unconditionally_ issues
-a warning whenever it executes such a function call. (If you don't like
-the warning, fix your code! It's incorrect, after all.)
+ Because this is such a bad practice, âgawkâ _unconditionally_ issues
+a warning whenever it executes such a function call. (If you donât like
+the warning, fix your code! Itâs incorrect, after all.)
---------- Footnotes ----------
(1) Said person might even be you, sometime in the future, at which
-point you will wonder, "what was I thinking?!?"
+point you will wonder, âwhat was I thinking?!?â
File: gawk.info, Node: Return Statement, Next: Dynamic Typing, Prev:
Function Calling, Up: User-defined
-9.2.4 The 'return' Statement
+9.2.4 The âreturnâ Statement
----------------------------
As seen in several earlier examples, the body of a user-defined function
-can contain a 'return' statement. This statement returns control to the
-calling part of the 'awk' program. It can also be used to return a
-value for use in the rest of the 'awk' program. It looks like this:
+can contain a âreturnâ statement. This statement returns control to the
+calling part of the âawkâ program. It can also be used to return a
+value for use in the rest of the âawkâ program. It looks like this:
- 'return' [EXPRESSION]
+ âreturnâ [EXPRESSION]
The EXPRESSION part is optional. Due most likely to an oversight,
POSIX does not define what the return value is if you omit the
EXPRESSION. Technically speaking, this makes the returned value
undefined, and therefore, unpredictable. In practice, though, all
-versions of 'awk' simply return the null string, which acts like zero if
+versions of âawkâ simply return the null string, which acts like zero if
used in a numeric context.
- A 'return' statement without an EXPRESSION is assumed at the end of
+ A âreturnâ statement without an EXPRESSION is assumed at the end of
every function definition. So, if control reaches the end of the
function body, then technically the function returns an unpredictable
-value. In practice, it returns the empty string. 'awk' does _not_ warn
+value. In practice, it returns the empty string. âawkâ does _not_ warn
you if you use the return value of such a function.
Sometimes, you want to write a function for what it does, not for
-what it returns. Such a function corresponds to a 'void' function in C,
-C++, or Java, or to a 'procedure' in Ada. Thus, it may be appropriate
+what it returns. Such a function corresponds to a âvoidâ function in C,
+C++, or Java, or to a âprocedureâ in Ada. Thus, it may be appropriate
to not return any value; simply bear in mind that you should not be
using the return value of such a function.
@@ -15255,15 +15255,15 @@ value for the largest number among the elements of an
array:
return ret
}
-You call 'maxelt()' with one argument, which is an array name. The
-local variables 'i' and 'ret' are not intended to be arguments; there is
-nothing to stop you from passing more than one argument to 'maxelt()'
-but the results would be strange. The extra space before 'i' in the
-function parameter list indicates that 'i' and 'ret' are local
+You call âmaxelt()â with one argument, which is an array name. The
+local variables âiâ and âretâ are not intended to be arguments; there
is
+nothing to stop you from passing more than one argument to âmaxelt()â
+but the results would be strange. The extra space before âiâ in the
+function parameter list indicates that âiâ and âretâ are local
variables. You should follow this convention when defining functions.
- The following program uses the 'maxelt()' function. It loads an
-array, calls 'maxelt()', and then reports the maximum number in that
+ The following program uses the âmaxelt()â function. It loads an
+array, calls âmaxelt()â, and then reports the maximum number in that
array:
function maxelt(vec, i, ret)
@@ -15302,7 +15302,7 @@ File: gawk.info, Node: Dynamic Typing, Prev: Return
Statement, Up: User-defin
9.2.5 Functions and Their Effects on Variable Typing
----------------------------------------------------
-'awk' is a very fluid language. It is possible that 'awk' can't tell if
+âawkâ is a very fluid language. It is possible that âawkâ canât
tell if
an identifier represents a scalar variable or an array until runtime.
Here is an annotated sample program:
@@ -15319,11 +15319,11 @@ Here is an annotated sample program:
x = 1 # now not allowed, runtime error
}
- In this example, the first call to 'foo()' generates a fatal error,
-so 'awk' will not report the second error. If you comment out that
-call, though, then 'awk' does report the second error.
+ In this example, the first call to âfoo()â generates a fatal error,
+so âawkâ will not report the second error. If you comment out that
+call, though, then âawkâ does report the second error.
- Usually, such things aren't a big issue, but it's worth being aware
+ Usually, such things arenât a big issue, but itâs worth being aware
of them.
@@ -15332,21 +15332,21 @@ File: gawk.info, Node: Indirect Calls, Next:
Functions Summary, Prev: User-de
9.3 Indirect Function Calls
===========================
-This minor node describes an advanced, 'gawk'-specific extension.
+This minor node describes an advanced, âgawkâ-specific extension.
Often, you may wish to defer the choice of function to call until
runtime. For example, you may have different kinds of records, each of
which should be processed differently.
- Normally, you would have to use a series of 'if'-'else' statements to
-decide which function to call. By using "indirect" function calls, you
+ Normally, you would have to use a series of âifâ-âelseâ statements
to
+decide which function to call. By using âindirectâ function calls, you
can specify the name of the function to call as a string variable, and
-then call the function. Let's look at an example.
+then call the function. Letâs look at an example.
Suppose you have a file with your test scores for the classes you are
taking, and you wish to get the sum and the average of your test scores.
The first field is the class name. The following fields are the
-functions to call to process the data, up to a "marker" field 'data:'.
+functions to call to process the data, up to a âmarkerâ field âdata:â.
Following the marker, to the end of the record, are the various numeric
test scores.
@@ -15369,14 +15369,14 @@ test scores.
}
}
-This style of programming works, but can be awkward. With "indirect"
-function calls, you tell 'gawk' to use the _value_ of a variable as the
+This style of programming works, but can be awkward. With âindirectâ
+function calls, you tell âgawkâ to use the _value_ of a variable as the
_name_ of the function to call.
The syntax is similar to that of a regular function call: an
identifier immediately followed by an opening parenthesis, any
arguments, and then a closing parenthesis, with the addition of a
-leading '@' character:
+leading â@â character:
the_function = "sum"
result = @the_function() # calls the sum() function
@@ -15409,7 +15409,7 @@ using indirect function calls:
}
These two functions expect to work on fields; thus, the parameters
-'first' and 'last' indicate where in the fields to start and end.
+âfirstâ and âlastâ indicate where in the fields to start and end.
Otherwise, they perform the expected computations and are not unusual:
# For each record, print the class name and the requested statistics
@@ -15435,11 +15435,11 @@ Otherwise, they perform the expected computations and
are not unusual:
This is the main processing for each record. It prints the class
name (with underscores replaced with spaces). It then finds the start
-of the actual data, saving it in 'start'. The last part of the code
-loops through each function name (from '$2' up to the marker, 'data:'),
+of the actual data, saving it in âstartâ. The last part of the code
+loops through each function name (from â$2â up to the marker, âdata:â),
calling the function named by the field. The indirect function call
-itself occurs as a parameter in the call to 'printf'. (The 'printf'
-format string uses '%s' as the format specifier so that we can use
+itself occurs as a parameter in the call to âprintfâ. (The âprintfâ
+format string uses â%sâ as the format specifier so that we can use
functions that return strings, as well as numbers. Note that the result
from the indirect call is concatenated with the empty string, in order
to force it to be a string value.)
@@ -15447,29 +15447,29 @@ to force it to be a string value.)
Here is the result of running the program:
$ gawk -f indirectcall.awk class_data1
- -| Biology 101:
- -| sum: <352.8>
- -| average: <88.2>
- -|
- -| Chemistry 305:
- -| sum: <356.4>
- -| average: <89.1>
- -|
- -| English 401:
- -| sum: <376.1>
- -| average: <94.025>
+ ⣠Biology 101:
+ ⣠sum: <352.8>
+ ⣠average: <88.2>
+ â£
+ ⣠Chemistry 305:
+ ⣠sum: <356.4>
+ ⣠average: <89.1>
+ â£
+ ⣠English 401:
+ ⣠sum: <376.1>
+ ⣠average: <94.025>
The ability to use indirect function calls is more powerful than you
-may think at first. The C and C++ languages provide "function
-pointers," which are a mechanism for calling a function chosen at
+may think at first. The C and C++ languages provide âfunction
+pointers,â which are a mechanism for calling a function chosen at
runtime. One of the most well-known uses of this ability is the C
-'qsort()' function, which sorts an array using the famous "quicksort"
+âqsort()â function, which sorts an array using the famous âquicksortâ
algorithm (see the Wikipedia article
(https://en.wikipedia.org/wiki/Quicksort) for more information). To use
this function, you supply a pointer to a comparison function. This
mechanism allows you to sort arbitrary data in an arbitrary fashion.
- We can do something similar using 'gawk', like this:
+ We can do something similar using âgawkâ, like this:
# quicksort.awk --- Quicksort algorithm, with user-supplied
# comparison function
@@ -15501,9 +15501,9 @@ mechanism allows you to sort arbitrary data in an
arbitrary fashion.
data[j] = temp
}
- The 'quicksort()' function receives the 'data' array, the starting
-and ending indices to sort ('left' and 'right'), and the name of a
-function that performs a "less than" comparison. It then implements the
+ The âquicksort()â function receives the âdataâ array, the starting
+and ending indices to sort (âleftâ and ârightâ), and the name of a
+function that performs a âless thanâ comparison. It then implements the
quicksort algorithm.
To make use of the sorting function, we return to our previous
@@ -15523,14 +15523,14 @@ example. The first thing to do is write some
comparison functions:
return ((left + 0) >= (right + 0))
}
- The 'num_ge()' function is needed to perform a descending sort; when
-used to perform a "less than" test, it actually does the opposite
+ The ânum_ge()â function is needed to perform a descending sort; when
+used to perform a âless thanâ test, it actually does the opposite
(greater than or equal to), which yields data sorted in descending
order.
Next comes a sorting function. It is parameterized with the starting
and ending field numbers and the comparison function. It builds an
-array with the data and calls 'quicksort()' appropriately, and then
+array with the data and calls âquicksort()â appropriately, and then
formats the results as a single string:
# do_sort --- sort the data according to `compare'
@@ -15553,7 +15553,7 @@ formats the results as a single string:
return retval
}
- Finally, the two sorting functions call 'do_sort()', passing in the
+ Finally, the two sorting functions call âdo_sort()â, passing in the
names of the two comparison functions:
# sort --- sort the data in ascending order and return it as a string
@@ -15579,65 +15579,65 @@ names of the two comparison functions:
Finally, here are the results when the enhanced program is run:
$ gawk -f quicksort.awk -f indirectcall.awk class_data2
- -| Biology 101:
- -| sum: <352.8>
- -| average: <88.2>
- -| sort: <78.5 87.0 92.4 94.9>
- -| rsort: <94.9 92.4 87.0 78.5>
- -|
- -| Chemistry 305:
- -| sum: <356.4>
- -| average: <89.1>
- -| sort: <75.2 88.2 94.7 98.3>
- -| rsort: <98.3 94.7 88.2 75.2>
- -|
- -| English 401:
- -| sum: <376.1>
- -| average: <94.025>
- -| sort: <87.1 93.4 95.6 100.0>
- -| rsort: <100.0 95.6 93.4 87.1>
+ ⣠Biology 101:
+ ⣠sum: <352.8>
+ ⣠average: <88.2>
+ ⣠sort: <78.5 87.0 92.4 94.9>
+ ⣠rsort: <94.9 92.4 87.0 78.5>
+ â£
+ ⣠Chemistry 305:
+ ⣠sum: <356.4>
+ ⣠average: <89.1>
+ ⣠sort: <75.2 88.2 94.7 98.3>
+ ⣠rsort: <98.3 94.7 88.2 75.2>
+ â£
+ ⣠English 401:
+ ⣠sum: <376.1>
+ ⣠average: <94.025>
+ ⣠sort: <87.1 93.4 95.6 100.0>
+ ⣠rsort: <100.0 95.6 93.4 87.1>
Another example where indirect functions calls are useful can be
found in processing arrays. This is described in *note Walking
Arrays::.
- Remember that you must supply a leading '@' in front of an indirect
+ Remember that you must supply a leading â@â in front of an indirect
function call.
- Starting with version 4.1.2 of 'gawk', indirect function calls may
+ Starting with version 4.1.2 of âgawkâ, indirect function calls may
also be used with built-in functions and with extension functions (*note
Dynamic Extensions::). There are some limitations when calling built-in
functions indirectly, as follows.
- * You cannot pass a regular expression constant to a built-in
+ ⢠You cannot pass a regular expression constant to a built-in
function through an indirect function call. This applies to the
- 'sub()', 'gsub()', 'gensub()', 'match()', 'split()' and
- 'patsplit()' functions. However, you can pass a strongly typed
+ âsub()â, âgsub()â, âgensub()â, âmatch()â, âsplit()â
and
+ âpatsplit()â functions. However, you can pass a strongly typed
regexp constant (*note Strong Regexp Constants::).
- * If calling 'sub()' or 'gsub()', you may only pass two arguments,
+ ⢠If calling âsub()â or âgsub()â, you may only pass two arguments,
since those functions are unusual in that they update their third
- argument. This means that '$0' will be updated.
+ argument. This means that â$0â will be updated.
- * You cannot indirectly call built-in functions that can take '$0' as
+ ⢠You cannot indirectly call built-in functions that can take â$0â as
a default parameter; you must supply an argument instead. For
- example, you must pass an argument to 'length()' if calling it
+ example, you must pass an argument to âlength()â if calling it
indirectly.
- * Calling a built-in function indirectly with the wrong number of
+ ⢠Calling a built-in function indirectly with the wrong number of
arguments for that function causes a fatal error. For example,
- calling 'length()' with two arguments. These errors are found at
- runtime instead of when 'gawk' parses your program, since 'gawk'
- doesn't know until runtime if you have passed the correct number of
+ calling âlength()â with two arguments. These errors are found at
+ runtime instead of when âgawkâ parses your program, since âgawkâ
+ doesnât know until runtime if you have passed the correct number of
arguments or not.
- 'gawk' does its best to make indirect function calls efficient. For
+ âgawkâ does its best to make indirect function calls efficient. For
example, in the following case:
for (i = 1; i <= n; i++)
@the_function()
-'gawk' looks up the actual function to call only once.
+âgawkâ looks up the actual function to call only once.
File: gawk.info, Node: Functions Summary, Prev: Indirect Calls, Up:
Functions
@@ -15645,27 +15645,27 @@ File: gawk.info, Node: Functions Summary, Prev:
Indirect Calls, Up: Functions
9.4 Summary
===========
- * 'awk' provides built-in functions and lets you define your own
+ ⢠âawkâ provides built-in functions and lets you define your own
functions.
- * POSIX 'awk' provides three kinds of built-in functions: numeric,
- string, and I/O. 'gawk' provides functions that sort arrays, work
+ ⢠POSIX âawkâ provides three kinds of built-in functions: numeric,
+ string, and I/O. âgawkâ provides functions that sort arrays, work
with values representing time, do bit manipulation, determine
variable type (array versus scalar), and internationalize and
- localize programs. 'gawk' also provides several extensions to some
+ localize programs. âgawkâ also provides several extensions to some
of standard functions, typically in the form of additional
arguments.
- * Functions accept zero or more arguments and return a value. The
+ ⢠Functions accept zero or more arguments and return a value. The
expressions that provide the argument values are completely
evaluated before the function is called. Order of evaluation is
not defined. The return value can be ignored.
- * The handling of backslash in 'sub()' and 'gsub()' is not simple.
- It is more straightforward in 'gawk''s 'gensub()' function, but
+ ⢠The handling of backslash in âsub()â and âgsub()â is not simple.
+ It is more straightforward in âgawkââs âgensub()â function, but
that function still requires care in its use.
- * User-defined functions provide important capabilities but come with
+ ⢠User-defined functions provide important capabilities but come with
some syntactic inelegancies. In a function call, there cannot be
any space between the function name and the opening left
parenthesis of the argument list. Also, there is no provision for
@@ -15673,26 +15673,26 @@ File: gawk.info, Node: Functions Summary, Prev:
Indirect Calls, Up: Functions
to separate them visually from the real parameters by extra
whitespace.
- * User-defined functions may call other user-defined (and built-in)
+ ⢠User-defined functions may call other user-defined (and built-in)
functions and may call themselves recursively. Function parameters
- "hide" any global variables of the same names. You cannot use the
- name of a reserved variable (such as 'ARGC') as the name of a
+ âhideâ any global variables of the same names. You cannot use the
+ name of a reserved variable (such as âARGCâ) as the name of a
parameter in user-defined functions.
- * Scalar values are passed to user-defined functions by value. Array
+ ⢠Scalar values are passed to user-defined functions by value. Array
parameters are passed by reference; any changes made by the
function to array parameters are thus visible after the function
has returned.
- * Use the 'return' statement to return from a user-defined function.
- An optional expression becomes the function's return value. Only
+ ⢠Use the âreturnâ statement to return from a user-defined function.
+ An optional expression becomes the functionâs return value. Only
scalar values may be returned by a function.
- * If a variable that has never been used is passed to a user-defined
+ ⢠If a variable that has never been used is passed to a user-defined
function, how that function treats the variable can set its nature:
either scalar or array.
- * 'gawk' provides indirect function calls using a special syntax. By
+ ⢠âgawkâ provides indirect function calls using a special syntax. By
setting a variable to the name of a function, you can determine at
runtime what function will be called at that point in the program.
This is equivalent to function pointers in C and C++.
@@ -15700,16 +15700,16 @@ File: gawk.info, Node: Functions Summary, Prev:
Indirect Calls, Up: Functions
File: gawk.info, Node: Library Functions, Next: Sample Programs, Prev:
Functions, Up: Top
-10 A Library of 'awk' Functions
+10 A Library of âawkâ Functions
*******************************
-*note User-defined:: describes how to write your own 'awk' functions.
+*note User-defined:: describes how to write your own âawkâ functions.
Writing functions is important, because it allows you to encapsulate
algorithms and program tasks in a single place. It simplifies
programming, making program development more manageable and making
programs more readable.
- In their seminal 1976 book, 'Software Tools',(1) Brian Kernighan and
+ In their seminal 1976 book, âSoftware Toolsâ,(1) Brian Kernighan and
P.J. Plauger wrote:
Good Programming is not learned from generalities, but by seeing
@@ -15725,7 +15725,7 @@ their statement is correct, this major node and *note
Sample Programs::,
provide a good-sized body of code for you to read and, we hope, to learn
from.
- This major node presents a library of useful 'awk' functions. Many
+ This major node presents a library of useful âawkâ functions. Many
of the sample programs presented later in this Info file use these
functions. The functions are presented here in a progression from
simple to complex.
@@ -15733,23 +15733,23 @@ simple to complex.
*note Extract Program:: presents a program that you can use to
extract the source code for these example library functions and programs
from the Texinfo source for this Info file. (This has already been done
-as part of the 'gawk' distribution.)
+as part of the âgawkâ distribution.)
- If you have written one or more useful, general-purpose 'awk'
-functions and would like to contribute them to the 'awk' user community,
+ If you have written one or more useful, general-purpose âawkâ
+functions and would like to contribute them to the âawkâ user community,
see *note How To Contribute::, for more information.
The programs in this major node and in *note Sample Programs::,
-freely use 'gawk'-specific features. Rewriting these programs for
-different implementations of 'awk' is pretty straightforward:
+freely use âgawkâ-specific features. Rewriting these programs for
+different implementations of âawkâ is pretty straightforward:
- * Diagnostic error messages are sent to '/dev/stderr'. Use '| "cat
- 1>&2"' instead of '> "/dev/stderr"' if your system does not have a
- '/dev/stderr', or if you cannot use 'gawk'.
+ ⢠Diagnostic error messages are sent to â/dev/stderrâ. Use â| "cat
+ 1>&2"â instead of â> "/dev/stderr"â if your system does not have a
+ â/dev/stderrâ, or if you cannot use âgawkâ.
- * Finally, some of the programs choose to ignore upper- and lowercase
+ ⢠Finally, some of the programs choose to ignore upper- and lowercase
distinctions in their input. They do so by assigning one to
- 'IGNORECASE'. You can achieve almost the same effect(2) by adding
+ âIGNORECASEâ. You can achieve almost the same effect(2) by adding
the following rule to the beginning of the program:
# ignore case
@@ -15779,7 +15779,7 @@ different implementations of 'awk' is pretty
straightforward:
book have yet to be learned by a vast number of practicing programmers.
(2) The effects are not identical. Output of the transformed record
-will be in all lowercase, while 'IGNORECASE' preserves the original
+will be in all lowercase, while âIGNORECASEâ preserves the original
contents of the input record.
@@ -15788,32 +15788,32 @@ File: gawk.info, Node: Library Names, Next: General
Functions, Up: Library Fu
10.1 Naming Library Function Global Variables
=============================================
-Due to the way the 'awk' language evolved, variables are either "global"
-(usable by the entire program) or "local" (usable just by a specific
-function). There is no intermediate state analogous to 'static'
+Due to the way the âawkâ language evolved, variables are either
âglobalâ
+(usable by the entire program) or âlocalâ (usable just by a specific
+function). There is no intermediate state analogous to âstaticâ
variables in C.
Library functions often need to have global variables that they can
-use to preserve state information between calls to the function--for
-example, 'getopt()''s variable '_opti' (*note Getopt Function::). Such
-variables are called "private", as the only functions that need to use
+use to preserve state information between calls to the functionâfor
+example, âgetopt()ââs variable â_optiâ (*note Getopt Function::).
Such
+variables are called âprivateâ, as the only functions that need to use
them are the ones in the library.
When writing a library function, you should try to choose names for
your private variables that will not conflict with any variables used by
-either another library function or a user's main program. For example,
-a name like 'i' or 'j' is not a good choice, because user programs often
+either another library function or a userâs main program. For example,
+a name like âiâ or âjâ is not a good choice, because user programs
often
use variable names like these for their own purposes.
The example programs shown in this major node all start the names of
-their private variables with an underscore ('_'). Users generally don't
+their private variables with an underscore (â_â). Users generally donât
use leading underscores in their variable names, so this convention
immediately decreases the chances that the variable names will be
-accidentally shared with the user's program.
+accidentally shared with the userâs program.
In addition, several of the library functions use a prefix that helps
-indicate what function or set of functions use the variables--for
-example, '_pw_byname()' in the user database routines (*note Passwd
+indicate what function or set of functions use the variablesâfor
+example, â_pw_byname()â in the user database routines (*note Passwd
Functions::). This convention is recommended, as it even further
decreases the chance of inadvertent conflict among variable names. Note
that this convention is used equally well for variable names and for
@@ -15821,15 +15821,15 @@ private function names.(1)
As a final note on variable naming, if a function makes global
variables available for use by a main program, it is a good convention
-to start those variables' names with a capital letter--for example,
-'getopt()''s 'Opterr' and 'Optind' variables (*note Getopt Function::).
+to start those variablesâ names with a capital letterâfor example,
+âgetopt()ââs âOpterrâ and âOptindâ variables (*note Getopt
Function::).
The leading capital letter indicates that it is global, while the fact
that the variable name is not all capital letters indicates that the
-variable is not one of 'awk''s predefined variables, such as 'FS'.
+variable is not one of âawkââs predefined variables, such as âFSâ.
It is also important that _all_ variables in library functions that
do not need to save state are, in fact, declared local.(2) If this is
-not done, the variables could accidentally be used in the user's
+not done, the variables could accidentally be used in the userâs
program, leading to bugs that are very difficult to track down:
function lib_func(x, y, l1, l2)
@@ -15842,29 +15842,29 @@ program, leading to bugs that are very difficult to
track down:
A different convention, common in the Tcl community, is to use a
single associative array to hold the values needed by the library
-function(s), or "package." This significantly decreases the number of
+function(s), or âpackage.â This significantly decreases the number of
actual global names in use. For example, the functions described in
*note Passwd Functions:: might have used array elements
-'PW_data["inited"]', 'PW_data["total"]', 'PW_data["count"]', and
-'PW_data["awklib"]', instead of '_pw_inited', '_pw_awklib', '_pw_total',
-and '_pw_count'.
+âPW_data["inited"]â, âPW_data["total"]â, âPW_data["count"]â, and
+âPW_data["awklib"]â, instead of â_pw_initedâ, â_pw_awklibâ,
â_pw_totalâ,
+and â_pw_countâ.
The conventions presented in this minor node are exactly that:
-conventions. You are not required to write your programs this way--we
+conventions. You are not required to write your programs this wayâwe
merely recommend that you do so.
- Beginning with version 5.0, 'gawk' provides a powerful mechanism for
-solving the problems described in this section: "namespaces".
+ Beginning with version 5.0, âgawkâ provides a powerful mechanism for
+solving the problems described in this section: ânamespacesâ.
Namespaces and their use are described in detail in *note Namespaces::.
---------- Footnotes ----------
(1) Although all the library routines could have been rewritten to
use this convention, this was not done, in order to show how our own
-'awk' programming style has evolved and to provide some basis for this
+âawkâ programming style has evolved and to provide some basis for this
discussion.
- (2) 'gawk''s '--dump-variables' command-line option is useful for
+ (2) âgawkââs â--dump-variablesâ command-line option is useful for
verifying this.
@@ -15879,10 +15879,10 @@ programming use.
* Menu:
* Strtonum Function:: A replacement for the built-in
- 'strtonum()' function.
-* Assert Function:: A function for assertions in 'awk'
+ âstrtonum()â function.
+* Assert Function:: A function for assertions in âawkâ
programs.
-* Round Function:: A function for rounding if 'sprintf()'
+* Round Function:: A function for rounding if âsprintf()â
does not do it correctly.
* Cliff Random Function:: The Cliff Random Number Generator.
* Ordinal Functions:: Functions for using characters as numbers and
@@ -15899,9 +15899,9 @@ File: gawk.info, Node: Strtonum Function, Next:
Assert Function, Up: General
10.2.1 Converting Strings to Numbers
------------------------------------
-The 'strtonum()' function (*note String Functions::) is a 'gawk'
+The âstrtonum()â function (*note String Functions::) is a âgawkâ
extension. The following function provides an implementation for other
-versions of 'awk':
+versions of âawkâ:
# mystrtonum --- convert string to number
@@ -15959,24 +15959,24 @@ versions of 'awk':
The function first looks for C-style octal numbers (base 8). If the
input string matches a regular expression describing octal numbers, then
-'mystrtonum()' loops through each character in the string. It sets 'k'
-to the index in '"1234567"' of the current octal digit. The return
+âmystrtonum()â loops through each character in the string. It sets âkâ
+to the index in â"1234567"â of the current octal digit. The return
value will either be the same number as the digit, or zero if the
-character is not there, which will be true for a '0'. This is safe,
-because the regexp test in the 'if' ensures that only octal values are
+character is not there, which will be true for a â0â. This is safe,
+because the regexp test in the âifâ ensures that only octal values are
converted.
Similar logic applies to the code that checks for and converts a
-hexadecimal value, which starts with '0x' or '0X'. The use of
-'tolower()' simplifies the computation for finding the correct numeric
+hexadecimal value, which starts with â0xâ or â0Xâ. The use of
+âtolower()â simplifies the computation for finding the correct numeric
value for each hexadecimal digit.
Finally, if the string matches the (rather complicated) regexp for a
-regular decimal integer or floating-point number, the computation 'ret =
-str + 0' lets 'awk' convert the value to a number.
+regular decimal integer or floating-point number, the computation âret =
+str + 0â lets âawkâ convert the value to a number.
A commented-out test program is included, so that the function can be
-tested with 'gawk' and the results compared to the built-in 'strtonum()'
+tested with âgawkâ and the results compared to the built-in
âstrtonum()â
function.
@@ -15988,12 +15988,12 @@ File: gawk.info, Node: Assert Function, Next: Round
Function, Prev: Strtonum
When writing large programs, it is often useful to know that a condition
or set of conditions is true. Before proceeding with a particular
computation, you make a statement about what you believe to be the case.
-Such a statement is known as an "assertion". The C language provides an
-'<assert.h>' header file and corresponding 'assert()' macro that a
+Such a statement is known as an âassertionâ. The C language provides an
+â<assert.h>â header file and corresponding âassert()â macro that a
programmer can use to make assertions. If an assertion fails, the
-'assert()' macro arranges to print a diagnostic message describing the
+âassert()â macro arranges to print a diagnostic message describing the
condition that should have been true but was not, and then it kills the
-program. In C, using 'assert()' looks this:
+program. In C, using âassert()â looks this:
#include <assert.h>
@@ -16009,7 +16009,7 @@ program. In C, using 'assert()' looks this:
The C language makes it possible to turn the condition into a string
for use in printing the diagnostic message. This is not possible in
-'awk', so this 'assert()' function also requires a string version of the
+âawkâ, so this âassert()â function also requires a string version of
the
condition that is being tested. Following is the function:
# assert --- assert that a condition is true. Otherwise, exit.
@@ -16029,19 +16029,19 @@ condition that is being tested. Following is the
function:
exit 1
}
- The 'assert()' function tests the 'condition' parameter. If it is
-false, it prints a message to standard error, using the 'string'
+ The âassert()â function tests the âconditionâ parameter. If it is
+false, it prints a message to standard error, using the âstringâ
parameter to describe the failed condition. It then sets the variable
-'_assert_exit' to one and executes the 'exit' statement. The 'exit'
-statement jumps to the 'END' rule. If the 'END' rule finds
-'_assert_exit' to be true, it exits immediately.
+â_assert_exitâ to one and executes the âexitâ statement. The
âexitâ
+statement jumps to the âENDâ rule. If the âENDâ rule finds
+â_assert_exitâ to be true, it exits immediately.
- The purpose of the test in the 'END' rule is to keep any other 'END'
+ The purpose of the test in the âENDâ rule is to keep any other âENDâ
rules from running. When an assertion fails, the program should exit
-immediately. If no assertions fail, then '_assert_exit' is still false
-when the 'END' rule is run normally, and the rest of the program's 'END'
-rules execute. For all of this to work correctly, 'assert.awk' must be
-the first source file read by 'awk'. The function can be used in a
+immediately. If no assertions fail, then â_assert_exitâ is still false
+when the âENDâ rule is run normally, and the rest of the programâs
âENDâ
+rules execute. For all of this to work correctly, âassert.awkâ must be
+the first source file read by âawkâ. The function can be used in a
program in the following way:
function myfunc(a, b)
@@ -16054,16 +16054,16 @@ If the assertion fails, you see a message similar to
the following:
mydata:1357: assertion failed: a <= 5 && b >= 17.1
- There is a small problem with this version of 'assert()'. An 'END'
-rule is automatically added to the program calling 'assert()'.
-Normally, if a program consists of just a 'BEGIN' rule, the input files
+ There is a small problem with this version of âassert()â. An âENDâ
+rule is automatically added to the program calling âassert()â.
+Normally, if a program consists of just a âBEGINâ rule, the input files
and/or standard input are not read. However, now that the program has
-an 'END' rule, 'awk' attempts to read the input data files or standard
+an âENDâ rule, âawkâ attempts to read the input data files or standard
input (*note Using BEGIN/END::), most likely causing the program to hang
as it waits for input.
- There is a simple workaround to this: make sure that such a 'BEGIN'
-rule always ends with an 'exit' statement.
+ There is a simple workaround to this: make sure that such a âBEGINâ
+rule always ends with an âexitâ statement.
File: gawk.info, Node: Round Function, Next: Cliff Random Function, Prev:
Assert Function, Up: General Functions
@@ -16071,15 +16071,15 @@ File: gawk.info, Node: Round Function, Next: Cliff
Random Function, Prev: Ass
10.2.3 Rounding Numbers
-----------------------
-The way 'printf' and 'sprintf()' (*note Printf::) perform rounding often
-depends upon the system's C 'sprintf()' subroutine. On many machines,
-'sprintf()' rounding is "unbiased", which means it doesn't always round
+The way âprintfâ and âsprintf()â (*note Printf::) perform rounding
often
+depends upon the systemâs C âsprintf()â subroutine. On many machines,
+âsprintf()â rounding is âunbiasedâ, which means it doesnât always
round
a trailing .5 up, contrary to naive expectations. In unbiased rounding,
.5 rounds to even, rather than always up, so 1.5 rounds to 2 but 4.5
rounds to 4. This means that if you are using a format that does
-rounding (e.g., '"%.0f"'), you should check what your system does. The
+rounding (e.g., â"%.0f"â), you should check what your system does. The
following function does traditional rounding; it might be useful if your
-'awk''s 'printf' does unbiased rounding:
+âawkââs âprintfâ does unbiased rounding:
# round.awk --- do normal rounding
@@ -16118,9 +16118,9 @@ File: gawk.info, Node: Cliff Random Function, Next:
Ordinal Functions, Prev:
The Cliff random number generator
(http://mathworld.wolfram.com/CliffRandomNumberGenerator.html) is a very
-simple random number generator that "passes the noise sphere test for
-randomness by showing no structure." It is easily programmed, in less
-than 10 lines of 'awk' code:
+simple random number generator that âpasses the noise sphere test for
+randomness by showing no structure.â It is easily programmed, in less
+than 10 lines of âawkâ code:
# cliff_rand.awk --- generate Cliff random numbers
@@ -16134,9 +16134,9 @@ than 10 lines of 'awk' code:
return _cliff_seed
}
- This algorithm requires an initial "seed" of 0.1. Each new value
+ This algorithm requires an initial âseedâ of 0.1. Each new value
uses the current seed as input for the calculation. If the built-in
-'rand()' function (*note Numeric Functions::) isn't random enough, you
+ârand()â function (*note Numeric Functions::) isnât random enough, you
might try using this function instead.
@@ -16145,15 +16145,15 @@ File: gawk.info, Node: Ordinal Functions, Next:
Join Function, Prev: Cliff Ra
10.2.5 Translating Between Characters and Numbers
-------------------------------------------------
-One commercial implementation of 'awk' supplies a built-in function,
-'ord()', which takes a character and returns the numeric value for that
-character in the machine's character set. If the string passed to
-'ord()' has more than one character, only the first one is used.
+One commercial implementation of âawkâ supplies a built-in function,
+âord()â, which takes a character and returns the numeric value for that
+character in the machineâs character set. If the string passed to
+âord()â has more than one character, only the first one is used.
- The inverse of this function is 'chr()' (from the function of the
+ The inverse of this function is âchr()â (from the function of the
same name in Pascal), which takes a number and returns the corresponding
-character. Both functions are written very nicely in 'awk'; there is no
-real reason to build them into the 'awk' interpreter:
+character. Both functions are written very nicely in âawkâ; there is no
+real reason to build them into the âawkâ interpreter:
# ord.awk --- do ord and chr
@@ -16184,7 +16184,7 @@ real reason to build them into the 'awk' interpreter:
}
}
- Some explanation of the numbers used by '_ord_init()' is worthwhile.
+ Some explanation of the numbers used by â_ord_init()â is worthwhile.
The most prominent character set in use today is ASCII.(1) Although an
8-bit byte can hold 256 distinct values (from 0 to 255), ASCII only
defines characters that use the values from 0 to 127.(2) In the now
@@ -16219,9 +16219,9 @@ on some older systems, but they are not really worth
worrying about:
# }
An obvious improvement to these functions is to move the code for the
-'_ord_init' function into the body of the 'BEGIN' rule. It was written
-this way initially for ease of development. There is a "test program"
-in a 'BEGIN' rule, to test the function. It is commented out for
+â_ord_initâ function into the body of the âBEGINâ rule. It was written
+this way initially for ease of development. There is a âtest programâ
+in a âBEGINâ rule, to test the function. It is commented out for
production use.
---------- Footnotes ----------
@@ -16233,7 +16233,7 @@ tests such as used here prohibitively expensive.
(2) ASCII has been extended in many countries to use the values from
128 to 255 for country-specific characters. If your system uses these
-extensions, you can simplify '_ord_init()' to loop from 0 to 255.
+extensions, you can simplify â_ord_init()â to loop from 0 to 255.
File: gawk.info, Node: Join Function, Next: Getlocaltime Function, Prev:
Ordinal Functions, Up: General Functions
@@ -16243,15 +16243,15 @@ File: gawk.info, Node: Join Function, Next:
Getlocaltime Function, Prev: Ordi
When doing string processing, it is often useful to be able to join all
the strings in an array into one long string. The following function,
-'join()', accomplishes this task. It is used later in several of the
+âjoin()â, accomplishes this task. It is used later in several of the
application programs (*note Sample Programs::).
Good function design is important; this function needs to be general,
but it should also have a reasonable default behavior. It is called
with an array as well as the beginning and ending indices of the
elements in the array to be merged. This assumes that the array indices
-are numeric--a reasonable assumption, as the array was likely created
-with 'split()' (*note String Functions::):
+are numericâa reasonable assumption, as the array was likely created
+with âsplit()â (*note String Functions::):
# join.awk --- join an array into a string
@@ -16269,16 +16269,16 @@ with 'split()' (*note String Functions::):
An optional additional argument is the separator to use when joining
the strings back together. If the caller supplies a nonempty value,
-'join()' uses it; if it is not supplied, it has a null value. In this
-case, 'join()' uses a single space as a default separator for the
-strings. If the value is equal to 'SUBSEP', then 'join()' joins the
-strings with no separator between them. 'SUBSEP' serves as a "magic"
+âjoin()â uses it; if it is not supplied, it has a null value. In this
+case, âjoin()â uses a single space as a default separator for the
+strings. If the value is equal to âSUBSEPâ, then âjoin()â joins the
+strings with no separator between them. âSUBSEPâ serves as a âmagicâ
value to indicate that there should be no separation between the
component strings.(1)
---------- Footnotes ----------
- (1) It would be nice if 'awk' had an assignment operator for
+ (1) It would be nice if âawkâ had an assignment operator for
concatenation. The lack of an explicit operator for concatenation makes
string operations more difficult than they really need to be.
@@ -16288,15 +16288,15 @@ File: gawk.info, Node: Getlocaltime Function, Next:
Readfile Function, Prev:
10.2.7 Managing the Time of Day
-------------------------------
-The 'systime()' and 'strftime()' functions described in *note Time
+The âsystime()â and âstrftime()â functions described in *note Time
Functions:: provide the minimum functionality necessary for dealing with
-the time of day in human-readable form. Although 'strftime()' is
+the time of day in human-readable form. Although âstrftime()â is
extensive, the control formats are not necessarily easy to remember or
intuitively obvious when reading a program.
- The following function, 'getlocaltime()', populates a user-supplied
+ The following function, âgetlocaltime()â, populates a user-supplied
array with preformatted time information. It returns a string with the
-current time formatted in the same way as the 'date' utility:
+current time formatted in the same way as the âdateâ utility:
# getlocaltime.awk --- get the time of day in a usable format
@@ -16359,9 +16359,9 @@ current time formatted in the same way as the 'date'
utility:
}
The string indices are easier to use and read than the various
-formats required by 'strftime()'. The 'alarm' program presented in
+formats required by âstrftime()â. The âalarmâ program presented in
*note Alarm Program:: uses this function. A more general design for the
-'getlocaltime()' function would have allowed the user to supply an
+âgetlocaltime()â function would have allowed the user to supply an
optional timestamp value to use instead of the current time.
@@ -16387,8 +16387,8 @@ that might be as follows:
return contents
}
- This function reads from 'file' one record at a time, building up the
-full contents of the file in the local variable 'contents'. It works,
+ This function reads from âfileâ one record at a time, building up the
+full contents of the file in the local variable âcontentsâ. It works,
but is not necessarily efficient.
The following function, based on a suggestion by Denis Shirokov,
@@ -16407,13 +16407,13 @@ reads the entire contents of the named file in one
shot:
return tmp
}
- It works by setting 'RS' to '^$', a regular expression that will
-never match if the file has contents. 'gawk' reads data from the file
-into 'tmp', attempting to match 'RS'. The match fails after each read,
-but fails quickly, such that 'gawk' fills 'tmp' with the entire contents
-of the file. (*Note Records:: for information on 'RT' and 'RS'.)
+ It works by setting âRSâ to â^$â, a regular expression that will
+never match if the file has contents. âgawkâ reads data from the file
+into âtmpâ, attempting to match âRSâ. The match fails after each read,
+but fails quickly, such that âgawkâ fills âtmpâ with the entire
contents
+of the file. (*Note Records:: for information on âRTâ and âRSâ.)
- In the case that 'file' is empty, the return value is the null
+ In the case that âfileâ is empty, the return value is the null
string. Thus, calling code may use something like:
contents = readfile("/some/path")
@@ -16421,7 +16421,7 @@ string. Thus, calling code may use something like:
# file was empty ...
This tests the result to see if it is empty or not. An equivalent
-test would be 'contents == ""'.
+test would be âcontents == ""â.
*Note Extension Sample Readfile:: for an extension function that also
reads an entire file into memory.
@@ -16443,21 +16443,21 @@ frequently:
INPUT_PROGRAM | awk "$awkp" | /bin/sh
- For example, a program of his named 'flac-edit' has this form:
+ For example, a program of his named âflac-editâ has this form:
$ flac-edit -song="Whoope! That's Great" file.flac
It generates the following output, which is to be piped to the shell
-('/bin/sh'):
+(â/bin/shâ):
chmod +w file.flac
metaflac --remove-tag=TITLE file.flac
LANG=en_US.88591 metaflac --set-tag=TITLE='Whoope! That'"'"'s Great'
file.flac
chmod -w file.flac
- Note the need for shell quoting. The function 'shell_quote()' does
-it. 'SINGLE' is the one-character string '"'"' and 'QSINGLE' is the
-three-character string '"\"'\""':
+ Note the need for shell quoting. The function âshell_quote()â does
+it. âSINGLEâ is the one-character string â"'"â and âQSINGLEâ is
the
+three-character string â"\"'\""â:
# shell_quote --- quote an argument for passing to the shell
@@ -16486,8 +16486,8 @@ File: gawk.info, Node: Isnumeric Function, Prev:
Shell Quoting, Up: General F
A frequent programming question is how to ascertain whether a value is
numeric. This can be solved by using this example function
-'isnumeric()', which employs the trick of converting a string value to
-user input by using the 'split()' function:
+âisnumeric()â, which employs the trick of converting a string value to
+user input by using the âsplit()â function:
# isnumeric --- check whether a value is numeric
@@ -16509,11 +16509,11 @@ deciding whether a value is numeric or not, so if it
matters to you, you
may want to add an additional check for that.
Traditionally, it has been recommended to check for numeric values
-using the test 'x+0 == x'. This function is superior in two ways: it
+using the test âx+0 == xâ. This function is superior in two ways: it
will not report that unassigned variables contain numeric values; and it
-recognizes string values with numeric contents where 'CONVFMT' does not
-yield the original string. On the other hand, it uses the 'typeof()'
-function (*note Type Functions::), which is specific to 'gawk'.
+recognizes string values with numeric contents where âCONVFMTâ does not
+yield the original string. On the other hand, it uses the âtypeof()â
+function (*note Type Functions::), which is specific to âgawkâ.
File: gawk.info, Node: Data File Management, Next: Getopt Function, Prev:
General Functions, Up: Library Functions
@@ -16538,24 +16538,24 @@ File: gawk.info, Node: Filetrans Function, Next:
Rewind Function, Up: Data Fi
10.3.1 Noting Data file Boundaries
----------------------------------
-The 'BEGIN' and 'END' rules are each executed exactly once, at the
-beginning and end of your 'awk' program, respectively (*note
-BEGIN/END::). We (the 'gawk' authors) once had a user who mistakenly
-thought that the 'BEGIN' rules were executed at the beginning of each
-data file and the 'END' rules were executed at the end of each data
+The âBEGINâ and âENDâ rules are each executed exactly once, at the
+beginning and end of your âawkâ program, respectively (*note
+BEGIN/END::). We (the âgawkâ authors) once had a user who mistakenly
+thought that the âBEGINâ rules were executed at the beginning of each
+data file and the âENDâ rules were executed at the end of each data
file.
When informed that this was not the case, the user requested that we
-add new special patterns to 'gawk', named 'BEGIN_FILE' and 'END_FILE',
+add new special patterns to âgawkâ, named âBEGIN_FILEâ and
âEND_FILEâ,
that would have the desired behavior. He even supplied us the code to
do so.
- Adding these special patterns to 'gawk' wasn't necessary; the job can
-be done cleanly in 'awk' itself, as illustrated by the following library
-program. It arranges to call two user-supplied functions, 'beginfile()'
-and 'endfile()', at the beginning and end of each data file. Besides
+ Adding these special patterns to âgawkâ wasnât necessary; the job can
+be done cleanly in âawkâ itself, as illustrated by the following library
+program. It arranges to call two user-supplied functions, âbeginfile()â
+and âendfile()â, at the beginning and end of each data file. Besides
solving the problem in only nine(!) lines of code, it does so
-_portably_; this works with any implementation of 'awk':
+_portably_; this works with any implementation of âawkâ:
# transfile.awk
#
@@ -16574,28 +16574,28 @@ _portably_; this works with any implementation of
'awk':
END { endfile(FILENAME) }
- This file must be loaded before the user's "main" program, so that
+ This file must be loaded before the userâs âmainâ program, so that
the rule it supplies is executed first.
- This rule relies on 'awk''s 'FILENAME' variable, which automatically
+ This rule relies on âawkââs âFILENAMEâ variable, which
automatically
changes for each new data file. The current file name is saved in a
-private variable, '_oldfilename'. If 'FILENAME' does not equal
-'_oldfilename', then a new data file is being processed and it is
-necessary to call 'endfile()' for the old file. Because 'endfile()'
+private variable, â_oldfilenameâ. If âFILENAMEâ does not equal
+â_oldfilenameâ, then a new data file is being processed and it is
+necessary to call âendfile()â for the old file. Because âendfile()â
should only be called if a file has been processed, the program first
-checks to make sure that '_oldfilename' is not the null string. The
-program then assigns the current file name to '_oldfilename' and calls
-'beginfile()' for the file. Because, like all 'awk' variables,
-'_oldfilename' is initialized to the null string, this rule executes
+checks to make sure that â_oldfilenameâ is not the null string. The
+program then assigns the current file name to â_oldfilenameâ and calls
+âbeginfile()â for the file. Because, like all âawkâ variables,
+â_oldfilenameâ is initialized to the null string, this rule executes
correctly even for the first data file.
- The program also supplies an 'END' rule to do the final processing
-for the last file. Because this 'END' rule comes before any 'END' rules
-supplied in the "main" program, 'endfile()' is called first. Once
-again, the value of multiple 'BEGIN' and 'END' rules should be clear.
+ The program also supplies an âENDâ rule to do the final processing
+for the last file. Because this âENDâ rule comes before any âENDâ
rules
+supplied in the âmainâ program, âendfile()â is called first. Once
+again, the value of multiple âBEGINâ and âENDâ rules should be clear.
If the same data file occurs twice in a row on the command line, then
-'endfile()' and 'beginfile()' are not executed at the end of the first
+âendfile()â and âbeginfile()â are not executed at the end of the first
pass and at the beginning of the second pass. The following version
solves the problem:
@@ -16615,18 +16615,18 @@ solves the problem:
*note Wc Program:: shows how this library function can be used and
how it simplifies writing the main program.
- So Why Does 'gawk' Have 'BEGINFILE' and 'ENDFILE'?
+ So Why Does âgawkâ Have âBEGINFILEâ and âENDFILEâ?
- You are probably wondering, if 'beginfile()' and 'endfile()'
-functions can do the job, why does 'gawk' have 'BEGINFILE' and 'ENDFILE'
+ You are probably wondering, if âbeginfile()â and âendfile()â
+functions can do the job, why does âgawkâ have âBEGINFILEâ and
âENDFILEâ
patterns?
- Good question. Normally, if 'awk' cannot open a file, this causes an
+ Good question. Normally, if âawkâ cannot open a file, this causes an
immediate fatal error. In this case, there is no way for a user-defined
function to deal with the problem, as the mechanism for calling it
relies on the file being open and at the first record. Thus, the main
-reason for 'BEGINFILE' is to give you a "hook" to catch files that
-cannot be processed. 'ENDFILE' exists for symmetry, and because it
+reason for âBEGINFILEâ is to give you a âhookâ to catch files that
+cannot be processed. âENDFILEâ exists for symmetry, and because it
provides an easy way to do per-file cleanup processing. For more
information, refer to *note BEGINFILE/ENDFILE::.
@@ -16638,12 +16638,12 @@ File: gawk.info, Node: Rewind Function, Next: File
Checking, Prev: Filetrans
Another request for a new built-in function was for a function that
would make it possible to reread the current file. The requesting user
-didn't want to have to use 'getline' (*note Getline::) inside a loop.
+didnât want to have to use âgetlineâ (*note Getline::) inside a loop.
- However, as long as you are not in the 'END' rule, it is quite easy
+ However, as long as you are not in the âENDâ rule, it is quite easy
to arrange to immediately close the current input file and then start
-over with it from the top. For lack of a better name, we'll call the
-function 'rewind()':
+over with it from the top. For lack of a better name, weâll call the
+function ârewind()â:
# rewind.awk --- rewind the current file and start over
@@ -16663,39 +16663,39 @@ function 'rewind()':
nextfile
}
- The 'rewind()' function relies on the 'ARGIND' variable (*note
-Auto-set::), which is specific to 'gawk'. It also relies on the
-'nextfile' keyword (*note Nextfile Statement::). Because of this, you
-should not call it from an 'ENDFILE' rule. (This isn't necessary
-anyway, because 'gawk' goes to the next file as soon as an 'ENDFILE'
+ The ârewind()â function relies on the âARGINDâ variable (*note
+Auto-set::), which is specific to âgawkâ. It also relies on the
+ânextfileâ keyword (*note Nextfile Statement::). Because of this, you
+should not call it from an âENDFILEâ rule. (This isnât necessary
+anyway, because âgawkâ goes to the next file as soon as an âENDFILEâ
rule finishes!)
- You need to be careful calling 'rewind()'. You can end up causing
-infinite recursion if you don't pay attention. Here is an example use:
+ You need to be careful calling ârewind()â. You can end up causing
+infinite recursion if you donât pay attention. Here is an example use:
$ cat data
- -| a
- -| b
- -| c
- -| d
- -| e
+ ⣠a
+ ⣠b
+ ⣠c
+ ⣠d
+ ⣠e
$ cat test.awk
- -| FNR == 3 && ! rewound {
- -| rewound = 1
- -| rewind()
- -| }
- -|
- -| { print FILENAME, FNR, $0 }
+ ⣠FNR == 3 && ! rewound {
+ ⣠rewound = 1
+ ⣠rewind()
+ ⣠}
+ â£
+ ⣠{ print FILENAME, FNR, $0 }
$ gawk -f rewind.awk -f test.awk data
- -| data 1 a
- -| data 2 b
- -| data 1 a
- -| data 2 b
- -| data 3 c
- -| data 4 d
- -| data 5 e
+ ⣠data 1 a
+ ⣠data 2 b
+ ⣠data 1 a
+ ⣠data 2 b
+ ⣠data 3 c
+ ⣠data 4 d
+ ⣠data 5 e
File: gawk.info, Node: File Checking, Next: Empty Files, Prev: Rewind
Function, Up: Data File Management
@@ -16703,10 +16703,10 @@ File: gawk.info, Node: File Checking, Next: Empty
Files, Prev: Rewind Functio
10.3.3 Checking for Readable Data files
---------------------------------------
-Normally, if you give 'awk' a data file that isn't readable, it stops
+Normally, if you give âawkâ a data file that isnât readable, it stops
with a fatal error. There are times when you might want to just ignore
such files and keep going.(1) You can do this by prepending the
-following program to your 'awk' program:
+following program to your âawkâ program:
# readable.awk --- library file to skip over unreadable files
@@ -16722,18 +16722,18 @@ following program to your 'awk' program:
}
}
- This works, because the 'getline' won't be fatal. Removing the
-element from 'ARGV' with 'delete' skips the file (because it's no longer
+ This works, because the âgetlineâ wonât be fatal. Removing the
+element from âARGVâ with âdeleteâ skips the file (because itâs no
longer
in the list). See also *note ARGC and ARGV::.
- Because 'awk' variable names only allow the English letters, the
+ Because âawkâ variable names only allow the English letters, the
regular expression check purposely does not use character classes such
-as '[:alpha:]' and '[:alnum:]' (*note Bracket Expressions::).
+as â[:alpha:]â and â[:alnum:]â (*note Bracket Expressions::).
---------- Footnotes ----------
- (1) The 'BEGINFILE' special pattern (*note BEGINFILE/ENDFILE::)
-provides an alternative mechanism for dealing with files that can't be
+ (1) The âBEGINFILEâ special pattern (*note BEGINFILE/ENDFILE::)
+provides an alternative mechanism for dealing with files that canât be
opened. However, the code here provides a portable solution.
@@ -16742,19 +16742,19 @@ File: gawk.info, Node: Empty Files, Next: Ignoring
Assigns, Prev: File Checki
10.3.4 Checking for Zero-Length Files
-------------------------------------
-All known 'awk' implementations silently skip over zero-length files.
-This is a by-product of 'awk''s implicit
-read-a-record-and-match-against-the-rules loop: when 'awk' tries to read
+All known âawkâ implementations silently skip over zero-length files.
+This is a by-product of âawkââs implicit
+read-a-record-and-match-against-the-rules loop: when âawkâ tries to read
a record from an empty file, it immediately receives an end-of-file
indication, closes the file, and proceeds on to the next command-line
-data file, _without_ executing any user-level 'awk' program code.
+data file, _without_ executing any user-level âawkâ program code.
- Using 'gawk''s 'ARGIND' variable (*note Built-in Variables::), it is
+ Using âgawkââs âARGINDâ variable (*note Built-in Variables::), it
is
possible to detect when an empty data file has been skipped. Similar to
the library file presented in *note Filetrans Function::, the following
-library file calls a function named 'zerofile()' that the user must
+library file calls a function named âzerofile()â that the user must
provide. The arguments passed are the file name and the position in
-'ARGV' where it was found:
+âARGVâ where it was found:
# zerofile.awk --- library file to process empty input files
@@ -16773,18 +16773,18 @@ provide. The arguments passed are the file name and
the position in
zerofile(ARGV[Argind], Argind)
}
- The user-level variable 'Argind' allows the 'awk' program to track
-its progress through 'ARGV'. Whenever the program detects that 'ARGIND'
-is greater than 'Argind + 1', it means that one or more empty files were
-skipped. The action then calls 'zerofile()' for each such file,
-incrementing 'Argind' along the way.
+ The user-level variable âArgindâ allows the âawkâ program to track
+its progress through âARGVâ. Whenever the program detects that
âARGINDâ
+is greater than âArgind + 1â, it means that one or more empty files were
+skipped. The action then calls âzerofile()â for each such file,
+incrementing âArgindâ along the way.
- The 'Argind != ARGIND' rule simply keeps 'Argind' up to date in the
+ The âArgind != ARGINDâ rule simply keeps âArgindâ up to date in the
normal case.
- Finally, the 'END' rule catches the case of any empty files at the
+ Finally, the âENDâ rule catches the case of any empty files at the
end of the command-line arguments. Note that the test in the condition
-of the 'for' loop uses the '<=' operator, not '<'.
+of the âforâ loop uses the â<=â operator, not â<â.
File: gawk.info, Node: Ignoring Assigns, Prev: Empty Files, Up: Data File
Management
@@ -16792,13 +16792,13 @@ File: gawk.info, Node: Ignoring Assigns, Prev:
Empty Files, Up: Data File Man
10.3.5 Treating Assignments as File names
-----------------------------------------
-Occasionally, you might not want 'awk' to process command-line variable
+Occasionally, you might not want âawkâ to process command-line variable
assignments (*note Assignment Options::). In particular, if you have a
-file name that contains an '=' character, 'awk' treats the file name as
+file name that contains an â=â character, âawkâ treats the file name as
an assignment and does not process it.
Some users have suggested an additional command-line option for
-'gawk' to disable command-line assignments. However, some simple
+âgawkâ to disable command-line assignments. However, some simple
programming with a library file does the trick:
# noassign.awk --- library file to avoid the need for a
@@ -16821,10 +16821,10 @@ programming with a library file does the trick:
awk -v No_command_assign=1 -f noassign.awk -f yourprog.awk *
The function works by looping through the arguments. It prepends
-'./' to any argument that matches the form of a variable assignment,
+â./â to any argument that matches the form of a variable assignment,
turning that argument into a file name.
- The use of 'No_command_assign' allows you to disable command-line
+ The use of âNo_command_assignâ allows you to disable command-line
assignments at invocation time, by giving the variable a true value.
When not set, it is initially zero (i.e., false), so the command-line
arguments are left alone.
@@ -16836,32 +16836,32 @@ File: gawk.info, Node: Getopt Function, Next:
Passwd Functions, Prev: Data Fi
====================================
Most utilities on POSIX-compatible systems take options on the command
-line that can be used to change the way a program behaves. 'awk' is an
+line that can be used to change the way a program behaves. âawkâ is an
example of such a program (*note Options::). Often, options take
-"arguments" (i.e., data that the program needs to correctly obey the
-command-line option). For example, 'awk''s '-F' option requires a
+âargumentsâ (i.e., data that the program needs to correctly obey the
+command-line option). For example, âawkââs â-Fâ option requires a
string to use as the field separator. The first occurrence on the
-command line of either '--' or a string that does not begin with '-'
+command line of either â--â or a string that does not begin with â-â
ends the options.
- Modern Unix systems provide a C function named 'getopt()' for
+ Modern Unix systems provide a C function named âgetopt()â for
processing command-line arguments. The programmer provides a string
describing the one-letter options. If an option requires an argument,
-it is followed in the string with a colon. 'getopt()' is also passed
+it is followed in the string with a colon. âgetopt()â is also passed
the count and values of the command-line arguments and is called in a
-loop. 'getopt()' processes the command-line arguments for option
+loop. âgetopt()â processes the command-line arguments for option
letters. Each time around the loop, it returns a single character
-representing the next option letter that it finds, or '?' if it finds an
-invalid option. When it returns -1, there are no options left on the
+representing the next option letter that it finds, or â?â if it finds an
+invalid option. When it returns â1, there are no options left on the
command line.
- When using 'getopt()', options that do not take arguments can be
+ When using âgetopt()â, options that do not take arguments can be
grouped together. Furthermore, options that take arguments require that
the argument be present. The argument can immediately follow the option
letter, or it can be a separate command-line argument.
Given a hypothetical program that takes three command-line options,
-'-a', '-b', and '-c', where '-b' requires an argument, all of the
+â-aâ, â-bâ, and â-câ, where â-bâ requires an argument, all of
the
following are valid ways of invoking the program:
prog -a -b foo -c data1 data2 data3
@@ -16869,31 +16869,31 @@ following are valid ways of invoking the program:
prog -acbfoo data1 data2 data3
Notice that when the argument is grouped with its option, the rest of
-the argument is considered to be the option's argument. In this
-example, '-acbfoo' indicates that all of the '-a', '-b', and '-c'
-options were supplied, and that 'foo' is the argument to the '-b'
+the argument is considered to be the optionâs argument. In this
+example, â-acbfooâ indicates that all of the â-aâ, â-bâ, and
â-câ
+options were supplied, and that âfooâ is the argument to the â-bâ
option.
- 'getopt()' provides four external variables that the programmer can
+ âgetopt()â provides four external variables that the programmer can
use:
-'optind'
- The index in the argument value array ('argv') where the first
+âoptindâ
+ The index in the argument value array (âargvâ) where the first
nonoption command-line argument can be found.
-'optarg'
+âoptargâ
The string value of the argument to an option.
-'opterr'
- Usually 'getopt()' prints an error message when it finds an invalid
- option. Setting 'opterr' to zero disables this feature. (An
+âopterrâ
+ Usually âgetopt()â prints an error message when it finds an invalid
+ option. Setting âopterrâ to zero disables this feature. (An
application might want to print its own error message.)
-'optopt'
+âoptoptâ
The letter representing the command-line option.
- The following C fragment shows how 'getopt()' might process
-command-line arguments for 'awk':
+ The following C fragment shows how âgetopt()â might process
+command-line arguments for âawkâ:
int
main(int argc, char *argv[])
@@ -16924,24 +16924,24 @@ command-line arguments for 'awk':
...
}
- The GNU project's version of the original Unix utilities popularized
-the use of long command line options. For example, '--help' in addition
-to '-h'. Arguments to long options are either provided as separate
-command line arguments ('--source 'PROGRAM-TEXT'') or separated from the
-option with an '=' sign ('--source='PROGRAM-TEXT'').
+ The GNU projectâs version of the original Unix utilities popularized
+the use of long command line options. For example, â--helpâ in addition
+to â-hâ. Arguments to long options are either provided as separate
+command line arguments (â--source 'PROGRAM-TEXT'â) or separated from the
+option with an â=â sign (â--source='PROGRAM-TEXT'â).
- As a side point, 'gawk' actually uses the GNU 'getopt_long()'
+ As a side point, âgawkâ actually uses the GNU âgetopt_long()â
function to process both normal and GNU-style long options (*note
Options::).
- The abstraction provided by 'getopt()' is very useful and is quite
-handy in 'awk' programs as well. Following is an 'awk' version of
-'getopt()' that accepts both short and long options. (Support for long
+ The abstraction provided by âgetopt()â is very useful and is quite
+handy in âawkâ programs as well. Following is an âawkâ version of
+âgetopt()â that accepts both short and long options. (Support for long
options was supplied by Greg Minshall. We thank him.)
- This function highlights one of the greatest weaknesses in 'awk',
+ This function highlights one of the greatest weaknesses in âawkâ,
which is that it is very poor at manipulating single characters. The
-function needs repeated calls to 'substr()' in order to access
+function needs repeated calls to âsubstr()â in order to access
individual characters (*note String Functions::).(1)
The discussion that follows walks through the code a bit at a time:
@@ -16965,13 +16965,13 @@ individual characters (*note String Functions::).(1)
The function starts out with comments presenting a list of the global
variables it uses, what the return values are, what they mean, and any
-global variables that are "private" to this library function. Such
+global variables that are âprivateâ to this library function. Such
documentation is essential for any program, and particularly for library
functions.
- The 'getopt()' function first checks that it was indeed called with a
-string of options (the 'options' parameter). If both 'options' and
-'longoptions' have a zero length, 'getopt()' immediately returns -1:
+ The âgetopt()â function first checks that it was indeed called with a
+string of options (the âoptionsâ parameter). If both âoptionsâ and
+âlongoptionsâ have a zero length, âgetopt()â immediately returns â1:
function getopt(argc, argv, options, longopts, thisopt, i, j)
{
@@ -16987,18 +16987,18 @@ string of options (the 'options' parameter). If both
'options' and
return -1
}
- The next thing to check for is the end of the options. A '--' ends
+ The next thing to check for is the end of the options. A â--â ends
the command-line options, as does any command-line argument that does
-not begin with a '-' (unless it is an argument to a preceding option).
-'Optind' steps through the array of command-line arguments; it retains
-its value across calls to 'getopt()', because it is a global variable.
+not begin with a â-â (unless it is an argument to a preceding option).
+âOptindâ steps through the array of command-line arguments; it retains
+its value across calls to âgetopt()â, because it is a global variable.
- The regular expression '/^-[^:[:space:]/' checks for a '-' followed
+ The regular expression â/^-[^:[:space:]/â checks for a â-â followed
by anything that is not whitespace and not a colon. If the current
command-line argument does not match this pattern, it is not an option,
and it ends option processing. Now, we check to see if we are
processing a short (single letter) option, or a long option (indicated
-by two dashes, e.g., '--filename'). If it is a short option, we
+by two dashes, e.g., â--filenameâ). If it is a short option, we
continue on:
if (argv[Optind] !~ /^--/) { # if this is a short option
@@ -17018,30 +17018,30 @@ continue on:
return "?"
}
- The '_opti' variable tracks the position in the current command-line
-argument ('argv[Optind]'). If multiple options are grouped together
-with one '-' (e.g., '-abx'), it is necessary to return them to the user
+ The â_optiâ variable tracks the position in the current command-line
+argument (âargv[Optind]â). If multiple options are grouped together
+with one â-â (e.g., â-abxâ), it is necessary to return them to the user
one at a time.
- If '_opti' is equal to zero, it is set to two, which is the index in
-the string of the next character to look at (we skip the '-', which is
-at position one). The variable 'thisopt' holds the character, obtained
-with 'substr()'. It is saved in 'Optopt' for the main program to use.
+ If â_optiâ is equal to zero, it is set to two, which is the index in
+the string of the next character to look at (we skip the â-â, which is
+at position one). The variable âthisoptâ holds the character, obtained
+with âsubstr()â. It is saved in âOptoptâ for the main program to use.
- If 'thisopt' is not in the 'options' string, then it is an invalid
-option. If 'Opterr' is nonzero, 'getopt()' prints an error message on
+ If âthisoptâ is not in the âoptionsâ string, then it is an invalid
+option. If âOpterrâ is nonzero, âgetopt()â prints an error message on
the standard error that is similar to the message from the C version of
-'getopt()'.
+âgetopt()â.
Because the option is invalid, it is necessary to skip it and move on
-to the next option character. If '_opti' is greater than or equal to
+to the next option character. If â_optiâ is greater than or equal to
the length of the current command-line argument, it is necessary to move
-on to the next argument, so 'Optind' is incremented and '_opti' is reset
-to zero. Otherwise, 'Optind' is left alone and '_opti' is merely
+on to the next argument, so âOptindâ is incremented and â_optiâ is
reset
+to zero. Otherwise, âOptindâ is left alone and â_optiâ is merely
incremented.
- In any case, because the option is invalid, 'getopt()' returns '"?"'.
-The main program can examine 'Optopt' if it needs to know what the
+ In any case, because the option is invalid, âgetopt()â returns
â"?"â.
+The main program can examine âOptoptâ if it needs to know what the
invalid option letter actually is. Continuing on:
if (substr(options, i + 1, 1) == ":") {
@@ -17055,10 +17055,10 @@ invalid option letter actually is. Continuing on:
Optarg = ""
If the option requires an argument, the option letter is followed by
-a colon in the 'options' string. If there are remaining characters in
-the current command-line argument ('argv[Optind]'), then the rest of
-that string is assigned to 'Optarg'. Otherwise, the next command-line
-argument is used ('-xFOO' versus '-x FOO'). In either case, '_opti' is
+a colon in the âoptionsâ string. If there are remaining characters in
+the current command-line argument (âargv[Optind]â), then the rest of
+that string is assigned to âOptargâ. Otherwise, the next command-line
+argument is used (â-xFOOâ versus â-x FOOâ). In either case,
â_optiâ is
reset to zero, because there are no more characters left to examine in
the current command-line argument. Continuing:
@@ -17069,12 +17069,12 @@ the current command-line argument. Continuing:
_opti++
return thisopt
- Finally, for a short option, if '_opti' is either zero or greater
+ Finally, for a short option, if â_optiâ is either zero or greater
than the length of the current command-line argument, it means this
-element in 'argv' is through being processed, so 'Optind' is incremented
-to point to the next element in 'argv'. If neither condition is true,
-then only '_opti' is incremented, so that the next option letter can be
-processed on the next call to 'getopt()'.
+element in âargvâ is through being processed, so âOptindâ is
incremented
+to point to the next element in âargvâ. If neither condition is true,
+then only â_optiâ is incremented, so that the next option letter can be
+processed on the next call to âgetopt()â.
On the other hand, if the earlier test found that this was a long
option, we take a different branch:
@@ -17089,8 +17089,8 @@ option, we take a different branch:
First, we search this option for a possible embedded equal sign, as
the specification of long options allows an argument to an option
-'--someopt' to be specified as '--someopt=answer' as well as
-'--someopt answer'.
+â--someoptâ to be specified as â--someopt=answerâ as well as
+â--someopt answerâ.
i = match(longopts, "(^|,)" thisopt "($|[,:])")
if (i == 0) {
@@ -17100,19 +17100,19 @@ the specification of long options allows an argument
to an option
return "?"
}
- Next, we try to find the current option in 'longopts'. The regular
-expression given to 'match()', '"(^|,)" thisopt "($|[,:])"', matches
-this option at the beginning of 'longopts', or at the beginning of a
+ Next, we try to find the current option in âlongoptsâ. The regular
+expression given to âmatch()â, â"(^|,)" thisopt "($|[,:])"â, matches
+this option at the beginning of âlongoptsâ, or at the beginning of a
subsequent long option (the previous long option would have been
terminated by a comma), and, in any case, either at the end of the
-'longopts' string ('$'), or followed by a comma (separating this option
+âlongoptsâ string (â$â), or followed by a comma (separating this option
from a subsequent option) or a colon (indicating this long option takes
-an argument ('[,:]').
+an argument (â[,:]â).
Using this regular expression, we check to see if the current option
-might possibly be in 'longopts' (if 'longopts' is not specified, this
+might possibly be in âlongoptsâ (if âlongoptsâ is not specified, this
test will also fail). In case of an error, we possibly print an error
-message and then return '"?"'. Continuing on:
+message and then return â"?"â. Continuing on:
if (substr(longopts, i+1+length(thisopt), 1) == ":") {
if (j > 0)
@@ -17123,7 +17123,7 @@ message and then return '"?"'. Continuing on:
Optarg = ""
We now check to see if this option takes an argument and, if so, we
-set 'Optarg' to the value of that argument (either a value after an
+set âOptargâ to the value of that argument (either a value after an
equal sign specified on the command line, immediately adjoining the long
option string, or as the next argument on the command line).
@@ -17132,15 +17132,15 @@ option string, or as the next argument on the command
line).
}
}
- We increase 'Optind' (which we already increased once if a required
+ We increase âOptindâ (which we already increased once if a required
argument was separated from its option by an equal sign), and return the
long option (minus its leading dashes).
- The 'BEGIN' rule initializes both 'Opterr' and 'Optind' to one.
-'Opterr' is set to one, because the default behavior is for 'getopt()'
-to print a diagnostic message upon seeing an invalid option. 'Optind'
-is set to one, because there's no reason to look at the program name,
-which is in 'ARGV[0]':
+ The âBEGINâ rule initializes both âOpterrâ and âOptindâ to one.
+âOpterrâ is set to one, because the default behavior is for âgetopt()â
+to print a diagnostic message upon seeing an invalid option. âOptindâ
+is set to one, because thereâs no reason to look at the program name,
+which is in âARGV[0]â:
BEGIN {
Opterr = 1 # default is to diagnose
@@ -17159,57 +17159,57 @@ which is in 'ARGV[0]':
}
}
- The rest of the 'BEGIN' rule is a simple test program. Here are the
+ The rest of the âBEGINâ rule is a simple test program. Here are the
results of some sample runs of the test program:
$ awk -f getopt.awk -v _getopt_test=1 -- -a -cbARG bax -x
- -| c = <a>, Optarg = <>
- -| c = <c>, Optarg = <>
- -| c = <b>, Optarg = <ARG>
- -| non-option arguments:
- -| ARGV[3] = <bax>
- -| ARGV[4] = <-x>
+ ⣠c = <a>, Optarg = <>
+ ⣠c = <c>, Optarg = <>
+ ⣠c = <b>, Optarg = <ARG>
+ ⣠non-option arguments:
+ ⣠ARGV[3] = <bax>
+ ⣠ARGV[4] = <-x>
$ awk -f getopt.awk -v _getopt_test=1 -- -a -x -- xyz abc
- -| c = <a>, Optarg = <>
- error-> x -- invalid option
- -| c = <?>, Optarg = <>
- -| non-option arguments:
- -| ARGV[4] = <xyz>
- -| ARGV[5] = <abc>
+ ⣠c = <a>, Optarg = <>
+ errorâ x -- invalid option
+ ⣠c = <?>, Optarg = <>
+ ⣠non-option arguments:
+ ⣠ARGV[4] = <xyz>
+ ⣠ARGV[5] = <abc>
$ awk -f getopt.awk -v _getopt_test=1 -- -a \
> --longa -b xx --longb=foo=bar --otherd --otherc arg1 arg2
- -| c = <a>, Optarg = <>
- -| c = <longa>, Optarg = <>
- -| c = <b>, Optarg = <xx>
- -| c = <longb>, Optarg = <foo=bar>
- -| c = <otherd>, Optarg = <>
- -| c = <otherc>, Optarg = <>
- -| non-option arguments:
- -| ARGV[8] = <arg1>
- -| ARGV[9] = <arg2>
-
- In all the runs, the first '--' terminates the arguments to 'awk', so
-that it does not try to interpret the '-a', etc., as its own options.
-
- NOTE: After 'getopt()' is through, user-level code must clear out
- all the elements of 'ARGV' from 1 to 'Optind', so that 'awk' does
+ ⣠c = <a>, Optarg = <>
+ ⣠c = <longa>, Optarg = <>
+ ⣠c = <b>, Optarg = <xx>
+ ⣠c = <longb>, Optarg = <foo=bar>
+ ⣠c = <otherd>, Optarg = <>
+ ⣠c = <otherc>, Optarg = <>
+ ⣠non-option arguments:
+ ⣠ARGV[8] = <arg1>
+ ⣠ARGV[9] = <arg2>
+
+ In all the runs, the first â--â terminates the arguments to âawkâ,
so
+that it does not try to interpret the â-aâ, etc., as its own options.
+
+ NOTE: After âgetopt()â is through, user-level code must clear out
+ all the elements of âARGVâ from 1 to âOptindâ, so that âawkâ
does
not try to process the command-line options as file names.
- Using '#!' with the '-E' option may help avoid conflicts between your
-program's options and 'gawk''s options, as '-E' causes 'gawk' to abandon
+ Using â#!â with the â-Eâ option may help avoid conflicts between
your
+programâs options and âgawkââs options, as â-Eâ causes âgawkâ
to abandon
processing of further options (*note Executable Scripts:: and *note
Options::).
Several of the sample programs presented in *note Sample Programs::,
-use 'getopt()' to process their arguments.
+use âgetopt()â to process their arguments.
---------- Footnotes ----------
- (1) This function was written before 'gawk' acquired the ability to
-split strings into single characters using '""' as the separator. We
-have left it alone, as using 'substr()' is more portable.
+ (1) This function was written before âgawkâ acquired the ability to
+split strings into single characters using â""â as the separator. We
+have left it alone, as using âsubstr()â is more portable.
File: gawk.info, Node: Passwd Functions, Next: Group Functions, Prev:
Getopt Function, Up: Library Functions
@@ -17217,9 +17217,9 @@ File: gawk.info, Node: Passwd Functions, Next: Group
Functions, Prev: Getopt
10.5 Reading the User Database
==============================
-The 'PROCINFO' array (*note Built-in Variables::) provides access to the
-current user's real and effective user and group ID numbers, and, if
-available, the user's supplementary group set. However, because these
+The âPROCINFOâ array (*note Built-in Variables::) provides access to the
+current userâs real and effective user and group ID numbers, and, if
+available, the userâs supplementary group set. However, because these
are numbers, they do not provide very useful information to the average
user. There needs to be some way to find the user information
associated with the user and group ID numbers. This minor node presents
@@ -17228,21 +17228,21 @@ a suite of functions for retrieving information from
the user database.
from the group database.
The POSIX standard does not define the file where user information is
-kept. Instead, it provides the '<pwd.h>' header file and several C
+kept. Instead, it provides the â<pwd.h>â header file and several C
language subroutines for obtaining user information. The primary
-function is 'getpwent()', for "get password entry." The "password"
-comes from the original user database file, '/etc/passwd', which stores
-user information along with the encrypted passwords (hence the name).
+function is âgetpwent()â, for âget password entry.â The âpasswordâ
comes
+from the original user database file, â/etc/passwdâ, which stores user
+information along with the encrypted passwords (hence the name).
- Although an 'awk' program could simply read '/etc/passwd' directly,
-this file may not contain complete information about the system's set of
+ Although an âawkâ program could simply read â/etc/passwdâ directly,
+this file may not contain complete information about the systemâs set of
users.(1) To be sure you are able to produce a readable and complete
version of the user database, it is necessary to write a small C program
-that calls 'getpwent()'. 'getpwent()' is defined as returning a pointer
-to a 'struct passwd'. Each time it is called, it returns the next entry
-in the database. When there are no more entries, it returns 'NULL', the
-null pointer. When this happens, the C program should call 'endpwent()'
-to close the database. Following is 'pwcat', a C program that "cats"
+that calls âgetpwent()â. âgetpwent()â is defined as returning a
pointer
+to a âstruct passwdâ. Each time it is called, it returns the next entry
+in the database. When there are no more entries, it returns âNULLâ, the
+null pointer. When this happens, the C program should call âendpwent()â
+to close the database. Following is âpwcatâ, a C program that âcatsâ
the password database:
/*
@@ -17267,49 +17267,49 @@ the password database:
return 0;
}
- If you don't understand C, don't worry about it. The output from
-'pwcat' is the user database, in the traditional '/etc/passwd' format of
+ If you donât understand C, donât worry about it. The output from
+âpwcatâ is the user database, in the traditional â/etc/passwdâ format
of
colon-separated fields. The fields are:
Login name
- The user's login name.
+ The userâs login name.
Encrypted password
- The user's encrypted password. This may not be available on some
+ The userâs encrypted password. This may not be available on some
systems.
User-ID
- The user's numeric user ID number. (On some systems, it's a C
- 'long', and not an 'int'. Thus, we cast it to 'long' for all
+ The userâs numeric user ID number. (On some systems, itâs a C
+ âlongâ, and not an âintâ. Thus, we cast it to âlongâ for all
cases.)
Group-ID
- The user's numeric group ID number. (Similar comments about 'long'
- versus 'int' apply here.)
+ The userâs numeric group ID number. (Similar comments about âlongâ
+ versus âintâ apply here.)
Full name
- The user's full name, and perhaps other information associated with
+ The userâs full name, and perhaps other information associated with
the user.
Home directory
- The user's login (or "home") directory (familiar to shell
- programmers as '$HOME').
+ The userâs login (or âhomeâ) directory (familiar to shell
+ programmers as â$HOMEâ).
Login shell
The program that is run when the user logs in. This is usually a
shell, such as Bash.
- A few lines representative of 'pwcat''s output are as follows:
+ A few lines representative of âpwcatââs output are as follows:
$ pwcat
- -| root:x:0:1:Operator:/:/bin/sh
- -| nobody:*:65534:65534::/:
- -| daemon:*:1:1::/:
- -| sys:*:2:2::/:/bin/csh
- -| bin:*:3:3::/bin:
- -| arnold:xyzzy:2076:10:Arnold Robbins:/home/arnold:/bin/sh
- -| miriam:yxaay:112:10:Miriam Robbins:/home/miriam:/bin/sh
- -| andy:abcca2:113:10:Andy Jacobs:/home/andy:/bin/sh
+ ⣠root:x:0:1:Operator:/:/bin/sh
+ ⣠nobody:*:65534:65534::/:
+ ⣠daemon:*:1:1::/:
+ ⣠sys:*:2:2::/:/bin/csh
+ ⣠bin:*:3:3::/bin:
+ ⣠arnold:xyzzy:2076:10:Arnold Robbins:/home/arnold:/bin/sh
+ ⣠miriam:yxaay:112:10:Miriam Robbins:/home/miriam:/bin/sh
+ ⣠andy:abcca2:113:10:Andy Jacobs:/home/andy:/bin/sh
...
With that introduction, following is a group of functions for getting
@@ -17354,38 +17354,38 @@ the C functions of the same names:
$0 = olddol0
}
- The 'BEGIN' rule sets a private variable to the directory where
-'pwcat' is stored. Because it is used to help out an 'awk' library
-routine, we have chosen to put it in '/usr/local/libexec/awk'; however,
+ The âBEGINâ rule sets a private variable to the directory where
+âpwcatâ is stored. Because it is used to help out an âawkâ library
+routine, we have chosen to put it in â/usr/local/libexec/awkâ; however,
you might want it to be in a different directory on your system.
- The function '_pw_init()' fills three copies of the user information
+ The function â_pw_init()â fills three copies of the user information
into three associative arrays. The arrays are indexed by username
-('_pw_byname'), by user ID number ('_pw_byuid'), and by order of
-occurrence ('_pw_bycount'). The variable '_pw_inited' is used for
-efficiency, as '_pw_init()' needs to be called only once.
+(â_pw_bynameâ), by user ID number (â_pw_byuidâ), and by order of
+occurrence (â_pw_bycountâ). The variable â_pw_initedâ is used for
+efficiency, as â_pw_init()â needs to be called only once.
- Because this function uses 'getline' to read information from
-'pwcat', it first saves the values of 'FS', 'RS', and '$0'. It notes in
-the variable 'using_fw' whether field splitting with 'FIELDWIDTHS' is in
+ Because this function uses âgetlineâ to read information from
+âpwcatâ, it first saves the values of âFSâ, âRSâ, and â$0â.
It notes in
+the variable âusing_fwâ whether field splitting with âFIELDWIDTHSâ is
in
effect or not. Doing so is necessary, as these functions could be
-called from anywhere within a user's program, and the user may have his
+called from anywhere within a userâs program, and the user may have his
or her own way of splitting records and fields. This makes it possible
to restore the correct field-splitting mechanism later. The test can
-only be true for 'gawk'. It is false if using 'FS' or 'FPAT', or on
-some other 'awk' implementation.
+only be true for âgawkâ. It is false if using âFSâ or âFPATâ, or
on
+some other âawkâ implementation.
- The code that checks for using 'FPAT', using 'using_fpat' and
-'PROCINFO["FS"]', is similar.
+ The code that checks for using âFPATâ, using âusing_fpatâ and
+âPROCINFO["FS"]â, is similar.
The main part of the function uses a loop to read database lines,
split the lines into fields, and then store the lines into each array as
-necessary. When the loop is done, '_pw_init()' cleans up by closing the
-pipeline, setting '_pw_inited' to one, and restoring 'FS' (and
-'FIELDWIDTHS' or 'FPAT' if necessary), 'RS', and '$0'. The use of
-'_pw_count' is explained shortly.
+necessary. When the loop is done, â_pw_init()â cleans up by closing the
+pipeline, setting â_pw_initedâ to one, and restoring âFSâ (and
+âFIELDWIDTHSâ or âFPATâ if necessary), âRSâ, and â$0â. The
use of
+â_pw_countâ is explained shortly.
- The 'getpwnam()' function takes a username as a string argument. If
+ The âgetpwnam()â function takes a username as a string argument. If
that user is in the database, it returns the appropriate line.
Otherwise, it relies on the array reference to a nonexistent element to
create the element with the null string as its value:
@@ -17396,7 +17396,7 @@ create the element with the null string as its value:
return _pw_byname[name]
}
- Similarly, the 'getpwuid()' function takes a user ID number argument.
+ Similarly, the âgetpwuid()â function takes a user ID number argument.
If that user number is in the database, it returns the appropriate line.
Otherwise, it returns the null string:
@@ -17406,9 +17406,9 @@ Otherwise, it returns the null string:
return _pw_byuid[uid]
}
- The 'getpwent()' function simply steps through the database, one
-entry at a time. It uses '_pw_count' to track its current position in
-the '_pw_bycount' array:
+ The âgetpwent()â function simply steps through the database, one
+entry at a time. It uses â_pw_countâ to track its current position in
+the â_pw_bycountâ array:
function getpwent()
{
@@ -17418,8 +17418,8 @@ the '_pw_bycount' array:
return ""
}
- The 'endpwent()' function resets '_pw_count' to zero, so that
-subsequent calls to 'getpwent()' start over again:
+ The âendpwent()â function resets â_pw_countâ to zero, so that
+subsequent calls to âgetpwent()â start over again:
function endpwent()
{
@@ -17427,24 +17427,24 @@ subsequent calls to 'getpwent()' start over again:
}
A conscious design decision in this suite is that each subroutine
-calls '_pw_init()' to initialize the database arrays. The overhead of
+calls â_pw_init()â to initialize the database arrays. The overhead of
running a separate process to generate the user database, and the I/O to
-scan it, are only incurred if the user's main program actually calls one
-of these functions. If this library file is loaded along with a user's
+scan it, are only incurred if the userâs main program actually calls one
+of these functions. If this library file is loaded along with a userâs
program, but none of the routines are ever called, then there is no
extra runtime overhead. (The alternative is move the body of
-'_pw_init()' into a 'BEGIN' rule, which always runs 'pwcat'. This
+â_pw_init()â into a âBEGINâ rule, which always runs âpwcatâ. This
simplifies the code but runs an extra process that may never be needed.)
- In turn, calling '_pw_init()' is not too expensive, because the
-'_pw_inited' variable keeps the program from reading the data more than
+ In turn, calling â_pw_init()â is not too expensive, because the
+â_pw_initedâ variable keeps the program from reading the data more than
once. If you are worried about squeezing every last cycle out of your
-'awk' program, the check of '_pw_inited' could be moved out of
-'_pw_init()' and duplicated in all the other functions. In practice,
-this is not necessary, as most 'awk' programs are I/O-bound, and such a
+âawkâ program, the check of â_pw_initedâ could be moved out of
+â_pw_init()â and duplicated in all the other functions. In practice,
+this is not necessary, as most âawkâ programs are I/O-bound, and such a
change would clutter up the code.
- The 'id' program in *note Id Program:: uses these functions.
+ The âidâ program in *note Id Program:: uses these functions.
---------- Footnotes ----------
@@ -17459,12 +17459,12 @@ File: gawk.info, Node: Group Functions, Next:
Walking Arrays, Prev: Passwd Fu
Much of the discussion presented in *note Passwd Functions:: applies to
the group database as well. Although there has traditionally been a
-well-known file ('/etc/group') in a well-known format, the POSIX
-standard only provides a set of C library routines ('<grp.h>' and
-'getgrent()') for accessing the information. Even though this file may
+well-known file (â/etc/groupâ) in a well-known format, the POSIX
+standard only provides a set of C library routines (â<grp.h>â and
+âgetgrent()â) for accessing the information. Even though this file may
exist, it may not have complete information. Therefore, as with the
user database, it is necessary to have a small C program that generates
-the group database as its output. 'grcat', a C program that "cats" the
+the group database as its output. âgrcatâ, a C program that âcatsâ the
group database, is as follows:
/*
@@ -17499,35 +17499,35 @@ group database, is as follows:
separated with colons and represent the following information:
Group Name
- The group's name.
+ The groupâs name.
Group Password
- The group's encrypted password. In practice, this field is never
- used; it is usually empty or set to '*'.
+ The groupâs encrypted password. In practice, this field is never
+ used; it is usually empty or set to â*â.
Group ID Number
- The group's numeric group ID number; the association of name to
- number must be unique within the file. (On some systems it's a C
- 'long', and not an 'int'. Thus, we cast it to 'long' for all
+ The groupâs numeric group ID number; the association of name to
+ number must be unique within the file. (On some systems itâs a C
+ âlongâ, and not an âintâ. Thus, we cast it to âlongâ for all
cases.)
Group Member List
A comma-separated list of usernames. These users are members of
the group. Modern Unix systems allow users to be members of
several groups simultaneously. If your system does, then there are
- elements '"group1"' through '"groupN"' in 'PROCINFO' for those
- group ID numbers. (Note that 'PROCINFO' is a 'gawk' extension;
+ elements â"group1"â through â"groupN"â in âPROCINFOâ for those
+ group ID numbers. (Note that âPROCINFOâ is a âgawkâ extension;
*note Built-in Variables::.)
- Here is what running 'grcat' might produce:
+ Here is what running âgrcatâ might produce:
$ grcat
- -| wheel:*:0:arnold
- -| nogroup:*:65534:
- -| daemon:*:1:
- -| kmem:*:2:
- -| staff:*:10:arnold,miriam,andy
- -| other:*:20:
+ ⣠wheel:*:0:arnold
+ ⣠nogroup:*:65534:
+ ⣠daemon:*:1:
+ ⣠kmem:*:2:
+ ⣠staff:*:10:arnold,miriam,andy
+ ⣠other:*:20:
...
Here are the functions for obtaining information from the group
@@ -17587,23 +17587,23 @@ the same names:
$0 = olddol0
}
- The 'BEGIN' rule sets a private variable to the directory where
-'grcat' is stored. Because it is used to help out an 'awk' library
-routine, we have chosen to put it in '/usr/local/libexec/awk'. You
+ The âBEGINâ rule sets a private variable to the directory where
+âgrcatâ is stored. Because it is used to help out an âawkâ library
+routine, we have chosen to put it in â/usr/local/libexec/awkâ. You
might want it to be in a different directory on your system.
These routines follow the same general outline as the user database
-routines (*note Passwd Functions::). The '_gr_inited' variable is used
+routines (*note Passwd Functions::). The â_gr_initedâ variable is used
to ensure that the database is scanned no more than once. The
-'_gr_init()' function first saves 'FS', 'RS', and '$0', and then sets
-'FS' and 'RS' to the correct values for scanning the group information.
-It also takes care to note whether 'FIELDWIDTHS' or 'FPAT' is being
+â_gr_init()â function first saves âFSâ, âRSâ, and â$0â, and
then sets
+âFSâ and âRSâ to the correct values for scanning the group information.
+It also takes care to note whether âFIELDWIDTHSâ or âFPATâ is being
used, and to restore the appropriate field-splitting mechanism.
The group information is stored in several associative arrays. The
-arrays are indexed by group name ('_gr_byname'), by group ID number
-('_gr_bygid'), and by position in the database ('_gr_bycount'). There
-is an additional array indexed by username ('_gr_groupsbyuser'), which
+arrays are indexed by group name (â_gr_bynameâ), by group ID number
+(â_gr_bygidâ), and by position in the database (â_gr_bycountâ). There
+is an additional array indexed by username (â_gr_groupsbyuserâ), which
is a space-separated list of groups to which each user belongs.
Unlike in the user database, it is possible to have multiple records
@@ -17614,15 +17614,15 @@ following:
tvpeople:*:101:johnny,jay,arsenio
tvpeople:*:101:david,conan,tom,joan
- For this reason, '_gr_init()' looks to see if a group name or group
+ For this reason, â_gr_init()â looks to see if a group name or group
ID number is already seen. If so, the usernames are simply concatenated
onto the previous list of users.(1)
- Finally, '_gr_init()' closes the pipeline to 'grcat', restores 'FS'
-(and 'FIELDWIDTHS' or 'FPAT', if necessary), 'RS', and '$0', initializes
-'_gr_count' to zero (it is used later), and makes '_gr_inited' nonzero.
+ Finally, â_gr_init()â closes the pipeline to âgrcatâ, restores
âFSâ
+(and âFIELDWIDTHSâ or âFPATâ, if necessary), âRSâ, and â$0â,
initializes
+â_gr_countâ to zero (it is used later), and makes â_gr_initedâ nonzero.
- The 'getgrnam()' function takes a group name as its argument, and if
+ The âgetgrnam()â function takes a group name as its argument, and if
that group exists, it is returned. Otherwise, it relies on the array
reference to a nonexistent element to create the element with the null
string as its value:
@@ -17633,7 +17633,7 @@ string as its value:
return _gr_byname[group]
}
- The 'getgrgid()' function is similar; it takes a numeric group ID and
+ The âgetgrgid()â function is similar; it takes a numeric group ID and
looks up the information associated with that group ID:
function getgrgid(gid)
@@ -17642,7 +17642,7 @@ looks up the information associated with that group ID:
return _gr_bygid[gid]
}
- The 'getgruser()' function does not have a C counterpart. It takes a
+ The âgetgruser()â function does not have a C counterpart. It takes a
username and returns the list of groups that have the user as a member:
function getgruser(user)
@@ -17651,8 +17651,8 @@ username and returns the list of groups that have the
user as a member:
return _gr_groupsbyuser[user]
}
- The 'getgrent()' function steps through the database one entry at a
-time. It uses '_gr_count' to track its position in the list:
+ The âgetgrent()â function steps through the database one entry at a
+time. It uses â_gr_countâ to track its position in the list:
function getgrent()
{
@@ -17662,30 +17662,30 @@ time. It uses '_gr_count' to track its position in
the list:
return ""
}
- The 'endgrent()' function resets '_gr_count' to zero so that
-'getgrent()' can start over again:
+ The âendgrent()â function resets â_gr_countâ to zero so that
+âgetgrent()â can start over again:
function endgrent()
{
_gr_count = 0
}
- As with the user database routines, each function calls '_gr_init()'
+ As with the user database routines, each function calls â_gr_init()â
to initialize the arrays. Doing so only incurs the extra overhead of
-running 'grcat' if these functions are used (as opposed to moving the
-body of '_gr_init()' into a 'BEGIN' rule).
+running âgrcatâ if these functions are used (as opposed to moving the
+body of â_gr_init()â into a âBEGINâ rule).
Most of the work is in scanning the database and building the various
associative arrays. The functions that the user calls are themselves
-very simple, relying on 'awk''s associative arrays to do work.
+very simple, relying on âawkââs associative arrays to do work.
- The 'id' program in *note Id Program:: uses these functions.
+ The âidâ program in *note Id Program:: uses these functions.
---------- Footnotes ----------
(1) There is a subtle problem with the code just presented. Suppose
that the first time there were no names. This code adds the names with
-a leading comma. It also doesn't check that there is a '$4'.
+a leading comma. It also doesnât check that there is a â$4â.
File: gawk.info, Node: Walking Arrays, Next: Library Functions Summary,
Prev: Group Functions, Up: Library Functions
@@ -17693,11 +17693,11 @@ File: gawk.info, Node: Walking Arrays, Next:
Library Functions Summary, Prev:
10.7 Traversing Arrays of Arrays
================================
-*note Arrays of Arrays:: described how 'gawk' provides arrays of arrays.
+*note Arrays of Arrays:: described how âgawkâ provides arrays of arrays.
In particular, any element of an array may be either a scalar or another
-array. The 'isarray()' function (*note Type Functions::) lets you
+array. The âisarray()â function (*note Type Functions::) lets you
distinguish an array from a scalar. The following function,
-'walk_array()', recursively traverses an array, printing the element
+âwalk_array()â, recursively traverses an array, printing the element
indices and values. You call it with the array and a string
representing the name of the array:
@@ -17714,7 +17714,7 @@ representing the name of the array:
It works by looping over each element of the array. If any given
element is itself an array, the function calls itself recursively,
passing the subarray and a new string representing the current index.
-Otherwise, the function simply prints the element's name, index, and
+Otherwise, the function simply prints the elementâs name, index, and
value. Here is a main program to demonstrate:
BEGIN {
@@ -17731,12 +17731,12 @@ value. Here is a main program to demonstrate:
When run, the program produces the following output:
$ gawk -f walk_array.awk
- -| a[1] = 1
- -| a[2][1] = 21
- -| a[2][2] = 22
- -| a[3] = 3
- -| a[4][1][1] = 411
- -| a[4][2] = 42
+ ⣠a[1] = 1
+ ⣠a[2][1] = 21
+ ⣠a[2][2] = 22
+ ⣠a[3] = 3
+ ⣠a[4][1][1] = 411
+ ⣠a[4][2] = 42
The function just presented simply prints the name and value of each
scalar array element. However, it is easy to generalize it, by passing
@@ -17758,16 +17758,16 @@ function looks like this:
The arguments are as follows:
-'arr'
+âarrâ
The array.
-'name'
+ânameâ
The name of the array (a string).
-'process'
+âprocessâ
The name of the function to call.
-'do_arrays'
+âdo_arraysâ
If this is true, the function can handle elements that are
subarrays.
@@ -17775,7 +17775,7 @@ function looks like this:
further.
When run with the following scaffolding, the function produces the
-same results as does the earlier version of 'walk_array()':
+same results as does the earlier version of âwalk_array()â:
BEGIN {
a[1] = 1
@@ -17799,15 +17799,15 @@ File: gawk.info, Node: Library Functions Summary,
Next: Library Exercises, Pr
10.8 Summary
============
- * Reading programs is an excellent way to learn Good Programming.
+ ⢠Reading programs is an excellent way to learn Good Programming.
The functions and programs provided in this major node and the next
are intended to serve that purpose.
- * When writing general-purpose library functions, put some thought
- into how to name any global variables so that they won't conflict
- with variables from a user's program.
+ ⢠When writing general-purpose library functions, put some thought
+ into how to name any global variables so that they wonât conflict
+ with variables from a userâs program.
- * The functions presented here fit into the following categories:
+ ⢠The functions presented here fit into the following categories:
General problems
Number-to-string conversion, testing assertions, rounding,
@@ -17821,7 +17821,7 @@ File: gawk.info, Node: Library Functions Summary,
Next: Library Exercises, Pr
and treating assignments as file names
Processing command-line options
- An 'awk' version of the standard C 'getopt()' function
+ An âawkâ version of the standard C âgetopt()â function
Reading the user and group databases
Two sets of routines that parallel the C library versions
@@ -17835,22 +17835,22 @@ File: gawk.info, Node: Library Exercises, Prev:
Library Functions Summary, Up
10.9 Exercises
==============
- 1. In *note Empty Files::, we presented the 'zerofile.awk' program,
- which made use of 'gawk''s 'ARGIND' variable. Can this problem be
- solved without relying on 'ARGIND'? If so, how?
+ 1. In *note Empty Files::, we presented the âzerofile.awkâ program,
+ which made use of âgawkââs âARGINDâ variable. Can this problem
be
+ solved without relying on âARGINDâ? If so, how?
2. As a related challenge, revise that code to handle the case where
- an intervening value in 'ARGV' is a variable assignment.
+ an intervening value in âARGVâ is a variable assignment.
File: gawk.info, Node: Sample Programs, Next: Advanced Features, Prev:
Library Functions, Up: Top
-11 Practical 'awk' Programs
+11 Practical âawkâ Programs
***************************
*note Library Functions::, presents the idea that reading programs in a
language contributes to learning that language. This major node
-continues that theme, presenting a potpourri of 'awk' programs for your
+continues that theme, presenting a potpourri of âawkâ programs for your
reading enjoyment.
Many of these programs use library functions presented in *note
@@ -17860,7 +17860,7 @@ Library Functions::.
* Running Examples:: How to run these examples.
* Clones:: Clones of common utilities.
-* Miscellaneous Programs:: Some interesting 'awk' programs.
+* Miscellaneous Programs:: Some interesting âawkâ programs.
* Programs Summary:: Summary of programs.
* Programs Exercises:: Exercises.
@@ -17874,16 +17874,16 @@ To run a given program, you would typically do
something like this:
awk -f PROGRAM -- OPTIONS FILES
-Here, PROGRAM is the name of the 'awk' program (such as 'cut.awk'),
+Here, PROGRAM is the name of the âawkâ program (such as âcut.awkâ),
OPTIONS are any command-line options for the program that start with a
-'-', and FILES are the actual data files.
+â-â, and FILES are the actual data files.
- If your system supports the '#!' executable interpreter mechanism
+ If your system supports the â#!â executable interpreter mechanism
(*note Executable Scripts::), you can instead run your program directly:
cut.awk -c1-8 myfiles > results
- If your 'awk' is not 'gawk', you may instead need to use this:
+ If your âawkâ is not âgawkâ, you may instead need to use this:
cut.awk -- -c1-8 myfiles > results
@@ -17894,28 +17894,28 @@ File: gawk.info, Node: Clones, Next: Miscellaneous
Programs, Prev: Running Ex
==========================================
This minor node presents a number of POSIX utilities implemented in
-'awk'. Reinventing these programs in 'awk' is often enjoyable, because
+âawkâ. Reinventing these programs in âawkâ is often enjoyable, because
the algorithms can be very clearly expressed, and the code is usually
-very concise and simple. This is true because 'awk' does so much for
+very concise and simple. This is true because âawkâ does so much for
you.
It should be noted that these programs are not necessarily intended
to replace the installed versions on your system. Nor may all of these
programs be fully compliant with the most recent POSIX standard. This
-is not a problem; their purpose is to illustrate 'awk' language
-programming for "real-world" tasks.
+is not a problem; their purpose is to illustrate âawkâ language
+programming for âreal-worldâ tasks.
The programs are presented in alphabetical order.
* Menu:
-* Cut Program:: The 'cut' utility.
-* Egrep Program:: The 'egrep' utility.
-* Id Program:: The 'id' utility.
-* Split Program:: The 'split' utility.
-* Tee Program:: The 'tee' utility.
-* Uniq Program:: The 'uniq' utility.
-* Wc Program:: The 'wc' utility.
+* Cut Program:: The âcutâ utility.
+* Egrep Program:: The âegrepâ utility.
+* Id Program:: The âidâ utility.
+* Split Program:: The âsplitâ utility.
+* Tee Program:: The âteeâ utility.
+* Uniq Program:: The âuniqâ utility.
+* Wc Program:: The âwcâ utility.
File: gawk.info, Node: Cut Program, Next: Egrep Program, Up: Clones
@@ -17923,47 +17923,47 @@ File: gawk.info, Node: Cut Program, Next: Egrep
Program, Up: Clones
11.2.1 Cutting Out Fields and Columns
-------------------------------------
-The 'cut' utility selects, or "cuts," characters or fields from its
+The âcutâ utility selects, or âcuts,â characters or fields from its
standard input and sends them to its standard output. Fields are
separated by TABs by default, but you may supply a command-line option
-to change the field "delimiter" (i.e., the field-separator character).
-'cut''s definition of fields is less general than 'awk''s.
+to change the field âdelimiterâ (i.e., the field-separator character).
+âcutââs definition of fields is less general than âawkââs.
- A common use of 'cut' might be to pull out just the login names of
-logged-on users from the output of 'who'. For example, the following
+ A common use of âcutâ might be to pull out just the login names of
+logged-on users from the output of âwhoâ. For example, the following
pipeline generates a sorted, unique list of the logged-on users:
who | cut -c1-8 | sort | uniq
- The options for 'cut' are:
+ The options for âcutâ are:
-'-c LIST'
+â-c LISTâ
Use LIST as the list of characters to cut out. Items within the
list may be separated by commas, and ranges of characters can be
- separated with dashes. The list '1-8,15,22-35' specifies
+ separated with dashes. The list â1-8,15,22-35â specifies
characters 1 through 8, 15, and 22 through 35.
-'-d DELIM'
+â-d DELIMâ
Use DELIM as the field-separator character instead of the TAB
character.
-'-f LIST'
+â-f LISTâ
Use LIST as the list of fields to cut out.
-'-s'
+â-sâ
Suppress printing of lines that do not contain the field delimiter.
- The 'awk' implementation of 'cut' uses the 'getopt()' library
-function (*note Getopt Function::) and the 'join()' library function
+ The âawkâ implementation of âcutâ uses the âgetopt()â library
+function (*note Getopt Function::) and the âjoin()â library function
(*note Join Function::).
- The current POSIX version of 'cut' has options to cut fields based on
+ The current POSIX version of âcutâ has options to cut fields based on
both bytes and characters. This version does not attempt to implement
-those options, as 'awk' works exclusively in terms of characters.
+those options, as âawkâ works exclusively in terms of characters.
The program begins with a comment describing the options, the library
-functions needed, and a 'usage()' function that prints out a usage
-message and exits. 'usage()' is called if invalid arguments are
+functions needed, and a âusage()â function that prints out a usage
+message and exits. âusage()â is called if invalid arguments are
supplied:
# cut.awk --- implement cut in awk
@@ -17984,12 +17984,12 @@ supplied:
exit 1
}
- Next comes a 'BEGIN' rule that parses the command-line options. It
-sets 'FS' to a single TAB character, because that is 'cut''s default
+ Next comes a âBEGINâ rule that parses the command-line options. It
+sets âFSâ to a single TAB character, because that is âcutââs default
field separator. The rule then sets the output field separator to be
-the same as the input field separator. A loop using 'getopt()' steps
+the same as the input field separator. A loop using âgetopt()â steps
through the command-line options. Exactly one of the variables
-'by_fields' or 'by_chars' is set to true, to indicate that processing
+âby_fieldsâ or âby_charsâ is set to true, to indicate that processing
should be done by fields or by characters, respectively. When cutting
by characters, the output field separator is set to the null string:
@@ -18025,22 +18025,22 @@ by characters, the output field separator is set to
the null string:
ARGV[i] = ""
The code must take special care when the field delimiter is a space.
-Using a single space ('" "') for the value of 'FS' is incorrect--'awk'
+Using a single space (â" "â) for the value of âFSâ is
incorrectââawkâ
would separate fields with runs of spaces, TABs, and/or newlines, and we
want them to be separated with individual spaces. To this end, we save
-the original space character in the variable 'fs' for later use; after
-setting 'FS' to '"[ ]"' we can't use it directly to see if the field
+the original space character in the variable âfsâ for later use; after
+setting âFSâ to â"[ ]"â we canât use it directly to see if the field
delimiter character is in the string.
- Also remember that after 'getopt()' is through (as described in *note
-Getopt Function::), we have to clear out all the elements of 'ARGV' from
-1 to 'Optind', so that 'awk' does not try to process the command-line
+ Also remember that after âgetopt()â is through (as described in *note
+Getopt Function::), we have to clear out all the elements of âARGVâ from
+1 to âOptindâ, so that âawkâ does not try to process the command-line
options as file names.
After dealing with the command-line options, the program verifies
-that the options make sense. Only one or the other of '-c' and '-f'
+that the options make sense. Only one or the other of â-câ and â-fâ
should be used, and both require a field list. Then the program calls
-either 'set_fieldlist()' or 'set_charlist()' to pull apart the list of
+either âset_fieldlist()â or âset_charlist()â to pull apart the list of
fields or characters:
if (by_fields && by_chars)
@@ -18060,13 +18060,13 @@ fields or characters:
set_charlist()
}
- 'set_fieldlist()' splits the field list apart at the commas into an
+ âset_fieldlist()â splits the field list apart at the commas into an
array. Then, for each element of the array, it looks to see if the
element is actually a range, and if so, splits it apart. The function
checks the range to make sure that the first number is smaller than the
-second. Each number in the list is added to the 'flist' array, which
+second. Each number in the list is added to the âflistâ array, which
simply lists the fields that will be printed. Normal field splitting is
-used. The program lets 'awk' handle the job of doing the field
+used. The program lets âawkâ handle the job of doing the field
splitting:
function set_fieldlist( n, m, i, j, k, f, g)
@@ -18089,20 +18089,20 @@ splitting:
nfields = j - 1
}
- The 'set_charlist()' function is more complicated than
-'set_fieldlist()'. The idea here is to use 'gawk''s 'FIELDWIDTHS'
+ The âset_charlist()â function is more complicated than
+âset_fieldlist()â. The idea here is to use âgawkââs
âFIELDWIDTHSâ
variable (*note Constant Size::), which describes constant-width input.
When using a character list, that is exactly what we have.
- Setting up 'FIELDWIDTHS' is more complicated than simply listing the
+ Setting up âFIELDWIDTHSâ is more complicated than simply listing the
fields that need to be printed. We have to keep track of the fields to
print and also the intervening characters that have to be skipped. For
example, suppose you wanted characters 1 through 8, 15, and 22 through
-35. You would use '-c 1-8,15,22-35'. The necessary value for
-'FIELDWIDTHS' is '"8 6 1 6 14"'. This yields five fields, and the
-fields to print are '$1', '$3', and '$5'. The intermediate fields are
-"filler", which is stuff in between the desired data. 'flist' lists the
-fields to print, and 't' tracks the complete field list, including
+35. You would use â-c 1-8,15,22-35â. The necessary value for
+âFIELDWIDTHSâ is â"8 6 1 6 14"â. This yields five fields, and the
+fields to print are â$1â, â$3â, and â$5â. The intermediate fields
are
+âfillerâ, which is stuff in between the desired data. âflistâ lists
the
+fields to print, and âtâ tracks the complete field list, including
filler fields:
function set_charlist( field, i, j, f, g, n, m, t,
@@ -18145,15 +18145,15 @@ filler fields:
nfields = j - 1
}
- Next is the rule that processes the data. If the '-s' option is
-given, then 'suppress' is true. The first 'if' statement makes sure
-that the input record does have the field separator. If 'cut' is
-processing fields, 'suppress' is true, and the field separator character
+ Next is the rule that processes the data. If the â-sâ option is
+given, then âsuppressâ is true. The first âifâ statement makes sure
+that the input record does have the field separator. If âcutâ is
+processing fields, âsuppressâ is true, and the field separator character
is not in the record, then the record is skipped.
- If the record is valid, then 'gawk' has split the data into fields,
-either using the character in 'FS' or using fixed-length fields and
-'FIELDWIDTHS'. The loop goes through the list of fields that should be
+ If the record is valid, then âgawkâ has split the data into fields,
+either using the character in âFSâ or using fixed-length fields and
+âFIELDWIDTHSâ. The loop goes through the list of fields that should be
printed. The corresponding field is printed if it contains data. If
the next field also has data, then the separator character is written
out between the fields:
@@ -18172,10 +18172,10 @@ out between the fields:
print ""
}
- This version of 'cut' relies on 'gawk''s 'FIELDWIDTHS' variable to do
-the character-based cutting. It is possible in other 'awk'
-implementations to use 'substr()' (*note String Functions::), but it is
-also extremely painful. The 'FIELDWIDTHS' variable supplies an elegant
+ This version of âcutâ relies on âgawkââs âFIELDWIDTHSâ
variable to do
+the character-based cutting. It is possible in other âawkâ
+implementations to use âsubstr()â (*note String Functions::), but it is
+also extremely painful. The âFIELDWIDTHSâ variable supplies an elegant
solution to the problem of picking the input line apart by characters.
@@ -18184,75 +18184,75 @@ File: gawk.info, Node: Egrep Program, Next: Id
Program, Prev: Cut Program, U
11.2.2 Searching for Regular Expressions in Files
-------------------------------------------------
-The 'grep' family of programs searches files for patterns. These
-programs have an unusual history. Initially there was 'grep' (Global
+The âgrepâ family of programs searches files for patterns. These
+programs have an unusual history. Initially there was âgrepâ (Global
Regular Expression Print), which used what are now called Basic Regular
-Expressions (BREs). Later there was 'egrep' (Extended 'grep') which
+Expressions (BREs). Later there was âegrepâ (Extended âgrepâ) which
used what are now called Extended Regular Expressions (EREs). (These
-are almost identical to those available in 'awk'; *note Regexp::).
-There was also 'fgrep' (Fast 'grep'), which searched for matches of one
+are almost identical to those available in âawkâ; *note Regexp::).
+There was also âfgrepâ (Fast âgrepâ), which searched for matches of one
more fixed strings.
POSIX chose to combine these three programs into one, simply named
-'grep'. On a POSIX system, 'grep''s default behavior is to search using
-BREs. You use '-E' to specify the use of EREs, and '-F' to specify
+âgrepâ. On a POSIX system, âgrepââs default behavior is to search
using
+BREs. You use â-Eâ to specify the use of EREs, and â-Fâ to specify
searching for fixed strings.
- In practice, systems continue to come with separate 'egrep' and
-'fgrep' utilities, for backwards compatibility. This minor node
-provides an 'awk' implementation of 'egrep', which supports all of the
+ In practice, systems continue to come with separate âegrepâ and
+âfgrepâ utilities, for backwards compatibility. This minor node
+provides an âawkâ implementation of âegrepâ, which supports all of the
POSIX-mandated options. You invoke it as follows:
- 'egrep' [OPTIONS] ''PATTERN'' FILES ...
+ âegrepâ [OPTIONS] â'PATTERN'â FILES ...
The PATTERN is a regular expression. In typical usage, the regular
expression is quoted to prevent the shell from expanding any of the
-special characters as file name wildcards. Normally, 'egrep' prints the
+special characters as file name wildcards. Normally, âegrepâ prints the
lines that matched. If multiple file names are provided on the command
line, each output line is preceded by the name of the file and a colon.
- The options to 'egrep' are as follows:
+ The options to âegrepâ are as follows:
-'-c'
+â-câ
Print a count of the lines that matched the pattern, instead of the
lines themselves.
-'-e PATTERN'
- Use PATTERN as the regexp to match. The purpose of the '-e' option
- is to allow patterns that start with a '-'.
+â-e PATTERNâ
+ Use PATTERN as the regexp to match. The purpose of the â-eâ option
+ is to allow patterns that start with a â-â.
-'-i'
+â-iâ
Ignore case distinctions in both the pattern and the input data.
-'-l'
+â-lâ
Only print (list) the names of the files that matched, not the
lines that matched.
-'-q'
+â-qâ
Be quiet. No output is produced and the exit value indicates
whether the pattern was matched.
-'-s'
+â-sâ
Be silent. Do not print error messages for files that could not be
opened.
-'-v'
- Invert the sense of the test. 'egrep' prints the lines that do
+â-vâ
+ Invert the sense of the test. âegrepâ prints the lines that do
_not_ match the pattern and exits successfully if the pattern is
not matched.
-'-x'
+â-xâ
Match the entire input line in order to consider the match as
having succeeded.
- This version uses the 'getopt()' library function (*note Getopt
-Function::) and 'gawk''s 'BEGINFILE' and 'ENDFILE' special patterns
+ This version uses the âgetopt()â library function (*note Getopt
+Function::) and âgawkââs âBEGINFILEâ and âENDFILEâ special
patterns
(*note BEGINFILE/ENDFILE::).
- The program begins with descriptive comments and then a 'BEGIN' rule
-that processes the command-line arguments with 'getopt()'. The '-i'
-(ignore case) option is particularly easy with 'gawk'; we just use the
-'IGNORECASE' predefined variable (*note Built-in Variables::):
+ The program begins with descriptive comments and then a âBEGINâ rule
+that processes the command-line arguments with âgetopt()â. The â-iâ
+(ignore case) option is particularly easy with âgawkâ; we just use the
+âIGNORECASEâ predefined variable (*note Built-in Variables::):
# egrep.awk --- simulate egrep in awk
#
@@ -18296,15 +18296,15 @@ that processes the command-line arguments with
'getopt()'. The '-i'
}
Note the comment about invocation: Because several of the options
-overlap with 'gawk''s, a '--' is needed to tell 'gawk' to stop looking
+overlap with âgawkââs, a â--â is needed to tell âgawkâ to stop
looking
for options.
- Next comes the code that handles the 'egrep'-specific behavior.
-'egrep' uses the first nonoption on the command line if no pattern is
-supplied with '-e'. If the pattern is empty, that means no pattern was
-supplied, so it's necessary to print an error message and exit. The
-'awk' command-line arguments up to 'ARGV[Optind]' are cleared, so that
-'awk' won't try to process them as files. If no files are specified,
+ Next comes the code that handles the âegrepâ-specific behavior.
+âegrepâ uses the first nonoption on the command line if no pattern is
+supplied with â-eâ. If the pattern is empty, that means no pattern was
+supplied, so itâs necessary to print an error message and exit. The
+âawkâ command-line arguments up to âARGV[Optind]â are cleared, so that
+âawkâ wonât try to process them as files. If no files are specified,
the standard input is used, and if multiple files are specified, we make
sure to note this so that the file names can precede the matched lines
in the output:
@@ -18325,14 +18325,14 @@ in the output:
do_filenames++
}
- The 'BEGINFILE' rule executes when each new file is processed. In
-this case, it is fairly simple; it initializes a variable 'fcount' to
-zero. 'fcount' tracks how many lines in the current file matched the
+ The âBEGINFILEâ rule executes when each new file is processed. In
+this case, it is fairly simple; it initializes a variable âfcountâ to
+zero. âfcountâ tracks how many lines in the current file matched the
pattern.
- Here also is where we implement the '-s' option. We check if 'ERRNO'
-has been set, and if '-s' was supplied. In that case, it's necessary to
-move on to the next file. Otherwise 'gawk' would exit with an error:
+ Here also is where we implement the â-sâ option. We check if
âERRNOâ
+has been set, and if â-sâ was supplied. In that case, itâs necessary to
+move on to the next file. Otherwise âgawkâ would exit with an error:
BEGINFILE {
fcount = 0
@@ -18340,13 +18340,13 @@ move on to the next file. Otherwise 'gawk' would
exit with an error:
nextfile
}
- The 'ENDFILE' rule executes after each file has been processed. It
+ The âENDFILEâ rule executes after each file has been processed. It
affects the output only when the user wants a count of the number of
-lines that matched. 'no_print' is true only if the exit status is
-desired. 'count_only' is true if line counts are desired. 'egrep'
+lines that matched. âno_printâ is true only if the exit status is
+desired. âcount_onlyâ is true if line counts are desired. âegrepâ
therefore only prints line counts if printing and counting are enabled.
The output format must be adjusted depending upon the number of files to
-process. Finally, 'fcount' is added to 'total', so that we know the
+process. Finally, âfcountâ is added to âtotalâ, so that we know the
total number of lines that matched the pattern:
ENDFILE {
@@ -18361,24 +18361,24 @@ total number of lines that matched the pattern:
}
The following rule does most of the work of matching lines. The
-variable 'matches' is true (non-zero) if the line matched the pattern.
-If the user specified that the entire line must match (with '-x'), the
-code checks this condition by looking at the values of 'RSTART' and
-'RLENGTH'. If those indicate that the match is not over the full line,
-'matches' is set to zero (false).
+variable âmatchesâ is true (non-zero) if the line matched the pattern.
+If the user specified that the entire line must match (with â-xâ), the
+code checks this condition by looking at the values of âRSTARTâ and
+âRLENGTHâ. If those indicate that the match is not over the full line,
+âmatchesâ is set to zero (false).
If the user wants lines that did not match, we invert the sense of
-'matches' using the '!' operator. We then increment 'fcount' with the
-value of 'matches', which is either one or zero, depending upon a
+âmatchesâ using the â!â operator. We then increment âfcountâ with
the
+value of âmatchesâ, which is either one or zero, depending upon a
successful or unsuccessful match. If the line does not match, the
-'next' statement just moves on to the next input line.
+ânextâ statement just moves on to the next input line.
We make a number of additional tests, but only if we are not counting
-lines. First, if the user only wants the exit status ('no_print' is
+lines. First, if the user only wants the exit status (âno_printâ is
true), then it is enough to know that _one_ line in this file matched,
-and we can skip on to the next file with 'nextfile'. Similarly, if we
+and we can skip on to the next file with ânextfileâ. Similarly, if we
are only printing file names, we can print the file name, and then skip
-to the next file with 'nextfile'. Finally, each line is printed, with a
+to the next file with ânextfileâ. Finally, each line is printed, with a
leading file name, optional colon and line number, and the final colon
if necessary:
@@ -18414,14 +18414,14 @@ if necessary:
}
}
- The 'END' rule takes care of producing the correct exit status. If
+ The âENDâ rule takes care of producing the correct exit status. If
there are no matches, the exit status is one; otherwise, it is zero:
END {
exit (total == 0)
}
- The 'usage()' function prints a usage message in case of invalid
+ The âusage()â function prints a usage message in case of invalid
options, and then exits:
function usage()
@@ -18437,33 +18437,33 @@ File: gawk.info, Node: Id Program, Next: Split
Program, Prev: Egrep Program,
11.2.3 Printing Out User Information
------------------------------------
-The 'id' utility lists a user's real and effective user ID numbers, real
-and effective group ID numbers, and the user's group set, if any. 'id'
+The âidâ utility lists a userâs real and effective user ID numbers, real
+and effective group ID numbers, and the userâs group set, if any. âidâ
only prints the effective user ID and group ID if they are different
-from the real ones. If possible, 'id' also supplies the corresponding
+from the real ones. If possible, âidâ also supplies the corresponding
user and group names. The output might look like this:
$ id
- -| uid=1000(arnold) gid=1000(arnold)
groups=1000(arnold),4(adm),7(lp),27(sudo)
+ ⣠uid=1000(arnold) gid=1000(arnold)
groups=1000(arnold),4(adm),7(lp),27(sudo)
- This information is part of what is provided by 'gawk''s 'PROCINFO'
-array (*note Built-in Variables::). However, the 'id' utility provides
+ This information is part of what is provided by âgawkââs
âPROCINFOâ
+array (*note Built-in Variables::). However, the âidâ utility provides
a more palatable output than just individual numbers.
- The POSIX version of 'id' takes several options that give you control
-over the output's format, such as printing only real ids, or printing
+ The POSIX version of âidâ takes several options that give you control
+over the outputâs format, such as printing only real ids, or printing
only numbers or only names. Additionally, you can print the information
for a specific user, instead of that of the current user.
- Here is a version of POSIX 'id' written in 'awk'. It uses the
-'getopt()' library function (*note Getopt Function::), the user database
+ Here is a version of POSIX âidâ written in âawkâ. It uses the
+âgetopt()â library function (*note Getopt Function::), the user database
library functions (*note Passwd Functions::), and the group database
library functions (*note Group Functions::) from *note Library
Functions::.
The program is moderately straightforward. All the work is done in
-the 'BEGIN' rule. It starts with explanatory comments, a list of
-options, and then a 'usage()' function:
+the âBEGINâ rule. It starts with explanatory comments, a list of
+options, and then a âusage()â function:
# id.awk --- implement id in awk
#
@@ -18490,7 +18490,7 @@ options, and then a 'usage()' function:
exit 1
}
- The first step is to parse the options using 'getopt()', and to set
+ The first step is to parse the options using âgetopt()â, and to set
various flag variables according to the options given:
BEGIN {
@@ -18511,7 +18511,7 @@ various flag variables according to the options given:
}
The next step is to check that no conflicting options were provided.
-'-G' and '-r' are mutually exclusive. It is also not allowed to provide
+â-Gâ and â-râ are mutually exclusive. It is also not allowed to
provide
more than one user name on the command line:
if (groupset_only && real_ids_only)
@@ -18519,10 +18519,10 @@ more than one user name on the command line:
else if (ARGC - Optind > 1)
usage()
- The user and group ID numbers are obtained from 'PROCINFO' for the
+ The user and group ID numbers are obtained from âPROCINFOâ for the
current user, or from the user and password databases for a user
-supplied on the command line. In the latter case, 'real_ids_only' is
-set, since it's not possible to print information about the effective
+supplied on the command line. In the latter case, âreal_ids_onlyâ is
+set, since itâs not possible to print information about the effective
user and group IDs:
if (ARGC - Optind == 0) {
@@ -18538,22 +18538,22 @@ user and group IDs:
real_ids_only++
}
- The test in the 'for' loop is worth noting. Any supplementary groups
-in the 'PROCINFO' array have the indices '"group1"' through '"groupN"'
+ The test in the âforâ loop is worth noting. Any supplementary groups
+in the âPROCINFOâ array have the indices â"group1"â through
â"groupN"â
for some N (i.e., the total number of supplementary groups). However,
-we don't know in advance how many of these groups there are.
+we donât know in advance how many of these groups there are.
This loop works by starting at one, concatenating the value with
-'"group"', and then using 'in' to see if that value is in the array
-(*note Reference to Elements::). Eventually, 'i' increments past the
+â"group"â, and then using âinâ to see if that value is in the array
+(*note Reference to Elements::). Eventually, âiâ increments past the
last group in the array and the loop exits.
The loop is also correct if there are _no_ supplementary groups; then
-the condition is false the first time it's tested, and the loop body
+the condition is false the first time itâs tested, and the loop body
never executes.
Now, based on the options, we decide what information to print. For
-'-G' (print just the group set), we then select whether to print names
+â-Gâ (print just the group set), we then select whether to print names
or numbers. In either case, when done we exit:
if (groupset_only) {
@@ -18577,9 +18577,9 @@ or numbers. In either case, when done we exit:
exit 0
}
- Otherwise, for '-g' (effective group ID only), we check if '-r' was
+ Otherwise, for â-gâ (effective group ID only), we check if â-râ was
also provided, in which case we use the real group ID. Then based on
-'-n', we decide whether to print names or numbers. Here too, when done,
+â-nâ, we decide whether to print names or numbers. Here too, when done,
we exit:
else if (egid_only) {
@@ -18595,11 +18595,11 @@ we exit:
exit 0
}
- The 'get_first_field()' function extracts the group name from the
+ The âget_first_field()â function extracts the group name from the
group database entry for the given group ID.
- Similar processing logic applies to '-u' (effective user ID only),
-combined with '-r' and '-n':
+ Similar processing logic applies to â-uâ (effective user ID only),
+combined with â-râ and â-nâ:
else if (euid_only) {
id = real_ids_only ? uid : euid
@@ -18614,8 +18614,8 @@ combined with '-r' and '-n':
exit 0
}
- At this point, we haven't exited yet, so we print the regular,
-default output, based either on the current user's information, or that
+ At this point, we havenât exited yet, so we print the regular,
+default output, based either on the current userâs information, or that
of the user whose name was provided on the command line. We start with
the real user ID:
@@ -18623,7 +18623,7 @@ the real user ID:
pw = getpwuid(uid)
print_first_field(pw)
- The 'print_first_field()' function prints the user's login name from
+ The âprint_first_field()â function prints the userâs login name from
the password file entry, surrounded by parentheses. It is shown soon.
Printing the effective user ID is next:
@@ -18661,9 +18661,9 @@ Printing the effective user ID is next:
print ""
}
- The 'get_first_field()' function extracts the first field from a
+ The âget_first_field()â function extracts the first field from a
password or group file entry for use as a user or group name. Fields
-are separated by ':' characters:
+are separated by â:â characters:
function get_first_field(str, a)
{
@@ -18673,7 +18673,7 @@ are separated by ':' characters:
}
}
- This function is then used by 'print_first_field()' to output the
+ This function is then used by âprint_first_field()â to output the
given name surrounded by parentheses:
function print_first_field(str)
@@ -18685,11 +18685,11 @@ given name surrounded by parentheses:
These two functions simply isolate out some code that is used
repeatedly, making the whole program shorter and cleaner. In
particular, moving the check for the empty string into
-'get_first_field()' saves several lines of code.
+âget_first_field()â saves several lines of code.
- Finally, 'fill_info_for_user()' fetches user, group, and group set
+ Finally, âfill_info_for_user()â fetches user, group, and group set
information for the user named on the command. The code is fairly
-straightforward, merely requiring that we exit if the given user doesn't
+straightforward, merely requiring that we exit if the given user doesnât
exist:
function fill_info_for_user(user,
@@ -18706,7 +18706,7 @@ exist:
gid = fields[4] + 0
Getting the group set is a little awkward. The library routine
-'getgruser()' returns a list of group _names_. These have to be gone
+âgetgruser()â returns a list of group _names_. These have to be gone
through and turned back into group numbers, so that the rest of the code
will work as expected:
@@ -18725,50 +18725,50 @@ File: gawk.info, Node: Split Program, Next: Tee
Program, Prev: Id Program, U
11.2.4 Splitting a Large File into Pieces
-----------------------------------------
-The 'split' utility splits large text files into smaller pieces. The
-usage follows the POSIX standard for 'split' and is as follows:
+The âsplitâ utility splits large text files into smaller pieces. The
+usage follows the POSIX standard for âsplitâ and is as follows:
- 'split' ['-l' COUNT] ['-a' SUFFIX-LEN] [FILE [OUTNAME]]
- 'split' '-b' N['k'|'m']] ['-a' SUFFIX-LEN] [FILE [OUTNAME]]
+ âsplitâ [â-lâ COUNT] [â-aâ SUFFIX-LEN] [FILE [OUTNAME]]
+ âsplitâ â-bâ N[âkâ|âmâ]] [â-aâ SUFFIX-LEN] [FILE
[OUTNAME]]
- By default, the output files are named 'xaa', 'xab', and so on. Each
+ By default, the output files are named âxaaâ, âxabâ, and so on.
Each
file has 1,000 lines in it, with the likely exception of the last file.
- The 'split' program has evolved over time, and the current POSIX
+ The âsplitâ program has evolved over time, and the current POSIX
version is more complicated than the original Unix version. The options
and what they do are as follows:
-'-a' SUFFIX-LEN
+â-aâ SUFFIX-LEN
Use SUFFIX-LEN characters for the suffix. For example, if
- SUFFIX-LEN is four, the output files would range from 'xaaaa' to
- 'xzzzz'.
+ SUFFIX-LEN is four, the output files would range from âxaaaaâ to
+ âxzzzzâ.
-'-b' N['k'|'m']]
+â-bâ N[âkâ|âmâ]]
Instead of each file containing a specified number of lines, each
- file should have (at most) N bytes. Supplying a trailing 'k'
+ file should have (at most) N bytes. Supplying a trailing âkâ
multiplies N by 1,024, yielding kilobytes. Supplying a trailing
- 'm' multiplies N by 1,048,576 (1,024 * 1,024) yielding megabytes.
- (This option is mutually exclusive with '-l').
+ âmâ multiplies N by 1,048,576 (1,024 * 1,024) yielding megabytes.
+ (This option is mutually exclusive with â-lâ).
-'-l' COUNT
+â-lâ COUNT
Each file should have at most COUNT lines, instead of the default
- 1,000. (This option is mutually exclusive with '-b').
+ 1,000. (This option is mutually exclusive with â-bâ).
If supplied, FILE is the input file to read. Otherwise standard
input is processed. If supplied, OUTNAME is the leading prefix to use
-for file names, instead of 'x'.
+for file names, instead of âxâ.
- In order to use the '-b' option, 'gawk' should be invoked with its
-'-b' option (*note Options::), or with the environment variable 'LC_ALL'
-set to 'C', so that each input byte is treated as a separate
+ In order to use the â-bâ option, âgawkâ should be invoked with its
+â-bâ option (*note Options::), or with the environment variable
âLC_ALLâ
+set to âCâ, so that each input byte is treated as a separate
character.(1)
- Here is an implementation of 'split' in 'awk'. It uses the
-'getopt()' function presented in *note Getopt Function::.
+ Here is an implementation of âsplitâ in âawkâ. It uses the
+âgetopt()â function presented in *note Getopt Function::.
The program begins with a standard descriptive comment and then a
-'usage()' function describing the options. The variable 'common' keeps
-the function's lines short so that they look nice on the page:
+âusage()â function describing the options. The variable âcommonâ keeps
+the functionâs lines short so that they look nice on the page:
# split.awk --- do split in awk
#
@@ -18782,9 +18782,9 @@ the function's lines short so that they look nice on
the page:
exit 1
}
- Next, in a 'BEGIN' rule we set the default values and parse the
+ Next, in a âBEGINâ rule we set the default values and parse the
arguments. After that we initialize the data structures used to cycle
-the suffix from 'aa...' to 'zz...'. Finally we set the name of the
+the suffix from âaa...â to âzz...â. Finally we set the name of the
first output file:
BEGIN {
@@ -18847,48 +18847,48 @@ start with an uppercase letter:
}
Managing the file name suffix is interesting. Given a suffix of
-length three, say, the values go from 'aaa', 'aab', 'aac' and so on, all
-the way to 'zzx', 'zzy', and finally 'zzz'. There are two important
+length three, say, the values go from âaaaâ, âaabâ, âaacâ and so
on, all
+the way to âzzxâ, âzzyâ, and finally âzzzâ. There are two
important
aspects to this:
- * We have to be able to easily generate these suffixes, and in
- particular easily handle "rolling over"; for example, going from
- 'abz' to 'aca'.
+ ⢠We have to be able to easily generate these suffixes, and in
+ particular easily handle ârolling overâ; for example, going from
+ âabzâ to âacaâ.
- * We have to tell when we've finished with the last file, so that if
+ ⢠We have to tell when weâve finished with the last file, so that if
we still have more input data we can print an error message and
exit. The trick is to handle this _after_ using the last suffix,
and not when the final suffix is created.
- The computation is handled by 'compute_suffix()'. This function is
+ The computation is handled by âcompute_suffix()â. This function is
called every time a new file is opened.
- The flow here is messy, because we want to generate 'zzzz' (say), and
+ The flow here is messy, because we want to generate âzzzzâ (say), and
use it, and only produce an error after all the file name suffixes have
been used up. The logical steps are as follows:
- 1. Generate the suffix, saving the value in 'result' to return. To do
- this, the supplementary array 'Suffix_ind' contains one element for
+ 1. Generate the suffix, saving the value in âresultâ to return. To do
+ this, the supplementary array âSuffix_indâ contains one element for
each letter in the suffix. Each element ranges from 1 to 26,
acting as the index into a string containing all the lowercase
letters of the English alphabet. It is initialized by
- 'init_suffix_data()'. 'result' is built up one letter at a time,
- using each 'substr()'.
-
- 2. Prepare the data structures for the next time 'compute_suffix()' is
- called. To do this, we loop over 'Suffix_ind', _backwards_. If
- the current element is less than 26, it's incremented and the loop
- breaks ('abq' goes to 'abr'). Otherwise, the element is reset to
- one and we move down the list ('abz' to 'aca'). Thus, the
- 'Suffix_ind' array is always "one step ahead" of the actual file
+ âinit_suffix_data()â. âresultâ is built up one letter at a time,
+ using each âsubstr()â.
+
+ 2. Prepare the data structures for the next time âcompute_suffix()â is
+ called. To do this, we loop over âSuffix_indâ, _backwards_. If
+ the current element is less than 26, itâs incremented and the loop
+ breaks (âabqâ goes to âabrâ). Otherwise, the element is reset to
+ one and we move down the list (âabzâ to âacaâ). Thus, the
+ âSuffix_indâ array is always âone step aheadâ of the actual file
name suffix to be returned.
- 3. Check if we've gone past the limit of possible file names. If
- 'Reached_last' is true, print a message and exit. Otherwise, check
- if 'Suffix_ind' describes a suffix where all the letters are 'z'.
- If that's the case we're about to return the final suffix. If so,
- we set 'Reached_last' to true so that the _next_ call to
- 'compute_suffix()' will cause a failure.
+ 3. Check if weâve gone past the limit of possible file names. If
+ âReached_lastâ is true, print a message and exit. Otherwise, check
+ if âSuffix_indâ describes a suffix where all the letters are âzâ.
+ If thatâs the case weâre about to return the final suffix. If so,
+ we set âReached_lastâ to true so that the _next_ call to
+ âcompute_suffix()â will cause a failure.
Physically, the steps in the function occur in the order 3, 1, 2:
@@ -18918,8 +18918,8 @@ been used up. The logical steps are as follows:
return result
}
- The 'Suffix_ind' array and 'Reached_last' are initialized by
-'init_suffix_data()':
+ The âSuffix_indâ array and âReached_lastâ are initialized by
+âinit_suffix_data()â:
function init_suffix_data( i)
{
@@ -18929,8 +18929,8 @@ been used up. The logical steps are as follows:
Reached_last = 0
}
- The function 'on_last_file()' returns true if 'Suffix_ind' describes
-a suffix where all the letters are 'z' by checking that all the elements
+ The function âon_last_file()â returns true if âSuffix_indâ describes
+a suffix where all the letters are âzâ by checking that all the elements
in the array are equal to 26:
function on_last_file( i, on_last)
@@ -18946,11 +18946,11 @@ in the array are equal to 26:
The actual work of splitting the input file is done by the next two
rules. Since splitting by line count and splitting by byte count are
mutually exclusive, we simply use two separate rules, one for when
-'Line_count' is greater than zero, and another for when 'Byte_count' is
+âLine_countâ is greater than zero, and another for when âByte_countâ is
greater than zero.
- The variable 'tcount' counts how many lines have been processed so
-far. When it exceeds 'Line_count', it's time to close the previous file
+ The variable âtcountâ counts how many lines have been processed so
+far. When it exceeds âLine_countâ, itâs time to close the previous file
and switch to a new one:
Line_count > 0 {
@@ -18963,9 +18963,9 @@ and switch to a new one:
}
The rule for handling bytes is more complicated. Since lines most
-likely vary in length, the 'Byte_count' boundary may be hit in the
-middle of an input record. In that case, 'split' has to write enough of
-the first bytes of the input record to finish up 'Byte_count' bytes,
+likely vary in length, the âByte_countâ boundary may be hit in the
+middle of an input record. In that case, âsplitâ has to write enough of
+the first bytes of the input record to finish up âByte_countâ bytes,
close the file, open a new file, and write the rest of the record to the
new file. The logic here does all that:
@@ -18992,7 +18992,7 @@ new file. The logic here does all that:
print > Output
}
- Finally, the 'END' rule cleans up by closing the last output file:
+ Finally, the âENDâ rule cleans up by closing the last output file:
END {
close(Output)
@@ -19000,9 +19000,9 @@ new file. The logic here does all that:
---------- Footnotes ----------
- (1) Using '-b' twice requires separating 'gawk''s options from those
-of the program. For example: 'gawk -f getopt.awk -f split.awk -b -- -b
-42m large-file.txt split-'.
+ (1) Using â-bâ twice requires separating âgawkââs options from
those
+of the program. For example: âgawk -f getopt.awk -f split.awk -b -- -b
+42m large-file.txt split-â.
File: gawk.info, Node: Tee Program, Next: Uniq Program, Prev: Split
Program, Up: Clones
@@ -19010,25 +19010,25 @@ File: gawk.info, Node: Tee Program, Next: Uniq
Program, Prev: Split Program,
11.2.5 Duplicating Output into Multiple Files
---------------------------------------------
-The 'tee' program is known as a "pipe fitting." 'tee' copies its
+The âteeâ program is known as a âpipe fitting.â âteeâ copies its
standard input to its standard output and also duplicates it to the
files named on the command line. Its usage is as follows:
- 'tee' ['-a'] FILE ...
+ âteeâ [â-aâ] FILE ...
- The '-a' option tells 'tee' to append to the named files, instead of
+ The â-aâ option tells âteeâ to append to the named files, instead of
truncating them and starting over.
- The 'BEGIN' rule first makes a copy of all the command-line arguments
-into an array named 'copy'. 'ARGV[0]' is not needed, so it is not
-copied. 'tee' cannot use 'ARGV' directly, because 'awk' attempts to
-process each file name in 'ARGV' as input data.
+ The âBEGINâ rule first makes a copy of all the command-line arguments
+into an array named âcopyâ. âARGV[0]â is not needed, so it is not
+copied. âteeâ cannot use âARGVâ directly, because âawkâ attempts
to
+process each file name in âARGVâ as input data.
- If the first argument is '-a', then the flag variable 'append' is set
-to true, and both 'ARGV[1]' and 'copy[1]' are deleted. If 'ARGC' is
-less than two, then no file names were supplied and 'tee' prints a usage
-message and exits. Finally, 'awk' is forced to read the standard input
-by setting 'ARGV[1]' to '"-"' and 'ARGC' to two:
+ If the first argument is â-aâ, then the flag variable âappendâ is
set
+to true, and both âARGV[1]â and âcopy[1]â are deleted. If âARGCâ
is
+less than two, then no file names were supplied and âteeâ prints a usage
+message and exits. Finally, âawkâ is forced to read the standard input
+by setting âARGV[1]â to â"-"â and âARGCâ to two:
# tee.awk --- tee in awk
#
@@ -19077,13 +19077,13 @@ It is also possible to write the loop this way:
else
print > copy[i]
-This is more concise, but it is also less efficient. The 'if' is tested
+This is more concise, but it is also less efficient. The âifâ is tested
for each record and for each output file. By duplicating the loop body,
-the 'if' is only tested once for each input record. If there are N
-input records and M output files, the first method only executes N 'if'
-statements, while the second executes N'*'M 'if' statements.
+the âifâ is only tested once for each input record. If there are N
+input records and M output files, the first method only executes N âifâ
+statements, while the second executes Nâ*âM âifâ statements.
- Finally, the 'END' rule cleans up by closing all the output files:
+ Finally, the âENDâ rule cleans up by closing all the output files:
END {
for (i in copy)
@@ -19096,49 +19096,49 @@ File: gawk.info, Node: Uniq Program, Next: Wc
Program, Prev: Tee Program, Up
11.2.6 Printing Nonduplicated Lines of Text
-------------------------------------------
-The 'uniq' utility reads sorted lines of data on its standard input, and
+The âuniqâ utility reads sorted lines of data on its standard input, and
by default removes duplicate lines. In other words, it only prints
-unique lines--hence the name. 'uniq' has a number of options. The
-usage is as follows:
+unique linesâhence the name. âuniqâ has a number of options. The usage
+is as follows:
- 'uniq' ['-udc' ['-f N'] ['-s N']] [INPUTFILE [OUTPUTFILE]]
+ âuniqâ [â-udcâ [â-f Nâ] [â-s Nâ]] [INPUTFILE [OUTPUTFILE]]
- The options for 'uniq' are:
+ The options for âuniqâ are:
-'-d'
+â-dâ
Print only repeated (duplicated) lines.
-'-u'
+â-uâ
Print only nonrepeated (unique) lines.
-'-c'
- Count lines. This option overrides '-d' and '-u'. Both repeated
+â-câ
+ Count lines. This option overrides â-dâ and â-uâ. Both repeated
and nonrepeated lines are counted.
-'-f N'
+â-f Nâ
Skip N fields before comparing lines. The definition of fields is
- similar to 'awk''s default: nonwhitespace characters separated by
+ similar to âawkââs default: nonwhitespace characters separated by
runs of spaces and/or TABs.
-'-s N'
+â-s Nâ
Skip N characters before comparing lines. Any fields specified
- with '-f' are skipped first.
+ with â-fâ are skipped first.
-'INPUTFILE'
+âINPUTFILEâ
Data is read from the input file named on the command line, instead
of from the standard input.
-'OUTPUTFILE'
+âOUTPUTFILEâ
The generated output is sent to the named output file, instead of
to the standard output.
- Normally 'uniq' behaves as if both the '-d' and '-u' options are
+ Normally âuniqâ behaves as if both the â-dâ and â-uâ options are
provided.
- 'uniq' uses the 'getopt()' library function (*note Getopt Function::)
-and the 'join()' library function (*note Join Function::).
+ âuniqâ uses the âgetopt()â library function (*note Getopt
Function::)
+and the âjoin()â library function (*note Join Function::).
- The program begins with a 'usage()' function and then a brief outline
+ The program begins with a âusage()â function and then a brief outline
of the options and their meanings in comments:
# uniq.awk --- do uniq in awk
@@ -19158,9 +19158,9 @@ of the options and their meanings in comments:
# -f n skip n fields
# -s n skip n characters, skip fields first
- The POSIX standard for 'uniq' allows options to start with '+' as
-well as with '-'. An initial 'BEGIN' rule traverses the arguments
-changing any leading '+' to '-' so that the 'getopt()' function can
+ The POSIX standard for âuniqâ allows options to start with â+â as
+well as with â-â. An initial âBEGINâ rule traverses the arguments
+changing any leading â+â to â-â so that the âgetopt()â function can
parse the options:
# As of 2020, '+' can be used as the option character in addition to '-'
@@ -19179,11 +19179,11 @@ parse the options:
}
}
- The next 'BEGIN' rule deals with the command-line arguments and
+ The next âBEGINâ rule deals with the command-line arguments and
options. If no options are supplied, then the default is taken, to
print both repeated and nonrepeated lines. The output file, if
-provided, is assigned to 'outputfile'. Early on, 'outputfile' is
-initialized to the standard output, '/dev/stdout':
+provided, is assigned to âoutputfileâ. Early on, âoutputfileâ is
+initialized to the standard output, â/dev/stdoutâ:
BEGIN {
count = 1
@@ -19216,20 +19216,20 @@ initialized to the standard output, '/dev/stdout':
}
}
- The following function, 'are_equal()', compares the current line,
-'$0', to the previous line, 'last'. It handles skipping fields and
+ The following function, âare_equal()â, compares the current line,
+â$0â, to the previous line, âlastâ. It handles skipping fields and
characters. If no field count and no character count are specified,
-'are_equal()' returns one or zero depending upon the result of a simple
-string comparison of 'last' and '$0'.
+âare_equal()â returns one or zero depending upon the result of a simple
+string comparison of âlastâ and â$0â.
Otherwise, things get more complicated. If fields have to be
-skipped, each line is broken into an array using 'split()' (*note String
+skipped, each line is broken into an array using âsplit()â (*note String
Functions::); the desired fields are then joined back into a line using
-'join()'. The joined lines are stored in 'clast' and 'cline'. If no
-fields are skipped, 'clast' and 'cline' are set to 'last' and '$0',
-respectively. Finally, if characters are skipped, 'substr()' is used to
-strip off the leading 'charcount' characters in 'clast' and 'cline'.
-The two strings are then compared and 'are_equal()' returns the result:
+âjoin()â. The joined lines are stored in âclastâ and âclineâ. If
no
+fields are skipped, âclastâ and âclineâ are set to âlastâ and
â$0â,
+respectively. Finally, if characters are skipped, âsubstr()â is used to
+strip off the leading âcharcountâ characters in âclastâ and
âclineâ.
+The two strings are then compared and âare_equal()â returns the result:
function are_equal( n, m, clast, cline, alast, aline)
{
@@ -19254,23 +19254,23 @@ The two strings are then compared and 'are_equal()'
returns the result:
}
The following two rules are the body of the program. The first one
-is executed only for the very first line of data. It sets 'last' equal
-to '$0', so that subsequent lines of text have something to be compared
+is executed only for the very first line of data. It sets âlastâ equal
+to â$0â, so that subsequent lines of text have something to be compared
to.
- The second rule does the work. The variable 'equal' is one or zero,
-depending upon the results of 'are_equal()''s comparison. If 'uniq' is
+ The second rule does the work. The variable âequalâ is one or zero,
+depending upon the results of âare_equal()ââs comparison. If âuniqâ
is
counting repeated lines, and the lines are equal, then it increments the
-'count' variable. Otherwise, it prints the line and resets 'count',
+âcountâ variable. Otherwise, it prints the line and resets âcountâ,
because the two lines are not equal.
- If 'uniq' is not counting, and if the lines are equal, 'count' is
+ If âuniqâ is not counting, and if the lines are equal, âcountâ is
incremented. Nothing is printed, as the point is to remove duplicates.
-Otherwise, if 'uniq' is counting repeated lines and more than one line
-is seen, or if 'uniq' is counting nonrepeated lines and only one line is
-seen, then the line is printed, and 'count' is reset.
+Otherwise, if âuniqâ is counting repeated lines and more than one line
+is seen, or if âuniqâ is counting nonrepeated lines and only one line is
+seen, then the line is printed, and âcountâ is reset.
- Finally, similar logic is used in the 'END' rule to print the final
+ Finally, similar logic is used in the âENDâ rule to print the final
line of input data:
NR == 1 {
@@ -19322,14 +19322,14 @@ File: gawk.info, Node: Wc Program, Prev: Uniq
Program, Up: Clones
11.2.7 Counting Things
----------------------
-The 'wc' (word count) utility counts lines, words, characters and bytes
+The âwcâ (word count) utility counts lines, words, characters and bytes
in one or more input files.
* Menu:
* Bytes vs. Characters:: Modern character sets.
* Using extensions:: A brief intro to extensions.
-* wc program:: Code for 'wc.awk'.
+* wc program:: Code for âwc.awkâ.
File: gawk.info, Node: Bytes vs. Characters, Next: Using extensions, Up: Wc
Program
@@ -19345,23 +19345,23 @@ punctuation and control characters.
Today, the most popular character set in use is Unicode (of which
ASCII is a pure subset). Unicode provides tens of thousands of unique
-characters (called "code points") to cover most existing human languages
+characters (called âcode pointsâ) to cover most existing human languages
(living and dead) and a number of nonhuman ones as well (such as Klingon
-and J.R.R. Tolkien's elvish languages).
+and J.R.R. Tolkienâs elvish languages).
- To save space in files, Unicode code points are "encoded", where each
+ To save space in files, Unicode code points are âencodedâ, where each
character takes from one to four bytes in the file. UTF-8 is possibly
-the most popular of such "multibyte encodings".
+the most popular of such âmultibyte encodingsâ.
- The POSIX standard requires that 'awk' function in terms of
-characters, not bytes. Thus in 'gawk', 'length()', 'substr()',
-'split()', 'match()' and the other string functions (*note String
+ The POSIX standard requires that âawkâ function in terms of
+characters, not bytes. Thus in âgawkâ, âlength()â, âsubstr()â,
+âsplit()â, âmatch()â and the other string functions (*note String
Functions::) all work in terms of characters in the local character set,
-and not in terms of bytes. (Not all 'awk' implementations do so,
+and not in terms of bytes. (Not all âawkâ implementations do so,
though).
There is no standard, built-in way to distinguish characters from
-bytes in an 'awk' program. For an 'awk' implementation of 'wc', which
+bytes in an âawkâ program. For an âawkâ implementation of âwcâ,
which
needs to make such a distinction, we will have to use an external
extension.
@@ -19372,66 +19372,66 @@ File: gawk.info, Node: Using extensions, Next: wc
program, Prev: Bytes vs. Ch
...........................................
Loadable extensions are presented in full detail in *note Dynamic
-Extensions::. They provide a way to add functions to 'gawk' which can
+Extensions::. They provide a way to add functions to âgawkâ which can
call out to other facilities written in C or C++.
- For the purposes of 'wc.awk', it's enough to know that the extension
-is loaded with the '@load' directive, and the additional function we
-will use is called 'mbs_length()'. This function returns the number of
+ For the purposes of âwc.awkâ, itâs enough to know that the extension
+is loaded with the â@loadâ directive, and the additional function we
+will use is called âmbs_length()â. This function returns the number of
bytes in a string, not the number of characters.
- The '"mbs"' extension comes from the 'gawkextlib' project. *Note
+ The â"mbs"â extension comes from the âgawkextlibâ project. *Note
gawkextlib:: for more information.
File: gawk.info, Node: wc program, Prev: Using extensions, Up: Wc Program
-11.2.7.3 Code for 'wc.awk'
+11.2.7.3 Code for âwc.awkâ
..........................
-The usage for 'wc' is as follows:
+The usage for âwcâ is as follows:
- 'wc' ['-lwcm'] [FILES ...]
+ âwcâ [â-lwcmâ] [FILES ...]
- If no files are specified on the command line, 'wc' reads its
+ If no files are specified on the command line, âwcâ reads its
standard input. If there are multiple files, it also prints total
counts for all the files. The options and their meanings are as
follows:
-'-c'
- Count only bytes. Once upon a time, the 'c' in this option stood
- for "characters." But, as explained earlier, bytes and character
+â-câ
+ Count only bytes. Once upon a time, the âcâ in this option stood
+ for âcharacters.â But, as explained earlier, bytes and character
are no longer synonymous with each other.
-'-l'
+â-lâ
Count only lines.
-'-m'
+â-mâ
Count only characters.
-'-w'
- Count only words. A "word" is a contiguous sequence of
+â-wâ
+ Count only words. A âwordâ is a contiguous sequence of
nonwhitespace characters, separated by spaces and/or TABs.
- Luckily, this is the normal way 'awk' separates fields in its input
+ Luckily, this is the normal way âawkâ separates fields in its input
data.
- Implementing 'wc' in 'awk' is particularly elegant, because 'awk'
+ Implementing âwcâ in âawkâ is particularly elegant, because
âawkâ
does a lot of the work for us; it splits lines into words (i.e., fields)
and counts them, it counts lines (i.e., records), and it can easily tell
us how long a line is in characters.
- This program uses the 'getopt()' library function (*note Getopt
+ This program uses the âgetopt()â library function (*note Getopt
Function::) and the file-transition functions (*note Filetrans
Function::).
- This version has one notable difference from older versions of 'wc':
+ This version has one notable difference from older versions of âwcâ:
it always prints the counts in the order lines, words, characters and
-bytes. Older versions note the order of the '-l', '-w', and '-c'
+bytes. Older versions note the order of the â-lâ, â-wâ, and â-câ
options on the command line, and print the counts in that order. POSIX
does not mandate this behavior, though.
- The 'BEGIN' rule does the argument processing. The variable
-'print_total' is true if more than one file is named on the command
+ The âBEGINâ rule does the argument processing. The variable
+âprint_totalâ is true if more than one file is named on the command
line:
# wc.awk --- count lines, words, characters, bytes
@@ -19472,9 +19472,9 @@ line:
print_total = (ARGC - i > 1)
}
- The 'beginfile()' function is simple; it just resets the counts of
+ The âbeginfile()â function is simple; it just resets the counts of
lines, words, characters and bytes to zero, and saves the current file
-name in 'fname':
+name in âfnameâ:
function beginfile(file)
{
@@ -19482,10 +19482,10 @@ name in 'fname':
fname = FILENAME
}
- The 'endfile()' function adds the current file's numbers to the
+ The âendfile()â function adds the current fileâs numbers to the
running totals of lines, words, and characters. It then prints out
those numbers for the file that was just read. It relies on
-'beginfile()' to reset the numbers for the following data file:
+âbeginfile()â to reset the numbers for the following data file:
function endfile(file)
{
@@ -19505,13 +19505,13 @@ those numbers for the file that was just read. It
relies on
}
There is one rule that is executed for each line. It adds the length
-of the record, plus one, to 'chars'. Adding one plus the record length
+of the record, plus one, to âcharsâ. Adding one plus the record length
is needed because the newline character separating records (the value of
-'RS') is not part of the record itself, and thus not included in its
+âRSâ) is not part of the record itself, and thus not included in its
length. Similarly, it adds the length of the record in bytes, plus one,
-to 'bytes'. Next, 'lines' is incremented for each line read, and
-'words' is incremented by the value of 'NF', which is the number of
-"words" on this line:
+to âbytesâ. Next, âlinesâ is incremented for each line read, and
+âwordsâ is incremented by the value of âNFâ, which is the number of
+âwordsâ on this line:
# do per line
{
@@ -19521,7 +19521,7 @@ to 'bytes'. Next, 'lines' is incremented for each line
read, and
words += NF
}
- Finally, the 'END' rule simply prints the totals for all the files:
+ Finally, the âENDâ rule simply prints the totals for all the files:
END {
if (print_total) {
@@ -19540,17 +19540,17 @@ to 'bytes'. Next, 'lines' is incremented for each
line read, and
File: gawk.info, Node: Miscellaneous Programs, Next: Programs Summary,
Prev: Clones, Up: Sample Programs
-11.3 A Grab Bag of 'awk' Programs
+11.3 A Grab Bag of âawkâ Programs
=================================
-This minor node is a large "grab bag" of miscellaneous programs. We
+This minor node is a large âgrab bagâ of miscellaneous programs. We
hope you find them both interesting and enjoyable.
* Menu:
* Dupword Program:: Finding duplicated words in a document.
* Alarm Program:: An alarm clock.
-* Translate Program:: A program similar to the 'tr' utility.
+* Translate Program:: A program similar to the âtrâ utility.
* Labels Program:: Printing mailing labels.
* Word Sorting:: A program to produce a word usage count.
* History Sorting:: Eliminating duplicate entries from a history
@@ -19558,7 +19558,7 @@ hope you find them both interesting and enjoyable.
* Extract Program:: Pulling out programs from Texinfo source
files.
* Simple Sed:: A Simple Stream Editor.
-* Igawk Program:: A wrapper for 'awk' that includes
+* Igawk Program:: A wrapper for âawkâ that includes
files.
* Anagram Program:: Finding anagrams from a dictionary.
* Signature Program:: People do amazing things with too much time on
@@ -19572,22 +19572,22 @@ File: gawk.info, Node: Dupword Program, Next: Alarm
Program, Up: Miscellaneou
A common error when writing large amounts of prose is to accidentally
duplicate words. Typically you will see this in text as something like
-"the the program does the following..." When the text is online, often
+âthe the program does the following...â When the text is online, often
the duplicated words occur at the end of one line and the beginning of
another, making them very difficult to spot.
- This program, 'dupword.awk', scans through a file one line at a time
+ This program, âdupword.awkâ, scans through a file one line at a time
and looks for adjacent occurrences of the same word. It also saves the
-last word on a line (in the variable 'prev') for comparison with the
+last word on a line (in the variable âprevâ) for comparison with the
first word on the next line.
The first two statements make sure that the line is all lowercase, so
-that, for example, "The" and "the" compare equal to each other. The
+that, for example, âTheâ and âtheâ compare equal to each other. The
next statement replaces nonalphanumeric and nonwhitespace characters
with spaces, so that punctuation does not affect the comparison either.
The characters are replaced with spaces so that formatting controls
-don't create nonsense words (e.g., the Texinfo '@code{NF}' becomes
-'codeNF' if punctuation is simply deleted). The record is then resplit
+donât create nonsense words (e.g., the Texinfo â@code{NF}â becomes
+âcodeNFâ if punctuation is simply deleted). The record is then resplit
into fields, yielding just the actual words on the line, and ensuring
that there are no empty fields.
@@ -19619,29 +19619,29 @@ File: gawk.info, Node: Alarm Program, Next:
Translate Program, Prev: Dupword
-----------------------------
Nothing cures insomnia like a ringing alarm clock.
- -- _Arnold Robbins_
+ â _Arnold Robbins_
Sleep is for web developers.
- -- _Erik Quanstrom_
+ â _Erik Quanstrom_
- The following program is a simple "alarm clock" program. You give it
+ The following program is a simple âalarm clockâ program. You give it
a time of day and an optional message. At the specified time, it prints
the message on the standard output. In addition, you can give it the
number of times to repeat the message as well as a delay between
repetitions.
- This program uses the 'getlocaltime()' function from *note
+ This program uses the âgetlocaltime()â function from *note
Getlocaltime Function::.
- All the work is done in the 'BEGIN' rule. The first part is argument
+ All the work is done in the âBEGINâ rule. The first part is argument
checking and setting of defaults: the delay, the count, and the message
to print. If the user supplied a message without the ASCII BEL
-character (known as the "alert" character, '"\a"'), then it is added to
+character (known as the âalertâ character, â"\a"â), then it is added to
the message. (On many systems, printing the ASCII BEL generates an
audible alert. Thus, when the alarm goes off, the system calls
attention to itself in case the user is not looking at the computer.)
-Just for a change, this program uses a 'switch' statement (*note Switch
+Just for a change, this program uses a âswitchâ statement (*note Switch
Statement::), but the processing could be done with a series of
-'if'-'else' statements instead. Here is the program:
+âifâ-âelseâ statements instead. Here is the program:
# alarm.awk --- set an alarm
#
@@ -19721,12 +19721,12 @@ between the two is how long to wait before setting
off the alarm:
exit 1
}
- Finally, the program uses the 'system()' function (*note I/O
-Functions::) to call the 'sleep' utility. The 'sleep' utility simply
+ Finally, the program uses the âsystem()â function (*note I/O
+Functions::) to call the âsleepâ utility. The âsleepâ utility simply
pauses for the given number of seconds. If the exit status is not zero,
-the program assumes that 'sleep' was interrupted and exits. If 'sleep'
+the program assumes that âsleepâ was interrupted and exits. If âsleepâ
exited with an OK status (zero), then the program prints the message in
-a loop, again using 'sleep' to delay for however many seconds are
+a loop, again using âsleepâ to delay for however many seconds are
necessary:
# zzzzzz..... go away if interrupted
@@ -19751,53 +19751,53 @@ File: gawk.info, Node: Translate Program, Next:
Labels Program, Prev: Alarm P
11.3.3 Transliterating Characters
---------------------------------
-The system 'tr' utility transliterates characters. For example, it is
+The system âtrâ utility transliterates characters. For example, it is
often used to map uppercase letters into lowercase for further
processing:
GENERATE DATA | tr 'A-Z' 'a-z' | PROCESS DATA ...
- 'tr' requires two lists of characters.(1) When processing the input,
+ âtrâ requires two lists of characters.(1) When processing the input,
the first character in the first list is replaced with the first
character in the second list, the second character in the first list is
replaced with the second character in the second list, and so on. If
-there are more characters in the "from" list than in the "to" list, the
-last character of the "to" list is used for the remaining characters in
-the "from" list.
+there are more characters in the âfromâ list than in the âtoâ list, the
+last character of the âtoâ list is used for the remaining characters in
+the âfromâ list.
Once upon a time, a user proposed adding a transliteration function
-to 'gawk'. The following program was written to prove that character
+to âgawkâ. The following program was written to prove that character
transliteration could be done with a user-level function. This program
-is not as complete as the system 'tr' utility, but it does most of the
+is not as complete as the system âtrâ utility, but it does most of the
job.
- The 'translate' program was written long before 'gawk' acquired the
+ The âtranslateâ program was written long before âgawkâ acquired the
ability to split each character in a string into separate array
-elements. Thus, it makes repeated use of the 'substr()', 'index()', and
-'gsub()' built-in functions (*note String Functions::). There are two
-functions. The first, 'stranslate()', takes three arguments:
+elements. Thus, it makes repeated use of the âsubstr()â, âindex()â,
and
+âgsub()â built-in functions (*note String Functions::). There are two
+functions. The first, âstranslate()â, takes three arguments:
-'from'
+âfromâ
A list of characters from which to translate
-'to'
+âtoâ
A list of characters to which to translate
-'target'
+âtargetâ
The string on which to do the translation
- Associative arrays make the translation part fairly easy. 't_ar'
-holds the "to" characters, indexed by the "from" characters. Then a
-simple loop goes through 'from', one character at a time. For each
-character in 'from', if the character appears in 'target', it is
-replaced with the corresponding 'to' character.
+ Associative arrays make the translation part fairly easy. ât_arâ
+holds the âtoâ characters, indexed by the âfromâ characters. Then a
+simple loop goes through âfromâ, one character at a time. For each
+character in âfromâ, if the character appears in âtargetâ, it is
+replaced with the corresponding âtoâ character.
- The 'translate()' function calls 'stranslate()', using '$0' as the
-target. The main program sets two global variables, 'FROM' and 'TO',
-from the command line, and then changes 'ARGV' so that 'awk' reads from
+ The âtranslate()â function calls âstranslate()â, using â$0â as
the
+target. The main program sets two global variables, âFROMâ and âTOâ,
+from the command line, and then changes âARGVâ so that âawkâ reads from
the standard input.
- Finally, the processing rule simply calls 'translate()' for each
+ Finally, the processing rule simply calls âtranslate()â for each
record:
# translate.awk --- do tr-like stuff
@@ -19848,29 +19848,29 @@ record:
}
It is possible to do character transliteration in a user-level
-function, but it is not necessarily efficient, and we (the 'gawk'
+function, but it is not necessarily efficient, and we (the âgawkâ
developers) started to consider adding a built-in function. However,
shortly after writing this program, we learned that Brian Kernighan had
-added the 'toupper()' and 'tolower()' functions to his 'awk' (*note
+added the âtoupper()â and âtolower()â functions to his âawkâ (*note
String Functions::). These functions handle the vast majority of the
cases where character transliteration is necessary, and so we chose to
-simply add those functions to 'gawk' as well and then leave well enough
+simply add those functions to âgawkâ as well and then leave well enough
alone.
- An obvious improvement to this program would be to set up the 't_ar'
-array only once, in a 'BEGIN' rule. However, this assumes that the
-"from" and "to" lists will never change throughout the lifetime of the
+ An obvious improvement to this program would be to set up the ât_arâ
+array only once, in a âBEGINâ rule. However, this assumes that the
+âfromâ and âtoâ lists will never change throughout the lifetime of the
program.
Another obvious improvement is to enable the use of ranges, such as
-'a-z', as allowed by the 'tr' utility. Look at the code for 'cut.awk'
+âa-zâ, as allowed by the âtrâ utility. Look at the code for
âcut.awkâ
(*note Cut Program::) for inspiration.
---------- Footnotes ----------
(1) On some older systems, including Solaris, the system version of
-'tr' may require that the lists be written as range expressions enclosed
-in square brackets ('[a-z]') and quoted, to prevent the shell from
+âtrâ may require that the lists be written as range expressions enclosed
+in square brackets (â[a-z]â) and quoted, to prevent the shell from
attempting a file name expansion. This is not a feature.
@@ -19879,30 +19879,30 @@ File: gawk.info, Node: Labels Program, Next: Word
Sorting, Prev: Translate Pr
11.3.4 Printing Mailing Labels
------------------------------
-Here is a "real-world"(1) program. This script reads lists of names and
+Here is a âreal-worldâ(1) program. This script reads lists of names and
addresses and generates mailing labels. Each page of labels has 20
labels on it, two across and 10 down. The addresses are guaranteed to
be no more than five lines of data. Each address is separated from the
next by a blank line.
- The basic idea is to read 20 labels' worth of data. Each line of
-each label is stored in the 'line' array. The single rule takes care of
-filling the 'line' array and printing the page when 20 labels have been
+ The basic idea is to read 20 labelsâ worth of data. Each line of
+each label is stored in the âlineâ array. The single rule takes care of
+filling the âlineâ array and printing the page when 20 labels have been
read.
- The 'BEGIN' rule simply sets 'RS' to the empty string, so that 'awk'
-splits records at blank lines (*note Records::). It sets 'MAXLINES' to
+ The âBEGINâ rule simply sets âRSâ to the empty string, so that
âawkâ
+splits records at blank lines (*note Records::). It sets âMAXLINESâ to
100, because 100 is the maximum number of lines on the page (20 * 5 =
100).
- Most of the work is done in the 'printpage()' function. The label
-lines are stored sequentially in the 'line' array. But they have to
-print horizontally: 'line[1]' next to 'line[6]', 'line[2]' next to
-'line[7]', and so on. Two loops accomplish this. The outer loop,
-controlled by 'i', steps through every 10 lines of data; this is each
-row of labels. The inner loop, controlled by 'j', goes through the
-lines within the row. As 'j' goes from 0 to 4, 'i+j' is the 'j'th line
-in the row, and 'i+j+5' is the entry next to it. The output ends up
+ Most of the work is done in the âprintpage()â function. The label
+lines are stored sequentially in the âlineâ array. But they have to
+print horizontally: âline[1]â next to âline[6]â, âline[2]â next to
+âline[7]â, and so on. Two loops accomplish this. The outer loop,
+controlled by âiâ, steps through every 10 lines of data; this is each
+row of labels. The inner loop, controlled by âjâ, goes through the
+lines within the row. As âjâ goes from 0 to 4, âi+jâ is the âjâth
line
+in the row, and âi+j+5â is the entry next to it. The output ends up
looking something like this:
line 1 line 6
@@ -19912,7 +19912,7 @@ looking something like this:
line 5 line 10
...
-The 'printf' format string '%-41s' left-aligns the data and prints it
+The âprintfâ format string â%-41sâ left-aligns the data and prints it
within a fixed-width field.
As a final note, an extra blank line is printed at lines 21 and 61,
@@ -19921,7 +19921,7 @@ particular brand of labels in use when the program was
written. You
will also note that there are two blank lines at the top and two blank
lines at the bottom.
- The 'END' rule arranges to flush the final page of labels; there may
+ The âENDâ rule arranges to flush the final page of labels; there may
not have been an even multiple of 20 labels in the data:
# labels.awk --- print mailing labels
@@ -19976,8 +19976,8 @@ not have been an even multiple of 20 labels in the data:
---------- Footnotes ----------
- (1) "Real world" is defined as "a program actually used to get
-something done."
+ (1) âReal worldâ is defined as âa program actually used to get
+something done.â
File: gawk.info, Node: Word Sorting, Next: History Sorting, Prev: Labels
Program, Up: Miscellaneous Programs
@@ -20006,33 +20006,33 @@ useful format.
printf "%s\t%d\n", word, freq[word]
}
- The program relies on 'awk''s default field-splitting mechanism to
-break each line up into "words" and uses an associative array named
-'freq', indexed by each word, to count the number of times the word
-occurs. In the 'END' rule, it prints the counts.
+ The program relies on âawkââs default field-splitting mechanism to
+break each line up into âwordsâ and uses an associative array named
+âfreqâ, indexed by each word, to count the number of times the word
+occurs. In the âENDâ rule, it prints the counts.
This program has several problems that prevent it from being useful
on real text files:
- * The 'awk' language considers upper- and lowercase characters to be
- distinct. Therefore, "bartender" and "Bartender" are not treated
+ ⢠The âawkâ language considers upper- and lowercase characters to be
+ distinct. Therefore, âbartenderâ and âBartenderâ are not treated
as the same word. This is undesirable, because words are
capitalized if they begin sentences in normal text, and a frequency
analyzer should not be sensitive to capitalization.
- * Words are detected using the 'awk' convention that fields are
+ ⢠Words are detected using the âawkâ convention that fields are
separated just by whitespace. Other characters in the input
- (except newlines) don't have any special meaning to 'awk'. This
+ (except newlines) donât have any special meaning to âawkâ. This
means that punctuation characters count as part of words.
- * The output does not come out in any useful order. You're more
+ ⢠The output does not come out in any useful order. Youâre more
likely to be interested in which words occur most frequently or in
having an alphabetized table of how frequently each word occurs.
- The first problem can be solved by using 'tolower()' to remove case
-distinctions. The second problem can be solved by using 'gsub()' to
+ The first problem can be solved by using âtolower()â to remove case
+distinctions. The second problem can be solved by using âgsub()â to
remove punctuation characters. Finally, we solve the third problem by
-using the system 'sort' utility to process the output of the 'awk'
+using the system âsortâ utility to process the output of the âawkâ
script. Here is the new version of the program:
# wordfreq.awk --- print list of word frequencies
@@ -20050,29 +20050,29 @@ script. Here is the new version of the program:
printf "%s\t%d\n", word, freq[word]
}
- The regexp '/[^[:alnum:]_[:blank:]]/' might have been written
-'/[[:punct:]]/', but then underscores would also be removed, and we want
+ The regexp â/[^[:alnum:]_[:blank:]]/â might have been written
+â/[[:punct:]]/â, but then underscores would also be removed, and we want
to keep them.
- Assuming we have saved this program in a file named 'wordfreq.awk',
-and that the data is in 'file1', the following pipeline:
+ Assuming we have saved this program in a file named âwordfreq.awkâ,
+and that the data is in âfile1â, the following pipeline:
awk -f wordfreq.awk file1 | sort -k 2nr
-produces a table of the words appearing in 'file1' in order of
+produces a table of the words appearing in âfile1â in order of
decreasing frequency.
- The 'awk' program suitably massages the data and produces a word
-frequency table, which is not ordered. The 'awk' script's output is
-then sorted by the 'sort' utility and printed on the screen.
+ The âawkâ program suitably massages the data and produces a word
+frequency table, which is not ordered. The âawkâ scriptâs output is
+then sorted by the âsortâ utility and printed on the screen.
- The options given to 'sort' specify a sort that uses the second field
+ The options given to âsortâ specify a sort that uses the second field
of each input line (skipping one field), that the sort keys should be
-treated as numeric quantities (otherwise '15' would come before '5'),
+treated as numeric quantities (otherwise â15â would come before â5â),
and that the sorting should be done in descending (reverse) order.
- The 'sort' could even be done from within the program, by changing
-the 'END' action to:
+ The âsortâ could even be done from within the program, by changing
+the âENDâ action to:
END {
sort = "sort -k 2nr"
@@ -20084,7 +20084,7 @@ the 'END' action to:
This way of sorting must be used on systems that do not have true
pipes at the command-line (or batch-file) level. See the general
operating system documentation for more information on how to use the
-'sort' program.
+âsortâ program.
File: gawk.info, Node: History Sorting, Next: Extract Program, Prev: Word
Sorting, Up: Miscellaneous Programs
@@ -20092,7 +20092,7 @@ File: gawk.info, Node: History Sorting, Next: Extract
Program, Prev: Word Sor
11.3.6 Removing Duplicates from Unsorted Text
---------------------------------------------
-The 'uniq' program (*note Uniq Program::) removes duplicate lines from
+The âuniqâ program (*note Uniq Program::) removes duplicate lines from
_sorted_ data.
Suppose, however, you need to remove duplicate lines from a data file
@@ -20103,13 +20103,13 @@ repeat a command several times in a row.
Occasionally you might want to
compact the history by removing duplicate entries. Yet it is desirable
to maintain the order of the original commands.
- This simple program does the job. It uses two arrays. The 'data'
-array is indexed by the text of each line. For each line, 'data[$0]' is
+ This simple program does the job. It uses two arrays. The âdataâ
+array is indexed by the text of each line. For each line, âdata[$0]â is
incremented. If a particular line has not been seen before, then
-'data[$0]' is zero. In this case, the text of the line is stored in
-'lines[count]'. Each element of 'lines' is a unique command, and the
-indices of 'lines' indicate the order in which those lines are
-encountered. The 'END' rule simply prints out the lines, in order:
+âdata[$0]â is zero. In this case, the text of the line is stored in
+âlines[count]â. Each element of âlinesâ is a unique command, and the
+indices of âlinesâ indicate the order in which those lines are
+encountered. The âENDâ rule simply prints out the lines, in order:
# histsort.awk --- compact a shell history file
# Thanks to Byron Rakitzis for the general idea
@@ -20125,12 +20125,12 @@ encountered. The 'END' rule simply prints out the
lines, in order:
}
This program also provides a foundation for generating other useful
-information. For example, using the following 'print' statement in the
-'END' rule indicates how often a particular command is used:
+information. For example, using the following âprintâ statement in the
+âENDâ rule indicates how often a particular command is used:
print data[lines[i]], lines[i]
-This works because 'data[$0]' is incremented each time a line is seen.
+This works because âdata[$0]â is incremented each time a line is seen.
Rick van Rein offers the following one-liner to do the same job of
removing duplicates from unsorted text:
@@ -20142,7 +20142,7 @@ too obscure:
awk '! seen[$0]++'
-This version uses the expression as a pattern, relying on 'awk''s
+This version uses the expression as a pattern, relying on âawkââs
default action of printing the line when the pattern is true.
@@ -20152,13 +20152,13 @@ File: gawk.info, Node: Extract Program, Next:
Simple Sed, Prev: History Sorti
----------------------------------------------------
The nodes *note Library Functions::, and *note Sample Programs::, are
-the top level nodes for a large number of 'awk' programs. If you want
+the top level nodes for a large number of âawkâ programs. If you want
to experiment with these programs, it is tedious to type them in by
hand. Here we present a program that can extract parts of a Texinfo
input file into separate files.
This Info file is written in Texinfo
-(https://www.gnu.org/software/texinfo/), the GNU Project's document
+(https://www.gnu.org/software/texinfo/), the GNU Projectâs document
formatting language. A single Texinfo source file can be used to
produce both printed documentation, with TeX, and online documentation.
(The Texinfo language is described fully, starting with *note Texinfo:
@@ -20167,35 +20167,35 @@ produce both printed documentation, with TeX, and
online documentation.
For our purposes, it is enough to know three things about Texinfo
input files:
- * The "at" symbol ('@') is special in Texinfo, much as the backslash
- ('\') is in C or 'awk'. Literal '@' symbols are represented in
- Texinfo source files as '@@'.
+ ⢠The âatâ symbol (â@â) is special in Texinfo, much as the
backslash
+ (â\â) is in C or âawkâ. Literal â@â symbols are represented
in
+ Texinfo source files as â@@â.
- * Comments start with either '@c' or '@comment'. The file-extraction
+ ⢠Comments start with either â@câ or â@commentâ. The
file-extraction
program works by using special comments that start at the beginning
of a line.
- * Lines containing '@group' and '@end group' commands bracket example
+ ⢠Lines containing â@groupâ and â@end groupâ commands bracket
example
text that should not be split across a page boundary.
- (Unfortunately, TeX isn't always smart enough to do things exactly
+ (Unfortunately, TeX isnât always smart enough to do things exactly
right, so we have to give it some help.)
- The following program, 'extract.awk', reads through a Texinfo source
+ The following program, âextract.awkâ, reads through a Texinfo source
file and does two things, based on the special comments. Upon seeing
-'@c system ...', it runs a command, by extracting the command text from
-the control line and passing it on to the 'system()' function (*note I/O
-Functions::). Upon seeing '@c file FILENAME', each subsequent line is
-sent to the file FILENAME, until '@c endfile' is encountered. The rules
-in 'extract.awk' match either '@c' or '@comment' by letting the 'omment'
-part be optional. Lines containing '@group' and '@end group' are simply
-removed. 'extract.awk' uses the 'join()' library function (*note Join
+â@c system ...â, it runs a command, by extracting the command text from
+the control line and passing it on to the âsystem()â function (*note I/O
+Functions::). Upon seeing â@c file FILENAMEâ, each subsequent line is
+sent to the file FILENAME, until â@c endfileâ is encountered. The rules
+in âextract.awkâ match either â@câ or â@commentâ by letting the
âommentâ
+part be optional. Lines containing â@groupâ and â@end groupâ are
simply
+removed. âextract.awkâ uses the âjoin()â library function (*note Join
Function::).
- The example programs in the online Texinfo source for 'GAWK:
-Effective AWK Programming' ('gawktexi.in') have all been bracketed
-inside 'file' and 'endfile' lines. The 'gawk' distribution uses a copy
-of 'extract.awk' to extract the sample programs and install many of them
-in a standard directory where 'gawk' can find them. The Texinfo file
+ The example programs in the online Texinfo source for âGAWK:
+Effective AWK Programmingâ (âgawktexi.inâ) have all been bracketed
+inside âfileâ and âendfileâ lines. The âgawkâ distribution uses a
copy
+of âextract.awkâ to extract the sample programs and install many of them
+in a standard directory where âgawkâ can find them. The Texinfo file
looks something like this:
...
@@ -20217,11 +20217,11 @@ looks something like this:
@end example
...
- 'extract.awk' begins by setting 'IGNORECASE' to one, so that mixed
-upper- and lowercase letters in the directives won't matter.
+ âextract.awkâ begins by setting âIGNORECASEâ to one, so that mixed
+upper- and lowercase letters in the directives wonât matter.
- The first rule handles calling 'system()', checking that a command is
-given ('NF' is at least three) and also checking that the command exits
+ The first rule handles calling âsystem()â, checking that a command is
+given (âNFâ is at least three) and also checking that the command exits
with a zero exit status, signifying OK:
# extract.awk --- extract files and run programs from Texinfo files
@@ -20245,33 +20245,33 @@ with a zero exit status, signifying OK:
}
}
-The variable 'e' is used so that the rule fits nicely on the screen.
+The variable âeâ is used so that the rule fits nicely on the screen.
The second rule handles moving data into files. It verifies that a
file name is given in the directive. If the file named is not the
current file, then the current file is closed. Keeping the current file
-open until a new file is encountered allows the use of the '>'
+open until a new file is encountered allows the use of the â>â
redirection for printing the contents, keeping open-file management
simple.
- The 'for' loop does the work. It reads lines using 'getline' (*note
+ The âforâ loop does the work. It reads lines using âgetlineâ (*note
Getline::). For an unexpected end-of-file, it calls the
-'unexpected_eof()' function. If the line is an "endfile" line, then it
-breaks out of the loop. If the line is an '@group' or '@end group'
+âunexpected_eof()â function. If the line is an âendfileâ line, then it
+breaks out of the loop. If the line is an â@groupâ or â@end groupâ
line, then it ignores it and goes on to the next line. Similarly,
comments within examples are also ignored.
Most of the work is in the following few lines. If the line has no
-'@' symbols, the program can print it directly. Otherwise, each leading
-'@' must be stripped off. To remove the '@' symbols, the line is split
-into separate elements of the array 'a', using the 'split()' function
-(*note String Functions::). The '@' symbol is used as the separator
-character. Each element of 'a' that is empty indicates two successive
-'@' symbols in the original line. For each two empty elements ('@@' in
-the original file), we have to add a single '@' symbol back in.
-
- When the processing of the array is finished, 'join()' is called with
-the value of 'SUBSEP' (*note Multidimensional::), to rejoin the pieces
+â@â symbols, the program can print it directly. Otherwise, each leading
+â@â must be stripped off. To remove the â@â symbols, the line is split
+into separate elements of the array âaâ, using the âsplit()â function
+(*note String Functions::). The â@â symbol is used as the separator
+character. Each element of âaâ that is empty indicates two successive
+â@â symbols in the original line. For each two empty elements (â@@â in
+the original file), we have to add a single â@â symbol back in.
+
+ When the processing of the array is finished, âjoin()â is called with
+the value of âSUBSEPâ (*note Multidimensional::), to rejoin the pieces
back into a single line. That line is then printed to the output file:
/^@c(omment)?[ \t]+file/ {
@@ -20313,8 +20313,8 @@ back into a single line. That line is then printed to
the output file:
}
}
- An important thing to note is the use of the '>' redirection. Output
-done with '>' only opens the file once; it stays open and subsequent
+ An important thing to note is the use of the â>â redirection. Output
+done with â>â only opens the file once; it stays open and subsequent
output is appended to the file (*note Redirection::). This makes it
easy to mix program text and explanatory prose for the same sample
source file (as has been done here!) without any hassle. The file is
@@ -20322,11 +20322,11 @@ only closed when a new data file name is encountered
or at the end of
the input file.
When a new file name is encountered, instead of closing the file, the
-program saves the name of the current file in 'filelist'. This makes it
+program saves the name of the current file in âfilelistâ. This makes it
possible to interleave the code for more than one file in the Texinfo
input file. (Previous versions of this program _did_ close the file.
-But because of the '>' redirection, a file whose parts were not all one
-after the other ended up getting clobbered.) An 'END' rule then closes
+But because of the â>â redirection, a file whose parts were not all one
+after the other ended up getting clobbered.) An âENDâ rule then closes
all the open files when processing is finished:
END {
@@ -20335,7 +20335,7 @@ all the open files when processing is finished:
close(f)
}
- Finally, the function 'unexpected_eof()' prints an appropriate error
+ Finally, the function âunexpected_eof()â prints an appropriate error
message and then exits:
function unexpected_eof()
@@ -20351,21 +20351,21 @@ File: gawk.info, Node: Simple Sed, Next: Igawk
Program, Prev: Extract Program
11.3.8 A Simple Stream Editor
-----------------------------
-The 'sed' utility is a "stream editor", a program that reads a stream of
+The âsedâ utility is a âstream editorâ, a program that reads a stream
of
data, makes changes to it, and passes it on. It is often used to make
global changes to a large file or to a stream of data generated by a
-pipeline of commands. Although 'sed' is a complicated program in its
+pipeline of commands. Although âsedâ is a complicated program in its
own right, its most common use is to perform global substitutions in the
middle of a pipeline:
COMMAND1 < orig.data | sed 's/old/new/g' | COMMAND2 > result
- Here, 's/old/new/g' tells 'sed' to look for the regexp 'old' on each
-input line and globally replace it with the text 'new' (i.e., all the
-occurrences on a line). This is similar to 'awk''s 'gsub()' function
+ Here, âs/old/new/gâ tells âsedâ to look for the regexp âoldâ on
each
+input line and globally replace it with the text ânewâ (i.e., all the
+occurrences on a line). This is similar to âawkââs âgsub()â function
(*note String Functions::).
- The following program, 'awksed.awk', accepts at least two
+ The following program, âawksed.awkâ, accepts at least two
command-line arguments: the pattern to look for and the text to replace
it with. Any additional arguments are treated as data file names to
process. If none are provided, the standard input is used:
@@ -20399,32 +20399,32 @@ process. If none are provided, the standard input is
used:
print
}
- The program relies on 'gawk''s ability to have 'RS' be a regexp, as
-well as on the setting of 'RT' to the actual text that terminates the
+ The program relies on âgawkââs ability to have âRSâ be a regexp,
as
+well as on the setting of âRTâ to the actual text that terminates the
record (*note Records::).
- The idea is to have 'RS' be the pattern to look for. 'gawk'
-automatically sets '$0' to the text between matches of the pattern.
-This is text that we want to keep, unmodified. Then, by setting 'ORS'
-to the replacement text, a simple 'print' statement outputs the text we
+ The idea is to have âRSâ be the pattern to look for. âgawkâ
+automatically sets â$0â to the text between matches of the pattern.
+This is text that we want to keep, unmodified. Then, by setting âORSâ
+to the replacement text, a simple âprintâ statement outputs the text we
want to keep, followed by the replacement text.
There is one wrinkle to this scheme, which is what to do if the last
-record doesn't end with text that matches 'RS'. Using a 'print'
+record doesnât end with text that matches âRSâ. Using a âprintâ
statement unconditionally prints the replacement text, which is not
-correct. However, if the file did not end in text that matches 'RS',
-'RT' is set to the null string. In this case, we can print '$0' using
-'printf' (*note Printf::).
-
- The 'BEGIN' rule handles the setup, checking for the right number of
-arguments and calling 'usage()' if there is a problem. Then it sets
-'RS' and 'ORS' from the command-line arguments and sets 'ARGV[1]' and
-'ARGV[2]' to the null string, so that they are not treated as file names
+correct. However, if the file did not end in text that matches âRSâ,
+âRTâ is set to the null string. In this case, we can print â$0â using
+âprintfâ (*note Printf::).
+
+ The âBEGINâ rule handles the setup, checking for the right number of
+arguments and calling âusage()â if there is a problem. Then it sets
+âRSâ and âORSâ from the command-line arguments and sets âARGV[1]â
and
+âARGV[2]â to the null string, so that they are not treated as file names
(*note ARGC and ARGV::).
- The 'usage()' function prints an error message and exits. Finally,
+ The âusage()â function prints an error message and exits. Finally,
the single rule handles the printing scheme outlined earlier, using
-'print' or 'printf' as appropriate, depending upon the value of 'RT'.
+âprintâ or âprintfâ as appropriate, depending upon the value of
âRTâ.
File: gawk.info, Node: Igawk Program, Next: Anagram Program, Prev: Simple
Sed, Up: Miscellaneous Programs
@@ -20432,18 +20432,18 @@ File: gawk.info, Node: Igawk Program, Next: Anagram
Program, Prev: Simple Sed
11.3.9 An Easy Way to Use Library Functions
-------------------------------------------
-In *note Include Files::, we saw how 'gawk' provides a built-in
-file-inclusion capability. However, this is a 'gawk' extension. This
+In *note Include Files::, we saw how âgawkâ provides a built-in
+file-inclusion capability. However, this is a âgawkâ extension. This
minor node provides the motivation for making file inclusion available
-for standard 'awk', and shows how to do it using a combination of shell
-and 'awk' programming.
+for standard âawkâ, and shows how to do it using a combination of shell
+and âawkâ programming.
- Using library functions in 'awk' can be very beneficial. It
+ Using library functions in âawkâ can be very beneficial. It
encourages code reuse and the writing of general functions. Programs
are smaller and therefore clearer. However, using library functions is
-only easy when writing 'awk' programs; it is painful when running them,
-requiring multiple '-f' options. If 'gawk' is unavailable, then so too
-is the 'AWKPATH' environment variable and the ability to put 'awk'
+only easy when writing âawkâ programs; it is painful when running them,
+requiring multiple â-fâ options. If âgawkâ is unavailable, then so too
+is the âAWKPATHâ environment variable and the ability to put âawkâ
functions into a library directory (*note Options::). It would be nice
to be able to write programs in the following manner:
@@ -20459,94 +20459,94 @@ to be able to write programs in the following manner:
...
}
- The following program, 'igawk.sh', provides this service. It
-simulates 'gawk''s searching of the 'AWKPATH' variable and also allows
-"nested" includes (i.e., a file that is included with '@include' can
-contain further '@include' statements). 'igawk' makes an effort to only
-include files once, so that nested includes don't accidentally include a
+ The following program, âigawk.shâ, provides this service. It
+simulates âgawkââs searching of the âAWKPATHâ variable and also
allows
+ânestedâ includes (i.e., a file that is included with â@includeâ can
+contain further â@includeâ statements). âigawkâ makes an effort to
only
+include files once, so that nested includes donât accidentally include a
library function twice.
- 'igawk' should behave just like 'gawk' externally. This means it
-should accept all of 'gawk''s command-line arguments, including the
-ability to have multiple source files specified via '-f' and the ability
+ âigawkâ should behave just like âgawkâ externally. This means it
+should accept all of âgawkââs command-line arguments, including the
+ability to have multiple source files specified via â-fâ and the ability
to mix command-line and library source files.
- The program is written using the POSIX Shell ('sh') command
+ The program is written using the POSIX Shell (âshâ) command
language.(1) It works as follows:
- 1. Loop through the arguments, saving anything that doesn't represent
- 'awk' source code for later, when the expanded program is run.
+ 1. Loop through the arguments, saving anything that doesnât represent
+ âawkâ source code for later, when the expanded program is run.
- 2. For any arguments that do represent 'awk' text, put the arguments
+ 2. For any arguments that do represent âawkâ text, put the arguments
into a shell variable that will be expanded. There are two cases:
- a. Literal text, provided with '-e' or '--source'. This text is
+ a. Literal text, provided with â-eâ or â--sourceâ. This text is
just appended directly.
- b. Source file names, provided with '-f'. We use a neat trick
- and append '@include FILENAME' to the shell variable's
+ b. Source file names, provided with â-fâ. We use a neat trick
+ and append â@include FILENAMEâ to the shell variableâs
contents. Because the file-inclusion program works the way
- 'gawk' does, this gets the text of the file included in the
+ âgawkâ does, this gets the text of the file included in the
program at the correct point.
- 3. Run an 'awk' program (naturally) over the shell variable's contents
- to expand '@include' statements. The expanded program is placed in
+ 3. Run an âawkâ program (naturally) over the shell variableâs contents
+ to expand â@includeâ statements. The expanded program is placed in
a second shell variable.
- 4. Run the expanded program with 'gawk' and any other original
+ 4. Run the expanded program with âgawkâ and any other original
command-line arguments that the user supplied (such as the data
file names).
This program uses shell variables extensively: for storing
-command-line arguments and the text of the 'awk' program that will
-expand the user's program, for the user's original program, and for the
+command-line arguments and the text of the âawkâ program that will
+expand the userâs program, for the userâs original program, and for the
expanded program. Doing so removes some potential problems that might
arise were we to use temporary files instead, at the cost of making the
script somewhat more complicated.
The initial part of the program turns on shell tracing if the first
-argument is 'debug'.
+argument is âdebugâ.
The next part loops through all the command-line arguments. There
are several cases of interest:
-'--'
- This ends the arguments to 'igawk'. Anything else should be passed
- on to the user's 'awk' program without being evaluated.
-
-'-W'
- This indicates that the next option is specific to 'gawk'. To make
- argument processing easier, the '-W' is appended to the front of
- the remaining arguments and the loop continues. (This is an 'sh'
- programming trick. Don't worry about it if you are not familiar
- with 'sh'.)
-
-'-v', '-F'
- These are saved and passed on to 'gawk'.
-
-'-f', '--file', '--file=', '-Wfile='
- The file name is appended to the shell variable 'program' with an
- '@include' statement. The 'expr' utility is used to remove the
- leading option part of the argument (e.g., '--file='). (Typical
- 'sh' usage would be to use the 'echo' and 'sed' utilities to do
- this work. Unfortunately, some versions of 'echo' evaluate escape
+â--â
+ This ends the arguments to âigawkâ. Anything else should be passed
+ on to the userâs âawkâ program without being evaluated.
+
+â-Wâ
+ This indicates that the next option is specific to âgawkâ. To make
+ argument processing easier, the â-Wâ is appended to the front of
+ the remaining arguments and the loop continues. (This is an âshâ
+ programming trick. Donât worry about it if you are not familiar
+ with âshâ.)
+
+â-vâ, â-Fâ
+ These are saved and passed on to âgawkâ.
+
+â-fâ, â--fileâ, â--file=â, â-Wfile=â
+ The file name is appended to the shell variable âprogramâ with an
+ â@includeâ statement. The âexprâ utility is used to remove the
+ leading option part of the argument (e.g., â--file=â). (Typical
+ âshâ usage would be to use the âechoâ and âsedâ utilities to
do
+ this work. Unfortunately, some versions of âechoâ evaluate escape
sequences in their arguments, possibly mangling the program text.
- Using 'expr' avoids this problem.)
+ Using âexprâ avoids this problem.)
-'--source', '--source=', '-Wsource='
- The source text is appended to 'program'.
+â--sourceâ, â--source=â, â-Wsource=â
+ The source text is appended to âprogramâ.
-'--version', '-Wversion'
- 'igawk' prints its version number, runs 'gawk --version' to get the
- 'gawk' version information, and then exits.
+â--versionâ, â-Wversionâ
+ âigawkâ prints its version number, runs âgawk --versionâ to get
the
+ âgawkâ version information, and then exits.
- If none of the '-f', '--file', '-Wfile', '--source', or '-Wsource'
+ If none of the â-fâ, â--fileâ, â-Wfileâ, â--sourceâ, or
â-Wsourceâ
arguments are supplied, then the first nonoption argument should be the
-'awk' program. If there are no command-line arguments left, 'igawk'
+âawkâ program. If there are no command-line arguments left, âigawkâ
prints an error message and exits. Otherwise, the first argument is
-appended to 'program'. In any case, after the arguments have been
-processed, the shell variable 'program' contains the complete text of
-the original 'awk' program.
+appended to âprogramâ. In any case, after the arguments have been
+processed, the shell variable âprogramâ contains the complete text of
+the original âawkâ program.
The program is as follows:
@@ -20626,26 +20626,26 @@ the original 'awk' program.
# At this point, `program' has the program.
- The 'awk' program to process '@include' directives is stored in the
-shell variable 'expand_prog'. Doing this keeps the shell script
-readable. The 'awk' program reads through the user's program, one line
-at a time, using 'getline' (*note Getline::). The input file names and
-'@include' statements are managed using a stack. As each '@include' is
-encountered, the current file name is "pushed" onto the stack and the
-file named in the '@include' directive becomes the current file name.
-As each file is finished, the stack is "popped," and the previous input
+ The âawkâ program to process â@includeâ directives is stored in the
+shell variable âexpand_progâ. Doing this keeps the shell script
+readable. The âawkâ program reads through the userâs program, one line
+at a time, using âgetlineâ (*note Getline::). The input file names and
+â@includeâ statements are managed using a stack. As each â@includeâ is
+encountered, the current file name is âpushedâ onto the stack and the
+file named in the â@includeâ directive becomes the current file name.
+As each file is finished, the stack is âpopped,â and the previous input
file becomes the current input file again. The process is started by
making the original file the first one on the stack.
- The 'pathto()' function does the work of finding the full path to a
-file. It simulates 'gawk''s behavior when searching the 'AWKPATH'
+ The âpathto()â function does the work of finding the full path to a
+file. It simulates âgawkââs behavior when searching the âAWKPATHâ
environment variable (*note AWKPATH Variable::). If a file name has a
-'/' in it, no path search is done. Similarly, if the file name is
-'"-"', then that string is used as-is. Otherwise, the file name is
+â/â in it, no path search is done. Similarly, if the file name is
+â"-"â, then that string is used as-is. Otherwise, the file name is
concatenated with the name of each directory in the path, and an attempt
is made to open the generated file name. The only way to test if a file
-can be read in 'awk' is to go ahead and try to read it with 'getline';
-this is what 'pathto()' does.(2) If the file can be read, it is closed
+can be read in âawkâ is to go ahead and try to read it with âgetlineâ;
+this is what âpathto()â does.(2) If the file can be read, it is closed
and the file name is returned:
expand_prog='
@@ -20669,9 +20669,9 @@ and the file name is returned:
return ""
}
- The main program is contained inside one 'BEGIN' rule. The first
-thing it does is set up the 'pathlist' array that 'pathto()' uses.
-After splitting the path on ':', null elements are replaced with '"."',
+ The main program is contained inside one âBEGINâ rule. The first
+thing it does is set up the âpathlistâ array that âpathto()â uses.
+After splitting the path on â:â, null elements are replaced with â"."â,
which represents the current directory:
BEGIN {
@@ -20682,21 +20682,21 @@ which represents the current directory:
pathlist[i] = "."
}
- The stack is initialized with 'ARGV[1]', which will be
-'"/dev/stdin"'. The main loop comes next. Input lines are read in
-succession. Lines that do not start with '@include' are printed
-verbatim. If the line does start with '@include', the file name is in
-'$2'. 'pathto()' is called to generate the full path. If it cannot,
+ The stack is initialized with âARGV[1]â, which will be
+â"/dev/stdin"â. The main loop comes next. Input lines are read in
+succession. Lines that do not start with â@includeâ are printed
+verbatim. If the line does start with â@includeâ, the file name is in
+â$2â. âpathto()â is called to generate the full path. If it cannot,
then the program prints an error message and continues.
The next thing to check is if the file is included already. The
-'processed' array is indexed by the full file name of each included file
+âprocessedâ array is indexed by the full file name of each included file
and it tracks this information for us. If the file is seen again, a
warning message is printed. Otherwise, the new file name is pushed onto
the stack and processing continues.
- Finally, when 'getline' encounters the end of the input file, the
-file is closed and the stack is popped. When 'stackptr' is less than
+ Finally, when âgetlineâ encounters the end of the input file, the
+file is closed and the stack is popped. When âstackptrâ is less than
zero, the program is done:
stackptr = 0
@@ -20731,85 +20731,85 @@ zero, the program is done:
EOF
)
- The shell construct 'COMMAND << MARKER' is called a "here document".
+ The shell construct âCOMMAND << MARKERâ is called a âhere documentâ.
Everything in the shell script up to the MARKER is fed to COMMAND as
input. The shell processes the contents of the here document for
variable and command substitution (and possibly other things as well,
depending upon the shell).
- The shell construct '$(...)' is called "command substitution". The
+ The shell construct â$(...)â is called âcommand substitutionâ. The
output of the command inside the parentheses is substituted into the
command line. Because the result is used in a variable assignment, it
is saved as a single string, even if the results contain whitespace.
- The expanded program is saved in the variable 'processed_program'.
-It's done in these steps:
+ The expanded program is saved in the variable âprocessed_programâ.
+Itâs done in these steps:
- 1. Run 'gawk' with the '@include'-processing program (the value of the
- 'expand_prog' shell variable) reading standard input.
+ 1. Run âgawkâ with the â@includeâ-processing program (the value of
the
+ âexpand_progâ shell variable) reading standard input.
- 2. Standard input is the contents of the user's program, from the
- shell variable 'program'. Feed its contents to 'gawk' via a here
+ 2. Standard input is the contents of the userâs program, from the
+ shell variable âprogramâ. Feed its contents to âgawkâ via a here
document.
3. Save the results of this processing in the shell variable
- 'processed_program' by using command substitution.
+ âprocessed_programâ by using command substitution.
- The last step is to call 'gawk' with the expanded program, along with
+ The last step is to call âgawkâ with the expanded program, along with
the original options and command-line arguments that the user supplied:
eval gawk $opts -- '"$processed_program"' '"$@"'
- The 'eval' command is a shell construct that reruns the shell's
+ The âevalâ command is a shell construct that reruns the shellâs
parsing process. This keeps things properly quoted.
- This version of 'igawk' represents the fifth version of this program.
+ This version of âigawkâ represents the fifth version of this program.
There are four key simplifications that make the program work better:
- * Using '@include' even for the files named with '-f' makes building
- the initial collected 'awk' program much simpler; all the
- '@include' processing can be done once.
+ ⢠Using â@includeâ even for the files named with â-fâ makes
building
+ the initial collected âawkâ program much simpler; all the
+ â@includeâ processing can be done once.
- * Not trying to save the line read with 'getline' in the 'pathto()'
- function when testing for the file's accessibility for use with the
+ ⢠Not trying to save the line read with âgetlineâ in the
âpathto()â
+ function when testing for the fileâs accessibility for use with the
main program simplifies things considerably.
- * Using a 'getline' loop in the 'BEGIN' rule does it all in one
+ ⢠Using a âgetlineâ loop in the âBEGINâ rule does it all in one
place. It is not necessary to call out to a separate loop for
- processing nested '@include' statements.
+ processing nested â@includeâ statements.
- * Instead of saving the expanded program in a temporary file, putting
+ ⢠Instead of saving the expanded program in a temporary file, putting
it in a shell variable avoids some potential security problems.
This has the disadvantage that the script relies upon more features
- of the 'sh' language, making it harder to follow for those who
- aren't familiar with 'sh'.
+ of the âshâ language, making it harder to follow for those who
+ arenât familiar with âshâ.
Also, this program illustrates that it is often worthwhile to combine
-'sh' and 'awk' programming together. You can usually accomplish quite a
+âshâ and âawkâ programming together. You can usually accomplish quite
a
lot, without having to resort to low-level programming in C or C++, and
it is frequently easier to do certain kinds of string and argument
-manipulation using the shell than it is in 'awk'.
+manipulation using the shell than it is in âawkâ.
- Finally, 'igawk' shows that it is not always necessary to add new
+ Finally, âigawkâ shows that it is not always necessary to add new
features to a program; they can often be layered on top.(3)
- Before 'gawk' acquired its built-in '@include' mechanism, 'igawk' and
-its manual page were installed as part of the regular 'gawk'
-installation ('make install'). This is no longer done, because it's no
-longer necessary. But we've kept the program in this Info file for its
+ Before âgawkâ acquired its built-in â@includeâ mechanism,
âigawkâ and
+its manual page were installed as part of the regular âgawkâ
+installation (âmake installâ). This is no longer done, because itâs no
+longer necessary. But weâve kept the program in this Info file for its
educational value.
---------- Footnotes ----------
- (1) Fully explaining the 'sh' language is beyond the scope of this
+ (1) Fully explaining the âshâ language is beyond the scope of this
book. We provide some minimal explanations, but see a good shell
programming book if you wish to understand things in more depth.
- (2) On some very old versions of 'awk', the test 'getline junk < t'
+ (2) On some very old versions of âawkâ, the test âgetline junk < tâ
can loop forever if the file exists but is empty.
- (3) 'gawk' does '@include' processing itself in order to support the
-use of 'awk' programs as Web CGI scripts.
+ (3) âgawkâ does â@includeâ processing itself in order to support the
+use of âawkâ programs as Web CGI scripts.
File: gawk.info, Node: Anagram Program, Next: Signature Program, Prev:
Igawk Program, Up: Miscellaneous Programs
@@ -20817,12 +20817,12 @@ File: gawk.info, Node: Anagram Program, Next:
Signature Program, Prev: Igawk
11.3.10 Finding Anagrams from a Dictionary
------------------------------------------
-An interesting programming challenge is to search for "anagrams" in a
-word list (such as '/usr/share/dict/words' on many GNU/Linux systems).
+An interesting programming challenge is to search for âanagramsâ in a
+word list (such as â/usr/share/dict/wordsâ on many GNU/Linux systems).
One word is an anagram of another if both words contain the same letters
-(e.g., "babbling" and "blabbing").
+(e.g., âbabblingâ and âblabbingâ).
- Column 2, Problem C, of Jon Bentley's 'Programming Pearls', Second
+ Column 2, Problem C, of Jon Bentleyâs âProgramming Pearlsâ, Second
Edition, presents an elegant algorithm. The idea is to give words that
are anagrams a common signature, sort all the words together by their
signatures, and then print them. Dr. Bentley observes that taking the
@@ -20849,7 +20849,7 @@ dimension is the word itself:
data[key][$1] = $1 # Store word with signature
}
- The 'word2key()' function creates the signature. It splits the word
+ The âword2key()â function creates the signature. It splits the word
apart into individual letters, sorts the letters, and then joins them
back together:
@@ -20866,8 +20866,8 @@ back together:
return result
}
- Finally, the 'END' rule traverses the array and prints out the
-anagram lists. It sends the output to the system 'sort' command because
+ Finally, the âENDâ rule traverses the array and prints out the
+anagram lists. It sends the output to the system âsortâ command because
otherwise the anagrams would appear in arbitrary order:
END {
@@ -20908,10 +20908,10 @@ File: gawk.info, Node: Signature Program, Prev:
Anagram Program, Up: Miscella
The following program was written by Davide Brini and is published on
his website (http://backreference.org/2011/02/03/obfuscated-awk/). It
-serves as his signature in the Usenet group 'comp.lang.awk'. He
+serves as his signature in the Usenet group âcomp.lang.awkâ. He
supplies the following copyright terms:
- Copyright (C) 2008 Davide Brini
+ Copyright © 2008 Davide Brini
Copying and distribution of the code published in this page, with
or without modification, are permitted in any medium without
@@ -20926,7 +20926,7 @@ supplies the following copyright terms:
O+X*(o*(o+O)+O),+x+O+X*o,x*(x-o),(o+X+x)*o*o-(x-O-O),O+(X-x)*(X+O),x-O}'
We leave it to you to determine what the program does. (If you are
-truly desperate to understand it, see Chris Johansen's explanation,
+truly desperate to understand it, see Chris Johansenâs explanation,
which is embedded in the Texinfo source file for this Info file.)
@@ -20935,26 +20935,26 @@ File: gawk.info, Node: Programs Summary, Next:
Programs Exercises, Prev: Misc
11.4 Summary
============
- * The programs provided in this major node continue on the theme that
+ ⢠The programs provided in this major node continue on the theme that
reading programs is an excellent way to learn Good Programming.
- * Using '#!' to make 'awk' programs directly runnable makes them
- easier to use. Otherwise, invoke the program using 'awk -f ...'.
+ ⢠Using â#!â to make âawkâ programs directly runnable makes them
+ easier to use. Otherwise, invoke the program using âawk -f ...â.
- * Reimplementing standard POSIX programs in 'awk' is a pleasant
- exercise; 'awk''s expressive power lets you write such programs in
+ ⢠Reimplementing standard POSIX programs in âawkâ is a pleasant
+ exercise; âawkââs expressive power lets you write such programs in
relatively few lines of code, yet they are functionally complete
and usable.
- * One of standard 'awk''s weaknesses is working with individual
- characters. The ability to use 'split()' with the empty string as
+ ⢠One of standard âawkââs weaknesses is working with individual
+ characters. The ability to use âsplit()â with the empty string as
the separator can considerably simplify such tasks.
- * The examples here demonstrate the usefulness of the library
+ ⢠The examples here demonstrate the usefulness of the library
functions from *note Library Functions:: for a number of real (if
small) programs.
- * Besides reinventing POSIX wheels, other programs solved a selection
+ ⢠Besides reinventing POSIX wheels, other programs solved a selection
of interesting problems, such as finding duplicate words in text,
printing mailing labels, and finding anagrams.
@@ -20964,51 +20964,51 @@ File: gawk.info, Node: Programs Exercises, Prev:
Programs Summary, Up: Sample
11.5 Exercises
==============
- 1. Rewrite 'cut.awk' (*note Cut Program::) using 'split()' with '""'
+ 1. Rewrite âcut.awkâ (*note Cut Program::) using âsplit()â with
â""â
as the separator.
- 2. In *note Egrep Program::, we mentioned that 'egrep -i' could be
- simulated in versions of 'awk' without 'IGNORECASE' by using
- 'tolower()' on the line and the pattern. In a footnote there, we
+ 2. In *note Egrep Program::, we mentioned that âegrep -iâ could be
+ simulated in versions of âawkâ without âIGNORECASEâ by using
+ âtolower()â on the line and the pattern. In a footnote there, we
also mentioned that this solution has a bug: the translated line is
output, and not the original one. Fix this problem.
- 3. The POSIX version of 'id' takes options that control which
- information is printed. Modify the 'awk' version (*note Id
+ 3. The POSIX version of âidâ takes options that control which
+ information is printed. Modify the âawkâ version (*note Id
Program::) to accept the same arguments and perform in the same
way.
- 4. The 'split.awk' program (*note Split Program::) assumes that
- letters are contiguous in the character set, which isn't true for
+ 4. The âsplit.awkâ program (*note Split Program::) assumes that
+ letters are contiguous in the character set, which isnât true for
EBCDIC systems. Fix this problem. (Hint: Consider a different way
- to work through the alphabet, without relying on 'ord()' and
- 'chr()'.)
+ to work through the alphabet, without relying on âord()â and
+ âchr()â.)
- 5. In 'uniq.awk' (*note Uniq Program::, the logic for choosing which
- lines to print represents a "state machine", which is "a device
+ 5. In âuniq.awkâ (*note Uniq Program::, the logic for choosing which
+ lines to print represents a âstate machineâ, which is âa device
which can be in one of a set number of stable conditions depending
on its previous condition and on the present values of its
- inputs."(1) Brian Kernighan suggests that "an alternative approach
+ inputs.â(1) Brian Kernighan suggests that âan alternative approach
to state machines is to just read the input into an array, then use
- indexing. It's almost always easier code, and for most inputs
- where you would use this, just as fast." Rewrite the logic to
+ indexing. Itâs almost always easier code, and for most inputs
+ where you would use this, just as fast.â Rewrite the logic to
follow this suggestion.
- 6. Why can't the 'wc.awk' program (*note Wc Program::) just use the
- value of 'FNR' in 'endfile()'? Hint: Examine the code in *note
+ 6. Why canât the âwc.awkâ program (*note Wc Program::) just use the
+ value of âFNRâ in âendfile()â? Hint: Examine the code in *note
Filetrans Function::.
- 7. Manipulation of individual characters in the 'translate' program
- (*note Translate Program::) is painful using standard 'awk'
- functions. Given that 'gawk' can split strings into individual
- characters using '""' as the separator, how might you use this
+ 7. Manipulation of individual characters in the âtranslateâ program
+ (*note Translate Program::) is painful using standard âawkâ
+ functions. Given that âgawkâ can split strings into individual
+ characters using â""â as the separator, how might you use this
feature to simplify the program?
- 8. The 'extract.awk' program (*note Extract Program::) was written
- before 'gawk' had the 'gensub()' function. Use it to simplify the
+ 8. The âextract.awkâ program (*note Extract Program::) was written
+ before âgawkâ had the âgensub()â function. Use it to simplify the
code.
- 9. Compare the performance of the 'awksed.awk' program (*note Simple
+ 9. Compare the performance of the âawksed.awkâ program (*note Simple
Sed::) with the more straightforward:
BEGIN {
@@ -21019,12 +21019,12 @@ File: gawk.info, Node: Programs Exercises, Prev:
Programs Summary, Up: Sample
{ gsub(pat, repl); print }
- 10. What are the advantages and disadvantages of 'awksed.awk' versus
- the real 'sed' utility?
+ 10. What are the advantages and disadvantages of âawksed.awkâ versus
+ the real âsedâ utility?
11. In *note Igawk Program::, we mentioned that not trying to save the
- line read with 'getline' in the 'pathto()' function when testing
- for the file's accessibility for use with the main program
+ line read with âgetlineâ in the âpathto()â function when testing
+ for the fileâs accessibility for use with the main program
simplifies things considerably. What problem does this engender
though?
@@ -21032,26 +21032,26 @@ File: gawk.info, Node: Programs Exercises, Prev:
Programs Summary, Up: Sample
necessary to add new features to a program, consider the idea of
having two files in a directory in the search path:
- 'default.awk'
+ âdefault.awkâ
This file contains a set of default library functions, such as
- 'getopt()' and 'assert()'.
+ âgetopt()â and âassert()â.
- 'site.awk'
+ âsite.awkâ
This file contains library functions that are specific to a
site or installation; i.e., locally developed functions.
- Having a separate file allows 'default.awk' to change with new
- 'gawk' releases, without requiring the system administrator to
+ Having a separate file allows âdefault.awkâ to change with new
+ âgawkâ releases, without requiring the system administrator to
update it each time by adding the local functions.
- One user suggested that 'gawk' be modified to automatically read
+ One user suggested that âgawkâ be modified to automatically read
these files upon startup. Instead, it would be very simple to
- modify 'igawk' to do this. Since 'igawk' can process nested
- '@include' directives, 'default.awk' could simply contain
- '@include' statements for the desired library functions. Make this
+ modify âigawkâ to do this. Since âigawkâ can process nested
+ â@includeâ directives, âdefault.awkâ could simply contain
+ â@includeâ statements for the desired library functions. Make this
change.
- 13. Modify 'anagram.awk' (*note Anagram Program::), to avoid the use
- of the external 'sort' utility.
+ 13. Modify âanagram.awkâ (*note Anagram Program::), to avoid the use
+ of the external âsortâ utility.
---------- Footnotes ----------
@@ -21061,51 +21061,51 @@ File: gawk.info, Node: Programs Exercises, Prev:
Programs Summary, Up: Sample
File: gawk.info, Node: Advanced Features, Next: Internationalization, Prev:
Sample Programs, Up: Top
-12 Advanced Features of 'gawk'
+12 Advanced Features of âgawkâ
******************************
Write documentation as if whoever reads it is a violent psychopath
who knows where you live.
- -- _Steve English, as quoted by Peter Langston_
+ â _Steve English, as quoted by Peter Langston_
- This major node discusses advanced features in 'gawk'. It's a bit of
-a "grab bag" of items that are otherwise unrelated to each other.
-First, we look at a command-line option that allows 'gawk' to recognize
-nondecimal numbers in input data, not just in 'awk' programs. Then,
-'gawk''s special features for sorting arrays are presented. Next,
+ This major node discusses advanced features in âgawkâ. Itâs a bit of
+a âgrab bagâ of items that are otherwise unrelated to each other.
+First, we look at a command-line option that allows âgawkâ to recognize
+nondecimal numbers in input data, not just in âawkâ programs. Then,
+âgawkââs special features for sorting arrays are presented. Next,
two-way I/O, discussed briefly in earlier parts of this Info file, is
described in full detail, along with the basics of TCP/IP networking.
-We then see how 'gawk' can "profile" an 'awk' program, making it
+We then see how âgawkâ can âprofileâ an âawkâ program, making it
possible to tune it for performance. Next, we present an experimental
-feature that allows you to preserve the values of 'awk' variables and
-arrays between runs of 'gawk'. Finally, we discuss the philosophy
-behind 'gawk''s extension mechanism.
+feature that allows you to preserve the values of âawkâ variables and
+arrays between runs of âgawkâ. Finally, we discuss the philosophy
+behind âgawkââs extension mechanism.
Additional advanced features are discussed in separate major nodes of
their own:
- * *note Internationalization::, discusses how to internationalize
- your 'awk' programs, so that they can speak multiple national
+ ⢠*note Internationalization::, discusses how to internationalize
+ your âawkâ programs, so that they can speak multiple national
languages.
- * *note Debugger::, describes 'gawk''s built-in command-line debugger
- for debugging 'awk' programs.
+ ⢠*note Debugger::, describes âgawkââs built-in command-line
debugger
+ for debugging âawkâ programs.
- * *note Arbitrary Precision Arithmetic::, describes how you can use
- 'gawk' to perform arbitrary-precision arithmetic.
+ ⢠*note Arbitrary Precision Arithmetic::, describes how you can use
+ âgawkâ to perform arbitrary-precision arithmetic.
- * *note Dynamic Extensions::, discusses the ability to dynamically
- add new built-in functions to 'gawk'.
+ ⢠*note Dynamic Extensions::, discusses the ability to dynamically
+ add new built-in functions to âgawkâ.
* Menu:
* Nondecimal Data:: Allowing nondecimal input data.
-* Boolean Typed Values:: Values with 'number|bool' type.
+* Boolean Typed Values:: Values with ânumber|boolâ type.
* Array Sorting:: Facilities for controlling array traversal and
sorting arrays.
* Two-way I/O:: Two-way communications with another process.
-* TCP/IP Networking:: Using 'gawk' for network programming.
-* Profiling:: Profiling your 'awk' programs.
+* TCP/IP Networking:: Using âgawkâ for network programming.
+* Profiling:: Profiling your âawkâ programs.
* Persistent Memory:: Preserving data between runs.
* Extension Philosophy:: What should be built-in and what should not.
* Advanced Features Summary:: Summary of advanced features.
@@ -21116,29 +21116,29 @@ File: gawk.info, Node: Nondecimal Data, Next:
Boolean Typed Values, Up: Advan
12.1 Allowing Nondecimal Input Data
===================================
-If you run 'gawk' with the '--non-decimal-data' option, you can have
+If you run âgawkâ with the â--non-decimal-dataâ option, you can have
nondecimal values in your input data:
$ echo 0123 123 0x123 |
> gawk --non-decimal-data '{ printf "%d, %d, %d\n", $1, $2, $3 }'
- -| 83, 123, 291
+ ⣠83, 123, 291
- For this feature to work, write your program so that 'gawk' treats
+ For this feature to work, write your program so that âgawkâ treats
your data as numeric:
$ echo 0123 123 0x123 | gawk '{ print $1, $2, $3 }'
- -| 0123 123 0x123
+ ⣠0123 123 0x123
-The 'print' statement treats its expressions as strings. Although the
+The âprintâ statement treats its expressions as strings. Although the
fields can act as numbers when necessary, they are still strings, so
-'print' does not try to treat them numerically. You need to add zero to
+âprintâ does not try to treat them numerically. You need to add zero to
a field to force it to be treated as a number. For example:
$ echo 0123 123 0x123 | gawk --non-decimal-data '
> { print $1, $2, $3
> print $1 + 0, $2 + 0, $3 + 0 }'
- -| 0123 123 0x123
- -| 83 123 291
+ ⣠0123 123 0x123
+ ⣠83 123 291
Because it is common to have decimal data with leading zeros, and
because using this facility could lead to surprising results, the
@@ -21146,12 +21146,12 @@ default is to leave it disabled. If you want it, you
must explicitly
request it.
CAUTION: _Use of this option is not recommended._ It can break old
- programs very badly. Instead, use the 'strtonum()' function to
+ programs very badly. Instead, use the âstrtonum()â function to
convert your data (*note String Functions::). This makes your
programs easier to write and easier to read, and leads to less
surprising results.
- This option may disappear in a future version of 'gawk'.
+ This option may disappear in a future version of âgawkâ.
File: gawk.info, Node: Boolean Typed Values, Next: Array Sorting, Prev:
Nondecimal Data, Up: Advanced Features
@@ -21159,41 +21159,41 @@ File: gawk.info, Node: Boolean Typed Values, Next:
Array Sorting, Prev: Nonde
12.2 Boolean Typed Values
=========================
-Scalar values in 'awk' are either numbers or strings. 'gawk' also
-supports values of type 'regexp' (*note Strong Regexp Constants::).
+Scalar values in âawkâ are either numbers or strings. âgawkâ also
+supports values of type âregexpâ (*note Strong Regexp Constants::).
- As described in *note Truth Values::, Boolean values in 'awk' don't
-have a separate type: a value counts as "true" if it is nonzero or
-non-null, and as "false" otherwise.
+ As described in *note Truth Values::, Boolean values in âawkâ donât
+have a separate type: a value counts as âtrueâ if it is nonzero or
+non-null, and as âfalseâ otherwise.
When interchanging data with languages that do have a real Boolean
type, using a standard format such as JSON or XML, the lack of a true
-Boolean type in 'awk' is problematic. (See, for example, the 'json'
-extension provided by the 'gawkextlib' project
+Boolean type in âawkâ is problematic. (See, for example, the âjsonâ
+extension provided by the âgawkextlibâ project
(https://sourceforge.net/projects/gawkextlib).)
- It's easy to import Boolean data into 'awk', but then the fact that
+ Itâs easy to import Boolean data into âawkâ, but then the fact that
it was originally Boolean is lost. Exporting data is even harder;
-there's no way to indicate that a value is really Boolean.
+thereâs no way to indicate that a value is really Boolean.
- To solve this problem, 'gawk' provides a function named 'mkbool()'.
-It takes one argument, which is any 'awk' expression, and it returns a
+ To solve this problem, âgawkâ provides a function named âmkbool()â.
+It takes one argument, which is any âawkâ expression, and it returns a
value of Boolean type.
- The returned values are normal 'awk' numeric values, with values of
+ The returned values are normal âawkâ numeric values, with values of
either one or zero, depending upon the truth value of the original
-expression passed in the call to 'mkbool()'.
+expression passed in the call to âmkbool()â.
- The 'typeof()' function (*note Type Functions::) returns
-'"number|bool"' for these values.
+ The âtypeof()â function (*note Type Functions::) returns
+â"number|bool"â for these values.
- Thus Boolean-typed values _are_ numbers as far as 'gawk' is
+ Thus Boolean-typed values _are_ numbers as far as âgawkâ is
concerned, except that extension code can treat them as Booleans if
desired.
While it would have been possible to add two new built-in variables
-of Boolean type named 'TRUE' and 'FALSE', doing so would undoubtedly
-have broken many existing 'awk' programs. Instead, having a "generator"
+of Boolean type named âTRUEâ and âFALSEâ, doing so would undoubtedly
+have broken many existing âawkâ programs. Instead, having a
âgeneratorâ
function that creates Boolean values gives flexibility, without breaking
as much existing code.
@@ -21203,10 +21203,10 @@ File: gawk.info, Node: Array Sorting, Next: Two-way
I/O, Prev: Boolean Typed
12.3 Controlling Array Traversal and Array Sorting
==================================================
-'gawk' lets you control the order in which a 'for (INDX in ARRAY)' loop
+âgawkâ lets you control the order in which a âfor (INDX in ARRAY)â loop
traverses an array.
- In addition, two built-in functions, 'asort()' and 'asorti()', let
+ In addition, two built-in functions, âasort()â and âasorti()â, let
you sort arrays based on the array values and indices, respectively.
These two functions also provide control over the sorting criteria used
to order the elements during sorting.
@@ -21214,7 +21214,7 @@ to order the elements during sorting.
* Menu:
* Controlling Array Traversal:: How to use PROCINFO["sorted_in"].
-* Array Sorting Functions:: How to use 'asort()' and 'asorti()'.
+* Array Sorting Functions:: How to use âasort()â and âasorti()â.
File: gawk.info, Node: Controlling Array Traversal, Next: Array Sorting
Functions, Up: Array Sorting
@@ -21222,19 +21222,19 @@ File: gawk.info, Node: Controlling Array Traversal,
Next: Array Sorting Functi
12.3.1 Controlling Array Traversal
----------------------------------
-By default, the order in which a 'for (INDX in ARRAY)' loop scans an
+By default, the order in which a âfor (INDX in ARRAY)â loop scans an
array is not defined; it is generally based upon the internal
-implementation of arrays inside 'awk'.
+implementation of arrays inside âawkâ.
Often, though, it is desirable to be able to loop over the elements
-in a particular order that you, the programmer, choose. 'gawk' lets you
+in a particular order that you, the programmer, choose. âgawkâ lets you
do this.
*note Controlling Scanning:: describes how you can assign special,
-predefined values to 'PROCINFO["sorted_in"]' in order to control the
-order in which 'gawk' traverses an array during a 'for' loop.
+predefined values to âPROCINFO["sorted_in"]â in order to control the
+order in which âgawkâ traverses an array during a âforâ loop.
- In addition, the value of 'PROCINFO["sorted_in"]' can be a function
+ In addition, the value of âPROCINFO["sorted_in"]â can be a function
name.(1) This lets you traverse an array based on any custom criterion.
The array elements are ordered according to the return value of this
function. The comparison function should be defined with at least four
@@ -21246,22 +21246,22 @@ arguments:
RETURN < 0; 0; OR > 0
}
- Here, 'i1' and 'i2' are the indices, and 'v1' and 'v2' are the
-corresponding values of the two elements being compared. Either 'v1' or
-'v2', or both, can be arrays if the array being traversed contains
+ Here, âi1â and âi2â are the indices, and âv1â and âv2â are
the
+corresponding values of the two elements being compared. Either âv1â or
+âv2â, or both, can be arrays if the array being traversed contains
subarrays as values. (*Note Arrays of Arrays:: for more information
about subarrays.) The three possible return values are interpreted as
follows:
-'comp_func(i1, v1, i2, v2) < 0'
- Index 'i1' comes before index 'i2' during loop traversal.
+âcomp_func(i1, v1, i2, v2) < 0â
+ Index âi1â comes before index âi2â during loop traversal.
-'comp_func(i1, v1, i2, v2) == 0'
- Indices 'i1' and 'i2' come together, but the relative order with
+âcomp_func(i1, v1, i2, v2) == 0â
+ Indices âi1â and âi2â come together, but the relative order with
respect to each other is undefined.
-'comp_func(i1, v1, i2, v2) > 0'
- Index 'i1' comes after index 'i2' during loop traversal.
+âcomp_func(i1, v1, i2, v2) > 0â
+ Index âi1â comes after index âi2â during loop traversal.
Our first comparison function can be used to scan an array in
numerical order of the indices:
@@ -21301,7 +21301,7 @@ traversal:
return (v1 < v2) ? -1 : (v1 != v2)
}
- Here is a main program to demonstrate how 'gawk' behaves using each
+ Here is a main program to demonstrate how âgawkâ behaves using each
of the previous functions:
BEGIN {
@@ -21326,26 +21326,26 @@ of the previous functions:
Here are the results when the program is run:
$ gawk -f compdemo.awk
- -| Sort function: cmp_num_idx Sort by numeric index
- -| data[two] = 20
- -| data[one] = 10 Both strings are numerically zero
- -| data[10] = one
- -| data[20] = two
- -| data[100] = 100
- -|
- -| Sort function: cmp_str_val Sort by element values as strings
- -| data[one] = 10
- -| data[100] = 100 String 100 is less than string 20
- -| data[two] = 20
- -| data[10] = one
- -| data[20] = two
- -|
- -| Sort function: cmp_num_str_val Sort all numeric values before all
strings
- -| data[one] = 10
- -| data[two] = 20
- -| data[100] = 100
- -| data[10] = one
- -| data[20] = two
+ ⣠Sort function: cmp_num_idx Sort by numeric index
+ ⣠data[two] = 20
+ ⣠data[one] = 10 Both strings are numerically zero
+ ⣠data[10] = one
+ ⣠data[20] = two
+ ⣠data[100] = 100
+ â£
+ ⣠Sort function: cmp_str_val Sort by element values as strings
+ ⣠data[one] = 10
+ ⣠data[100] = 100 String 100 is less than string 20
+ ⣠data[two] = 20
+ ⣠data[10] = one
+ ⣠data[20] = two
+ â£
+ ⣠Sort function: cmp_num_str_val Sort all numeric values before all
strings
+ ⣠data[one] = 10
+ ⣠data[two] = 20
+ ⣠data[100] = 100
+ ⣠data[10] = one
+ ⣠data[20] = two
Consider sorting the entries of a GNU/Linux system password file
according to login name. The following program sorts records by a
@@ -21377,15 +21377,15 @@ specific field position and can be used for this
purpose:
}
}
- The first field in each entry of the password file is the user's
+ The first field in each entry of the password file is the userâs
login name, and the fields are separated by colons. Each record defines
a subarray, with each field as an element in the subarray. Running the
program produces the following output:
$ gawk -v POS=1 -F: -f sort.awk /etc/passwd
- -| adm:x:3:4:adm:/var/adm:/sbin/nologin
- -| apache:x:48:48:Apache:/var/www:/sbin/nologin
- -| avahi:x:70:70:Avahi daemon:/:/sbin/nologin
+ ⣠adm:x:3:4:adm:/var/adm:/sbin/nologin
+ ⣠apache:x:48:48:Apache:/var/www:/sbin/nologin
+ ⣠avahi:x:70:70:Avahi daemon:/:/sbin/nologin
...
The comparison should normally always return the same value when
@@ -21432,39 +21432,39 @@ traversal, and the sky is really the limit when it
comes to designing
such a function.
When string comparisons are made during a sort, either for element
-values where one or both aren't numbers, or for element indices handled
-as strings, the value of 'IGNORECASE' (*note Built-in Variables::)
+values where one or both arenât numbers, or for element indices handled
+as strings, the value of âIGNORECASEâ (*note Built-in Variables::)
controls whether the comparisons treat corresponding upper- and
lowercase letters as equivalent or distinct.
Another point to keep in mind is that in the case of subarrays, the
element values can themselves be arrays; a production comparison
-function should use the 'isarray()' function (*note Type Functions::) to
+function should use the âisarray()â function (*note Type Functions::) to
check for this, and choose a defined sorting order for subarrays.
- All sorting based on 'PROCINFO["sorted_in"]' is disabled in POSIX
-mode, because the 'PROCINFO' array is not special in that case.
+ All sorting based on âPROCINFO["sorted_in"]â is disabled in POSIX
+mode, because the âPROCINFOâ array is not special in that case.
As a side note, sorting the array indices before traversing the array
has been reported to add a 15% to 20% overhead to the execution time of
-'awk' programs. For this reason, sorted array traversal is not the
+âawkâ programs. For this reason, sorted array traversal is not the
default.
---------- Footnotes ----------
- (1) This is why the predefined sorting orders start with an '@'
+ (1) This is why the predefined sorting orders start with an â@â
character, which cannot be part of an identifier.
File: gawk.info, Node: Array Sorting Functions, Prev: Controlling Array
Traversal, Up: Array Sorting
-12.3.2 Sorting Array Values and Indices with 'gawk'
+12.3.2 Sorting Array Values and Indices with âgawkâ
---------------------------------------------------
-In most 'awk' implementations, sorting an array requires writing a
-'sort()' function. This can be educational for exploring different
-sorting algorithms, but usually that's not the point of the program.
-'gawk' provides the built-in 'asort()' and 'asorti()' functions (*note
+In most âawkâ implementations, sorting an array requires writing a
+âsort()â function. This can be educational for exploring different
+sorting algorithms, but usually thatâs not the point of the program.
+âgawkâ provides the built-in âasort()â and âasorti()â functions
(*note
String Functions::) for sorting arrays. For example:
POPULATE THE ARRAY data
@@ -21472,30 +21472,30 @@ String Functions::) for sorting arrays. For example:
for (i = 1; i <= n; i++)
DO SOMETHING WITH data[i]
- After the call to 'asort()', the array 'data' is indexed from 1 to
-some number N, the total number of elements in 'data'. (This count is
-'asort()''s return value.) 'data[1]' <= 'data[2]' <= 'data[3]', and so
+ After the call to âasort()â, the array âdataâ is indexed from 1 to
+some number N, the total number of elements in âdataâ. (This count is
+âasort()ââs return value.) âdata[1]â <= âdata[2]â <=
âdata[3]â, and so
on. The default comparison is based on the type of the elements (*note
Typing and Comparison::). All numeric values come before all string
values, which in turn come before all subarrays.
- An important side effect of calling 'asort()' is that _the array's
-original indices are irrevocably lost_. As this isn't always desirable,
-'asort()' accepts a second argument:
+ An important side effect of calling âasort()â is that _the arrayâs
+original indices are irrevocably lost_. As this isnât always desirable,
+âasort()â accepts a second argument:
POPULATE THE ARRAY source
n = asort(source, dest)
for (i = 1; i <= n; i++)
DO SOMETHING WITH dest[i]
- In this case, 'gawk' copies the 'source' array into the 'dest' array
-and then sorts 'dest', destroying its indices. However, the 'source'
+ In this case, âgawkâ copies the âsourceâ array into the âdestâ
array
+and then sorts âdestâ, destroying its indices. However, the âsourceâ
array is not affected.
- Often, what's needed is to sort on the values of the _indices_
-instead of the values of the elements. To do that, use the 'asorti()'
+ Often, whatâs needed is to sort on the values of the _indices_
+instead of the values of the elements. To do that, use the âasorti()â
function. The interface and behavior are identical to that of
-'asort()', except that the index values are used for sorting and become
+âasort()â, except that the index values are used for sorting and become
the values of the result array:
{ source[$0] = some_func($0) }
@@ -21511,15 +21511,15 @@ the values of the result array:
}
}
- So far, so good. Now it starts to get interesting. Both 'asort()'
-and 'asorti()' accept a third string argument to control comparison of
-array elements. When we introduced 'asort()' and 'asorti()' in *note
+ So far, so good. Now it starts to get interesting. Both âasort()â
+and âasorti()â accept a third string argument to control comparison of
+array elements. When we introduced âasort()â and âasorti()â in *note
String Functions::, we ignored this third argument; however, now is the
time to describe how this argument affects these two functions.
Basically, the third argument specifies how the array is to be
-sorted. There are two possibilities. As with 'PROCINFO["sorted_in"]',
-this argument may be one of the predefined names that 'gawk' provides
+sorted. There are two possibilities. As with âPROCINFO["sorted_in"]â,
+this argument may be one of the predefined names that âgawkâ provides
(*note Controlling Scanning::), or it may be the name of a user-defined
function (*note Controlling Array Traversal::).
@@ -21527,29 +21527,29 @@ function (*note Controlling Array Traversal::).
chooses_, taking into account just the indices, just the values, or
both. This is extremely powerful.
- Once the array is sorted, 'asort()' takes the _values_ in their final
-order and uses them to fill in the result array, whereas 'asorti()'
+ Once the array is sorted, âasort()â takes the _values_ in their final
+order and uses them to fill in the result array, whereas âasorti()â
takes the _indices_ in their final order and uses them to fill in the
result array.
- NOTE: Copying array indices and elements isn't expensive in terms
- of memory. Internally, 'gawk' maintains "reference counts" to
- data. For example, when 'asort()' copies the first array to the
- second one, there is only one copy of the original array elements'
+ NOTE: Copying array indices and elements isnât expensive in terms
+ of memory. Internally, âgawkâ maintains âreference countsâ to
+ data. For example, when âasort()â copies the first array to the
+ second one, there is only one copy of the original array elementsâ
data, even though both arrays use the values.
You may use the same array for both the first and second arguments to
-'asort()' and 'asorti()'. Doing so only makes sense if you are also
-supplying the third argument, since 'awk' doesn't provide a way to pass
+âasort()â and âasorti()â. Doing so only makes sense if you are also
+supplying the third argument, since âawkâ doesnât provide a way to pass
that third argument without also passing the first and second ones.
- Because 'IGNORECASE' affects string comparisons, the value of
-'IGNORECASE' also affects sorting for both 'asort()' and 'asorti()'.
-Note also that the locale's sorting order does _not_ come into play;
+ Because âIGNORECASEâ affects string comparisons, the value of
+âIGNORECASEâ also affects sorting for both âasort()â and
âasorti()â.
+Note also that the localeâs sorting order does _not_ come into play;
comparisons are based on character values only.(1)
The following example demonstrates the use of a comparison function
-with 'asort()'. The comparison function, 'case_fold_compare()', maps
+with âasort()â. The comparison function, âcase_fold_compare()â, maps
both values to lowercase in order to compare them ignoring case.
# case_fold_compare --- compare as strings, ignoring case
@@ -21591,23 +21591,23 @@ both values to lowercase in order to compare them
ignoring case.
When run, we get the following:
$ gawk -f case_fold_compare.awk
- -| A a B b c C D d e E F f g G H h i I J j k K l L M m
- -| n N O o p P Q q r R S s t T u U V v w W X x y Y z Z
+ ⣠A a B b c C D d e E F f g G H h i I J j k K l L M m
+ ⣠n N O o p P Q q r R S s t T u U V v w W X x y Y z Z
- NOTE: "Under the hood," 'gawk' uses the C library 'qsort()'
- function to manage the sorting. 'qsort()' can call itself
+ NOTE: âUnder the hood,â âgawkâ uses the C library âqsort()â
+ function to manage the sorting. âqsort()â can call itself
recursively. This means that when you write a comparison function,
you should be careful to avoid the use of global variables and
arrays; use only local variables and arrays that you declare as
additional parameters to the comparison function. Otherwise, you
are likely to cause unintentional memory corruption in your global
- arrays and possibly cause 'gawk' itself to fail.
+ arrays and possibly cause âgawkâ itself to fail.
---------- Footnotes ----------
(1) This is true because locale-based comparison occurs only when in
-POSIX-compatibility mode, and because 'asort()' and 'asorti()' are
-'gawk' extensions, they are not available in that case.
+POSIX-compatibility mode, and because âasort()â and âasorti()â are
+âgawkâ extensions, they are not available in that case.
File: gawk.info, Node: Two-way I/O, Next: TCP/IP Networking, Prev: Array
Sorting, Up: Advanced Features
@@ -21633,13 +21633,13 @@ temporary files:
This works, but not elegantly. Among other things, it requires that the
program be run in a directory that cannot be shared among users; for
-example, '/tmp' will not do, as another user might happen to be using a
+example, â/tmpâ will not do, as another user might happen to be using a
temporary file with the same name.(1)
- However, with 'gawk', it is possible to open a _two-way_ pipe to
-another process. The second process is termed a "coprocess", as it runs
-in parallel with 'gawk'. The two-way connection is created using the
-'|&' operator (borrowed from the Korn shell, 'ksh'):(2)
+ However, with âgawkâ, it is possible to open a _two-way_ pipe to
+another process. The second process is termed a âcoprocessâ, as it runs
+in parallel with âgawkâ. The two-way connection is created using the
+â|&â operator (borrowed from the Korn shell, âkshâ):(2)
do {
print DATA |& "subprogram"
@@ -21647,42 +21647,42 @@ in parallel with 'gawk'. The two-way connection is
created using the
} while (DATA LEFT TO PROCESS)
close("subprogram")
- The first time an I/O operation is executed using the '|&' operator,
-'gawk' creates a two-way pipeline to a child process that runs the other
-program. Output created with 'print' or 'printf' is written to the
-program's standard input, and output from the program's standard output
-can be read by the 'gawk' program using 'getline'. As is the case with
-processes started by '|', the subprogram can be any program, or pipeline
+ The first time an I/O operation is executed using the â|&â operator,
+âgawkâ creates a two-way pipeline to a child process that runs the other
+program. Output created with âprintâ or âprintfâ is written to the
+programâs standard input, and output from the programâs standard output
+can be read by the âgawkâ program using âgetlineâ. As is the case with
+processes started by â|â, the subprogram can be any program, or pipeline
of programs, that can be started by the shell.
There are some cautionary items to be aware of:
- * As the code inside 'gawk' currently stands, the coprocess's
- standard error goes to the same place that the parent 'gawk''s
- standard error goes. It is not possible to read the child's
+ ⢠As the code inside âgawkâ currently stands, the coprocessâs
+ standard error goes to the same place that the parent âgawkââs
+ standard error goes. It is not possible to read the childâs
standard error separately.
- * I/O buffering may be a problem. 'gawk' automatically flushes all
+ ⢠I/O buffering may be a problem. âgawkâ automatically flushes all
output down the pipe to the coprocess. However, if the coprocess
- does not flush its output, 'gawk' may hang when doing a 'getline'
- in order to read the coprocess's results. This could lead to a
- situation known as "deadlock", where each process is waiting for
+ does not flush its output, âgawkâ may hang when doing a âgetlineâ
+ in order to read the coprocessâs results. This could lead to a
+ situation known as âdeadlockâ, where each process is waiting for
the other one to do something.
It is possible to close just one end of the two-way pipe to a
-coprocess, by supplying a second argument to the 'close()' function of
-either '"to"' or '"from"' (*note Close Files And Pipes::). These
-strings tell 'gawk' to close the end of the pipe that sends data to the
+coprocess, by supplying a second argument to the âclose()â function of
+either â"to"â or â"from"â (*note Close Files And Pipes::). These
+strings tell âgawkâ to close the end of the pipe that sends data to the
coprocess or the end that reads from it, respectively.
- This is particularly necessary in order to use the system 'sort'
-utility as part of a coprocess; 'sort' must read _all_ of its input data
-before it can produce any output. The 'sort' program does not receive
-an end-of-file indication until 'gawk' closes the write end of the pipe.
+ This is particularly necessary in order to use the system âsortâ
+utility as part of a coprocess; âsortâ must read _all_ of its input data
+before it can produce any output. The âsortâ program does not receive
+an end-of-file indication until âgawkâ closes the write end of the pipe.
- When you have finished writing data to the 'sort' utility, you can
-close the '"to"' end of the pipe, and then start reading sorted data via
-'getline'. For example:
+ When you have finished writing data to the âsortâ utility, you can
+close the â"to"â end of the pipe, and then start reading sorted data via
+âgetlineâ. For example:
BEGIN {
command = "LC_ALL=C sort"
@@ -21698,34 +21698,34 @@ close the '"to"' end of the pipe, and then start
reading sorted data via
}
This program writes the letters of the alphabet in reverse order, one
-per line, down the two-way pipe to 'sort'. It then closes the write end
-of the pipe, so that 'sort' receives an end-of-file indication. This
-causes 'sort' to sort the data and write the sorted data back to the
-'gawk' program. Once all of the data has been read, 'gawk' terminates
+per line, down the two-way pipe to âsortâ. It then closes the write end
+of the pipe, so that âsortâ receives an end-of-file indication. This
+causes âsortâ to sort the data and write the sorted data back to the
+âgawkâ program. Once all of the data has been read, âgawkâ terminates
the coprocess and exits.
- As a side note, the assignment 'LC_ALL=C' in the 'sort' command
-ensures traditional Unix (ASCII) sorting from 'sort'. This is not
-strictly necessary here, but it's good to know how to do this.
+ As a side note, the assignment âLC_ALL=Câ in the âsortâ command
+ensures traditional Unix (ASCII) sorting from âsortâ. This is not
+strictly necessary here, but itâs good to know how to do this.
- Be careful when closing the '"from"' end of a two-way pipe; in this
-case 'gawk' waits for the child process to exit, which may cause your
+ Be careful when closing the â"from"â end of a two-way pipe; in this
+case âgawkâ waits for the child process to exit, which may cause your
program to hang. (Thus, this particular feature is of much less use in
-practice than being able to close the '"to"' end.)
+practice than being able to close the â"to"â end.)
- CAUTION: Normally, it is a fatal error to write to the '"to"' end
+ CAUTION: Normally, it is a fatal error to write to the â"to"â end
of a two-way pipe which has been closed, and it is also a fatal
- error to read from the '"from"' end of a two-way pipe that has been
+ error to read from the â"from"â end of a two-way pipe that has been
closed.
- You may set 'PROCINFO["COMMAND", "NONFATAL"]' to make such
+ You may set âPROCINFO["COMMAND", "NONFATAL"]â to make such
operations become nonfatal. If you do so, you then need to check
- 'ERRNO' after each 'print', 'printf', or 'getline'. *Note
+ âERRNOâ after each âprintâ, âprintfâ, or âgetlineâ. *Note
Nonfatal::, for more information.
You may also use pseudo-ttys (ptys) for two-way communication instead
of pipes, if your system supports them. This is done on a per-command
-basis, by setting a special element in the 'PROCINFO' array (*note
+basis, by setting a special element in the âPROCINFOâ array (*note
Auto-set::), like so:
command = "sort -nr" # command, save in convenience variable
@@ -21733,33 +21733,33 @@ Auto-set::), like so:
print ... |& command # start two-way pipe
...
-If your system does not have ptys, or if all the system's ptys are in
-use, 'gawk' automatically falls back to using regular pipes.
+If your system does not have ptys, or if all the systemâs ptys are in
+use, âgawkâ automatically falls back to using regular pipes.
Using ptys usually avoids the buffer deadlock issues described
earlier, at some loss in performance. This is because the tty driver
-buffers and sends data line-by-line. On systems with the 'stdbuf' (part
+buffers and sends data line-by-line. On systems with the âstdbufâ (part
of the GNU Coreutils package
(https://www.gnu.org/software/coreutils/coreutils.html)), you can use
that program instead of ptys.
Note also that ptys are not fully transparent. Certain binary
-control codes, such 'Ctrl-d' for end-of-file, are interpreted by the tty
+control codes, such âCtrl-dâ for end-of-file, are interpreted by the tty
driver and not passed through.
- CAUTION: Finally, coprocesses open up the possibility of "deadlock"
- between 'gawk' and the program running in the coprocess. This can
- occur if you send "too much" data to the coprocess before reading
+ CAUTION: Finally, coprocesses open up the possibility of âdeadlockâ
+ between âgawkâ and the program running in the coprocess. This can
+ occur if you send âtoo muchâ data to the coprocess before reading
any back; each process is blocked writing data with no one
- available to read what they've already written. There is no
+ available to read what theyâve already written. There is no
workaround for deadlock; careful programming and knowledge of the
behavior of the coprocess are required.
The following example, due to Andrew Schorr, demonstrates how using
ptys can help deal with buffering deadlocks.
- Suppose 'gawk' were unable to add numbers. You could use a coprocess
-to do it. Here's an exceedingly simple program written for that
+ Suppose âgawkâ were unable to add numbers. You could use a coprocess
+to do it. Hereâs an exceedingly simple program written for that
purpose:
$ cat add.c
@@ -21775,29 +21775,29 @@ purpose:
}
$ cc -O add.c -o add Compile the program
- You could then write an exceedingly simple 'gawk' program to add
+ You could then write an exceedingly simple âgawkâ program to add
numbers by passing them to the coprocess:
$ echo 1 2 |
> gawk -v cmd=./add '{ print |& cmd; cmd |& getline x; print x }'
- And it would deadlock, because 'add.c' fails to call
-'setlinebuf(stdout)'. The 'add' program freezes.
+ And it would deadlock, because âadd.câ fails to call
+âsetlinebuf(stdout)â. The âaddâ program freezes.
Now try instead:
$ echo 1 2 |
> gawk -v cmd=add 'BEGIN { PROCINFO[cmd, "pty"] = 1 }
> { print |& cmd; cmd |& getline x; print x }'
- -| 3
+ ⣠3
- By using a pty, 'gawk' fools the standard I/O library into thinking
+ By using a pty, âgawkâ fools the standard I/O library into thinking
it has an interactive session, so it defaults to line buffering. And
now, magically, it works!
---------- Footnotes ----------
- (1) Michael Brennan suggests the use of 'rand()' to generate unique
+ (1) Michael Brennan suggests the use of ârand()â to generate unique
file names. This is a valid point; nevertheless, temporary files remain
more difficult to use than two-way pipes.
@@ -21807,15 +21807,15 @@ in Bash.
File: gawk.info, Node: TCP/IP Networking, Next: Profiling, Prev: Two-way
I/O, Up: Advanced Features
-12.5 Using 'gawk' for Network Programming
+12.5 Using âgawkâ for Network Programming
=========================================
- 'EMRED':
+ âEMREDâ:
A host is a host from coast to coast,
- and nobody talks to a host that's close,
- unless the host that isn't close
+ and nobody talks to a host thatâs close,
+ unless the host that isnât close
is busy, hung, or dead.
- -- _Mike O'Brien (aka Mr. Protocol)_
+ â _Mike OâBrien (aka Mr. Protocol)_
In addition to being able to open a two-way pipeline to a coprocess
on the same system (*note Two-way I/O::), it is possible to make a
@@ -21823,32 +21823,32 @@ two-way connection to another process on another
system across an IP
network connection.
You can think of this as just a _very long_ two-way pipeline to a
-coprocess. The way 'gawk' decides that you want to use TCP/IP
+coprocess. The way âgawkâ decides that you want to use TCP/IP
networking is by recognizing special file names that begin with one of
-'/inet/', '/inet4/', or '/inet6/'.
+â/inet/â, â/inet4/â, or â/inet6/â.
The full syntax of the special file name is
-'/NET-TYPE/PROTOCOL/LOCAL-PORT/REMOTE-HOST/REMOTE-PORT'. The components
+â/NET-TYPE/PROTOCOL/LOCAL-PORT/REMOTE-HOST/REMOTE-PORTâ. The components
are:
NET-TYPE
- Specifies the kind of Internet connection to make. Use '/inet4/'
- to force IPv4, and '/inet6/' to force IPv6. Plain '/inet/' (which
+ Specifies the kind of Internet connection to make. Use â/inet4/â
+ to force IPv4, and â/inet6/â to force IPv6. Plain â/inet/â (which
used to be the only option) uses the system default, most likely
IPv4.
PROTOCOL
- The protocol to use over IP. This must be either 'tcp', or 'udp',
+ The protocol to use over IP. This must be either âtcpâ, or âudpâ,
for a TCP or UDP IP connection, respectively. TCP should be used
for most applications.
LOCAL-PORT
- The local TCP or UDP port number to use. Use a port number of '0'
+ The local TCP or UDP port number to use. Use a port number of â0â
when you want the system to pick a port. This is what you should
do when writing a TCP or UDP client. You may also use a well-known
- service name, such as 'smtp' or 'http', in which case 'gawk'
+ service name, such as âsmtpâ or âhttpâ, in which case âgawkâ
attempts to determine the predefined port number using the C
- 'getaddrinfo()' function.
+ âgetaddrinfo()â function.
REMOTE-HOST
The IP address or fully qualified domain name of the Internet host
@@ -21856,10 +21856,10 @@ REMOTE-HOST
REMOTE-PORT
The TCP or UDP port number to use on the given REMOTE-HOST. Again,
- use '0' if you don't care, or else a well-known service name.
+ use â0â if you donât care, or else a well-known service name.
NOTE: Failure in opening a two-way socket will result in a nonfatal
- error being returned to the calling code. The value of 'ERRNO'
+ error being returned to the calling code. The value of âERRNOâ
indicates the error (*note Auto-set::).
Consider the following very simple example:
@@ -21871,42 +21871,42 @@ REMOTE-PORT
close(Service)
}
- This program reads the current date and time from the local system's
-TCP 'daytime' server. It then prints the results and closes the
+ This program reads the current date and time from the local systemâs
+TCP âdaytimeâ server. It then prints the results and closes the
connection.
- Because this topic is extensive, the use of 'gawk' for TCP/IP
+ Because this topic is extensive, the use of âgawkâ for TCP/IP
programming is documented separately. *Note General Introduction:
(gawkinet)Top, for a much more complete introduction and discussion, as
well as extensive examples.
- NOTE: 'gawk' can only open direct sockets. There is currently no
+ NOTE: âgawkâ can only open direct sockets. There is currently no
way to access services available over Secure Socket Layer (SSL);
- this includes any web service whose URL starts with 'https://'.
+ this includes any web service whose URL starts with âhttps://â.
File: gawk.info, Node: Profiling, Next: Persistent Memory, Prev: TCP/IP
Networking, Up: Advanced Features
-12.6 Profiling Your 'awk' Programs
+12.6 Profiling Your âawkâ Programs
==================================
-You may produce execution traces of your 'awk' programs. This is done
-by passing the option '--profile' to 'gawk'. When 'gawk' has finished
+You may produce execution traces of your âawkâ programs. This is done
+by passing the option â--profileâ to âgawkâ. When âgawkâ has
finished
running, it creates a profile of your program in a file named
-'awkprof.out'. Because it is profiling, it also executes up to 45%
-slower than 'gawk' normally does.
+âawkprof.outâ. Because it is profiling, it also executes up to 45%
+slower than âgawkâ normally does.
- As shown in the following example, the '--profile' option can be used
-to change the name of the file where 'gawk' will write the profile:
+ As shown in the following example, the â--profileâ option can be used
+to change the name of the file where âgawkâ will write the profile:
gawk --profile=myprog.prof -f myprog.awk data1 data2
-In the preceding example, 'gawk' places the profile in 'myprog.prof'
-instead of in 'awkprof.out'.
+In the preceding example, âgawkâ places the profile in âmyprog.profâ
+instead of in âawkprof.outâ.
- Here is a sample session showing a simple 'awk' program, its input
-data, and the results from running 'gawk' with the '--profile' option.
-First, the 'awk' program:
+ Here is a sample session showing a simple âawkâ program, its input
+data, and the results from running âgawkâ with the â--profileâ option.
+First, the âawkâ program:
BEGIN { print "First BEGIN rule" }
@@ -21942,9 +21942,9 @@ First, the 'awk' program:
foo
junk
- Here is the 'awkprof.out' that results from running the 'gawk'
+ Here is the âawkprof.outâ that results from running the âgawkâ
profiler on this program and data (this example also illustrates that
-'awk' programmers sometimes get up very early in the morning to work):
+âawkâ programmers sometimes get up very early in the morning to work):
# gawk profile, created Mon Sep 29 05:16:21 2014
@@ -21996,66 +21996,66 @@ profiler on this program and data (this example also
illustrates that
This example illustrates many of the basic features of profiling
output. They are as follows:
- * The program is printed in the order 'BEGIN' rules, 'BEGINFILE'
- rules, pattern-action rules, 'ENDFILE' rules, 'END' rules, and
- functions, listed alphabetically. Multiple 'BEGIN' and 'END' rules
- retain their separate identities, as do multiple 'BEGINFILE' and
- 'ENDFILE' rules.
-
- * Pattern-action rules have two counts. The first count, to the left
- of the rule, shows how many times the rule's pattern was _tested_.
- The second count, to the right of the rule's opening left brace in
- a comment, shows how many times the rule's action was _executed_.
- The difference between the two indicates how many times the rule's
+ ⢠The program is printed in the order âBEGINâ rules, âBEGINFILEâ
+ rules, patternâaction rules, âENDFILEâ rules, âENDâ rules, and
+ functions, listed alphabetically. Multiple âBEGINâ and âENDâ
rules
+ retain their separate identities, as do multiple âBEGINFILEâ and
+ âENDFILEâ rules.
+
+ ⢠Patternâaction rules have two counts. The first count, to the left
+ of the rule, shows how many times the ruleâs pattern was _tested_.
+ The second count, to the right of the ruleâs opening left brace in
+ a comment, shows how many times the ruleâs action was _executed_.
+ The difference between the two indicates how many times the ruleâs
pattern evaluated to false.
- * Similarly, the count for an 'if'-'else' statement shows how many
+ ⢠Similarly, the count for an âifâ-âelseâ statement shows how many
times the condition was tested. To the right of the opening left
- brace for the 'if''s body is a count showing how many times the
- condition was true. The count for the 'else' indicates how many
+ brace for the âifââs body is a count showing how many times the
+ condition was true. The count for the âelseâ indicates how many
times the test failed.
- * The count for a loop header (such as 'for' or 'while') shows how
- many times the loop test was executed. (Because of this, you can't
+ ⢠The count for a loop header (such as âforâ or âwhileâ) shows how
+ many times the loop test was executed. (Because of this, you canât
just look at the count on the first statement in a rule to
determine how many times the rule was executed. If the first
statement is a loop, the count is misleading.)
- * For user-defined functions, the count next to the 'function'
+ ⢠For user-defined functions, the count next to the âfunctionâ
keyword indicates how many times the function was called. The
counts next to the statements in the body show how many times those
statements were executed.
- * The layout uses "K&R" style with TABs. Braces are used everywhere,
- even when the body of an 'if', 'else', or loop is only a single
+ ⢠The layout uses âK&Râ style with TABs. Braces are used everywhere,
+ even when the body of an âifâ, âelseâ, or loop is only a single
statement.
- * Parentheses are used only where needed, as indicated by the
+ ⢠Parentheses are used only where needed, as indicated by the
structure of the program and the precedence rules. For example,
- '(3 + 5) * 4' means add three and five, then multiply the total by
- four. However, '3 + 5 * 4' has no parentheses, and means '3 + (5 *
- 4)'. However, explicit parentheses in the source program are
+ â(3 + 5) * 4â means add three and five, then multiply the total by
+ four. However, â3 + 5 * 4â has no parentheses, and means â3 + (5 *
+ 4)â. However, explicit parentheses in the source program are
retained.
- * Parentheses are used around the arguments to 'print' and 'printf'
- only when the 'print' or 'printf' statement is followed by a
- redirection. Similarly, if the target of a redirection isn't a
+ ⢠Parentheses are used around the arguments to âprintâ and
âprintfâ
+ only when the âprintâ or âprintfâ statement is followed by a
+ redirection. Similarly, if the target of a redirection isnât a
scalar, it gets parenthesized.
- * 'gawk' supplies leading comments in front of the 'BEGIN' and 'END'
- rules, the 'BEGINFILE' and 'ENDFILE' rules, the pattern-action
+ ⢠âgawkâ supplies leading comments in front of the âBEGINâ and
âENDâ
+ rules, the âBEGINFILEâ and âENDFILEâ rules, the patternâaction
rules, and the functions.
- * Functions are listed alphabetically. All functions in the 'awk'
+ ⢠Functions are listed alphabetically. All functions in the âawkâ
namespace are listed first, in alphabetical order. Then come the
functions in namespaces. The namespaces are listed in alphabetical
order, and the functions within each namespace are listed
alphabetically.
The profiled version of your program may not look exactly like what
-you typed when you wrote it. This is because 'gawk' creates the
-profiled version by "pretty-printing" its internal representation of the
-program. The advantage to this is that 'gawk' can produce a standard
+you typed when you wrote it. This is because âgawkâ creates the
+profiled version by âpretty-printingâ its internal representation of the
+program. The advantage to this is that âgawkâ can produce a standard
representation. Also, things such as:
/foo/
@@ -22067,25 +22067,25 @@ come out as:
}
which is correct, but possibly unexpected. (If a program uses both
-'print $0' and plain 'print', that distinction is retained.)
+âprint $0â and plain âprintâ, that distinction is retained.)
- Besides creating profiles when a program has completed, 'gawk' can
-produce a profile while it is running. This is useful if your 'awk'
+ Besides creating profiles when a program has completed, âgawkâ can
+produce a profile while it is running. This is useful if your âawkâ
program goes into an infinite loop and you want to see what has been
-executed. To use this feature, run 'gawk' with the '--profile' option
+executed. To use this feature, run âgawkâ with the â--profileâ option
in the background:
$ gawk --profile -f myprog &
[1] 13992
The shell prints a job number and process ID number; in this case,
-13992. Use the 'kill' command to send the 'USR1' signal to 'gawk':
+13992. Use the âkillâ command to send the âUSR1â signal to âgawkâ:
$ kill -USR1 13992
As usual, the profiled version of the program is written to
-'awkprof.out', or to a different file if one was specified with the
-'--profile' option.
+âawkprof.outâ, or to a different file if one was specified with the
+â--profileâ option.
Along with the regular profile, as shown earlier, the profile file
includes a trace of any active functions:
@@ -22097,39 +22097,39 @@ includes a trace of any active functions:
# 1. foo
# -- main --
- You may send 'gawk' the 'USR1' signal as many times as you like.
+ You may send âgawkâ the âUSR1â signal as many times as you like.
Each time, the profile and function call trace are appended to the
output profile file.
- If you use the 'HUP' signal instead of the 'USR1' signal, 'gawk'
+ If you use the âHUPâ signal instead of the âUSR1â signal, âgawkâ
produces the profile and the function call trace and then exits.
- When 'gawk' runs on MS-Windows systems, it uses the 'INT' and 'QUIT'
-signals for producing the profile, and in the case of the 'INT' signal,
-'gawk' exits. This is because these systems don't support the 'kill'
+ When âgawkâ runs on MS-Windows systems, it uses the âINTâ and
âQUITâ
+signals for producing the profile, and in the case of the âINTâ signal,
+âgawkâ exits. This is because these systems donât support the âkillâ
command, so the only signals you can deliver to a program are those
-generated by the keyboard. The 'INT' signal is generated by the
-'Ctrl-c' or 'Ctrl-BREAK' key, while the 'QUIT' signal is generated by
-the 'Ctrl-\' key.
+generated by the keyboard. The âINTâ signal is generated by the
+âCtrl-câ or âCtrl-BREAKâ key, while the âQUITâ signal is generated
by
+the âCtrl-\â key.
- Finally, 'gawk' also accepts another option, '--pretty-print'. When
-called this way, 'gawk' "pretty-prints" the program into 'awkprof.out',
+ Finally, âgawkâ also accepts another option, â--pretty-printâ. When
+called this way, âgawkâ âpretty-printsâ the program into
âawkprof.outâ,
without any execution counts.
- NOTE: Once upon a time, the '--pretty-print' option would also run
+ NOTE: Once upon a time, the â--pretty-printâ option would also run
your program. This is no longer the case.
There is a significant difference between the output created when
profiling, and that created when pretty-printing. Pretty-printed output
preserves the original comments that were in the program, although their
placement may not correspond exactly to their original locations in the
-source code. However, no comments should be lost. Also, 'gawk' does
+source code. However, no comments should be lost. Also, âgawkâ does
the best it can to preserve the distinction between comments at the end
-of a statement and comments on lines by themselves. This isn't always
+of a statement and comments on lines by themselves. This isnât always
perfect, though.
However, as a deliberate design decision, profiling output _omits_
-the original program's comments. This allows you to focus on the
+the original programâs comments. This allows you to focus on the
execution count data and helps you avoid the temptation to use the
profiler for pretty-printing.
@@ -22139,8 +22139,8 @@ pretty-print your code once development is completed,
and then use the
result as the final version of your program.
Because the internal representation of your program is formatted to
-recreate an 'awk' program, profiling and pretty-printing automatically
-disable 'gawk''s default optimizations.
+recreate an âawkâ program, profiling and pretty-printing automatically
+disable âgawkââs default optimizations.
Profiling and pretty-printing also preserve the original format of
numeric constants; if you used an octal or hexadecimal value in your
@@ -22152,48 +22152,48 @@ File: gawk.info, Node: Persistent Memory, Next:
Extension Philosophy, Prev: P
12.7 Preserving Data Between Runs
=================================
-Starting with version 5.2, 'gawk' supports "persistent memory". This
-experimental feature stores the values of all of 'gawk''s variables,
+Starting with version 5.2, âgawkâ supports âpersistent memoryâ. This
+experimental feature stores the values of all of âgawkââs variables,
arrays and user-defined functions in a persistent heap, which resides in
a file in the filesystem. When persistent memory is not in use (the
-normal case), 'gawk''s data resides in ephemeral system memory.
+normal case), âgawkââs data resides in ephemeral system memory.
Persistent memory is enabled on certain 64-bit systems supporting the
-'mmap()' and 'munmap()' system calls. 'gawk' must be compiled as a
+âmmap()â and âmunmap()â system calls. âgawkâ must be compiled as a
non-PIE (Position Independent Executable) binary, since the persistent
-store ends up holding pointers to functions held within the 'gawk'
+store ends up holding pointers to functions held within the âgawkâ
executable. This also means that to use the persistent memory, you must
-use the same 'gawk' executable from run to run.
+use the same âgawkâ executable from run to run.
- You can see if your version of 'gawk' supports persistent memory like
+ You can see if your version of âgawkâ supports persistent memory like
so:
$ gawk --version
- -| GNU Awk 5.2.1, API 3.2, PMA Avon 8-g1, (GNU MPFR 4.1.0, GNU MP 6.2.1)
- -| Copyright (C) 1989, 1991-2022 Free Software Foundation.
+ ⣠GNU Awk 5.2.1, API 3.2, PMA Avon 8-g1, (GNU MPFR 4.1.0, GNU MP 6.2.1)
+ ⣠Copyright (C) 1989, 1991-2022 Free Software Foundation.
...
-If you see the 'PMA' with a version indicator, then it's supported.
+If you see the âPMAâ with a version indicator, then itâs supported.
As of this writing, persistent memory has only been tested on
GNU/Linux, Cygwin, Solaris 2.11, Intel architecture macOS systems,
FreeBSD 13.1 and OpenBSD 7.1. On all others, persistent memory is
disabled by default. You can force it to be enabled by exporting the
-shell variable 'REALLY_USE_PERSIST_MALLOC' with a nonempty value before
-running 'configure' (*note Quick Installation::). If you do so and all
+shell variable âREALLY_USE_PERSIST_MALLOCâ with a nonempty value before
+running âconfigureâ (*note Quick Installation::). If you do so and all
the tests pass, please let the maintainer know.
To use persistent memory, follow these steps:
1. Create a new, empty sparse file of the desired size. For example,
- four gigabytes. On a GNU/Linux system, you can use the 'truncate'
+ four gigabytes. On a GNU/Linux system, you can use the âtruncateâ
utility:
$ truncate -s 4G data.pma
- 2. Provide the path to the data file in the 'GAWK_PERSIST_FILE'
+ 2. Provide the path to the data file in the âGAWK_PERSIST_FILEâ
environment variable. This is best done by placing the value in
- the environment just for the run of 'gawk', like so:
+ the environment just for the run of âgawkâ, like so:
$ GAWK_PERSIST_FILE=data.pma gawk 'BEGIN { print ++i }'
1
@@ -22207,107 +22207,107 @@ the tests pass, please let the maintainer know.
3
As shown, in subsequent runs using the same data file, the values
- of 'gawk''s variables are preserved. However, 'gawk''s special
- variables, such as 'NR', are reset upon each run. Only the
+ of âgawkââs variables are preserved. However, âgawkââs
special
+ variables, such as âNRâ, are reset upon each run. Only the
variables defined by the program are preserved across runs.
Interestingly, the program that you execute need not be the same from
run to run; the persistent store only maintains the values of variables,
-arrays, and user-defined functions, not the totality of 'gawk''s
+arrays, and user-defined functions, not the totality of âgawkââs
internal state. This lets you share data between unrelated programs,
eliminating the need for scripts to communicate via text files.
- Terence Kelly, the author of the persistent memory allocator 'gawk'
+ Terence Kelly, the author of the persistent memory allocator âgawkâ
uses, provides the following advice about the backing file:
Regarding backing file size, I recommend making it far larger than
all of the data that will ever reside in it, assuming that the file
- system supports sparse files. The "pay only for what you use"
+ system supports sparse files. The âpay only for what you useâ
aspect of sparse files ensures that the actual storage resource
- footprint of the backing file will meet the application's needs but
+ footprint of the backing file will meet the applicationâs needs but
will be as small as possible. If the file system does _not_
- support sparse files, there's a dilemma: Making the backing file
+ support sparse files, thereâs a dilemma: Making the backing file
too large is wasteful, but making it too small risks memory
- exhaustion, i.e., 'pma_malloc()' returns 'NULL'. But persistent
- 'gawk' should still work even without sparse files.
+ exhaustion, i.e., âpma_malloc()â returns âNULLâ. But persistent
+ âgawkâ should still work even without sparse files.
- You can disable the use of the persistent memory allocator in 'gawk'
-with the '--disable-pma' option to the 'configure' command at the time
-that you build 'gawk' (*note Unix Installation::).
+ You can disable the use of the persistent memory allocator in âgawkâ
+with the â--disable-pmaâ option to the âconfigureâ command at the time
+that you build âgawkâ (*note Unix Installation::).
- You can set the 'PMA_VERBOSITY' environment variable to a value
+ You can set the âPMA_VERBOSITYâ environment variable to a value
between zero and three to control how much debugging and error
-information the persistent memory allocator will print. 'gawk' sets the
-default to one. See the 'support/pma.c' source code to understand what
+information the persistent memory allocator will print. âgawkâ sets the
+default to one. See the âsupport/pma.câ source code to understand what
the different verbosity levels are.
- NOTE: If you use MPFR mode (the '-M' option) on the first run of a
+ NOTE: If you use MPFR mode (the â-Mâ option) on the first run of a
program using persistent memory, you _must_ continue to use it on
- all subsequent runs. Similarly, if you don't use '-M' on the first
+ all subsequent runs. Similarly, if you donât use â-Mâ on the first
run, do not use it on any subsequent runs.
Mixing and matching MPFR mode and regular mode with the same
- backing file is not allowed. 'gawk' detects such a situation and
+ backing file is not allowed. âgawkâ detects such a situation and
issues a fatal error message.
Additionally, the GNU/Linux CIFS filesystem is known to not work
- well with the PMA allocator. Don't use a backing file on a CIFS
+ well with the PMA allocator. Donât use a backing file on a CIFS
filesystem.
- Terence Kelly has provided a separate 'Persistent-Memory 'gawk' User
-Manual' document, which is included in the 'gawk' distribution. It is
+ Terence Kelly has provided a separate âPersistent-Memory âgawkâ User
+Manualâ document, which is included in the âgawkâ distribution. It is
worth reading. *Note General Introduction: (pm-gawk)Top.
Here are additional articles and web links that provide more
-information about persistent memory and why it's useful in a scripting
-language like 'gawk'.
+information about persistent memory and why itâs useful in a scripting
+language like âgawkâ.
<https://web.eecs.umich.edu/~tpkelly/pma/>
- This is the canonical source for Terence Kelly's Persistent Memory
+ This is the canonical source for Terence Kellyâs Persistent Memory
Allocator (PMA). The latest source code and user manual will always
be available at this location. Kelly may be reached directly at
any of the following email addresses: <tpkelly@acm.org>,
<tpkelly@cs.princeton.edu>, or <tpkelly@eecs.umich.edu>.
-'Persistent Memory Allocation'
- Terence Kelly, Zi Fan Tan, Jianan Li, and Haris Volos, ACM 'Queue'
+âPersistent Memory Allocationâ
+ Terence Kelly, Zi Fan Tan, Jianan Li, and Haris Volos, ACM âQueueâ
magazine, Vol. 20 No. 2 (March/April 2022), PDF
(https://dl.acm.org/doi/pdf/10.1145/3534855), HTML
(https://queue.acm.org/detail.cfm?id=3534855). This paper explains
- the design of the PMA allocator used in persistent 'gawk'.
+ the design of the PMA allocator used in persistent âgawkâ.
-'Persistent Scripting'
+âPersistent Scriptingâ
Zi Fan Tan, Jianan Li, Haris Volos, and Terence Kelly, Non-Volatile
Memory Workshop (NVMW) 2022, <http://nvmw.ucsd.edu/program/>. This
paper motivates and describes a research prototype of persistent
- 'gawk' and presents performance evaluations on Intel Optane
+ âgawkâ and presents performance evaluations on Intel Optane
non-volatile memory; note that the interface differs slightly.
-'Persistent Memory Programming on Conventional Hardware'
- Terence Kelly, ACM 'Queue' magazine Vol. 17 No. 4 (July/Aug
+âPersistent Memory Programming on Conventional Hardwareâ
+ Terence Kelly, ACM âQueueâ magazine Vol. 17 No. 4 (July/Aug
2019), PDF (https://dl.acm.org/doi/pdf/10.1145/3358955.3358957),
HTML (https://queue.acm.org/detail.cfm?id=3358957). This paper
describes simple techniques for persistent memory for C/C++ code on
conventional computers that lack non-volatile memory hardware.
-'Is Persistent Memory Persistent?'
- Terence Kelly, ACM 'Queue' magazine Vol. 18 No. 2 (March/April
+âIs Persistent Memory Persistent?â
+ Terence Kelly, ACM âQueueâ magazine Vol. 18 No. 2 (March/April
2020), PDF (https://dl.acm.org/doi/pdf/10.1145/3400899.3400902),
HTML (https://queue.acm.org/detail.cfm?id=3400902). This paper
describes a simple and robust testbed for testing software against
real power failures.
-'Crashproofing the Original NoSQL Key/Value Store'
- Terence Kelly, ACM 'Queue' magazine Vol. 19 No. 4 (July/Aug
+âCrashproofing the Original NoSQL Key/Value Storeâ
+ Terence Kelly, ACM âQueueâ magazine Vol. 19 No. 4 (July/Aug
2021), PDF (https://dl.acm.org/doi/pdf/10.1145/3487019.3487353),
HTML (https://queue.acm.org/detail.cfm?id=3487353). This paper
- describes a crash-tolerance feature added to GNU DBM' ('gdbm').
+ describes a crash-tolerance feature added to GNU DBMâ (âgdbmâ).
When Terence Kelly published his papers, his collaborators produced a
-prototype integration of PMA with 'gawk'. That version used a
-(mandatory!) option '--persist=FILE' to specify the file for storing
-the persistent heap. If this option is given to 'gawk', it produces a
-fatal error message instructing the user to use the 'GAWK_PERSIST_FILE'
+prototype integration of PMA with âgawkâ. That version used a
+(mandatory!) option â--persist=FILEâ to specify the file for storing
+the persistent heap. If this option is given to âgawkâ, it produces a
+fatal error message instructing the user to use the âGAWK_PERSIST_FILEâ
environment variable instead. Except for this paragraph, that option is
otherwise undocumented.
@@ -22320,7 +22320,7 @@ If it becomes burdensome,(1) then the feature will be
removed.
---------- Footnotes ----------
(1) Meaning, there are too many bug reports, or too many strange
-differences in behavior from when 'gawk' is run normally.
+differences in behavior from when âgawkâ is run normally.
File: gawk.info, Node: Extension Philosophy, Next: Advanced Features
Summary, Prev: Persistent Memory, Up: Advanced Features
@@ -22328,34 +22328,34 @@ File: gawk.info, Node: Extension Philosophy, Next:
Advanced Features Summary,
12.8 Builtin Features versus Extensions
=======================================
-As this and subsequent major nodes show, 'gawk' has a large number of
-extensions over standard 'awk' built-in to the program. These have
+As this and subsequent major nodes show, âgawkâ has a large number of
+extensions over standard âawkâ built-in to the program. These have
developed over time. More recently, the focus has moved to using the
extension mechanism (*note Dynamic Extensions::) for adding features.
-This minor node discusses the "guiding philosophy" behind what should be
+This minor node discusses the âguiding philosophyâ behind what should be
added to the interpreter as a built-in feature versus what should be
done in extensions.
There are several goals:
- 1. Keep the language 'awk'; it should not become unrecognizable, even
- if programs in it will only run on 'gawk'.
+ 1. Keep the language âawkâ; it should not become unrecognizable, even
+ if programs in it will only run on âgawkâ.
2. Keep the core from getting any larger unless absolutely necessary.
- 3. Add new functionality either in 'awk' scripts ('-f', '@include') or
- in loadable extensions written in C or C++ ('-l', '@load').
+ 3. Add new functionality either in âawkâ scripts (â-fâ,
â@includeâ) or
+ in loadable extensions written in C or C++ (â-lâ, â@loadâ).
4. Extend the core interpreter only if some feature is:
A. Truly desirable.
B. Cannot be done via library files or loadable extensions.
C. Can be implemented without too much pain in the core.
- Combining modules with 'awk' files is a powerful technique. Some of
+ Combining modules with âawkâ files is a powerful technique. Some of
the sample extensions demonstrate this.
Loading extensions and library files should not be done
-automatically, because then there's overhead that most users don't want
+automatically, because then thereâs overhead that most users donât want
or need.
@@ -22364,60 +22364,60 @@ File: gawk.info, Node: Advanced Features Summary,
Prev: Extension Philosophy,
12.9 Summary
============
- * The '--non-decimal-data' option causes 'gawk' to treat octal- and
+ ⢠The â--non-decimal-dataâ option causes âgawkâ to treat octal-
and
hexadecimal-looking input data as octal and hexadecimal. This
option should be used with caution or not at all; use of
- 'strtonum()' is preferable. Note that this option may disappear in
- a future version of 'gawk'.
+ âstrtonum()â is preferable. Note that this option may disappear in
+ a future version of âgawkâ.
- * You can take over complete control of sorting in 'for (INDX in
- ARRAY)' array traversal by setting 'PROCINFO["sorted_in"]' to the
+ ⢠You can take over complete control of sorting in âfor (INDX in
+ ARRAY)â array traversal by setting âPROCINFO["sorted_in"]â to the
name of a user-defined function that does the comparison of array
elements based on index and value.
- * Similarly, you can supply the name of a user-defined comparison
- function as the third argument to either 'asort()' or 'asorti()' to
+ ⢠Similarly, you can supply the name of a user-defined comparison
+ function as the third argument to either âasort()â or âasorti()â
to
control how those functions sort arrays. Or you may provide one of
the predefined control strings that work for
- 'PROCINFO["sorted_in"]'.
+ âPROCINFO["sorted_in"]â.
- * You can use the '|&' operator to create a two-way pipe to a
- coprocess. You read from the coprocess with 'getline' and write to
- it with 'print' or 'printf'. Use 'close()' to close off the
+ ⢠You can use the â|&â operator to create a two-way pipe to a
+ coprocess. You read from the coprocess with âgetlineâ and write to
+ it with âprintâ or âprintfâ. Use âclose()â to close off the
coprocess completely, or optionally, close off one side of the
two-way communications.
- * By using special file names with the '|&' operator, you can open a
+ ⢠By using special file names with the â|&â operator, you can open a
TCP/IP (or UDP/IP) connection to remote hosts on the Internet.
- 'gawk' supports both IPv4 and IPv6.
+ âgawkâ supports both IPv4 and IPv6.
- * You can generate statement count profiles of your program. This
+ ⢠You can generate statement count profiles of your program. This
can help you determine which parts of your program may be taking
the most time and let you tune them more easily. Sending the
- 'USR1' signal while profiling causes 'gawk' to dump the profile and
+ âUSR1â signal while profiling causes âgawkâ to dump the profile
and
keep going, including a function call stack.
- * You can also just "pretty-print" the program.
+ ⢠You can also just âpretty-printâ the program.
- * Persistent memory allows you to preserve the values of variables
- and arrays between runs of 'gawk'. This feature is currently
+ ⢠Persistent memory allows you to preserve the values of variables
+ and arrays between runs of âgawkâ. This feature is currently
experimental.
- * New features should be developed using the extension mechanism if
+ ⢠New features should be developed using the extension mechanism if
possible; they should be added to the core interpreter only as a
last resort.
File: gawk.info, Node: Internationalization, Next: Debugger, Prev: Advanced
Features, Up: Top
-13 Internationalization with 'gawk'
+13 Internationalization with âgawkâ
***********************************
Moon... Gorgeous... MEDITATION!
- -- _Pretty Guardian Sailor Moon Eternal, The Movie_
+ â _Pretty Guardian Sailor Moon Eternal, The Movie_
It probably sounded better in Japanese.
- -- _Malka Robbins_
+ â _Malka Robbins_
Once upon a time, computer makers wrote software that worked only in
English. Eventually, hardware and software vendors noticed that if
@@ -22428,21 +22428,21 @@ became a common practice.
For many years, the ability to provide internationalization was
largely restricted to programs written in C and C++. This major node
-describes the underlying library 'gawk' uses for internationalization,
-as well as how 'gawk' makes internationalization features available at
-the 'awk' program level. Having internationalization available at the
-'awk' level gives software developers additional flexibility--they are
-no longer forced to write in C or C++ when internationalization is a
+describes the underlying library âgawkâ uses for internationalization,
+as well as how âgawkâ makes internationalization features available at
+the âawkâ program level. Having internationalization available at the
+âawkâ level gives software developers additional flexibilityâthey are no
+longer forced to write in C or C++ when internationalization is a
requirement.
* Menu:
* I18N and L10N:: Internationalization and Localization.
-* Explaining gettext:: How GNU 'gettext' works.
+* Explaining gettext:: How GNU âgettextâ works.
* Programmer i18n:: Features for the programmer.
* Translator i18n:: Features for the translator.
* I18N Example:: A simple i18n example.
-* Gawk I18N:: 'gawk' is also internationalized.
+* Gawk I18N:: âgawkâ is also internationalized.
* I18N Summary:: Summary of I18N stuff.
@@ -22451,9 +22451,9 @@ File: gawk.info, Node: I18N and L10N, Next:
Explaining gettext, Up: Internati
13.1 Internationalization and Localization
==========================================
-"Internationalization" means writing (or modifying) a program once, in
+âInternationalizationâ means writing (or modifying) a program once, in
such a way that it can use multiple languages without requiring further
-source code changes. "Localization" means providing the data necessary
+source code changes. âLocalizationâ means providing the data necessary
for an internationalized program to work in a particular language. Most
typically, these terms refer to features such as the language used for
printing error messages, the language used to read responses, and
@@ -22463,77 +22463,77 @@ read.
File: gawk.info, Node: Explaining gettext, Next: Programmer i18n, Prev:
I18N and L10N, Up: Internationalization
-13.2 GNU 'gettext'
+13.2 GNU âgettextâ
==================
-'gawk' uses GNU 'gettext' to provide its internationalization features.
-The facilities in GNU 'gettext' focus on messages: strings printed by a
-program, either directly or via formatting with 'printf' or
-'sprintf()'.(1)
+âgawkâ uses GNU âgettextâ to provide its internationalization features.
+The facilities in GNU âgettextâ focus on messages: strings printed by a
+program, either directly or via formatting with âprintfâ or
+âsprintf()â.(1)
- When using GNU 'gettext', each application has its own "text domain".
-This is a unique name, such as 'kpilot' or 'gawk', that identifies the
+ When using GNU âgettextâ, each application has its own âtext
domainâ.
+This is a unique name, such as âkpilotâ or âgawkâ, that identifies the
application. A complete application may have multiple
-components--programs written in C or C++, as well as scripts written in
-'sh' or 'awk'. All of the components use the same text domain.
+componentsâprograms written in C or C++, as well as scripts written in
+âshâ or âawkâ. All of the components use the same text domain.
- To make the discussion concrete, assume we're writing an application
-named 'guide'. Internationalization consists of the following steps, in
+ To make the discussion concrete, assume weâre writing an application
+named âguideâ. Internationalization consists of the following steps, in
this order:
- 1. The programmer reviews the source for all of 'guide''s components
+ 1. The programmer reviews the source for all of âguideââs components
and marks each string that is a candidate for translation. For
- example, '"`-F': option required"' is a good candidate for
+ example, â"`-F': option required"â is a good candidate for
translation. A table with strings of option names is not (e.g.,
- 'gawk''s '--profile' option should remain the same, no matter what
+ âgawkââs â--profileâ option should remain the same, no matter
what
the local language).
- 2. The programmer indicates the application's text domain ('"guide"')
- to the 'gettext' library, by calling the 'textdomain()' function.
+ 2. The programmer indicates the applicationâs text domain (â"guide"â)
+ to the âgettextâ library, by calling the âtextdomain()â function.
3. Messages from the application are extracted from the source code
- and collected into a portable object template file ('guide.pot'),
+ and collected into a portable object template file (âguide.potâ),
which lists the strings and their translations. The translations
are initially empty. The original (usually English) messages serve
as the key for lookup of the translations.
- 4. For each language with a translator, 'guide.pot' is copied to a
- portable object file ('.po') and translations are created and
+ 4. For each language with a translator, âguide.potâ is copied to a
+ portable object file (â.poâ) and translations are created and
shipped with the application. For example, there might be a
- 'fr.po' for a French translation.
+ âfr.poâ for a French translation.
- 5. Each language's '.po' file is converted into a binary message
- object ('.gmo') file. A message object file contains the original
+ 5. Each languageâs â.poâ file is converted into a binary message
+ object (â.gmoâ) file. A message object file contains the original
messages and their translations in a binary format that allows fast
lookup of translations at runtime.
- 6. When 'guide' is built and installed, the binary translation files
+ 6. When âguideâ is built and installed, the binary translation files
are installed in a standard place.
- 7. For testing and development, it is possible to tell 'gettext' to
- use '.gmo' files in a different directory than the standard one by
- using the 'bindtextdomain()' function.
+ 7. For testing and development, it is possible to tell âgettextâ to
+ use â.gmoâ files in a different directory than the standard one by
+ using the âbindtextdomain()â function.
- 8. At runtime, 'guide' looks up each string via a call to 'gettext()'.
+ 8. At runtime, âguideâ looks up each string via a call to
âgettext()â.
The returned string is the translated string if available, or the
original string if not.
9. If necessary, it is possible to access messages from a different
text domain than the one belonging to the application, without
- having to switch the application's default text domain back and
+ having to switch the applicationâs default text domain back and
forth.
In C (or C++), the string marking and dynamic translation lookup are
-accomplished by wrapping each string in a call to 'gettext()':
+accomplished by wrapping each string in a call to âgettext()â:
printf("%s", gettext("Don't Panic!\n"));
The tools that extract messages from source code pull out all strings
-enclosed in calls to 'gettext()'.
+enclosed in calls to âgettext()â.
- The GNU 'gettext' developers, recognizing that typing 'gettext(...)'
+ The GNU âgettextâ developers, recognizing that typing âgettext(...)â
over and over again is both painful and ugly to look at, use the macro
-'_' (an underscore) to make things easier:
+â_â (an underscore) to make things easier:
/* In the standard header file: */
#define _(str) gettext(str)
@@ -22544,63 +22544,63 @@ over and over again is both painful and ugly to look
at, use the macro
This reduces the typing overhead to just three extra characters per
string and is considerably easier to read as well.
- There are locale "categories" for different types of locale-related
-information. The defined locale categories that 'gettext' knows about
+ There are locale âcategoriesâ for different types of locale-related
+information. The defined locale categories that âgettextâ knows about
are:
-'LC_MESSAGES'
- Text messages. This is the default category for 'gettext'
+âLC_MESSAGESâ
+ Text messages. This is the default category for âgettextâ
operations, but it is possible to supply a different one
explicitly, if necessary. (It is almost never necessary to supply
a different category.)
-'LC_COLLATE'
+âLC_COLLATEâ
Text-collation information (i.e., how different characters and/or
groups of characters sort in a given language).
-'LC_CTYPE'
+âLC_CTYPEâ
Character-type information (alphabetic, digit, upper- or lowercase,
and so on) as well as character encoding. This information is
accessed via the POSIX character classes in regular expressions,
- such as '/[[:alnum:]]/' (*note Bracket Expressions::).
+ such as â/[[:alnum:]]/â (*note Bracket Expressions::).
-'LC_MONETARY'
+âLC_MONETARYâ
Monetary information, such as the currency symbol, and whether the
symbol goes before or after a number.
-'LC_NUMERIC'
+âLC_NUMERICâ
Numeric information, such as which characters to use for the
decimal point and the thousands separator.(2)
-'LC_TIME'
+âLC_TIMEâ
Time- and date-related information, such as 12- or 24-hour clock,
month printed before or after the day in a date, local month
abbreviations, and so on.
-'LC_ALL'
- All of the above. (Not too useful in the context of 'gettext'.)
+âLC_ALLâ
+ All of the above. (Not too useful in the context of âgettextâ.)
NOTE: As described in *note Locales::, environment variables with
- the same name as the locale categories ('LC_CTYPE', 'LC_ALL', etc.)
- influence 'gawk''s behavior (and that of other utilities).
+ the same name as the locale categories (âLC_CTYPEâ, âLC_ALLâ,
etc.)
+ influence âgawkââs behavior (and that of other utilities).
- Normally, these variables also affect how the 'gettext' library
- finds translations. However, the 'LANGUAGE' environment variable
- overrides the 'LC_XXX' variables. Many GNU/Linux systems may
- define this variable without your knowledge, causing 'gawk' to not
+ Normally, these variables also affect how the âgettextâ library
+ finds translations. However, the âLANGUAGEâ environment variable
+ overrides the âLC_XXXâ variables. Many GNU/Linux systems may
+ define this variable without your knowledge, causing âgawkâ to not
find the correct translations. If this happens to you, look to see
- if 'LANGUAGE' is defined, and if so, use the shell's 'unset'
+ if âLANGUAGEâ is defined, and if so, use the shellâs âunsetâ
command to remove it.
- For testing translations of 'gawk' itself, you can set the
-'GAWK_LOCALE_DIR' environment variable. See the documentation for the C
-'bindtextdomain()' function and also see *note Other Environment
+ For testing translations of âgawkâ itself, you can set the
+âGAWK_LOCALE_DIRâ environment variable. See the documentation for the C
+âbindtextdomain()â function and also see *note Other Environment
Variables::.
---------- Footnotes ----------
- (1) For some operating systems, the 'gawk' port doesn't support GNU
-'gettext'. Therefore, these features are not available if you are using
+ (1) For some operating systems, the âgawkâ port doesnât support GNU
+âgettextâ. Therefore, these features are not available if you are using
one of those operating systems. Sorry.
(2) Americans use a comma every three decimal places and a period for
@@ -22610,73 +22610,73 @@ the decimal point, while many Europeans do exactly
the opposite:
File: gawk.info, Node: Programmer i18n, Next: Translator i18n, Prev:
Explaining gettext, Up: Internationalization
-13.3 Internationalizing 'awk' Programs
+13.3 Internationalizing âawkâ Programs
======================================
-'gawk' provides the following variables for internationalization:
+âgawkâ provides the following variables for internationalization:
-'TEXTDOMAIN'
- This variable indicates the application's text domain. For
- compatibility with GNU 'gettext', the default value is
- '"messages"'.
+âTEXTDOMAINâ
+ This variable indicates the applicationâs text domain. For
+ compatibility with GNU âgettextâ, the default value is
+ â"messages"â.
-'_"your message here"'
+â_"your message here"â
String constants marked with a leading underscore are candidates
for translation at runtime. String constants without a leading
underscore are not translated.
- 'gawk' provides the following functions for internationalization:
+ âgawkâ provides the following functions for internationalization:
-'dcgettext(STRING [, DOMAIN [, CATEGORY]])'
+âdcgettext(STRING [, DOMAIN [, CATEGORY]])â
Return the translation of STRING in text domain DOMAIN for locale
category CATEGORY. The default value for DOMAIN is the current
- value of 'TEXTDOMAIN'. The default value for CATEGORY is
- '"LC_MESSAGES"'.
+ value of âTEXTDOMAINâ. The default value for CATEGORY is
+ â"LC_MESSAGES"â.
If you supply a value for CATEGORY, it must be a string equal to
one of the known locale categories described in *note Explaining
- gettext::. You must also supply a text domain. Use 'TEXTDOMAIN'
+ gettext::. You must also supply a text domain. Use âTEXTDOMAINâ
if you want to use the current domain.
- CAUTION: The order of arguments to the 'awk' version of the
- 'dcgettext()' function is purposely different from the order
- for the C version. The 'awk' version's order was chosen to be
- simple and to allow for reasonable 'awk'-style default
+ CAUTION: The order of arguments to the âawkâ version of the
+ âdcgettext()â function is purposely different from the order
+ for the C version. The âawkâ versionâs order was chosen to be
+ simple and to allow for reasonable âawkâ-style default
arguments.
-'dcngettext(STRING1, STRING2, NUMBER [, DOMAIN [, CATEGORY]])'
+âdcngettext(STRING1, STRING2, NUMBER [, DOMAIN [, CATEGORY]])â
Return the plural form used for NUMBER of the translation of
STRING1 and STRING2 in text domain DOMAIN for locale category
CATEGORY. STRING1 is the English singular variant of a message,
and STRING2 is the English plural variant of the same message. The
- default value for DOMAIN is the current value of 'TEXTDOMAIN'. The
- default value for CATEGORY is '"LC_MESSAGES"'.
+ default value for DOMAIN is the current value of âTEXTDOMAINâ. The
+ default value for CATEGORY is â"LC_MESSAGES"â.
- The same remarks about argument order as for the 'dcgettext()'
+ The same remarks about argument order as for the âdcgettext()â
function apply.
-'bindtextdomain(DIRECTORY [, DOMAIN ])'
- Change the directory in which 'gettext' looks for '.gmo' files, in
+âbindtextdomain(DIRECTORY [, DOMAIN ])â
+ Change the directory in which âgettextâ looks for â.gmoâ files, in
case they will not or cannot be placed in the standard locations
(e.g., during testing). Return the directory in which DOMAIN is
- "bound."
+ âbound.â
- The default DOMAIN is the value of 'TEXTDOMAIN'. If DIRECTORY is
- the null string ('""'), then 'bindtextdomain()' returns the current
+ The default DOMAIN is the value of âTEXTDOMAINâ. If DIRECTORY is
+ the null string (â""â), then âbindtextdomain()â returns the
current
binding for the given DOMAIN.
- To use these facilities in your 'awk' program, follow these steps:
+ To use these facilities in your âawkâ program, follow these steps:
- 1. Set the variable 'TEXTDOMAIN' to the text domain of your program.
- This is best done in a 'BEGIN' rule (*note BEGIN/END::), or it can
- also be done via the '-v' command-line option (*note Options::):
+ 1. Set the variable âTEXTDOMAINâ to the text domain of your program.
+ This is best done in a âBEGINâ rule (*note BEGIN/END::), or it can
+ also be done via the â-vâ command-line option (*note Options::):
BEGIN {
TEXTDOMAIN = "guide"
...
}
- 2. Mark all translatable strings with a leading underscore ('_')
+ 2. Mark all translatable strings with a leading underscore (â_â)
character. It _must_ be adjacent to the opening quote of the
string. For example:
@@ -22685,7 +22685,7 @@ File: gawk.info, Node: Programmer i18n, Next:
Translator i18n, Prev: Explaini
printf(_"Number of users is %d\n", nusers)
3. If you are creating strings dynamically, you can still translate
- them, using the 'dcgettext()' built-in function:(1)
+ them, using the âdcgettext()â built-in function:(1)
if (groggy)
message = dcgettext("%d customers disturbing me\n", "adminprog")
@@ -22693,12 +22693,12 @@ File: gawk.info, Node: Programmer i18n, Next:
Translator i18n, Prev: Explaini
message = dcgettext("enjoying %d customers\n", "adminprog")
printf(message, ncustomers)
- Here, the call to 'dcgettext()' supplies a different text domain
- ('"adminprog"') in which to find the message, but it uses the
- default '"LC_MESSAGES"' category.
+ Here, the call to âdcgettext()â supplies a different text domain
+ (â"adminprog"â) in which to find the message, but it uses the
+ default â"LC_MESSAGES"â category.
- The previous example only works if 'ncustomers' is greater than
- one. This example would be better done with 'dcngettext()':
+ The previous example only works if âncustomersâ is greater than
+ one. This example would be better done with âdcngettext()â:
if (groggy)
message = dcngettext("%d customer disturbing me\n",
@@ -22710,9 +22710,9 @@ File: gawk.info, Node: Programmer i18n, Next:
Translator i18n, Prev: Explaini
ncustomers, "adminprog")
printf(message, ncustomers)
- 4. During development, you might want to put the '.gmo' file in a
+ 4. During development, you might want to put the â.gmoâ file in a
private directory for testing. This is done with the
- 'bindtextdomain()' built-in function:
+ âbindtextdomain()â built-in function:
BEGIN {
TEXTDOMAIN = "guide" # our text domain
@@ -22726,7 +22726,7 @@ File: gawk.info, Node: Programmer i18n, Next:
Translator i18n, Prev: Explaini
}
*Note I18N Example:: for an example program showing the steps to
-create and use translations from 'awk'.
+create and use translations from âawkâ.
---------- Footnotes ----------
@@ -22735,23 +22735,23 @@ create and use translations from 'awk'.
File: gawk.info, Node: Translator i18n, Next: I18N Example, Prev:
Programmer i18n, Up: Internationalization
-13.4 Translating 'awk' Programs
+13.4 Translating âawkâ Programs
===============================
-Once a program's translatable strings have been marked, they must be
-extracted to create the initial '.pot' file. As part of translation, it
-is often helpful to rearrange the order in which arguments to 'printf'
+Once a programâs translatable strings have been marked, they must be
+extracted to create the initial â.potâ file. As part of translation, it
+is often helpful to rearrange the order in which arguments to âprintfâ
are output.
- 'gawk''s '--gen-pot' command-line option extracts the messages and is
-discussed next. After that, 'printf''s ability to rearrange the order
-for 'printf' arguments at runtime is covered.
+ âgawkââs â--gen-potâ command-line option extracts the messages
and is
+discussed next. After that, âprintfââs ability to rearrange the order
+for âprintfâ arguments at runtime is covered.
* Menu:
* String Extraction:: Extracting marked strings.
-* Printf Ordering:: Rearranging 'printf' arguments.
-* I18N Portability:: 'awk'-level portability issues.
+* Printf Ordering:: Rearranging âprintfâ arguments.
+* I18N Portability:: âawkâ-level portability issues.
File: gawk.info, Node: String Extraction, Next: Printf Ordering, Up:
Translator i18n
@@ -22759,36 +22759,36 @@ File: gawk.info, Node: String Extraction, Next:
Printf Ordering, Up: Translat
13.4.1 Extracting Marked Strings
--------------------------------
-Once your 'awk' program is working, and all the strings have been marked
-and you've set (and perhaps bound) the text domain, it is time to
-produce translations. First, use the '--gen-pot' command-line option to
-create the initial '.pot' file:
+Once your âawkâ program is working, and all the strings have been marked
+and youâve set (and perhaps bound) the text domain, it is time to
+produce translations. First, use the â--gen-potâ command-line option to
+create the initial â.potâ file:
gawk --gen-pot -f guide.awk > guide.pot
- When run with '--gen-pot', 'gawk' does not execute your program.
+ When run with â--gen-potâ, âgawkâ does not execute your program.
Instead, it parses it as usual and prints all marked strings to standard
-output in the format of a GNU 'gettext' Portable Object file. Also
+output in the format of a GNU âgettextâ Portable Object file. Also
included in the output are any constant strings that appear as the first
-argument to 'dcgettext()' or as the first and second argument to
-'dcngettext()'.(1) You should distribute the generated '.pot' file with
-your 'awk' program; translators will eventually use it to provide you
+argument to âdcgettext()â or as the first and second argument to
+âdcngettext()â.(1) You should distribute the generated â.potâ file
with
+your âawkâ program; translators will eventually use it to provide you
translations that you can also then distribute. *Note I18N Example::
for the full list of steps to go through to create and test translations
-for 'guide'.
+for âguideâ.
---------- Footnotes ----------
- (1) The 'xgettext' utility that comes with GNU 'gettext' can handle
-'.awk' files.
+ (1) The âxgettextâ utility that comes with GNU âgettextâ can handle
+â.awkâ files.
File: gawk.info, Node: Printf Ordering, Next: I18N Portability, Prev:
String Extraction, Up: Translator i18n
-13.4.2 Rearranging 'printf' Arguments
+13.4.2 Rearranging âprintfâ Arguments
-------------------------------------
-Format strings for 'printf' and 'sprintf()' (*note Printf::) present a
+Format strings for âprintfâ and âsprintf()â (*note Printf::) present a
special problem for translation. Consider the following:(1)
printf(_"String `%s' has %d characters\n",
@@ -22799,20 +22799,20 @@ special problem for translation. Consider the
following:(1)
"%d Zeichen lang ist die Zeichenkette `%s'\n"
The problem should be obvious: the order of the format specifications
-is different from the original! Even though 'gettext()' can return the
+is different from the original! Even though âgettext()â can return the
translated string at runtime, it cannot change the argument order in the
-call to 'printf'.
+call to âprintfâ.
- To solve this problem, 'printf' format specifiers may have an
-additional optional element, which we call a "positional specifier".
+ To solve this problem, âprintfâ format specifiers may have an
+additional optional element, which we call a âpositional specifierâ.
For example:
"%2$d Zeichen lang ist die Zeichenkette `%1$s'\n"
Here, the positional specifier consists of an integer count, which
-indicates which argument to use, and a '$'. Counts are one-based, and
+indicates which argument to use, and a â$â. Counts are one-based, and
the format string itself is _not_ included. Thus, in the following
-example, 'string' is the first argument and 'length(string)' is the
+example, âstringâ is the first argument and âlength(string)â is the
second:
$ gawk 'BEGIN {
@@ -22820,7 +22820,7 @@ second:
> printf "%2$d characters live in \"%1$s\"\n",
> string, length(string)
> }'
- -| 11 characters live in "Don't Panic"
+ ⣠11 characters live in "Don't Panic"
If present, positional specifiers come first in the format
specification, before the flags, the field width, and/or the precision.
@@ -22832,42 +22832,42 @@ precision capability:
> printf("%*.*s\n", 10, 20, "hello")
> printf("%3$*2$.*1$s\n", 20, 10, "hello")
> }'
- -| hello
- -| hello
+ ⣠hello
+ ⣠hello
- NOTE: When using '*' with a positional specifier, the '*' comes
- first, then the integer position, and then the '$'. This is
+ NOTE: When using â*â with a positional specifier, the â*â comes
+ first, then the integer position, and then the â$â. This is
somewhat counterintuitive.
- 'gawk' does not allow you to mix regular format specifiers and those
+ âgawkâ does not allow you to mix regular format specifiers and those
with positional specifiers in the same string:
$ gawk 'BEGIN { printf "%d %3$s\n", 1, 2, "hi" }'
- error-> gawk: cmd. line:1: fatal: must use `count$' on all formats or none
+ errorâ gawk: cmd. line:1: fatal: must use `count$' on all formats or
none
- NOTE: There are some pathological cases that 'gawk' may fail to
+ NOTE: There are some pathological cases that âgawkâ may fail to
diagnose. In such cases, the output may not be what you expect.
- It's still a bad idea to try mixing them, even if 'gawk' doesn't
+ Itâs still a bad idea to try mixing them, even if âgawkâ doesnât
detect it.
- Although positional specifiers can be used directly in 'awk'
+ Although positional specifiers can be used directly in âawkâ
programs, their primary purpose is to help in producing correct
translations of format strings into languages different from the one in
which the program is first written.
---------- Footnotes ----------
- (1) This example is borrowed from the GNU 'gettext' manual.
+ (1) This example is borrowed from the GNU âgettextâ manual.
File: gawk.info, Node: I18N Portability, Prev: Printf Ordering, Up:
Translator i18n
-13.4.3 'awk' Portability Issues
+13.4.3 âawkâ Portability Issues
-------------------------------
-'gawk''s internationalization features were purposely chosen to have as
-little impact as possible on the portability of 'awk' programs that use
-them to other versions of 'awk'. Consider this program:
+âgawkââs internationalization features were purposely chosen to have as
+little impact as possible on the portability of âawkâ programs that use
+them to other versions of âawkâ. Consider this program:
BEGIN {
TEXTDOMAIN = "guide"
@@ -22876,19 +22876,19 @@ them to other versions of 'awk'. Consider this
program:
print _"don't panic!"
}
-As written, it won't work on other versions of 'awk'. However, it is
+As written, it wonât work on other versions of âawkâ. However, it is
actually almost portable, requiring very little change:
- * Assignments to 'TEXTDOMAIN' won't have any effect, because
- 'TEXTDOMAIN' is not special in other 'awk' implementations.
+ ⢠Assignments to âTEXTDOMAINâ wonât have any effect, because
+ âTEXTDOMAINâ is not special in other âawkâ implementations.
- * Non-GNU versions of 'awk' treat marked strings as the concatenation
- of a variable named '_' with the string following it.(1)
- Typically, the variable '_' has the null string ('""') as its
+ ⢠Non-GNU versions of âawkâ treat marked strings as the concatenation
+ of a variable named â_â with the string following it.(1)
+ Typically, the variable â_â has the null string (â""â) as its
value, leaving the original string constant as the result.
- * By defining "dummy" functions to replace 'dcgettext()',
- 'dcngettext()', and 'bindtextdomain()', the 'awk' program can be
+ ⢠By defining âdummyâ functions to replace âdcgettext()â,
+ âdcngettext()â, and âbindtextdomain()â, the âawkâ program can
be
made to run, but all the messages are output in the original
language. For example:
@@ -22907,22 +22907,22 @@ actually almost portable, requiring very little
change:
return (number == 1 ? string1 : string2)
}
- * The use of positional specifications in 'printf' or 'sprintf()' is
- _not_ portable. To support 'gettext()' at the C level, many
- systems' C versions of 'sprintf()' do support positional
+ ⢠The use of positional specifications in âprintfâ or âsprintf()â
is
+ _not_ portable. To support âgettext()â at the C level, many
+ systemsâ C versions of âsprintf()â do support positional
specifiers. But it works only if enough arguments are supplied in
- the function call. Many versions of 'awk' pass 'printf' formats
+ the function call. Many versions of âawkâ pass âprintfâ formats
and arguments unchanged to the underlying C library version of
- 'sprintf()', but only one format and argument at a time. What
- happens if a positional specification is used is anybody's guess.
+ âsprintf()â, but only one format and argument at a time. What
+ happens if a positional specification is used is anybodyâs guess.
However, because the positional specifications are primarily for
- use in _translated_ format strings, and because non-GNU 'awk's
+ use in _translated_ format strings, and because non-GNU âawkâs
never retrieve the translated string, this should not be a problem
in practice.
---------- Footnotes ----------
- (1) This is good fodder for an "Obfuscated 'awk'" contest.
+ (1) This is good fodder for an âObfuscated âawkââ contest.
File: gawk.info, Node: I18N Example, Next: Gawk I18N, Prev: Translator
i18n, Up: Internationalization
@@ -22930,8 +22930,8 @@ File: gawk.info, Node: I18N Example, Next: Gawk I18N,
Prev: Translator i18n,
13.5 A Simple Internationalization Example
==========================================
-Now let's look at a step-by-step example of how to internationalize and
-localize a simple 'awk' program, using 'guide.awk' as our original
+Now letâs look at a step-by-step example of how to internationalize and
+localize a simple âawkâ program, using âguide.awkâ as our original
source:
BEGIN {
@@ -22942,7 +22942,7 @@ source:
print "Pardon me, Zaphod who?"
}
-Run 'gawk --gen-pot' to create the '.pot' file:
+Run âgawk --gen-potâ to create the â.potâ file:
$ gawk --gen-pot -f guide.awk > guide.pot
@@ -22958,14 +22958,14 @@ This produces:
This original portable object template file is saved and reused for
-each language into which the application is translated. The 'msgid' is
-the original string and the 'msgstr' is the translation.
+each language into which the application is translated. The âmsgidâ is
+the original string and the âmsgstrâ is the translation.
NOTE: Strings not marked with a leading underscore do not appear in
- the 'guide.pot' file.
+ the âguide.potâ file.
Next, the messages must be translated. Here is a translation to a
-hypothetical dialect of English, called "Mellow":(1)
+hypothetical dialect of English, called âMellowâ:(1)
$ cp guide.pot guide-mellow.po
ADD TRANSLATIONS TO guide-mellow.po ...
@@ -22988,65 +22988,65 @@ Following are the translations:
other operating systems.
The next step is to make the directory to hold the binary message
-object file and then to create the 'guide.mo' file. The directory has
-the form 'LOCALE/LC_MESSAGES', where LOCALE is a locale name known to
-the C 'gettext' routines.
+object file and then to create the âguide.moâ file. The directory has
+the form âLOCALE/LC_MESSAGESâ, where LOCALE is a locale name known to
+the C âgettextâ routines.
How do we know which locale to use? It turns out that there are four
-different environment variables used by the C 'gettext' routines. In
-order, they are '$LANGUAGE', '$LC_ALL', '$LANG', and '$LC_MESSAGES'.(2)
-Thus, we check the value of '$LANGUAGE':
+different environment variables used by the C âgettextâ routines. In
+order, they are â$LANGUAGEâ, â$LC_ALLâ, â$LANGâ, and
â$LC_MESSAGESâ.(2)
+Thus, we check the value of â$LANGUAGEâ:
$ echo $LANGUAGE
- -| en_US.UTF-8
+ ⣠en_US.UTF-8
We next make the directories:
$ mkdir en_US.UTF-8 en_US.UTF-8/LC_MESSAGES
- The 'msgfmt' utility converts the human-readable '.po' file into a
-machine-readable '.mo' file. By default, 'msgfmt' creates a file named
-'messages'. This file must be renamed and placed in the proper
-directory (using the '-o' option) so that 'gawk' can find it:
+ The âmsgfmtâ utility converts the human-readable â.poâ file into a
+machine-readable â.moâ file. By default, âmsgfmtâ creates a file named
+âmessagesâ. This file must be renamed and placed in the proper
+directory (using the â-oâ option) so that âgawkâ can find it:
$ msgfmt guide-mellow.po -o en_US.UTF-8/LC_MESSAGES/guide.mo
Finally, we run the program to test it:
$ gawk -f guide.awk
- -| Hey man, relax!
- -| Like, the scoop is 42
- -| Pardon me, Zaphod who?
+ ⣠Hey man, relax!
+ ⣠Like, the scoop is 42
+ ⣠Pardon me, Zaphod who?
- If the three replacement functions for 'dcgettext()', 'dcngettext()',
-and 'bindtextdomain()' (*note I18N Portability::) are in a file named
-'libintl.awk', then we can run 'guide.awk' unchanged as follows:
+ If the three replacement functions for âdcgettext()â,
âdcngettext()â,
+and âbindtextdomain()â (*note I18N Portability::) are in a file named
+âlibintl.awkâ, then we can run âguide.awkâ unchanged as follows:
$ gawk --posix -f guide.awk -f libintl.awk
- -| Don't Panic
- -| The Answer Is 42
- -| Pardon me, Zaphod who?
+ ⣠Don't Panic
+ ⣠The Answer Is 42
+ ⣠Pardon me, Zaphod who?
---------- Footnotes ----------
- (1) Perhaps it would be better if it were called "Hippy." Ah, well.
+ (1) Perhaps it would be better if it were called âHippy.â Ah, well.
- (2) Well, sort of. It seems that if '$LC_ALL' is set to 'C', then no
+ (2) Well, sort of. It seems that if â$LC_ALLâ is set to âCâ, then
no
translations are done. Go figure.
File: gawk.info, Node: Gawk I18N, Next: I18N Summary, Prev: I18N Example,
Up: Internationalization
-13.6 'gawk' Can Speak Your Language
+13.6 âgawkâ Can Speak Your Language
===================================
-'gawk' itself has been internationalized using the GNU 'gettext'
-package. (GNU 'gettext' is described in complete detail in *Note GNU
-'gettext' utilities: (gettext)Top.) As of this writing, the latest
-version of GNU 'gettext' is version 0.19.8.1
+âgawkâ itself has been internationalized using the GNU âgettextâ
+package. (GNU âgettextâ is described in complete detail in *Note GNU
+âgettextâ utilities: (gettext)Top.) As of this writing, the latest
+version of GNU âgettextâ is version 0.19.8.1
(ftp://ftp.gnu.org/gnu/gettext/gettext-0.19.8.1.tar.gz).
- If a translation of 'gawk''s messages exists, then 'gawk' produces
+ If a translation of âgawkââs messages exists, then âgawkâ produces
usage messages, warnings, and fatal errors in the local language.
@@ -23055,51 +23055,51 @@ File: gawk.info, Node: I18N Summary, Prev: Gawk
I18N, Up: Internationalizatio
13.7 Summary
============
- * Internationalization means writing a program such that it can use
+ ⢠Internationalization means writing a program such that it can use
multiple languages without requiring source code changes.
Localization means providing the data necessary for an
internationalized program to work in a particular language.
- * 'gawk' uses GNU 'gettext' to let you internationalize and localize
- 'awk' programs. A program's text domain identifies the program for
+ ⢠âgawkâ uses GNU âgettextâ to let you internationalize and
localize
+ âawkâ programs. A programâs text domain identifies the program for
grouping all messages and other data together.
- * You mark a program's strings for translation by preceding them with
+ ⢠You mark a programâs strings for translation by preceding them with
an underscore. Once that is done, the strings are extracted into a
- '.pot' file. This file is copied for each language into a '.po'
- file, and the '.po' files are compiled into '.gmo' files for use at
+ â.potâ file. This file is copied for each language into a â.poâ
+ file, and the â.poâ files are compiled into â.gmoâ files for use
at
runtime.
- * You can use positional specifications with 'sprintf()' and 'printf'
+ ⢠You can use positional specifications with âsprintf()â and
âprintfâ
to rearrange the placement of argument values in formatted strings
and output. This is useful for the translation of format control
strings.
- * The internationalization features have been designed so that they
- can be easily worked around in a standard 'awk'.
+ ⢠The internationalization features have been designed so that they
+ can be easily worked around in a standard âawkâ.
- * 'gawk' itself has been internationalized and ships with a number of
+ ⢠âgawkâ itself has been internationalized and ships with a number of
translations for its messages.
File: gawk.info, Node: Debugger, Next: Namespaces, Prev:
Internationalization, Up: Top
-14 Debugging 'awk' Programs
+14 Debugging âawkâ Programs
***************************
It would be nice if computer programs worked perfectly the first time
they were run, but in real life, this rarely happens for programs of any
complexity. Thus, most programming languages have facilities available
-for "debugging" programs, and 'awk' is no exception.
+for âdebuggingâ programs, and âawkâ is no exception.
- The 'gawk' debugger is purposely modeled after the GNU Debugger (GDB)
+ The âgawkâ debugger is purposely modeled after the GNU Debugger (GDB)
(https://www.gnu.org/software/gdb/) command-line debugger. If you are
-familiar with GDB, learning how to use 'gawk' for debugging your
+familiar with GDB, learning how to use âgawkâ for debugging your
programs is easy.
* Menu:
-* Debugging:: Introduction to 'gawk' debugger.
+* Debugging:: Introduction to âgawkâ debugger.
* Sample Debugging Session:: Sample debugging session.
* List of Debugger Commands:: Main debugger commands.
* Readline Support:: Readline support.
@@ -23109,11 +23109,11 @@ programs is easy.
File: gawk.info, Node: Debugging, Next: Sample Debugging Session, Up:
Debugger
-14.1 Introduction to the 'gawk' Debugger
+14.1 Introduction to the âgawkâ Debugger
========================================
This minor node introduces debugging in general and begins the
-discussion of debugging in 'gawk'.
+discussion of debugging in âgawkâ.
* Menu:
@@ -23131,28 +23131,28 @@ File: gawk.info, Node: Debugging Concepts, Next:
Debugging Terms, Up: Debuggi
ahead to *note Awk Debugging::.)
Of course, a debugging program cannot remove bugs for you, because it
-has no way of knowing what you or your users consider a "bug" versus a
-"feature." (Sometimes, we humans have a hard time with this ourselves.)
+has no way of knowing what you or your users consider a âbugâ versus a
+âfeature.â (Sometimes, we humans have a hard time with this ourselves.)
In that case, what can you expect from such a tool? The answer to that
depends on the language being debugged, but in general, you can expect
at least the following:
- * The ability to watch a program execute its instructions one by one,
+ ⢠The ability to watch a program execute its instructions one by one,
giving you, the programmer, the opportunity to think about what is
happening on a time scale of seconds, minutes, or hours, rather
than the nanosecond time scale at which the code usually runs.
- * The opportunity to not only passively observe the operation of your
+ ⢠The opportunity to not only passively observe the operation of your
program, but to control it and try different paths of execution,
without having to change your source files.
- * The chance to see the values of data in the program at any point in
+ ⢠The chance to see the values of data in the program at any point in
execution, and also to change that data on the fly, to see how that
affects what happens afterward. (This often includes the ability
to look at internal data structures besides the variables you
actually defined in your code.)
- * The ability to obtain additional information about your program's
+ ⢠The ability to obtain additional information about your programâs
state or even its internal structure.
All of these tools provide a great amount of help in using your own
@@ -23170,44 +23170,44 @@ Before diving in to the details, we need to introduce
several important
concepts that apply to just about all debuggers. The following list
defines terms used throughout the rest of this major node:
-"Stack frame"
+âStack frameâ
Programs generally call functions during the course of their
execution. One function can call another, or a function can call
itself (recursion). You can view the chain of called functions
(main program calls A, which calls B, which calls C), as a stack of
executing functions: the currently running function is the topmost
one on the stack, and when it finishes (returns), the next one down
- then becomes the active function. Such a stack is termed a "call
- stack".
+ then becomes the active function. Such a stack is termed a âcall
+ stackâ.
For each function on the call stack, the system maintains a data
- area that contains the function's parameters, local variables, and
- return value, as well as any other "bookkeeping" information needed
- to manage the call stack. This data area is termed a "stack
- frame".
+ area that contains the functionâs parameters, local variables, and
+ return value, as well as any other âbookkeepingâ information needed
+ to manage the call stack. This data area is termed a âstack
+ frameâ.
- 'gawk' also follows this model, and gives you access to the call
+ âgawkâ also follows this model, and gives you access to the call
stack and to each stack frame. You can see the call stack, as well
as from where each function on the stack was invoked. Commands
that print the call stack print information about each stack frame
(as detailed later on).
-"Breakpoint"
+âBreakpointâ
During debugging, you often wish to let the program run until it
reaches a certain point, and then continue execution from there one
statement (or instruction) at a time. The way to do this is to set
- a "breakpoint" within the program. A breakpoint is where the
+ a âbreakpointâ within the program. A breakpoint is where the
execution of the program should break off (stop), so that you can
- take over control of the program's execution. You can add and
+ take over control of the programâs execution. You can add and
remove as many breakpoints as you like.
-"Watchpoint"
+âWatchpointâ
A watchpoint is similar to a breakpoint. The difference is that
breakpoints are oriented around the code: stop when a certain point
in the code is reached. A watchpoint, however, specifies that
program execution should stop when a _data value_ is changed. This
is useful, as sometimes it happens that a variable receives an
- erroneous value, and it's hard to track down where this happens
+ erroneous value, and itâs hard to track down where this happens
just by looking at the code. By using a watchpoint, you can stop
whenever a variable is assigned to, and usually find the errant
code quite quickly.
@@ -23215,39 +23215,39 @@ defines terms used throughout the rest of this major
node:
File: gawk.info, Node: Awk Debugging, Prev: Debugging Terms, Up: Debugging
-14.1.3 'awk' Debugging
+14.1.3 âawkâ Debugging
----------------------
-Debugging an 'awk' program has some specific aspects that are not shared
+Debugging an âawkâ program has some specific aspects that are not shared
with programs written in other languages.
- First of all, the fact that 'awk' programs usually take input line by
+ First of all, the fact that âawkâ programs usually take input line by
line from a file or files and operate on those lines using specific
rules makes it especially useful to organize viewing the execution of
-the program in terms of these rules. As we will see, each 'awk' rule is
+the program in terms of these rules. As we will see, each âawkâ rule is
treated almost like a function call, with its own specific block of
instructions.
- In addition, because 'awk' is by design a very concise language, it
-is easy to lose sight of everything that is going on "inside" each line
-of 'awk' code. The debugger provides the opportunity to look at the
-individual primitive instructions carried out by the higher-level 'awk'
+ In addition, because âawkâ is by design a very concise language, it
+is easy to lose sight of everything that is going on âinsideâ each line
+of âawkâ code. The debugger provides the opportunity to look at the
+individual primitive instructions carried out by the higher-level âawkâ
commands.(1)
---------- Footnotes ----------
- (1) The "primitive instructions" are defined by 'gawk' itself; the
+ (1) The âprimitive instructionsâ are defined by âgawkâ itself; the
debugger does not work at the level of machine instructions.
File: gawk.info, Node: Sample Debugging Session, Next: List of Debugger
Commands, Prev: Debugging, Up: Debugger
-14.2 Sample 'gawk' Debugging Session
+14.2 Sample âgawkâ Debugging Session
====================================
-In order to illustrate the use of 'gawk' as a debugger, let's look at a
-sample debugging session. We will use the 'awk' implementation of the
-POSIX 'uniq' command presented earlier (*note Uniq Program::) as our
+In order to illustrate the use of âgawkâ as a debugger, letâs look at a
+sample debugging session. We will use the âawkâ implementation of the
+POSIX âuniqâ command presented earlier (*note Uniq Program::) as our
example.
* Menu:
@@ -23261,27 +23261,27 @@ File: gawk.info, Node: Debugger Invocation, Next:
Finding The Bug, Up: Sample
14.2.1 How to Start the Debugger
--------------------------------
-Starting the debugger is almost exactly like running 'gawk' normally,
-except you have to pass an additional option, '--debug', or the
-corresponding short option, '-D'. The file(s) containing the program
+Starting the debugger is almost exactly like running âgawkâ normally,
+except you have to pass an additional option, â--debugâ, or the
+corresponding short option, â-Dâ. The file(s) containing the program
and any supporting code are given on the command line as arguments to
-one or more '-f' options. ('gawk' is not designed to debug command-line
+one or more â-fâ options. (âgawkâ is not designed to debug
command-line
programs, only programs contained in files.) In our case, we invoke the
debugger like this:
$ gawk -D -f getopt.awk -f join.awk -f uniq.awk -- -1 inputfile
-where both 'getopt.awk' and 'uniq.awk' are in '$AWKPATH'. (Experienced
+where both âgetopt.awkâ and âuniq.awkâ are in â$AWKPATHâ.
(Experienced
users of GDB or similar debuggers should note that this syntax is
-slightly different from what you are used to. With the 'gawk' debugger,
+slightly different from what you are used to. With the âgawkâ debugger,
you give the arguments for running the program in the command line to
-the debugger rather than as part of the 'run' command at the debugger
-prompt.) The '--' ends 'gawk''s command line options. It's not
-strictly necessary here, but it is needed if an option to the 'awk'
-program conflicts with a 'gawk' option. The '-1' is an option to
-'uniq.awk'.
+the debugger rather than as part of the ârunâ command at the debugger
+prompt.) The â--â ends âgawkââs command line options. Itâs not
+strictly necessary here, but it is needed if an option to the âawkâ
+program conflicts with a âgawkâ option. The â-1â is an option to
+âuniq.awkâ.
- Instead of immediately running the program on 'inputfile', as 'gawk'
+ Instead of immediately running the program on âinputfileâ, as âgawkâ
would ordinarily do, the debugger merely loads all the program source
files, compiles them internally, and then gives us a prompt:
@@ -23296,8 +23296,8 @@ File: gawk.info, Node: Finding The Bug, Prev:
Debugger Invocation, Up: Sample
14.2.2 Finding the Bug
----------------------
-Let's say that we are having a problem using (a faulty version of)
-'uniq.awk' in "field-skipping" mode, and it doesn't seem to be catching
+Letâs say that we are having a problem using (a faulty version of)
+âuniq.awkâ in âfield-skippingâ mode, and it doesnât seem to be
catching
lines which should be identical when skipping the first field, such as:
awk is a wonderful program!
@@ -23318,163 +23318,163 @@ we wrote:
The first thing we usually want to do when trying to investigate a
problem like this is to put a breakpoint in the program so that we can
watch it at work and catch what it is doing wrong. A reasonable spot
-for a breakpoint in 'uniq.awk' is at the beginning of the function
-'are_equal()', which compares the current line with the previous one.
-To set the breakpoint, use the 'b' (breakpoint) command:
+for a breakpoint in âuniq.awkâ is at the beginning of the function
+âare_equal()â, which compares the current line with the previous one.
+To set the breakpoint, use the âbâ (breakpoint) command:
gawk> b are_equal
- -| Breakpoint 1 set at file `awklib/eg/prog/uniq.awk', line 63
+ ⣠Breakpoint 1 set at file `awklib/eg/prog/uniq.awk', line 63
The debugger tells us the file and line number where the breakpoint
-is. Now type 'r' or 'run' and the program runs until it hits the
+is. Now type ârâ or ârunâ and the program runs until it hits the
breakpoint for the first time:
gawk> r
- -| Starting program:
- -| Stopping in Rule ...
- -| Breakpoint 1, are_equal(n, m, clast, cline, alast, aline)
+ ⣠Starting program:
+ ⣠Stopping in Rule ...
+ ⣠Breakpoint 1, are_equal(n, m, clast, cline, alast, aline)
at `awklib/eg/prog/uniq.awk':63
- -| 63 if (fcount == 0 && charcount == 0)
+ ⣠63 if (fcount == 0 && charcount == 0)
gawk>
- Now we can look at what's going on inside our program. First of all,
-let's see how we got to where we are. At the prompt, we type 'bt'
-(short for "backtrace"), and the debugger responds with a listing of the
+ Now we can look at whatâs going on inside our program. First of all,
+letâs see how we got to where we are. At the prompt, we type âbtâ
+(short for âbacktraceâ), and the debugger responds with a listing of the
current stack frames:
gawk> bt
- -| #0 are_equal(n, m, clast, cline, alast, aline)
+ ⣠#0 are_equal(n, m, clast, cline, alast, aline)
at `awklib/eg/prog/uniq.awk':68
- -| #1 in main() at `awklib/eg/prog/uniq.awk':88
+ ⣠#1 in main() at `awklib/eg/prog/uniq.awk':88
- This tells us that 'are_equal()' was called by the main program at
-line 88 of 'uniq.awk'. (This is not a big surprise, because this is the
-only call to 'are_equal()' in the program, but in more complex programs,
+ This tells us that âare_equal()â was called by the main program at
+line 88 of âuniq.awkâ. (This is not a big surprise, because this is the
+only call to âare_equal()â in the program, but in more complex programs,
knowing who called a function and with what parameters can be the key to
finding the source of the problem.)
- Now that we're in 'are_equal()', we can start looking at the values
-of some variables. Let's say we type 'p n' ('p' is short for "print").
-We would expect to see the value of 'n', a parameter to 'are_equal()'.
+ Now that weâre in âare_equal()â, we can start looking at the values
+of some variables. Letâs say we type âp nâ (âpâ is short for
âprintâ).
+We would expect to see the value of ânâ, a parameter to âare_equal()â.
Actually, the debugger gives us:
gawk> p n
- -| n = untyped variable
+ ⣠n = untyped variable
-In this case, 'n' is an uninitialized local variable, because the
+In this case, ânâ is an uninitialized local variable, because the
function was called without arguments (*note Function Calls::).
A more useful variable to display might be the current record:
gawk> p $0
- -| $0 = "gawk is a wonderful program!"
+ ⣠$0 = "gawk is a wonderful program!"
This might be a bit puzzling at first, as this is the second line of our
-test input. Let's look at 'NR':
+test input. Letâs look at âNRâ:
gawk> p NR
- -| NR = 2
+ ⣠NR = 2
-So we can see that 'are_equal()' was only called for the second record
+So we can see that âare_equal()â was only called for the second record
of the file. Of course, this is because our program contains a rule for
-'NR == 1':
+âNR == 1â:
NR == 1 {
last = $0
next
}
- OK, let's just check that that rule worked correctly:
+ OK, letâs just check that that rule worked correctly:
gawk> p last
- -| last = "awk is a wonderful program!"
+ ⣠last = "awk is a wonderful program!"
Everything we have done so far has verified that the program has
-worked as planned, up to and including the call to 'are_equal()', so the
+worked as planned, up to and including the call to âare_equal()â, so the
problem must be inside this function. To investigate further, we must
-begin "stepping through" the lines of 'are_equal()'. We start by typing
-'n' (for "next"):
+begin âstepping throughâ the lines of âare_equal()â. We start by
typing
+ânâ (for ânextâ):
gawk> n
- -| 66 if (fcount > 0) {
+ ⣠66 if (fcount > 0) {
- This tells us that 'gawk' is now ready to execute line 66, which
-decides whether to give the lines the special "field-skipping" treatment
-indicated by the '-1' command-line option. (Notice that we skipped from
+ This tells us that âgawkâ is now ready to execute line 66, which
+decides whether to give the lines the special âfield-skippingâ treatment
+indicated by the â-1â command-line option. (Notice that we skipped from
where we were before, at line 63, to here, because the condition in line
-63, 'if (fcount == 0 && charcount == 0)', was false.)
+63, âif (fcount == 0 && charcount == 0)â, was false.)
Continuing to step, we now get to the splitting of the current and
last records:
gawk> n
- -| 67 n = split(last, alast)
+ ⣠67 n = split(last, alast)
gawk> n
- -| 68 m = split($0, aline)
+ ⣠68 m = split($0, aline)
At this point, we should be curious to see what our records were
split into, so we try to look:
gawk> p n m alast aline
- -| n = 5
- -| m = untyped variable
- -| alast = array, 5 elements
- -| aline = untyped variable
+ ⣠n = 5
+ ⣠m = untyped variable
+ ⣠alast = array, 5 elements
+ ⣠aline = untyped variable
-(The 'p' command can take more than one argument, similar to 'awk''s
-'print' statement.)
+(The âpâ command can take more than one argument, similar to âawkââs
+âprintâ statement.)
This is kind of disappointing, though. All we found out is that
-there are five elements in 'alast'; 'm' and 'aline' don't have values
-because we are at line 68 but haven't executed it yet. This information
+there are five elements in âalastâ; âmâ and âalineâ donât have
values
+because we are at line 68 but havenât executed it yet. This information
is useful enough (we now know that none of the words were accidentally
left out), but what if we want to see inside the array?
The first choice would be to use subscripts:
gawk> p alast[0]
- -| "0" not in array `alast'
+ ⣠"0" not in array `alast'
Oops!
gawk> p alast[1]
- -| alast["1"] = "awk"
+ ⣠alast["1"] = "awk"
- This would be kind of slow for a 100-member array, though, so 'gawk'
+ This would be kind of slow for a 100-member array, though, so âgawkâ
provides a shortcut (reminiscent of another language not to be
mentioned):
gawk> p @alast
- -| alast["1"] = "awk"
- -| alast["2"] = "is"
- -| alast["3"] = "a"
- -| alast["4"] = "wonderful"
- -| alast["5"] = "program!"
+ ⣠alast["1"] = "awk"
+ ⣠alast["2"] = "is"
+ ⣠alast["3"] = "a"
+ ⣠alast["4"] = "wonderful"
+ ⣠alast["5"] = "program!"
- It looks like we got this far OK. Let's take another step or two:
+ It looks like we got this far OK. Letâs take another step or two:
gawk> n
- -| 69 clast = join(alast, fcount, n)
+ ⣠69 clast = join(alast, fcount, n)
gawk> n
- -| 70 cline = join(aline, fcount, m)
+ ⣠70 cline = join(aline, fcount, m)
Well, here we are at our error (sorry to spoil the suspense). What
we had in mind was to join the fields starting from the second one to
make the virtual record to compare, and if the first field were numbered
-zero, this would work. Let's look at what we've got:
+zero, this would work. Letâs look at what weâve got:
gawk> p cline clast
- -| cline = "gawk is a wonderful program!"
- -| clast = "awk is a wonderful program!"
+ ⣠cline = "gawk is a wonderful program!"
+ ⣠clast = "awk is a wonderful program!"
- Hey, those look pretty familiar! They're just our original,
+ Hey, those look pretty familiar! Theyâre just our original,
unaltered input records. A little thinking (the human brain is still
the best debugging tool), and we realize that we were off by one!
We get out of the debugger:
gawk> q
- -| The program is running. Exit anyway (y/n)? y
+ ⣠The program is running. Exit anyway (y/n)? y
Then we get into an editor:
@@ -23489,28 +23489,28 @@ File: gawk.info, Node: List of Debugger Commands,
Next: Readline Support, Pre
14.3 Main Debugger Commands
===========================
-The 'gawk' debugger command set can be divided into the following
+The âgawkâ debugger command set can be divided into the following
categories:
- * Breakpoint control
+ ⢠Breakpoint control
- * Execution control
+ ⢠Execution control
- * Viewing and changing data
+ ⢠Viewing and changing data
- * Working with the stack
+ ⢠Working with the stack
- * Getting information
+ ⢠Getting information
- * Miscellaneous
+ ⢠Miscellaneous
Each of these are discussed in the following subsections. In the
following descriptions, commands that may be abbreviated show the
abbreviation on a second description line. A debugger command name may
also be truncated if that partial name is unambiguous. The debugger has
the built-in capability to automatically repeat the previous command
-just by hitting 'Enter'. This works for the commands 'list', 'next',
-'nexti', 'step', 'stepi', and 'continue' executed without any argument.
+just by hitting âEnterâ. This works for the commands âlistâ,
ânextâ,
+ânextiâ, âstepâ, âstepiâ, and âcontinueâ executed without any
argument.
* Menu:
@@ -23533,8 +23533,8 @@ debugging session is to get your breakpoints set up,
because your
program will otherwise just run as if it was not under the debugger.
The commands for controlling breakpoints are:
-'break' [[FILENAME':']N | FUNCTION] ['"EXPRESSION"']
-'b' [[FILENAME':']N | FUNCTION] ['"EXPRESSION"']
+âbreakâ [[FILENAMEâ:â]N | FUNCTION] [â"EXPRESSION"â]
+âbâ [[FILENAMEâ:â]N | FUNCTION] [â"EXPRESSION"â]
Without any argument, set a breakpoint at the next instruction to
be executed in the selected stack frame. Arguments can be one of
the following:
@@ -23542,7 +23542,7 @@ The commands for controlling breakpoints are:
N
Set a breakpoint at line number N in the current source file.
- FILENAME':'N
+ FILENAMEâ:âN
Set a breakpoint at line number N in source file FILENAME.
FUNCTION
@@ -23550,15 +23550,15 @@ The commands for controlling breakpoints are:
function FUNCTION.
Each breakpoint is assigned a number that can be used to delete it
- from the breakpoint list using the 'delete' command.
+ from the breakpoint list using the âdeleteâ command.
With a breakpoint, you may also supply a condition. This is an
- 'awk' expression (enclosed in double quotes) that the debugger
+ âawkâ expression (enclosed in double quotes) that the debugger
evaluates whenever the breakpoint is reached. If the condition is
true, then the debugger stops execution and prompts for a command.
Otherwise, it continues executing the program.
-'clear' [[FILENAME':']N | FUNCTION]
+âclearâ [[FILENAMEâ:â]N | FUNCTION]
Without any argument, delete any breakpoint at the next instruction
to be executed in the selected stack frame. If the program stops
at a breakpoint, this deletes that breakpoint so that the program
@@ -23569,16 +23569,16 @@ The commands for controlling breakpoints are:
Delete breakpoint(s) set at line number N in the current
source file.
- FILENAME':'N
+ FILENAMEâ:âN
Delete breakpoint(s) set at line number N in source file
FILENAME.
FUNCTION
Delete breakpoint(s) set at entry to function FUNCTION.
-'condition' N '"EXPRESSION"'
+âconditionâ N â"EXPRESSION"â
Add a condition to existing breakpoint or watchpoint N. The
- condition is an 'awk' expression _enclosed in double quotes_ that
+ condition is an âawkâ expression _enclosed in double quotes_ that
the debugger evaluates whenever the breakpoint or watchpoint is
reached. If the condition is true, then the debugger stops
execution and prompts for a command. Otherwise, the debugger
@@ -23586,36 +23586,36 @@ The commands for controlling breakpoints are:
not specified, any existing condition is removed (i.e., the
breakpoint or watchpoint is made unconditional).
-'delete' [N1 N2 ...] [N-M]
-'d' [N1 N2 ...] [N-M]
+âdeleteâ [N1 N2 ...] [NâM]
+âdâ [N1 N2 ...] [NâM]
Delete specified breakpoints or a range of breakpoints. Delete all
defined breakpoints if no argument is supplied.
-'disable' [N1 N2 ... | N-M]
+âdisableâ [N1 N2 ... | NâM]
Disable specified breakpoints or a range of breakpoints. Without
any argument, disable all breakpoints.
-'enable' ['del' | 'once'] [N1 N2 ...] [N-M]
-'e' ['del' | 'once'] [N1 N2 ...] [N-M]
+âenableâ [âdelâ | âonceâ] [N1 N2 ...] [NâM]
+âeâ [âdelâ | âonceâ] [N1 N2 ...] [NâM]
Enable specified breakpoints or a range of breakpoints. Without
any argument, enable all breakpoints. Optionally, you can specify
how to enable the breakpoints:
- 'del'
+ âdelâ
Enable the breakpoints temporarily, then delete each one when
the program stops at it.
- 'once'
+ âonceâ
Enable the breakpoints temporarily, then disable each one when
the program stops at it.
-'ignore' N COUNT
+âignoreâ N COUNT
Ignore breakpoint number N the next COUNT times it is hit.
-'tbreak' [[FILENAME':']N | FUNCTION]
-'t' [[FILENAME':']N | FUNCTION]
+âtbreakâ [[FILENAMEâ:â]N | FUNCTION]
+âtâ [[FILENAMEâ:â]N | FUNCTION]
Set a temporary breakpoint (enabled for only one stop). The
- arguments are the same as for 'break'.
+ arguments are the same as for âbreakâ.
File: gawk.info, Node: Debugger Execution Control, Next: Viewing And
Changing Data, Prev: Breakpoint Control, Up: List of Debugger Commands
@@ -23627,18 +23627,18 @@ Now that your breakpoints are ready, you can start
running the program
and observing its behavior. There are more commands for controlling
execution of the program than we saw in our earlier example:
-'commands' [N]
-'silent'
+âcommandsâ [N]
+âsilentâ
...
-'end'
+âendâ
Set a list of commands to be executed upon stopping at a breakpoint
or watchpoint. N is the breakpoint or watchpoint number. Without
a number, the last one set is used. The actual commands follow,
- starting on the next line, and terminated by the 'end' command. If
- the command 'silent' is in the list, the usual messages about
+ starting on the next line, and terminated by the âendâ command. If
+ the command âsilentâ is in the list, the usual messages about
stopping at a breakpoint and the source line are not printed. Any
- command in the list that resumes execution (e.g., 'continue')
- terminates the list (an implicit 'end'), and subsequent commands
+ command in the list that resumes execution (e.g., âcontinueâ)
+ terminates the list (an implicit âendâ), and subsequent commands
are ignored. For example:
gawk> commands
@@ -23650,57 +23650,57 @@ execution of the program than we saw in our earlier
example:
> end
gawk>
-'continue' [COUNT]
-'c' [COUNT]
+âcontinueâ [COUNT]
+âcâ [COUNT]
Resume program execution. If continued from a breakpoint and COUNT
is specified, ignore the breakpoint at that location the next COUNT
times before stopping.
-'finish'
+âfinishâ
Execute until the selected stack frame returns. Print the returned
value.
-'next' [COUNT]
-'n' [COUNT]
+ânextâ [COUNT]
+ânâ [COUNT]
Continue execution to the next source line, stepping over function
calls. The argument COUNT controls how many times to repeat the
- action, as in 'step'.
+ action, as in âstepâ.
-'nexti' [COUNT]
-'ni' [COUNT]
+ânextiâ [COUNT]
+âniâ [COUNT]
Execute one (or COUNT) instruction(s), stepping over function
calls.
-'return' [VALUE]
+âreturnâ [VALUE]
Cancel execution of a function call. If VALUE (either a string or
- a number) is specified, it is used as the function's return value.
+ a number) is specified, it is used as the functionâs return value.
If used in a frame other than the innermost one (the currently
executing function; i.e., frame number 0), discard all inner frames
in addition to the selected one, and the caller of that frame
becomes the innermost frame.
-'run'
-'r'
+ârunâ
+ârâ
Start/restart execution of the program. When restarting, the
debugger retains the current breakpoints, watchpoints, command
history, automatic display variables, and debugger options.
-'step' [COUNT]
-'s' [COUNT]
+âstepâ [COUNT]
+âsâ [COUNT]
Continue execution until control reaches a different source line in
the current stack frame, stepping inside any function called within
the line. If the argument COUNT is supplied, steps that many times
before stopping, unless it encounters a breakpoint or watchpoint.
-'stepi' [COUNT]
-'si' [COUNT]
+âstepiâ [COUNT]
+âsiâ [COUNT]
Execute one (or COUNT) instruction(s), stepping inside function
- calls. (For illustration of what is meant by an "instruction" in
- 'gawk', see the output shown under 'dump' in *note Miscellaneous
+ calls. (For illustration of what is meant by an âinstructionâ in
+ âgawkâ, see the output shown under âdumpâ in *note Miscellaneous
Debugger Commands::.)
-'until' [[FILENAME':']N | FUNCTION]
-'u' [[FILENAME':']N | FUNCTION]
+âuntilâ [[FILENAMEâ:â]N | FUNCTION]
+âuâ [[FILENAMEâ:â]N | FUNCTION]
Without any argument, continue execution until a line past the
current line in the current stack frame is reached. With an
argument, continue execution until the specified location is
@@ -23712,88 +23712,88 @@ File: gawk.info, Node: Viewing And Changing Data,
Next: Execution Stack, Prev
14.3.3 Viewing and Changing Data
--------------------------------
-The commands for viewing and changing variables inside of 'gawk' are:
+The commands for viewing and changing variables inside of âgawkâ are:
-'display' [VAR | '$'N]
- Add variable VAR (or field '$N') to the display list. The value of
+âdisplayâ [VAR | â$âN]
+ Add variable VAR (or field â$Nâ) to the display list. The value of
the variable or field is displayed each time the program stops.
Each variable added to the list is identified by a unique number:
gawk> display x
- -| 10: x = 1
+ ⣠10: x = 1
This displays the assigned item number, the variable name, and its
current value. If the display variable refers to a function
parameter, it is silently deleted from the list as soon as the
execution reaches a context where no such variable of the given
- name exists. Without argument, 'display' displays the current
+ name exists. Without argument, âdisplayâ displays the current
values of items on the list.
-'eval "AWK STATEMENTS"'
+âeval "AWK STATEMENTS"â
Evaluate AWK STATEMENTS in the context of the running program. You
- can do anything that an 'awk' program would do: assign values to
+ can do anything that an âawkâ program would do: assign values to
variables, call functions, and so on.
- NOTE: You cannot use 'eval' to execute a statement containing
- any of the following: 'exit', 'getline', 'next', 'nextfile',
- or 'return'.
+ NOTE: You cannot use âevalâ to execute a statement containing
+ any of the following: âexitâ, âgetlineâ, ânextâ,
ânextfileâ,
+ or âreturnâ.
-'eval' PARAM, ...
+âevalâ PARAM, ...
AWK STATEMENTS
-'end'
- This form of 'eval' is similar, but it allows you to define "local
- variables" that exist in the context of the AWK STATEMENTS, instead
+âendâ
+ This form of âevalâ is similar, but it allows you to define âlocal
+ variablesâ that exist in the context of the AWK STATEMENTS, instead
of using variables or function parameters defined by the program.
-'print' VAR1[',' VAR2 ...]
-'p' VAR1[',' VAR2 ...]
- Print the value of a 'gawk' variable or field. Fields must be
+âprintâ VAR1[â,â VAR2 ...]
+âpâ VAR1[â,â VAR2 ...]
+ Print the value of a âgawkâ variable or field. Fields must be
referenced by constants:
gawk> print $3
This prints the third field in the input record (if the specified
- field does not exist, it prints 'Null field'). A variable can be
+ field does not exist, it prints âNull fieldâ). A variable can be
an array element, with the subscripts being constant string values.
To print the contents of an array, prefix the name of the array
- with the '@' symbol:
+ with the â@â symbol:
gawk> print @a
This prints the indices and the corresponding values for all
- elements in the array 'a'.
+ elements in the array âaâ.
-'printf' FORMAT [',' ARG ...]
+âprintfâ FORMAT [â,â ARG ...]
Print formatted text. The FORMAT may include escape sequences,
- such as '\n' (*note Escape Sequences::). No newline is printed
+ such as â\nâ (*note Escape Sequences::). No newline is printed
unless one is specified.
-'set' VAR'='VALUE
- Assign a constant (number or string) value to an 'awk' variable or
+âsetâ VARâ=âVALUE
+ Assign a constant (number or string) value to an âawkâ variable or
field. String values must be enclosed between double quotes
- ('"'...'"').
+ (â"â...â"â).
- You can also set special 'awk' variables, such as 'FS', 'NF', 'NR',
+ You can also set special âawkâ variables, such as âFSâ, âNFâ,
âNRâ,
and so on.
-'watch' VAR | '$'N ['"EXPRESSION"']
-'w' VAR | '$'N ['"EXPRESSION"']
- Add variable VAR (or field '$N') to the watch list. The debugger
+âwatchâ VAR | â$âN [â"EXPRESSION"â]
+âwâ VAR | â$âN [â"EXPRESSION"â]
+ Add variable VAR (or field â$Nâ) to the watch list. The debugger
then stops whenever the value of the variable or field changes.
Each watched item is assigned a number that can be used to delete
- it from the watch list using the 'unwatch' command.
+ it from the watch list using the âunwatchâ command.
With a watchpoint, you may also supply a condition. This is an
- 'awk' expression (enclosed in double quotes) that the debugger
+ âawkâ expression (enclosed in double quotes) that the debugger
evaluates whenever the watchpoint is reached. If the condition is
true, then the debugger stops execution and prompts for a command.
- Otherwise, 'gawk' continues executing the program.
+ Otherwise, âgawkâ continues executing the program.
-'undisplay' [N]
+âundisplayâ [N]
Remove item number N (or all items, if no argument) from the
automatic display list.
-'unwatch' [N]
+âunwatchâ [N]
Remove item number N (or all items, if no argument) from the watch
list.
@@ -23803,37 +23803,37 @@ File: gawk.info, Node: Execution Stack, Next:
Debugger Info, Prev: Viewing An
14.3.4 Working with the Stack
-----------------------------
-Whenever you run a program that contains any function calls, 'gawk'
+Whenever you run a program that contains any function calls, âgawkâ
maintains a stack of all of the function calls leading up to where the
program is right now. You can see how you got to where you are, and
also move around in the stack to see what the state of things was in the
functions that called the one you are in. The commands for doing this
are:
-'backtrace' [COUNT]
-'bt' [COUNT]
-'where' [COUNT]
+âbacktraceâ [COUNT]
+âbtâ [COUNT]
+âwhereâ [COUNT]
Print a backtrace of all function calls (stack frames), or
innermost COUNT frames if COUNT > 0. Print the outermost COUNT
frames if COUNT < 0. The backtrace displays the name and arguments
to each function, the source file name, and the line number. The
- alias 'where' for 'backtrace' is provided for longtime GDB users
+ alias âwhereâ for âbacktraceâ is provided for longtime GDB users
who may be used to that command.
-'down' [COUNT]
+âdownâ [COUNT]
Move COUNT (default 1) frames down the stack toward the innermost
frame. Then select and print the frame.
-'frame' [N]
-'f' [N]
+âframeâ [N]
+âfâ [N]
Select and print stack frame N. Frame 0 is the currently
- executing, or "innermost", frame (function call); frame 1 is the
+ executing, or âinnermostâ, frame (function call); frame 1 is the
frame that called the innermost one. The highest-numbered frame is
the one for the main program. The printed information consists of
the frame number, function and argument names, source file, and the
source line.
-'up' [COUNT]
+âupâ [COUNT]
Move COUNT (default 1) frames up the stack toward the outermost
frame. Then select and print the frame.
@@ -23845,106 +23845,106 @@ File: gawk.info, Node: Debugger Info, Next:
Miscellaneous Debugger Commands,
Besides looking at the values of variables, there is often a need to get
other sorts of information about the state of your program and of the
-debugging environment itself. The 'gawk' debugger has one command that
-provides this information, appropriately called 'info'. 'info' is used
+debugging environment itself. The âgawkâ debugger has one command that
+provides this information, appropriately called âinfoâ. âinfoâ is used
with one of a number of arguments that tell it exactly what you want to
know:
-'info' WHAT
-'i' WHAT
+âinfoâ WHAT
+âiâ WHAT
The value for WHAT should be one of the following:
- 'args'
+ âargsâ
List arguments of the selected frame.
- 'break'
+ âbreakâ
List all currently set breakpoints.
- 'display'
+ âdisplayâ
List all items in the automatic display list.
- 'frame'
+ âframeâ
Give a description of the selected stack frame.
- 'functions'
+ âfunctionsâ
List all function definitions including source file names and
line numbers.
- 'locals'
+ âlocalsâ
List local variables of the selected frame.
- 'source'
+ âsourceâ
Print the name of the current source file. Each time the
program stops, the current source file is the file containing
the current instruction. When the debugger first starts, the
- current source file is the first file included via the '-f'
- option. The 'list FILENAME:LINENO' command can be used at any
+ current source file is the first file included via the â-fâ
+ option. The âlist FILENAME:LINENOâ command can be used at any
time to change the current source.
- 'sources'
+ âsourcesâ
List all program sources.
- 'variables'
+ âvariablesâ
List all global variables.
- 'watch'
+ âwatchâ
List all items in the watch list.
Additional commands give you control over the debugger, the ability
-to save the debugger's state, and the ability to run debugger commands
+to save the debuggerâs state, and the ability to run debugger commands
from a file. The commands are:
-'option' [NAME['='VALUE]]
-'o' [NAME['='VALUE]]
+âoptionâ [NAME[â=âVALUE]]
+âoâ [NAME[â=âVALUE]]
Without an argument, display the available debugger options and
- their current values. 'option NAME' shows the current value of the
- named option. 'option NAME=VALUE' assigns a new value to the named
+ their current values. âoption NAMEâ shows the current value of the
+ named option. âoption NAME=VALUEâ assigns a new value to the named
option. The available options are:
- 'history_size'
+ âhistory_sizeâ
Set the maximum number of lines to keep in the history file
- './.gawk_history'. The default is 100.
+ â./.gawk_historyâ. The default is 100.
- 'listsize'
- Specify the number of lines that 'list' prints. The default
+ âlistsizeâ
+ Specify the number of lines that âlistâ prints. The default
is 15.
- 'outfile'
- Send 'gawk' output to a file; debugger output still goes to
- standard output. An empty string ('""') resets output to
+ âoutfileâ
+ Send âgawkâ output to a file; debugger output still goes to
+ standard output. An empty string (â""â) resets output to
standard output.
- 'prompt'
- Change the debugger prompt. The default is 'gawk> '.
+ âpromptâ
+ Change the debugger prompt. The default is âgawk> â.
- 'save_history' ['on' | 'off']
- Save command history to file './.gawk_history'. The default
- is 'on'.
+ âsave_historyâ [âonâ | âoffâ]
+ Save command history to file â./.gawk_historyâ. The default
+ is âonâ.
- 'save_options' ['on' | 'off']
- Save current options to file './.gawkrc' upon exit. The
- default is 'on'. Options are read back into the next session
+ âsave_optionsâ [âonâ | âoffâ]
+ Save current options to file â./.gawkrcâ upon exit. The
+ default is âonâ. Options are read back into the next session
upon startup.
- 'trace' ['on' | 'off']
- Turn instruction tracing on or off. The default is 'off'.
+ âtraceâ [âonâ | âoffâ]
+ Turn instruction tracing on or off. The default is âoffâ.
-'save' FILENAME
+âsaveâ FILENAME
Save the commands from the current session to the given file name,
- so that they can be replayed using the 'source' command.
+ so that they can be replayed using the âsourceâ command.
-'source' FILENAME
+âsourceâ FILENAME
Run command(s) from a file; an error in any command does not
terminate execution of subsequent commands. Comments (lines
- starting with '#') are allowed in a command file. Empty lines are
- ignored; they do _not_ repeat the last command. You can't restart
- the program by having more than one 'run' command in the file.
- Also, the list of commands may include additional 'source'
- commands; however, the 'gawk' debugger will not source the same
+ starting with â#â) are allowed in a command file. Empty lines are
+ ignored; they do _not_ repeat the last command. You canât restart
+ the program by having more than one ârunâ command in the file.
+ Also, the list of commands may include additional âsourceâ
+ commands; however, the âgawkâ debugger will not source the same
file more than once in order to avoid infinite recursion.
- In addition to, or instead of, the 'source' command, you can use
- the '-D FILE' or '--debug=FILE' command-line options to execute
+ In addition to, or instead of, the âsourceâ command, you can use
+ the â-D FILEâ or â--debug=FILEâ command-line options to execute
commands from a file non-interactively (*note Options::).
@@ -23956,90 +23956,90 @@ File: gawk.info, Node: Miscellaneous Debugger
Commands, Prev: Debugger Info,
There are a few more commands that do not fit into the previous
categories, as follows:
-'dump' [FILENAME]
+âdumpâ [FILENAME]
Dump byte code of the program to standard output or to the file
named in FILENAME. This prints a representation of the internal
- instructions that 'gawk' executes to implement the 'awk' commands
+ instructions that âgawkâ executes to implement the âawkâ commands
in a program. This can be very enlightening, as the following
- partial dump of Davide Brini's obfuscated code (*note Signature
+ partial dump of Davide Briniâs obfuscated code (*note Signature
Program::) demonstrates:
gawk> dump
- -| # BEGIN
- -|
- -| [ 1:0xfcd340] Op_rule : [in_rule = BEGIN] [source_file
= brini.awk]
- -| [ 1:0xfcc240] Op_push_i : "~" [MALLOC|STRING|STRCUR]
- -| [ 1:0xfcc2a0] Op_push_i : "~" [MALLOC|STRING|STRCUR]
- -| [ 1:0xfcc280] Op_match :
- -| [ 1:0xfcc1e0] Op_store_var : O
- -| [ 1:0xfcc2e0] Op_push_i : "==" [MALLOC|STRING|STRCUR]
- -| [ 1:0xfcc340] Op_push_i : "==" [MALLOC|STRING|STRCUR]
- -| [ 1:0xfcc320] Op_equal :
- -| [ 1:0xfcc200] Op_store_var : o
- -| [ 1:0xfcc380] Op_push : o
- -| [ 1:0xfcc360] Op_plus_i : 0 [MALLOC|NUMCUR|NUMBER]
- -| [ 1:0xfcc220] Op_push_lhs : o [do_reference = true]
- -| [ 1:0xfcc300] Op_assign_plus :
- -| [ :0xfcc2c0] Op_pop :
- -| [ 1:0xfcc400] Op_push : O
- -| [ 1:0xfcc420] Op_push_i : "" [MALLOC|STRING|STRCUR]
- -| [ :0xfcc4a0] Op_no_op :
- -| [ 1:0xfcc480] Op_push : O
- -| [ :0xfcc4c0] Op_concat : [expr_count = 3] [concat_flag
= 0]
- -| [ 1:0xfcc3c0] Op_store_var : x
- -| [ 1:0xfcc440] Op_push_lhs : X [do_reference = true]
- -| [ 1:0xfcc3a0] Op_postincrement :
- -| [ 1:0xfcc4e0] Op_push : x
- -| [ 1:0xfcc540] Op_push : o
- -| [ 1:0xfcc500] Op_plus :
- -| [ 1:0xfcc580] Op_push : o
- -| [ 1:0xfcc560] Op_plus :
- -| [ 1:0xfcc460] Op_leq :
- -| [ :0xfcc5c0] Op_jmp_false : [target_jmp = 0xfcc5e0]
- -| [ 1:0xfcc600] Op_push_i : "%c" [MALLOC|STRING|STRCUR]
- -| [ :0xfcc660] Op_no_op :
- -| [ 1:0xfcc520] Op_assign_concat : c
- -| [ :0xfcc620] Op_jmp : [target_jmp = 0xfcc440]
+ ⣠# BEGIN
+ â£
+ ⣠[ 1:0xfcd340] Op_rule : [in_rule = BEGIN]
[source_file = brini.awk]
+ ⣠[ 1:0xfcc240] Op_push_i : "~" [MALLOC|STRING|STRCUR]
+ ⣠[ 1:0xfcc2a0] Op_push_i : "~" [MALLOC|STRING|STRCUR]
+ ⣠[ 1:0xfcc280] Op_match :
+ ⣠[ 1:0xfcc1e0] Op_store_var : O
+ ⣠[ 1:0xfcc2e0] Op_push_i : "==" [MALLOC|STRING|STRCUR]
+ ⣠[ 1:0xfcc340] Op_push_i : "==" [MALLOC|STRING|STRCUR]
+ ⣠[ 1:0xfcc320] Op_equal :
+ ⣠[ 1:0xfcc200] Op_store_var : o
+ ⣠[ 1:0xfcc380] Op_push : o
+ ⣠[ 1:0xfcc360] Op_plus_i : 0 [MALLOC|NUMCUR|NUMBER]
+ ⣠[ 1:0xfcc220] Op_push_lhs : o [do_reference = true]
+ ⣠[ 1:0xfcc300] Op_assign_plus :
+ ⣠[ :0xfcc2c0] Op_pop :
+ ⣠[ 1:0xfcc400] Op_push : O
+ ⣠[ 1:0xfcc420] Op_push_i : "" [MALLOC|STRING|STRCUR]
+ ⣠[ :0xfcc4a0] Op_no_op :
+ ⣠[ 1:0xfcc480] Op_push : O
+ ⣠[ :0xfcc4c0] Op_concat : [expr_count = 3] [concat_flag
= 0]
+ ⣠[ 1:0xfcc3c0] Op_store_var : x
+ ⣠[ 1:0xfcc440] Op_push_lhs : X [do_reference = true]
+ ⣠[ 1:0xfcc3a0] Op_postincrement :
+ ⣠[ 1:0xfcc4e0] Op_push : x
+ ⣠[ 1:0xfcc540] Op_push : o
+ ⣠[ 1:0xfcc500] Op_plus :
+ ⣠[ 1:0xfcc580] Op_push : o
+ ⣠[ 1:0xfcc560] Op_plus :
+ ⣠[ 1:0xfcc460] Op_leq :
+ ⣠[ :0xfcc5c0] Op_jmp_false : [target_jmp = 0xfcc5e0]
+ ⣠[ 1:0xfcc600] Op_push_i : "%c" [MALLOC|STRING|STRCUR]
+ ⣠[ :0xfcc660] Op_no_op :
+ ⣠[ 1:0xfcc520] Op_assign_concat : c
+ ⣠[ :0xfcc620] Op_jmp : [target_jmp = 0xfcc440]
...
- -| [ 2:0xfcc5a0] Op_K_printf : [expr_count = 17]
[redir_type = ""]
- -| [ :0xfcc140] Op_no_op :
- -| [ :0xfcc1c0] Op_atexit :
- -| [ :0xfcc640] Op_stop :
- -| [ :0xfcc180] Op_no_op :
- -| [ :0xfcd150] Op_after_beginfile :
- -| [ :0xfcc160] Op_no_op :
- -| [ :0xfcc1a0] Op_after_endfile :
+ ⣠[ 2:0xfcc5a0] Op_K_printf : [expr_count = 17]
[redir_type = ""]
+ ⣠[ :0xfcc140] Op_no_op :
+ ⣠[ :0xfcc1c0] Op_atexit :
+ ⣠[ :0xfcc640] Op_stop :
+ ⣠[ :0xfcc180] Op_no_op :
+ ⣠[ :0xfcd150] Op_after_beginfile :
+ ⣠[ :0xfcc160] Op_no_op :
+ ⣠[ :0xfcc1a0] Op_after_endfile :
gawk>
-'exit'
- Exit the debugger. See the entry for 'quit', later in this list.
+âexitâ
+ Exit the debugger. See the entry for âquitâ, later in this list.
-'help'
-'h'
- Print a list of all of the 'gawk' debugger commands with a short
- summary of their usage. 'help COMMAND' prints the information
+âhelpâ
+âhâ
+ Print a list of all of the âgawkâ debugger commands with a short
+ summary of their usage. âhelp COMMANDâ prints the information
about the command COMMAND.
-'list' ['-' | '+' | N | FILENAME':'N | N-M | FUNCTION]
-'l' ['-' | '+' | N | FILENAME':'N | N-M | FUNCTION]
+âlistâ [â-â | â+â | N | FILENAMEâ:âN | NâM | FUNCTION]
+âlâ [â-â | â+â | N | FILENAMEâ:âN | NâM | FUNCTION]
Print the specified lines (default 15) from the current source file
- or the file named FILENAME. The possible arguments to 'list' are
+ or the file named FILENAME. The possible arguments to âlistâ are
as follows:
- '-' (Minus)
+ â-â (Minus)
Print lines before the lines last printed.
- '+'
- Print lines after the lines last printed. 'list' without any
+ â+â
+ Print lines after the lines last printed. âlistâ without any
argument does the same thing.
N
Print lines centered around line number N.
- N-M
+ NâM
Print lines from N to M.
- FILENAME':'N
+ FILENAMEâ:âN
Print lines centered around line number N in source file
FILENAME. This command may change the current source file.
@@ -24047,22 +24047,22 @@ categories, as follows:
Print lines centered around the beginning of the function
FUNCTION. This command may change the current source file.
-'quit'
-'q'
+âquitâ
+âqâ
Exit the debugger. Debugging is great fun, but sometimes we all
have to tend to other obligations in life, and sometimes we find
the bug and are free to go on to the next one! As we saw earlier,
if you are running a program, the debugger warns you when you type
- 'q' or 'quit', to make sure you really want to quit.
+ âqâ or âquitâ, to make sure you really want to quit.
-'trace' ['on' | 'off']
+âtraceâ [âonâ | âoffâ]
Turn on or off continuous printing of the instructions that are
- about to be executed, along with the 'awk' lines they implement.
- The default is 'off'.
+ about to be executed, along with the âawkâ lines they implement.
+ The default is âoffâ.
- It is to be hoped that most of the "opcodes" in these instructions
- are fairly self-explanatory, and using 'stepi' and 'nexti' while
- 'trace' is on will make them into familiar friends.
+ It is to be hoped that most of the âopcodesâ in these instructions
+ are fairly self-explanatory, and using âstepiâ and ânextiâ while
+ âtraceâ is on will make them into familiar friends.
File: gawk.info, Node: Readline Support, Next: Limitations, Prev: List of
Debugger Commands, Up: Debugger
@@ -24070,26 +24070,26 @@ File: gawk.info, Node: Readline Support, Next:
Limitations, Prev: List of Deb
14.4 Readline Support
=====================
-If 'gawk' is compiled with the GNU Readline library
+If âgawkâ is compiled with the GNU Readline library
(http://cnswww.cns.cwru.edu/php/chet/readline/readline.html), you can
-take advantage of that library's command completion and history
+take advantage of that libraryâs command completion and history
expansion features. The following types of completion are available:
Command completion
Command names.
Source file name completion
- Source file names. Relevant commands are 'break', 'clear', 'list',
- 'tbreak', and 'until'.
+ Source file names. Relevant commands are âbreakâ, âclearâ,
âlistâ,
+ âtbreakâ, and âuntilâ.
Argument completion
- Non-numeric arguments to a command. Relevant commands are 'enable'
- and 'info'.
+ Non-numeric arguments to a command. Relevant commands are âenableâ
+ and âinfoâ.
Variable name completion
Global variable names, and function arguments in the current
context if the program is running. Relevant commands are
- 'display', 'print', 'set', and 'watch'.
+ âdisplayâ, âprintâ, âsetâ, and âwatchâ.
File: gawk.info, Node: Limitations, Next: Debugging Summary, Prev: Readline
Support, Up: Debugger
@@ -24097,45 +24097,45 @@ File: gawk.info, Node: Limitations, Next: Debugging
Summary, Prev: Readline S
14.5 Limitations
================
-We hope you find the 'gawk' debugger useful and enjoyable to work with,
+We hope you find the âgawkâ debugger useful and enjoyable to work with,
but as with any program, especially in its early releases, it still has
-some limitations. A few that it's worth being aware of are:
+some limitations. A few that itâs worth being aware of are:
- * At this point, the debugger does not give a detailed explanation of
- what you did wrong when you type in something it doesn't like.
- Rather, it just responds 'syntax error'. When you do figure out
- what your mistake was, though, you'll feel like a real guru.
+ ⢠At this point, the debugger does not give a detailed explanation of
+ what you did wrong when you type in something it doesnât like.
+ Rather, it just responds âsyntax errorâ. When you do figure out
+ what your mistake was, though, youâll feel like a real guru.
- * If you perused the dump of opcodes in *note Miscellaneous Debugger
- Commands:: (or if you are already familiar with 'gawk' internals),
+ ⢠If you perused the dump of opcodes in *note Miscellaneous Debugger
+ Commands:: (or if you are already familiar with âgawkâ internals),
you will realize that much of the internal manipulation of data in
- 'gawk', as in many interpreters, is done on a stack. 'Op_push',
- 'Op_pop', and the like are the "bread and butter" of most 'gawk'
+ âgawkâ, as in many interpreters, is done on a stack. âOp_pushâ,
+ âOp_popâ, and the like are the âbread and butterâ of most
âgawkâ
code.
- Unfortunately, as of now, the 'gawk' debugger does not allow you to
- examine the stack's contents. That is, the intermediate results of
+ Unfortunately, as of now, the âgawkâ debugger does not allow you to
+ examine the stackâs contents. That is, the intermediate results of
expression evaluation are on the stack, but cannot be printed.
Rather, only variables that are defined in the program can be
printed. Of course, a workaround for this is to use more explicit
variables at the debugging stage and then change back to obscure,
perhaps more optimal code later.
- * There is no way to look "inside" the process of compiling regular
- expressions to see if you got it right. As an 'awk' programmer,
- you are expected to know the meaning of '/[^[:alnum:][:blank:]]/'.
+ ⢠There is no way to look âinsideâ the process of compiling regular
+ expressions to see if you got it right. As an âawkâ programmer,
+ you are expected to know the meaning of â/[^[:alnum:][:blank:]]/â.
- * The 'gawk' debugger is designed to be used by running a program
+ ⢠The âgawkâ debugger is designed to be used by running a program
(with all its parameters) on the command line, as described in
*note Debugger Invocation::. There is no way (as of now) to attach
- or "break into" a running program. This seems reasonable for a
+ or âbreak intoâ a running program. This seems reasonable for a
language that is used mainly for quickly executing, short programs.
- * The 'gawk' debugger only accepts source code supplied with the '-f'
- option. If you have a shell script that provides an 'awk' program
+ ⢠The âgawkâ debugger only accepts source code supplied with the
â-fâ
+ option. If you have a shell script that provides an âawkâ program
as a command line parameter, and you need to use the debugger, you
can write the script to a temporary file, and use that as the
- program, with the '-f' option. This might look like this:
+ program, with the â-fâ option. This might look like this:
cat << \EOF > /tmp/script.$$
... Your program here
@@ -24149,38 +24149,38 @@ File: gawk.info, Node: Debugging Summary, Prev:
Limitations, Up: Debugger
14.6 Summary
============
- * Programs rarely work correctly the first time. Finding bugs is
+ ⢠Programs rarely work correctly the first time. Finding bugs is
called debugging, and a program that helps you find bugs is a
- debugger. 'gawk' has a built-in debugger that works very similarly
+ debugger. âgawkâ has a built-in debugger that works very similarly
to the GNU Debugger, GDB.
- * Debuggers let you step through your program one statement at a
+ ⢠Debuggers let you step through your program one statement at a
time, examine and change variable and array values, and do a number
of other things that let you understand what your program is
actually doing (as opposed to what it is supposed to do).
- * Like most debuggers, the 'gawk' debugger works in terms of stack
+ ⢠Like most debuggers, the âgawkâ debugger works in terms of stack
frames, and lets you set both breakpoints (stop at a point in the
code) and watchpoints (stop when a data value changes).
- * The debugger command set is fairly complete, providing control over
+ ⢠The debugger command set is fairly complete, providing control over
breakpoints, execution, viewing and changing data, working with the
stack, getting information, and other tasks.
- * If the GNU Readline library is available when 'gawk' is compiled,
+ ⢠If the GNU Readline library is available when âgawkâ is compiled,
it is used by the debugger to provide command-line history and
editing.
- * Usually, the debugger does not not affect the program being
+ ⢠Usually, the debugger does not not affect the program being
debugged, but occasionally it can.
File: gawk.info, Node: Namespaces, Next: Arbitrary Precision Arithmetic,
Prev: Debugger, Up: Top
-15 Namespaces in 'gawk'
+15 Namespaces in âgawkâ
***********************
-This major node describes a feature that is specific to 'gawk'.
+This major node describes a feature that is specific to âgawkâ.
CAUTION: This feature described in this chapter is new. It is
entirely possible, and even likely, that there are dark corners (if
@@ -24190,43 +24190,43 @@ This major node describes a feature that is specific
to 'gawk'.
* Menu:
* Global Namespace:: The global namespace in standard
- 'awk'.
+ âawkâ.
* Qualified Names:: How to qualify names with a namespace.
* Default Namespace:: The default namespace.
* Changing The Namespace:: How to change the namespace.
* Naming Rules:: Namespace and Component Naming Rules.
* Internal Name Management:: How names are stored internally.
* Namespace Example:: An example of code using a namespace.
-* Namespace And Features:: Namespaces and other 'gawk' features.
+* Namespace And Features:: Namespaces and other âgawkâ features.
* Namespace Summary:: Summarizing namespaces.
File: gawk.info, Node: Global Namespace, Next: Qualified Names, Up:
Namespaces
-15.1 Standard 'awk''s Single Namespace
+15.1 Standard âawkââs Single Namespace
======================================
-In standard 'awk', there is a single, global, "namespace". This means
+In standard âawkâ, there is a single, global, ânamespaceâ. This means
that _all_ function names and global variable names must be unique. For
-example, two different 'awk' source files cannot both define a function
-named 'min()', or define the same identifier, used as a scalar in one
+example, two different âawkâ source files cannot both define a function
+named âmin()â, or define the same identifier, used as a scalar in one
and as an array in the other.
This situation is okay when programs are small, say a few hundred
lines, or even a few thousand, but it prevents the development of
-reusable libraries of 'awk' functions, and can inadvertently cause
+reusable libraries of âawkâ functions, and can inadvertently cause
independently-developed library files to accidentally step on each
-other's "private" global variables (*note Library Names::).
+otherâs âprivateâ global variables (*note Library Names::).
Most other programming languages solve this issue by providing some
-kind of namespace control: a way to say "this function is in namespace
-XXX, and that function is in namespace YYY." (Of course, there is then
+kind of namespace control: a way to say âthis function is in namespace
+XXX, and that function is in namespace YYY.â (Of course, there is then
still a single namespace for the namespaces, but the hope is that there
are much fewer namespaces in use by any given program, and thus much
less chance for collisions.) These facilities are sometimes referred to
-as "packages" or "modules".
+as âpackagesâ or âmodulesâ.
- Starting with version 5.0, 'gawk' provides a simple mechanism to put
+ Starting with version 5.0, âgawkâ provides a simple mechanism to put
functions and global variables into separate namespaces.
@@ -24235,20 +24235,20 @@ File: gawk.info, Node: Qualified Names, Next:
Default Namespace, Prev: Global
15.2 Qualified Names
====================
-A "qualified name" is an identifier that includes a namespace name, the
-namespace separator '::', and a "component" name. For example, one
-might have a function named 'posix::getpid()'. Here, the namespace is
-'posix' and the function name within the namespace (the component) is
-'getpid()'. The namespace and component names are separated by a
+A âqualified nameâ is an identifier that includes a namespace name, the
+namespace separator â::â, and a âcomponentâ name. For example, one
+might have a function named âposix::getpid()â. Here, the namespace is
+âposixâ and the function name within the namespace (the component) is
+âgetpid()â. The namespace and component names are separated by a
double-colon. Only one such separator is allowed in a qualified name.
- NOTE: Unlike C++, the '::' is _not_ an operator. No spaces are
- allowed between the namespace name, the '::', and the component
+ NOTE: Unlike C++, the â::â is _not_ an operator. No spaces are
+ allowed between the namespace name, the â::â, and the component
name.
You must use qualified names from one namespace to access variables
and functions in another. This is especially important when using
-variable names to index the special 'SYMTAB' array (*note Auto-set::),
+variable names to index the special âSYMTABâ array (*note Auto-set::),
and when making indirect function calls (*note Indirect Calls::).
@@ -24257,15 +24257,15 @@ File: gawk.info, Node: Default Namespace, Next:
Changing The Namespace, Prev:
15.3 The Default Namespace
==========================
-The default namespace, not surprisingly, is 'awk'. All of the
-predefined 'awk' and 'gawk' variables are in this namespace, and thus
-have qualified names like 'awk::ARGC', 'awk::NF', and so on.
+The default namespace, not surprisingly, is âawkâ. All of the
+predefined âawkâ and âgawkâ variables are in this namespace, and thus
+have qualified names like âawk::ARGCâ, âawk::NFâ, and so on.
Furthermore, even when you have changed the namespace for your
-current source file (*note Changing The Namespace::), 'gawk' forces
+current source file (*note Changing The Namespace::), âgawkâ forces
unqualified identifiers whose names are all uppercase letters to be in
-the 'awk' namespace. This makes it possible for you to easily reference
-'gawk''s global variables from different namespaces. It also keeps your
+the âawkâ namespace. This makes it possible for you to easily reference
+âgawkââs global variables from different namespaces. It also keeps your
code looking natural.
@@ -24274,7 +24274,7 @@ File: gawk.info, Node: Changing The Namespace, Next:
Naming Rules, Prev: Defa
15.4 Changing The Namespace
===========================
-In order to set the current namespace, use an '@namespace' directive at
+In order to set the current namespace, use an â@namespaceâ directive at
the top level of your program:
@namespace "passwd"
@@ -24283,30 +24283,30 @@ the top level of your program:
...
After this directive, all simple non-completely-uppercase identifiers
-are placed into the 'passwd' namespace.
+are placed into the âpasswdâ namespace.
You can change the namespace multiple times within a single source
file, although this is likely to become confusing if you do it too much.
NOTE: Association of unqualified identifiers to a namespace is
- handled while 'gawk' parses your program, _before_ it starts to
- run. There is no concept of a "current" namespace once your
+ handled while âgawkâ parses your program, _before_ it starts to
+ run. There is no concept of a âcurrentâ namespace once your
program starts executing. Be sure you understand this.
- Each source file for '-i' and '-f' starts out with an implicit
-'@namespace "awk"'. Similarly, each chunk of command-line code supplied
-with '-e' has such an implicit initial statement (*note Options::).
+ Each source file for â-iâ and â-fâ starts out with an implicit
+â@namespace "awk"â. Similarly, each chunk of command-line code supplied
+with â-eâ has such an implicit initial statement (*note Options::).
- Files included with '@include' (*note Include Files::) "push" and
-"pop" the current namespace. That is, each '@include' saves the current
-namespace and starts over with an implicit '@namespace "awk"' which
-remains in effect until an explicit '@namespace' directive is seen.
-When 'gawk' finishes processing the included file, the saved namespace
+ Files included with â@includeâ (*note Include Files::) âpushâ and
+âpopâ the current namespace. That is, each â@includeâ saves the
current
+namespace and starts over with an implicit â@namespace "awk"â which
+remains in effect until an explicit â@namespaceâ directive is seen.
+When âgawkâ finishes processing the included file, the saved namespace
is restored and processing continues where it left off in the original
file.
- The use of '@namespace' has no influence upon the order of execution
-of 'BEGIN', 'BEGINFILE', 'END', and 'ENDFILE' rules.
+ The use of â@namespaceâ has no influence upon the order of execution
+of âBEGINâ, âBEGINFILEâ, âENDâ, and âENDFILEâ rules.
File: gawk.info, Node: Naming Rules, Next: Internal Name Management, Prev:
Changing The Namespace, Up: Namespaces
@@ -24317,26 +24317,26 @@ File: gawk.info, Node: Naming Rules, Next: Internal
Name Management, Prev: Ch
A number of rules apply to the namespace and component names, as
follows.
- * It is a syntax error to use qualified names for function parameter
+ ⢠It is a syntax error to use qualified names for function parameter
names.
- * It is a syntax error to use any standard 'awk' reserved word (such
- as 'if' or 'for'), or the name of any standard built-in function
- (such as 'sin()' or 'gsub()') as either part of a qualified name.
+ ⢠It is a syntax error to use any standard âawkâ reserved word (such
+ as âifâ or âforâ), or the name of any standard built-in function
+ (such as âsin()â or âgsub()â) as either part of a qualified name.
Thus, the following produces a syntax error:
@namespace "example"
function gsub(str, pat, result) { ... }
- * Outside the 'awk' namespace, the names of the additional 'gawk'
- built-in functions (such as 'gensub()' or 'strftime()') _may_ be
+ ⢠Outside the âawkâ namespace, the names of the additional âgawkâ
+ built-in functions (such as âgensub()â or âstrftime()â) _may_ be
used as component names. The same set of names may be used as
namespace names, although this has the potential to be confusing.
- * The additional 'gawk' built-in functions may still be called from
- outside the 'awk' namespace by qualifying them. For example,
- 'awk::systime()'. Here is a somewhat silly example demonstrating
+ ⢠The additional âgawkâ built-in functions may still be called from
+ outside the âawkâ namespace by qualifying them. For example,
+ âawk::systime()â. Here is a somewhat silly example demonstrating
this rule and the previous one:
BEGIN {
@@ -24354,14 +24354,13 @@ follows.
systime()
}
-
When run, it produces output like this:
$ gawk -f systime.awk
- -| in awk namespace, systime() = 1500488503
- -| in testing namespace, systime() = 1500488503
+ ⣠in awk namespace, systime() = 1500488503
+ ⣠in testing namespace, systime() = 1500488503
- * 'gawk' pre-defined variable names may be used: 'NF::NR' is valid,
+ ⢠âgawkâ pre-defined variable names may be used: âNF::NRâ is
valid,
if possibly not all that useful.
@@ -24370,15 +24369,15 @@ File: gawk.info, Node: Internal Name Management,
Next: Namespace Example, Pre
15.6 Internal Name Management
=============================
-For backwards compatibility, all identifiers in the 'awk' namespace are
+For backwards compatibility, all identifiers in the âawkâ namespace are
stored internally as unadorned identifiers (that is, without a leading
-'awk::'). This is mainly relevant when using such identifiers as
-indices for 'SYMTAB', 'FUNCTAB', and 'PROCINFO["identifiers"]' (*note
+âawk::â). This is mainly relevant when using such identifiers as
+indices for âSYMTABâ, âFUNCTABâ, and âPROCINFO["identifiers"]â
(*note
Auto-set::), and for use in indirect function calls (*note Indirect
Calls::).
- In program code, to refer to variables and functions in the 'awk'
-namespace from another namespace, you must still use the 'awk::' prefix.
+ In program code, to refer to variables and functions in the âawkâ
+namespace from another namespace, you must still use the âawk::â prefix.
For example:
@namespace "awk" This is the default namespace
@@ -24406,8 +24405,8 @@ developed in *note Passwd Functions::. See there for
an explanation of
how the code works.
The formulation here, due mainly to Andrew Schorr, is rather elegant.
-All of the implementation functions and variables are in the 'passwd'
-namespace, whereas the main interface functions are defined in the 'awk'
+All of the implementation functions and variables are in the âpasswdâ
+namespace, whereas the main interface functions are defined in the âawkâ
namespace.
# ns_passwd.awk --- access password file information
@@ -24479,44 +24478,43 @@ namespace.
*note Library Names::, whereby global variable and function names start
with a capital letter.
- Here is a simple test program. Since it's in a separate file,
-unadorned identifiers are sought for in the 'awk' namespace:
+ Here is a simple test program. Since itâs in a separate file,
+unadorned identifiers are sought for in the âawkâ namespace:
BEGIN {
while ((p = getpwent()) != "")
print p
}
-
- Here's what happens when it's run:
+ Hereâs what happens when itâs run:
$ gawk -f ns_passwd.awk -f testpasswd.awk
- -| root:x:0:0:root:/root:/bin/bash
- -| daemon:x:1:1:daemon:/usr/sbin:/usr/sbin/nologin
- -| bin:x:2:2:bin:/bin:/usr/sbin/nologin
- -| sys:x:3:3:sys:/dev:/usr/sbin/nologin
+ ⣠root:x:0:0:root:/root:/bin/bash
+ ⣠daemon:x:1:1:daemon:/usr/sbin:/usr/sbin/nologin
+ ⣠bin:x:2:2:bin:/bin:/usr/sbin/nologin
+ ⣠sys:x:3:3:sys:/dev:/usr/sbin/nologin
...
File: gawk.info, Node: Namespace And Features, Next: Namespace Summary,
Prev: Namespace Example, Up: Namespaces
-15.8 Namespaces and Other 'gawk' Features
+15.8 Namespaces and Other âgawkâ Features
=========================================
This minor node looks briefly at how the namespace facility interacts
-with other important 'gawk' features.
+with other important âgawkâ features.
The profiler and pretty-printer (*note Profiling::) have been
enhanced to understand namespaces and the namespace naming rules
presented in *note Naming Rules::. In particular, the output groups
-functions in the same namespace together, and has '@namespace'
+functions in the same namespace together, and has â@namespaceâ
directives in front of rules as necessary. This allows component names
to be simple identifiers, instead of using qualified identifiers
everywhere.
Interaction with the debugger (*note Debugging::) has not had to
change (at least as of this writing). Some of the internal byte codes
-changed in order to accommodate namespaces, and the debugger's 'dump'
+changed in order to accommodate namespaces, and the debuggerâs âdumpâ
command was adjusted to match.
The extension API (*note Dynamic Extensions::) has always allowed for
@@ -24525,7 +24523,7 @@ previously implemented. However, the symbol lookup and
symbol update
routines did not have provision for including a namespace. That has now
been corrected (*note Symbol table by name::). *Note Extension Sample
Inplace::, for a nice example of an extension that leverages a namespace
-shared by cooperating 'awk' and C code.
+shared by cooperating âawkâ and C code.
File: gawk.info, Node: Namespace Summary, Prev: Namespace And Features, Up:
Namespaces
@@ -24533,60 +24531,60 @@ File: gawk.info, Node: Namespace Summary, Prev:
Namespace And Features, Up: N
15.9 Summary
============
- * Standard 'awk' provides a single namespace for all global
+ ⢠Standard âawkâ provides a single namespace for all global
identifiers (scalars, arrays, and functions). This is limiting
when one wants to develop libraries of reusable functions or
function suites.
- * 'gawk' provides multiple namespaces by using qualified names: names
- consisting of a namespace name, a double colon, '::', and a
+ ⢠âgawkâ provides multiple namespaces by using qualified names: names
+ consisting of a namespace name, a double colon, â::â, and a
component name. Namespace names might still possibly conflict, but
this is true of any language providing namespaces, modules, or
packages.
- * The default namespace is 'awk'. The rules for namespace and
+ ⢠The default namespace is âawkâ. The rules for namespace and
component names are provided in *note Naming Rules::. The rules
are designed in such a way as to make namespace-aware code continue
to look and work naturally while still providing the necessary
power and flexibility.
- * Other parts of 'gawk' have been extended as necessary to integrate
+ ⢠Other parts of âgawkâ have been extended as necessary to integrate
namespaces smoothly with their operation. This applies most
notably to the profiler / pretty-printer (*note Profiling::) and to
the extension facility (*note Dynamic Extensions::).
- * Overall, the namespace facility was designed and implemented such
- that backwards compatibility is paramount. Programs that don't use
+ ⢠Overall, the namespace facility was designed and implemented such
+ that backwards compatibility is paramount. Programs that donât use
namespaces should see absolutely no difference in behavior when run
- by a namespace-capable version of 'gawk'.
+ by a namespace-capable version of âgawkâ.
File: gawk.info, Node: Arbitrary Precision Arithmetic, Next: Dynamic
Extensions, Prev: Namespaces, Up: Top
-16 Arithmetic and Arbitrary-Precision Arithmetic with 'gawk'
+16 Arithmetic and Arbitrary-Precision Arithmetic with âgawkâ
************************************************************
This major node introduces some basic concepts relating to how computers
do arithmetic and defines some important terms. It then proceeds to
-describe floating-point arithmetic, which is what 'awk' uses for all its
+describe floating-point arithmetic, which is what âawkâ uses for all its
computations, including a discussion of arbitrary-precision
-floating-point arithmetic, which is a feature available only in 'gawk'.
+floating-point arithmetic, which is a feature available only in âgawkâ.
It continues on to present arbitrary-precision integers, and concludes
-with a description of some points where 'gawk' and the POSIX standard
+with a description of some points where âgawkâ and the POSIX standard
are not quite in agreement.
- NOTE: Most users of 'gawk' can safely skip this chapter. But if
- you want to do scientific calculations with 'gawk', this is the
+ NOTE: Most users of âgawkâ can safely skip this chapter. But if
+ you want to do scientific calculations with âgawkâ, this is the
place to be.
* Menu:
* Computer Arithmetic:: A quick intro to computer math.
* Math Definitions:: Defining terms used.
-* MPFR features:: The MPFR features in 'gawk'.
+* MPFR features:: The MPFR features in âgawkâ.
* FP Math Caution:: Things to know.
* Arbitrary Precision Integers:: Arbitrary Precision Integer Arithmetic with
- 'gawk'.
+ âgawkâ.
* Checking for MPFR:: How to check if MPFR is available.
* POSIX Floating Point Problems:: Standards Versus Existing Practice.
* Floating point summary:: Summary of floating point discussion.
@@ -24598,8 +24596,8 @@ File: gawk.info, Node: Computer Arithmetic, Next:
Math Definitions, Up: Arbit
=================================================
Until now, we have worked with data as either numbers or strings.
-Ultimately, however, computers represent everything in terms of "binary
-digits", or "bits". A decimal digit can take on any of 10 values: zero
+Ultimately, however, computers represent everything in terms of âbinary
+digitsâ, or âbitsâ. A decimal digit can take on any of 10 values: zero
through nine. A binary digit can take on any of two values, zero or
one. Using binary, computers (and computer software) can represent and
manipulate numerical and character data. In general, the more bits you
@@ -24623,17 +24621,17 @@ Decimal arithmetic
these instructions. There are also libraries that do decimal
arithmetic entirely in software.
- Despite the fact that some users expect 'gawk' to be performing
+ Despite the fact that some users expect âgawkâ to be performing
decimal arithmetic,(1) it does not do so.
Integer arithmetic
- In school, integer values were referred to as "whole" numbers--that
- is, numbers without any fractional part, such as 1, 42, or -17.
+ In school, integer values were referred to as âwholeâ numbersâthat
+ is, numbers without any fractional part, such as 1, 42, or â17.
The advantage to integer numbers is that they represent values
exactly. The disadvantage is that their range is limited.
- In computers, integer values come in two flavors: "signed" and
- "unsigned". Signed values may be negative or positive, whereas
+ In computers, integer values come in two flavors: âsignedâ and
+ âunsignedâ. Signed values may be negative or positive, whereas
unsigned values are always greater than or equal to zero.
In computer systems, integer arithmetic is exact, but the possible
@@ -24641,7 +24639,7 @@ Integer arithmetic
than floating-point arithmetic.
Floating-point arithmetic
- Floating-point numbers represent what were called in school "real"
+ Floating-point numbers represent what were called in school ârealâ
numbers (i.e., those that have a fractional part, such as
3.1415927). The advantage to floating-point numbers is that they
can represent a much larger range of values than can integers. The
@@ -24652,9 +24650,9 @@ Floating-point arithmetic
a limited range of values. There are software libraries that allow
the use of arbitrary-precision floating-point calculations.
- POSIX 'awk' uses "double-precision" floating-point numbers, which
- can hold more digits than "single-precision" floating-point
- numbers. 'gawk' has facilities for performing arbitrary-precision
+ POSIX âawkâ uses âdouble-precisionâ floating-point numbers, which
+ can hold more digits than âsingle-precisionâ floating-point
+ numbers. âgawkâ has facilities for performing arbitrary-precision
floating-point arithmetic, which we describe in more detail
shortly.
@@ -24663,7 +24661,7 @@ ranges. Integer values are usually either 32 or 64
bits in size.
Single-precision floating-point values occupy 32 bits, whereas
double-precision floating-point values occupy 64 bits.
(Quadruple-precision floating point values also exist. They occupy 128
-bits, but such numbers are not available in 'awk'.) Floating-point
+bits, but such numbers are not available in âawkâ.) Floating-point
values are always signed. The possible ranges of values are shown in
*note Table 16.1: table-numeric-ranges. and *note Table 16.2:
table-floating-point-ranges.
@@ -24671,10 +24669,10 @@ table-floating-point-ranges.
Representation Minimum value Maximum value
---------------------------------------------------------------------------
-32-bit signed integer -2,147,483,648 2,147,483,647
+32-bit signed integer â2,147,483,648 2,147,483,647
32-bit unsigned 0 4,294,967,295
integer
-64-bit signed integer -9,223,372,036,854,775,8089,223,372,036,854,775,807
+64-bit signed integer â9,223,372,036,854,775,8089,223,372,036,854,775,807
64-bit unsigned 0 18,446,744,073,709,551,615
integer
@@ -24697,7 +24695,7 @@ representations
---------- Footnotes ----------
- (1) We don't know why they expect this, but they do.
+ (1) We donât know why they expect this, but they do.
File: gawk.info, Node: Math Definitions, Next: MPFR features, Prev:
Computer Arithmetic, Up: Arbitrary Precision Arithmetic
@@ -24709,36 +24707,36 @@ The rest of this major node uses a number of terms.
Here are some
informal definitions that should help you work your way through the
material here:
-"Accuracy"
- A floating-point calculation's accuracy is how close it comes to
+âAccuracyâ
+ A floating-point calculationâs accuracy is how close it comes to
the real (paper and pencil) value.
-"Error"
- The difference between what the result of a computation "should be"
+âErrorâ
+ The difference between what the result of a computation âshould beâ
and what it actually is. It is best to minimize error as much as
possible.
-"Exponent"
+âExponentâ
The order of magnitude of a value; some number of bits in a
floating-point value store the exponent.
-"Inf"
+âInfâ
A special value representing infinity. Operations involving
another number and infinity produce infinity.
-"NaN"
- "Not a number." A special value that results from attempting a
+âNaNâ
+ âNot a number.â A special value that results from attempting a
calculation that has no answer as a real number. *Note Strange
values::, for more information about infinity and not-a-number
values.
-"Normalized"
+âNormalizedâ
How the significand (see later in this list) is usually stored.
The value is adjusted so that the first bit is one, and then that
leading one is assumed instead of physically stored. This provides
one extra bit of precision.
-"Precision"
+âPrecisionâ
The number of bits used to represent a floating-point number. The
more bits, the more digits you can represent. Binary and decimal
precisions are related approximately, according to the formula:
@@ -24748,20 +24746,20 @@ material here:
Here, _prec_ denotes the binary precision (measured in bits) and
_dps_ (short for decimal places) is the decimal digits.
-"Rounding mode"
+âRounding modeâ
How numbers are rounded up or down when necessary. More details
are provided later.
-"Significand"
+âSignificandâ
A floating-point value consists of the significand multiplied by 10
- to the power of the exponent. For example, in '1.2345e67', the
- significand is '1.2345'.
+ to the power of the exponent. For example, in â1.2345e67â, the
+ significand is â1.2345â.
-"Stability"
+âStabilityâ
From the Wikipedia article on numerical stability
- (https://en.wikipedia.org/wiki/Numerical_stability): "Calculations
+ (https://en.wikipedia.org/wiki/Numerical_stability): âCalculations
that can be proven not to magnify approximation errors are called
- "numerically stable"."
+ ânumerically stableâ.â
See the Wikipedia article on accuracy and precision
(https://en.wikipedia.org/wiki/Accuracy_and_precision) for more
@@ -24772,7 +24770,7 @@ and operations defined by the IEEE 754 standard. Three
of the standard
IEEE 754 types are 32-bit single precision, 64-bit double precision, and
128-bit quadruple precision. The standard also specifies extended
precision formats to allow greater precisions and larger exponent
-ranges. ('awk' uses only the 64-bit double-precision format.)
+ranges. (âawkâ uses only the 64-bit double-precision format.)
*note Table 16.3: table-ieee-formats. lists the precision and
exponent field values for the basic IEEE 754 binary formats.
@@ -24781,9 +24779,9 @@ exponent field values for the basic IEEE 754 binary
formats.
Name Total bits Precision Minimum Maximum
exponent exponent
---------------------------------------------------------------------------
-Single 32 24 -126 +127
-Double 64 53 -1022 +1023
-Quadruple 128 113 -16382 +16383
+Single 32 24 â126 +127
+Double 64 53 â1022 +1023
+Quadruple 128 113 â16382 +16383
Table 16.3: Basic IEEE format values
@@ -24793,11 +24791,11 @@ Table 16.3: Basic IEEE format values
File: gawk.info, Node: MPFR features, Next: FP Math Caution, Prev: Math
Definitions, Up: Arbitrary Precision Arithmetic
-16.3 Arbitrary-Precision Arithmetic Features in 'gawk'
+16.3 Arbitrary-Precision Arithmetic Features in âgawkâ
======================================================
This minor node briefly describes arbitrary-precision arithmetic in
-'gawk'.
+âgawkâ.
* Menu:
@@ -24810,8 +24808,8 @@ File: gawk.info, Node: MPFR On Parole, Next: MPFR
Intro, Up: MPFR features
16.3.1 Arbitrary Precision Arithmetic is On Parole!
---------------------------------------------------
-As of version 5.2, arbitrary precision arithmetic in 'gawk' is "on
-parole." The primary 'gawk' maintainer is no longer maintaining it.
+As of version 5.2, arbitrary precision arithmetic in âgawkâ is âon
+parole.â The primary âgawkâ maintainer is no longer maintaining it.
Fortunately, a volunteer from the development team has agreed to take it
over.
@@ -24820,14 +24818,14 @@ has led to endless bug reports, misuse of the feature
and public abuse
of the maintainer, for no real increased value.
If the situation with support changes, the feature will be removed
-from 'gawk'.
+from âgawkâ.
If you use this feature, you should consider finding a different
toolset with which to accomplish your goals.(1)
---------- Footnotes ----------
- (1) Of course, you can always continue to use a version of 'gawk'
+ (1) Of course, you can always continue to use a version of âgawkâ
that still supports arbitrary precision arithmetic. It simply will be
unmaintained.
@@ -24837,33 +24835,33 @@ File: gawk.info, Node: MPFR Intro, Prev: MPFR On
Parole, Up: MPFR features
16.3.2 Arbitrary Precision Introduction
---------------------------------------
-By default, 'gawk' uses the double-precision floating-point values
+By default, âgawkâ uses the double-precision floating-point values
supplied by the hardware of the system it runs on. However, if it was
-compiled to do so, and the '-M' command-line option is supplied, 'gawk'
+compiled to do so, and the â-Mâ command-line option is supplied, âgawkâ
uses the GNU MPFR (http://www.mpfr.org) and GNU MP (https://gmplib.org)
(GMP) libraries for arbitrary-precision arithmetic on numbers. You can
see if MPFR support is available like so:
$ gawk --version
- -| GNU Awk 5.2.1, API 3.2, PMA Avon 8-g1, (GNU MPFR 4.1.0, GNU MP 6.2.1)
- -| Copyright (C) 1989, 1991-2022 Free Software Foundation.
+ ⣠GNU Awk 5.2.1, API 3.2, PMA Avon 8-g1, (GNU MPFR 4.1.0, GNU MP 6.2.1)
+ ⣠Copyright (C) 1989, 1991-2022 Free Software Foundation.
...
-(You may see different version numbers than what's shown here. That's
-OK; what's important is to see that GNU MPFR and GNU MP are listed in
+(You may see different version numbers than whatâs shown here. Thatâs
+OK; whatâs important is to see that GNU MPFR and GNU MP are listed in
the output.)
- Additionally, there are a few elements available in the 'PROCINFO'
+ Additionally, there are a few elements available in the âPROCINFOâ
array to provide information about the MPFR and GMP libraries (*note
Auto-set::).
The MPFR library provides precise control over precisions and
rounding modes, and gives correctly rounded, reproducible,
-platform-independent results. With the '-M' command-line option, all
+platform-independent results. With the â-Mâ command-line option, all
floating-point arithmetic operators and numeric functions can yield
results to any desired precision level supported by MPFR.
- Two predefined variables, 'PREC' and 'ROUNDMODE', provide control
+ Two predefined variables, âPRECâ and âROUNDMODEâ, provide control
over the working precision and the rounding mode. The precision and the
rounding mode are set globally for every operation to follow. *Note
Setting precision:: and *note Setting the rounding mode:: for more
@@ -24876,7 +24874,7 @@ File: gawk.info, Node: FP Math Caution, Next:
Arbitrary Precision Integers, P
==============================================
Math class is tough!
- -- _Teen Talk Barbie, July 1992_
+ â _Teen Talk Barbie, July 1992_
This minor node provides a high-level overview of the issues involved
when doing lots of floating-point arithmetic.(1) The discussion applies
@@ -24897,9 +24895,9 @@ to both hardware and arbitrary-precision floating-point
arithmetic.
---------- Footnotes ----------
(1) There is a very nice paper on floating-point arithmetic
-(http://www.validlab.com/goldberg/paper.pdf) by David Goldberg, "What
-Every Computer Scientist Should Know About Floating-Point Arithmetic,"
-'ACM Computing Surveys' *23*, 1 (1991-03): 5-48. This is worth reading
+(http://www.validlab.com/goldberg/paper.pdf) by David Goldberg, âWhat
+Every Computer Scientist Should Know About Floating-Point Arithmetic,â
+âACM Computing Surveysâ *23*, 1 (1991-03): 5-48. This is worth reading
if you are interested in the details, but it does require a background
in computer science.
@@ -24932,28 +24930,28 @@ File: gawk.info, Node: Inexact representation,
Next: Comparing FP Values, Up:
...................................................
So, before you start to write any code, you should think about what you
-really want and what's really happening. Consider the two numbers in
+really want and whatâs really happening. Consider the two numbers in
the following example:
x = 0.875 # 1/2 + 1/4 + 1/8
y = 0.425
- Unlike the number in 'y', the number stored in 'x' is exactly
+ Unlike the number in âyâ, the number stored in âxâ is exactly
representable in binary because it can be written as a finite sum of one
-or more fractions whose denominators are all powers of two. When 'gawk'
+or more fractions whose denominators are all powers of two. When âgawkâ
reads a floating-point number from program source, it automatically
rounds that number to whatever precision your machine supports. If you
try to print the numeric content of a variable using an output format
-string of '"%.17g"', it may not produce the same number as you assigned
+string of â"%.17g"â, it may not produce the same number as you assigned
to it:
$ gawk 'BEGIN { x = 0.875; y = 0.425
> printf("%0.17g, %0.17g\n", x, y) }'
- -| 0.875, 0.42499999999999999
+ ⣠0.875, 0.42499999999999999
Often the error is so small you do not even notice it, and if you do,
you can always specify how much precision you would like in your output.
-Usually this is a format string like '"%.15g"', which, when used in the
+Usually this is a format string like â"%.15g"â, which, when used in the
previous example, produces an output identical to the input.
@@ -24968,11 +24966,11 @@ equal is generally a bad idea. Here is an example
where it does not
work like you would expect:
$ gawk 'BEGIN { print (0.1 + 12.2 == 12.3) }'
- -| 0
+ ⣠0
The general wisdom when comparing floating-point values is to see if
-they are within some small range of each other (called a "delta", or
-"tolerance"). You have to decide how small a delta is important to you.
+they are within some small range of each other (called a âdeltaâ, or
+âtoleranceâ). You have to decide how small a delta is important to you.
Code to do this looks something like the following:
delta = 0.00001 # for example
@@ -24982,9 +24980,9 @@ Code to do this looks something like the following:
else
# not ok
-(We assume that you have a simple absolute value function named 'abs()'
+(We assume that you have a simple absolute value function named âabs()â
defined elsewhere in your program.) If you write a function to compare
-values with a delta, you should be sure to use 'difference < abs(delta)'
+values with a delta, you should be sure to use âdifference < abs(delta)â
in case someone passes in a negative delta value.
@@ -24994,7 +24992,7 @@ File: gawk.info, Node: Errors accumulate, Next:
Strange values, Prev: Compari
..........................
The loss of accuracy during a single computation with floating-point
-numbers usually isn't enough to worry about. However, if you compute a
+numbers usually isnât enough to worry about. However, if you compute a
value that is the result of a sequence of floating-point operations, the
error can accumulate and greatly affect the computation itself. Here is
an attempt to compute the value of pi using one of its many series
@@ -25015,15 +25013,15 @@ causing the loop to terminate prematurely after
attempting to divide by
zero:
$ gawk -f pi.awk
- -| 3.215390309173475
- -| 3.159659942097510
- -| 3.146086215131467
- -| 3.142714599645573
+ ⣠3.215390309173475
+ ⣠3.159659942097510
+ ⣠3.146086215131467
+ ⣠3.142714599645573
...
- -| 3.224515243534819
- -| 2.791117213058638
- -| 0.000000000000000
- error-> gawk: pi.awk:6: fatal: division by zero attempted
+ ⣠3.224515243534819
+ ⣠2.791117213058638
+ ⣠0.000000000000000
+ errorâ gawk: pi.awk:6: fatal: division by zero attempted
Here is an additional example where the inaccuracies in internal
representations yield an unexpected result:
@@ -25033,20 +25031,20 @@ representations yield an unexpected result:
> i++
> print i
> }'
- -| 4
+ ⣠4
File: gawk.info, Node: Strange values, Prev: Errors accumulate, Up:
Inexactness of computations
-16.4.1.4 Floating Point Values They Didn't Talk About In School
+16.4.1.4 Floating Point Values They Didnât Talk About In School
...............................................................
Both IEEE 754 floating-point hardware, and MPFR, support two kinds of
-values that you probably didn't learn about in school. The first is
-"infinity", a special value, that can be either negative or positive,
+values that you probably didnât learn about in school. The first is
+âinfinityâ, a special value, that can be either negative or positive,
and which is either smaller than any other value (negative infinity), or
larger than any other value (positive infinity). When such values are
-generated, 'gawk' prints them as either '-inf' or '+inf', respectively.
+generated, âgawkâ prints them as either â-infâ or â+infâ,
respectively.
It accepts those strings as data input and converts them to the proper
floating-point values internally.
@@ -25054,37 +25052,37 @@ floating-point values internally.
Otherwise, operations (addition, subtraction, etc.) involving another
number and infinity produce mathematically reasonable results.
- The second kind of value is "not a number", or NaN for short.(1)
+ The second kind of value is ânot a numberâ, or NaN for short.(1)
This is a special value that results from attempting a calculation that
has no answer as a real number. In such a case, programs can either
receive a floating-point exception, or get NaN back as the result. The
IEEE 754 standard recommends that systems return NaN. Some examples:
-'sqrt(-1)'
+âsqrt(-1)â
This makes sense in the range of complex numbers, but not in the
range of real numbers, so the result is NaN.
-'log(-8)'
- -8 is out of the domain of 'log()', so the result is NaN.
+âlog(-8)â
+ â8 is out of the domain of âlog()â, so the result is NaN.
NaN values are strange. In particular, they cannot be compared with
-other floating point values; any such comparison, except for "is not
-equal to", returns false. NaN values are so much unequal to other
-values that even comparing two identical NaN values with '!=' returns
+other floating point values; any such comparison, except for âis not
+equal toâ, returns false. NaN values are so much unequal to other
+values that even comparing two identical NaN values with â!=â returns
true!
NaN values can also be signed, although it depends upon the
implementation as to which sign you get for any operation that returns a
-NaN. For example, on some systems, 'sqrt(-1)' returns a negative NaN. On
+NaN. For example, on some systems, âsqrt(-1)â returns a negative NaN. On
others, it returns a positive NaN.
- When such values are generated, 'gawk' prints them as either '-nan'
-or '+nan', respectively. Here too, 'gawk' accepts those strings as data
+ When such values are generated, âgawkâ prints them as either â-nanâ
+or â+nanâ, respectively. Here too, âgawkâ accepts those strings as
data
input and converts them to the proper floating-point values internally.
If you want to dive more deeply into this topic, you can find test
-programs in C, 'awk' and Python in the directory
-'awklib/eg/test-programs' in the 'gawk' distribution. These programs
+programs in C, âawkâ and Python in the directory
+âawklib/eg/test-programsâ in the âgawkâ distribution. These programs
enable comparison among programming languages as to how they handle NaN
and infinity values.
@@ -25106,23 +25104,23 @@ and associative laws do not hold completely, and
order of operation may
be important for your computation. Rounding error, cumulative precision
loss, and underflow are often troublesome.
- When 'gawk' tests the expressions '0.1 + 12.2' and '12.3' for
+ When âgawkâ tests the expressions â0.1 + 12.2â and â12.3â for
equality using the machine double-precision arithmetic, it decides that
they are not equal! (*Note Comparing FP Values::.) You can get the
result you want by increasing the precision; 56 bits in this case does
the job:
$ gawk -M -v PREC=56 'BEGIN { print (0.1 + 12.2 == 12.3) }'
- -| 1
+ ⣠1
If adding more bits is good, perhaps adding even more bits of
precision is better? Here is what happens if we use an even larger
-value of 'PREC':
+value of âPRECâ:
$ gawk -M -v PREC=201 'BEGIN { print (0.1 + 12.2 == 12.3) }'
- -| 0
+ ⣠0
- This is not a bug in 'gawk' or in the MPFR library. It is easy to
+ This is not a bug in âgawkâ or in the MPFR library. It is easy to
forget that the finite number of bits used to store the value is often
just an approximation after proper rounding. The test for equality
succeeds if and only if _all_ bits in the two operands are exactly the
@@ -25148,10 +25146,10 @@ In the example in *note Errors accumulate:::
> i++
> print i
> }'
- -| 4
+ ⣠4
you may or may not succeed in getting the correct result by choosing an
-arbitrarily large value for 'PREC'. Reformulation of the problem at
+arbitrarily large value for âPRECâ. Reformulation of the problem at
hand is often the correct approach in such situations.
@@ -25166,20 +25164,20 @@ operations in your calculation. The stability and
the accuracy of the
computation of pi in the earlier example can be enhanced by using the
following simple algebraic transformation:
- (sqrt(x * x + 1) - 1) / x == x / (sqrt(x * x + 1) + 1)
+ (sqrt(x * x + 1) - 1) / x â¡ x / (sqrt(x * x + 1) + 1)
After making this change, the program converges to pi in under 30
iterations:
$ gawk -f pi2.awk
- -| 3.215390309173473
- -| 3.159659942097501
- -| 3.146086215131436
- -| 3.142714599645370
- -| 3.141873049979825
+ ⣠3.215390309173473
+ ⣠3.159659942097501
+ ⣠3.146086215131436
+ ⣠3.142714599645370
+ ⣠3.141873049979825
...
- -| 3.141592653589797
- -| 3.141592653589797
+ ⣠3.141592653589797
+ ⣠3.141592653589797
File: gawk.info, Node: Setting precision, Next: Setting the rounding mode,
Prev: Try To Round, Up: FP Math Caution
@@ -25187,57 +25185,57 @@ File: gawk.info, Node: Setting precision, Next:
Setting the rounding mode, Pr
16.4.4 Setting the Precision
----------------------------
-'gawk' uses a global working precision; it does not keep track of the
+âgawkâ uses a global working precision; it does not keep track of the
precision or accuracy of individual numbers. Performing an arithmetic
operation or calling a built-in function rounds the result to the
current working precision. The default working precision is 53 bits,
-which you can modify using the predefined variable 'PREC'. You can also
+which you can modify using the predefined variable âPRECâ. You can also
set the value to one of the predefined case-insensitive strings shown in
*note Table 16.4: table-predefined-precision-strings, to emulate an IEEE
754 binary format.
-'PREC' IEEE 754 binary format
+âPRECâ IEEE 754 binary format
---------------------------------------------------
-'"half"' 16-bit half-precision
-'"single"' Basic 32-bit single precision
-'"double"' Basic 64-bit double precision
-'"quad"' Basic 128-bit quadruple precision
-'"oct"' 256-bit octuple precision
+â"half"â 16-bit half-precision
+â"single"â Basic 32-bit single precision
+â"double"â Basic 64-bit double precision
+â"quad"â Basic 128-bit quadruple precision
+â"oct"â 256-bit octuple precision
-Table 16.4: Predefined precision strings for 'PREC'
+Table 16.4: Predefined precision strings for âPRECâ
The following example illustrates the effects of changing precision
on arithmetic operations:
$ gawk -M -v PREC=100 'BEGIN { x = 1.0e-400; print x + 0
> PREC = "double"; print x + 0 }'
- -| 1e-400
- -| 0
+ ⣠1e-400
+ ⣠0
CAUTION: Be wary of floating-point constants! When reading a
- floating-point constant from program source code, 'gawk' uses the
- default precision (that of a C 'double'), unless overridden by an
- assignment to the special variable 'PREC' on the command line, to
+ floating-point constant from program source code, âgawkâ uses the
+ default precision (that of a C âdoubleâ), unless overridden by an
+ assignment to the special variable âPRECâ on the command line, to
store it internally as an MPFR number. Changing the precision
- using 'PREC' in the program text does _not_ change the precision of
+ using âPRECâ in the program text does _not_ change the precision of
a constant.
If you need to represent a floating-point constant at a higher
precision than the default and cannot use a command-line assignment
- to 'PREC', you should either specify the constant as a string, or
+ to âPRECâ, you should either specify the constant as a string, or
as a rational number, whenever possible. The following example
illustrates the differences among various ways to print a
floating-point constant:
$ gawk -M 'BEGIN { PREC = 113; printf("%0.25f\n", 0.1) }'
- -| 0.1000000000000000055511151
+ ⣠0.1000000000000000055511151
$ gawk -M -v PREC=113 'BEGIN { printf("%0.25f\n", 0.1) }'
- -| 0.1000000000000000000000000
+ ⣠0.1000000000000000000000000
$ gawk -M 'BEGIN { PREC = 113; printf("%0.25f\n", "0.1") }'
- -| 0.1000000000000000000000000
+ ⣠0.1000000000000000000000000
$ gawk -M 'BEGIN { PREC = 113; printf("%0.25f\n", 1/10) }'
- -| 0.1000000000000000000000000
+ ⣠0.1000000000000000000000000
File: gawk.info, Node: Setting the rounding mode, Prev: Setting precision,
Up: FP Math Caution
@@ -25245,28 +25243,28 @@ File: gawk.info, Node: Setting the rounding mode,
Prev: Setting precision, Up
16.4.5 Setting the Rounding Mode
--------------------------------
-The 'ROUNDMODE' variable provides program-level control over the
-rounding mode. The correspondence between 'ROUNDMODE' and the IEEE
+The âROUNDMODEâ variable provides program-level control over the
+rounding mode. The correspondence between âROUNDMODEâ and the IEEE
rounding modes is shown in *note Table 16.5: table-gawk-rounding-modes.
-Rounding mode IEEE name 'ROUNDMODE'
+Rounding mode IEEE name âROUNDMODEâ
---------------------------------------------------------------------------
-Round to nearest, ties to even 'roundTiesToEven' '"N"' or '"n"'
-Round toward positive infinity 'roundTowardPositive' '"U"' or '"u"'
-Round toward negative infinity 'roundTowardNegative' '"D"' or '"d"'
-Round toward zero 'roundTowardZero' '"Z"' or '"z"'
-Round away from zero '"A"' or '"a"'
+Round to nearest, ties to even âroundTiesToEvenâ â"N"â or
â"n"â
+Round toward positive infinity âroundTowardPositiveâ â"U"â or
â"u"â
+Round toward negative infinity âroundTowardNegativeâ â"D"â or
â"d"â
+Round toward zero âroundTowardZeroâ â"Z"â or
â"z"â
+Round away from zero â"A"â or â"a"â
-Table 16.5: 'gawk' rounding modes
+Table 16.5: âgawkâ rounding modes
- 'ROUNDMODE' has the default value '"N"', which selects the IEEE 754
-rounding mode 'roundTiesToEven'. In *note Table 16.5:
-table-gawk-rounding-modes, the value '"A"' selects rounding away from
+ âROUNDMODEâ has the default value â"N"â, which selects the IEEE 754
+rounding mode âroundTiesToEvenâ. In *note Table 16.5:
+table-gawk-rounding-modes, the value â"A"â selects rounding away from
zero. This is only available if your version of the MPFR library
-supports it; otherwise, setting 'ROUNDMODE' to '"A"' has no effect.
+supports it; otherwise, setting âROUNDMODEâ to â"A"â has no effect.
- The default mode 'roundTiesToEven' is the most preferred, but the
+ The default mode âroundTiesToEvenâ is the most preferred, but the
least intuitive. This method does the obvious thing for most values, by
rounding them up or down to the nearest digit. For example, rounding
1.132 to two digits yields 1.13, and rounding 1.157 yields 1.16.
@@ -25276,7 +25274,7 @@ between, things do not work the way you probably
learned in school. In
this case, the number is rounded to the nearest even digit. So rounding
0.125 to two digits rounds down to 0.12, but rounding 0.6875 to three
digits rounds up to 0.688. You probably have already encountered this
-rounding mode when using 'printf' to format floating-point numbers. For
+rounding mode when using âprintfâ to format floating-point numbers. For
example:
BEGIN {
@@ -25287,7 +25285,7 @@ example:
}
}
-produces the following output when run on the author's system:(1)
+produces the following output when run on the authorâs system:(1)
-3.5 => -4
-2.5 => -2
@@ -25299,7 +25297,7 @@ produces the following output when run on the author's
system:(1)
3.5 => 4
4.5 => 4
- The theory behind 'roundTiesToEven' is that it more or less evenly
+ The theory behind âroundTiesToEvenâ is that it more or less evenly
distributes upward and downward rounds of exact halves, which might
cause any accumulating round-off error to cancel itself out. This is
the default rounding mode for IEEE 754 computing functions and
@@ -25307,7 +25305,7 @@ operators.
Rounding Modes and Conversion
- It's important to understand that, along with 'CONVFMT' and 'OFMT',
+ Itâs important to understand that, along with âCONVFMTâ and
âOFMTâ,
the rounding mode affects how numbers are converted to strings. For
example, consider the following program:
@@ -25322,14 +25320,14 @@ example, consider the following program:
Running this program produces this output:
$ gawk -M -f roundmode.awk
- -| 3
- -| 4
+ ⣠3
+ ⣠4
The other rounding modes are rarely used. Rounding toward positive
-infinity ('roundTowardPositive') and toward negative infinity
-('roundTowardNegative') are often used to implement interval arithmetic,
+infinity (âroundTowardPositiveâ) and toward negative infinity
+(âroundTowardNegativeâ) are often used to implement interval arithmetic,
where you adjust the rounding mode to calculate upper and lower bounds
-for the range of output. The 'roundTowardZero' mode can be used for
+for the range of output. The âroundTowardZeroâ mode can be used for
converting floating-point numbers to integers. When rounding away from
zero, the nearest number with magnitude greater than or equal to the
value is selected.
@@ -25348,15 +25346,15 @@ change the rounding mode to be sure.
(1) It is possible for the output to be completely different if the C
library in your system does not use the IEEE 754 even-rounding rule to
-round halfway cases for 'printf'.
+round halfway cases for âprintfâ.
File: gawk.info, Node: Arbitrary Precision Integers, Next: Checking for
MPFR, Prev: FP Math Caution, Up: Arbitrary Precision Arithmetic
-16.5 Arbitrary-Precision Integer Arithmetic with 'gawk'
+16.5 Arbitrary-Precision Integer Arithmetic with âgawkâ
=======================================================
-When given the '-M' option, 'gawk' performs all integer arithmetic using
+When given the â-Mâ option, âgawkâ performs all integer arithmetic
using
GMP arbitrary-precision integers. Any number that looks like an integer
in a source or data file is stored as an arbitrary-precision integer.
The size of the integer is limited only by the available memory. For
@@ -25368,18 +25366,18 @@ the limits of ordinary hardware double-precision
floating-point values:
> print "number of digits =", length(x)
> print substr(x, 1, 20), "...", substr(x, length(x) - 19, 20)
> }'
- -| number of digits = 183231
- -| 62060698786608744707 ... 92256259918212890625
+ ⣠number of digits = 183231
+ ⣠62060698786608744707 ... 92256259918212890625
If instead you were to compute the same value using
arbitrary-precision floating-point values, the precision needed for
-correct output (using the formula 'prec = 3.322 * dps') would be 3.322 x
+correct output (using the formula âprec = 3.322 * dpsâ) would be 3.322 x
183231, or 608693.
The result from an arithmetic operation with an integer and a
floating-point value is a floating-point value with a precision equal to
the working precision. The following program calculates the eighth term
-in Sylvester's sequence(1) using a recurrence:
+in Sylvesterâs sequence(1) using a recurrence:
$ gawk -M 'BEGIN {
> s = 2.0
@@ -25387,16 +25385,16 @@ in Sylvester's sequence(1) using a recurrence:
> s = s * (s - 1) + 1
> print s
> }'
- -| 113423713055421845118910464
+ ⣠113423713055421845118910464
The output differs from the actual number,
113,423,713,055,421,844,361,000,443, because the default precision of 53
bits is not enough to represent the floating-point results exactly. You
can either increase the precision (100 bits is enough in this case), or
-replace the floating-point constant '2.0' with an integer, to perform
+replace the floating-point constant â2.0â with an integer, to perform
all computations using integer arithmetic to get the correct output.
- Sometimes 'gawk' must implicitly convert an arbitrary-precision
+ Sometimes âgawkâ must implicitly convert an arbitrary-precision
integer into an arbitrary-precision floating-point value. This is
primarily because the MPFR library does not always provide the relevant
interface to process arbitrary-precision integers or mixed-mode numbers
@@ -25418,13 +25416,13 @@ the following:
gawk -M 'BEGIN { n = 13; print n % 2 }'
- When dividing two arbitrary precision integers with either '/' or
-'%', the result is typically an arbitrary precision floating point value
+ When dividing two arbitrary precision integers with either â/â or
+â%â, the result is typically an arbitrary precision floating point value
(unless the denominator evenly divides into the numerator).
---------- Footnotes ----------
- (1) Weisstein, Eric W. 'Sylvester's Sequence'. From MathWorld--A
+ (1) Weisstein, Eric W. âSylvesterâs Sequenceâ. From MathWorldâA
Wolfram Web Resource
(<http://mathworld.wolfram.com/SylvestersSequence.html>).
@@ -25434,8 +25432,8 @@ File: gawk.info, Node: Checking for MPFR, Next: POSIX
Floating Point Problems,
16.6 How To Check If MPFR Is Available
======================================
-Occasionally, you might like to be able to check if 'gawk' was invoked
-with the '-M' option, enabling arbitrary-precision arithmetic. You can
+Occasionally, you might like to be able to check if âgawkâ was invoked
+with the â-Mâ option, enabling arbitrary-precision arithmetic. You can
do so with the following function, contributed by Andrew Schorr:
# adequate_math_precision --- return true if we have enough bits
@@ -25466,7 +25464,7 @@ arbitrary-precision arithmetic is available:
}
}
- Please be aware that 'exit' will jump to the 'END' rules, if present
+ Please be aware that âexitâ will jump to the âENDâ rules, if present
(*note Exit Statement::).
@@ -25475,95 +25473,95 @@ File: gawk.info, Node: POSIX Floating Point
Problems, Next: Floating point sum
16.7 Standards Versus Existing Practice
=======================================
-Historically, 'awk' has converted any nonnumeric-looking string to the
+Historically, âawkâ has converted any nonnumeric-looking string to the
numeric value zero, when required. Furthermore, the original definition
-of the language and the original POSIX standards specified that 'awk'
+of the language and the original POSIX standards specified that âawkâ
only understands decimal numbers (base 10), and not octal (base 8) or
hexadecimal numbers (base 16).
Changes in the language of the 2001 and 2004 POSIX standards can be
-interpreted to imply that 'awk' should support additional features.
+interpreted to imply that âawkâ should support additional features.
These features are:
- * Interpretation of floating-point data values specified in
- hexadecimal notation (e.g., '0xDEADBEEF'). (Note: data values,
+ ⢠Interpretation of floating-point data values specified in
+ hexadecimal notation (e.g., â0xDEADBEEFâ). (Note: data values,
_not_ source code constants.)
- * Support for the special IEEE 754 floating-point values "not a
- number" (NaN), positive infinity ("inf"), and negative infinity
- ("-inf"). In particular, the format for these values is as
+ ⢠Support for the special IEEE 754 floating-point values ânot a
+ numberâ (NaN), positive infinity (âinfâ), and negative infinity
+ (ââinfâ). In particular, the format for these values is as
specified by the ISO 1999 C standard, which ignores case and can
allow implementation-dependent additional characters after the
- 'nan' and allow either 'inf' or 'infinity'.
+ ânanâ and allow either âinfâ or âinfinityâ.
The first problem is that both of these are clear changes to
historical practice:
- * The 'gawk' maintainer feels that supporting hexadecimal
+ ⢠The âgawkâ maintainer feels that supporting hexadecimal
floating-point values, in particular, is ugly, and was never
intended by the original designers to be part of the language.
- * Allowing completely alphabetic strings to have valid numeric values
+ ⢠Allowing completely alphabetic strings to have valid numeric values
is also a very severe departure from historical practice.
- The second problem is that the 'gawk' maintainer feels that this
+ The second problem is that the âgawkâ maintainer feels that this
interpretation of the standard, which required a certain amount of
-"language lawyering" to arrive at in the first place, was not even
-intended by the standard developers. In other words, "We see how you
-got where you are, but we don't think that that's where you want to be."
+âlanguage lawyeringâ to arrive at in the first place, was not even
+intended by the standard developers. In other words, âWe see how you
+got where you are, but we donât think that thatâs where you want to be.â
Recognizing these issues, but attempting to provide compatibility
with the earlier versions of the standard, the 2008 POSIX standard added
-explicit wording to allow, but not require, that 'awk' support
-hexadecimal floating-point values and special values for "not a number"
+explicit wording to allow, but not require, that âawkâ support
+hexadecimal floating-point values and special values for ânot a numberâ
and infinity.
- Although the 'gawk' maintainer continues to feel that providing those
+ Although the âgawkâ maintainer continues to feel that providing those
features is inadvisable, nevertheless, on systems that support IEEE
floating point, it seems reasonable to provide _some_ way to support NaN
-and infinity values. The solution implemented in 'gawk' is as follows:
+and infinity values. The solution implemented in âgawkâ is as follows:
- * With the '--posix' command-line option, 'gawk' becomes "hands off."
- String values are passed directly to the system library's
- 'strtod()' function, and if it successfully returns a numeric
- value, that is what's used.(1) By definition, the results are not
+ ⢠With the â--posixâ command-line option, âgawkâ becomes âhands
off.â
+ String values are passed directly to the system libraryâs
+ âstrtod()â function, and if it successfully returns a numeric
+ value, that is whatâs used.(1) By definition, the results are not
portable across different systems. They are also a little
surprising:
$ echo nanny | gawk --posix '{ print $1 + 0 }'
- -| nan
+ ⣠nan
$ echo 0xDeadBeef | gawk --posix '{ print $1 + 0 }'
- -| 3735928559
+ ⣠3735928559
- * Without '--posix', 'gawk' interprets the four string values '+inf',
- '-inf', '+nan', and '-nan' specially, producing the corresponding
- special numeric values. The leading sign acts a signal to 'gawk'
+ ⢠Without â--posixâ, âgawkâ interprets the four string values
â+infâ,
+ â-infâ, â+nanâ, and â-nanâ specially, producing the
corresponding
+ special numeric values. The leading sign acts a signal to âgawkâ
(and the user) that the value is really numeric. Hexadecimal
floating point is not supported (unless you also use
- '--non-decimal-data', which is _not_ recommended). For example:
+ â--non-decimal-dataâ, which is _not_ recommended). For example:
$ echo nanny | gawk '{ print $1 + 0 }'
- -| 0
+ ⣠0
$ echo +nan | gawk '{ print $1 + 0 }'
- -| +nan
+ ⣠+nan
$ echo 0xDeadBeef | gawk '{ print $1 + 0 }'
- -| 0
+ ⣠0
- 'gawk' ignores case in the four special values. Thus, '+nan' and
- '+NaN' are the same.
+ âgawkâ ignores case in the four special values. Thus, â+nanâ and
+ â+NaNâ are the same.
- Besides handling input, 'gawk' also needs to print "correct" values
+ Besides handling input, âgawkâ also needs to print âcorrectâ values
on output when a value is either NaN or infinity. Starting with version
-4.2.2, for such values 'gawk' prints one of the four strings just
-described: '+inf', '-inf', '+nan', or '-nan'. Similarly, in POSIX mode,
-'gawk' prints the result of the system's C 'printf()' function using the
-'%g' format string for the value, whatever that may be.
+4.2.2, for such values âgawkâ prints one of the four strings just
+described: â+infâ, â-infâ, â+nanâ, or â-nanâ. Similarly, in
POSIX mode,
+âgawkâ prints the result of the systemâs C âprintf()â function using
the
+â%gâ format string for the value, whatever that may be.
NOTE: The sign used for NaN values can vary! The result depends
upon both the underlying system architecture and the underlying
- library used to format NaN values. In particular, it's possible to
+ library used to format NaN values. In particular, itâs possible to
get different results for the same function call depending upon
- whether or not 'gawk' is running in MPFR mode ('-M') or not.
+ whether or not âgawkâ is running in MPFR mode (â-Mâ) or not.
Caveat Emptor!
---------- Footnotes ----------
@@ -25576,41 +25574,41 @@ File: gawk.info, Node: Floating point summary,
Prev: POSIX Floating Point Prob
16.8 Summary
============
- * Most computer arithmetic is done using either integers or
- floating-point values. Standard 'awk' uses double-precision
+ ⢠Most computer arithmetic is done using either integers or
+ floating-point values. Standard âawkâ uses double-precision
floating-point values.
- * In the early 1990s Barbie mistakenly said, "Math class is tough!"
- Although math isn't tough, floating-point arithmetic isn't the same
+ ⢠In the early 1990s Barbie mistakenly said, âMath class is tough!â
+ Although math isnât tough, floating-point arithmetic isnât the same
as pencil-and-paper math, and care must be taken:
- - Not all numbers can be represented exactly.
+ â Not all numbers can be represented exactly.
- - Comparing values should use a delta, instead of being done
- directly with '==' and '!='.
+ â Comparing values should use a delta, instead of being done
+ directly with â==â and â!=â.
- - Errors accumulate.
+ â Errors accumulate.
- - Operations are not always truly associative or distributive.
+ â Operations are not always truly associative or distributive.
- * Increasing the accuracy can help, but it is not a panacea.
+ ⢠Increasing the accuracy can help, but it is not a panacea.
- * Often, increasing the accuracy and then rounding to the desired
+ ⢠Often, increasing the accuracy and then rounding to the desired
number of digits produces reasonable results.
- * Use '-M' (or '--bignum') to enable MPFR arithmetic. Use 'PREC' to
- set the precision in bits, and 'ROUNDMODE' to set the IEEE 754
+ ⢠Use â-Mâ (or â--bignumâ) to enable MPFR arithmetic. Use
âPRECâ to
+ set the precision in bits, and âROUNDMODEâ to set the IEEE 754
rounding mode.
- * With '-M', 'gawk' performs arbitrary-precision integer arithmetic
+ ⢠With â-Mâ, âgawkâ performs arbitrary-precision integer
arithmetic
using the GMP library. This is faster and more space-efficient
than using MPFR for the same calculations.
- * There are several areas with respect to floating-point numbers
- where 'gawk' disagrees with the POSIX standard. It pays to be
+ ⢠There are several areas with respect to floating-point numbers
+ where âgawkâ disagrees with the POSIX standard. It pays to be
aware of them.
- * Overall, there is no need to be unduly suspicious about the results
+ ⢠Overall, there is no need to be unduly suspicious about the results
from floating-point arithmetic. The lesson to remember is that
floating-point arithmetic is always more complex than arithmetic
using pencil and paper. In order to take advantage of the power of
@@ -25620,27 +25618,27 @@ File: gawk.info, Node: Floating point summary,
Prev: POSIX Floating Point Prob
round the display of your final results to the correct number of
significant decimal digits.
- * As general advice, avoid presenting numerical data in a manner that
+ ⢠As general advice, avoid presenting numerical data in a manner that
implies better precision than is actually the case.
File: gawk.info, Node: Dynamic Extensions, Next: Language History, Prev:
Arbitrary Precision Arithmetic, Up: Top
-17 Writing Extensions for 'gawk'
+17 Writing Extensions for âgawkâ
********************************
-It is possible to add new functions written in C or C++ to 'gawk' using
+It is possible to add new functions written in C or C++ to âgawkâ using
dynamically loaded libraries. This facility is available on systems
-that support the C 'dlopen()' and 'dlsym()' functions. This major node
+that support the C âdlopen()â and âdlsym()â functions. This major node
describes how to create extensions using code written in C or C++.
- If you don't know anything about C programming, you can safely skip
+ If you donât know anything about C programming, you can safely skip
this major node, although you may wish to review the documentation on
-the extensions that come with 'gawk' (*note Extension Samples::), and
-the information on the 'gawkextlib' project (*note gawkextlib::). The
-sample extensions are automatically built and installed when 'gawk' is.
+the extensions that come with âgawkâ (*note Extension Samples::), and
+the information on the âgawkextlibâ project (*note gawkextlib::). The
+sample extensions are automatically built and installed when âgawkâ is.
- NOTE: When '--sandbox' is specified, extensions are disabled (*note
+ NOTE: When â--sandboxâ is specified, extensions are disabled (*note
Options::).
* Menu:
@@ -25649,11 +25647,11 @@ sample extensions are automatically built and
installed when 'gawk' is.
* Plugin License:: A note about licensing.
* Extension Mechanism Outline:: An outline of how it works.
* Extension API Description:: A full description of the API.
-* Finding Extensions:: How 'gawk' finds compiled extensions.
+* Finding Extensions:: How âgawkâ finds compiled extensions.
* Extension Example:: Example C code for an extension.
* Extension Samples:: The sample extensions that ship with
- 'gawk'.
-* gawkextlib:: The 'gawkextlib' project.
+ âgawkâ.
+* gawkextlib:: The âgawkextlibâ project.
* Extension summary:: Extension summary.
* Extension Exercises:: Exercises.
@@ -25663,24 +25661,24 @@ File: gawk.info, Node: Extension Intro, Next:
Plugin License, Up: Dynamic Ext
17.1 Introduction
=================
-An "extension" (sometimes called a "plug-in") is a piece of external
-compiled code that 'gawk' can load at runtime to provide additional
+An âextensionâ (sometimes called a âplug-inâ) is a piece of external
+compiled code that âgawkâ can load at runtime to provide additional
functionality, over and above the built-in capabilities described in the
rest of this Info file.
Extensions are useful because they allow you (of course) to extend
-'gawk''s functionality. For example, they can provide access to system
-calls (such as 'chdir()' to change directory) and to other C library
-routines that could be of use. As with most software, "the sky is the
-limit"; if you can imagine something that you might want to do and can
+âgawkââs functionality. For example, they can provide access to system
+calls (such as âchdir()â to change directory) and to other C library
+routines that could be of use. As with most software, âthe sky is the
+limitâ; if you can imagine something that you might want to do and can
write in C or C++, you can write an extension to do it!
- Extensions are written in C or C++, using the "application
-programming interface" (API) defined for this purpose by the 'gawk'
+ Extensions are written in C or C++, using the âapplication
+programming interfaceâ (API) defined for this purpose by the âgawkâ
developers. The rest of this major node explains the facilities that
the API provides and how to use them, and presents a small example
extension. In addition, it documents the sample extensions included in
-the 'gawk' distribution and describes the 'gawkextlib' project. *Note
+the âgawkâ distribution and describes the âgawkextlibâ project. *Note
Extension Design::, for a discussion of the extension mechanism goals
and design.
@@ -25693,12 +25691,12 @@ File: gawk.info, Node: Plugin License, Next:
Extension Mechanism Outline, Pre
Every dynamic extension must be distributed under a license that is
compatible with the GNU GPL (*note Copying::).
- In order for the extension to tell 'gawk' that it is properly
+ In order for the extension to tell âgawkâ that it is properly
licensed, the extension must define the global symbol
-'plugin_is_GPL_compatible'. If this symbol does not exist, 'gawk' emits
+âplugin_is_GPL_compatibleâ. If this symbol does not exist, âgawkâ
emits
a fatal error and exits when it tries to load your extension.
- The declared type of the symbol should be 'int'. It does not need to
+ The declared type of the symbol should be âintâ. It does not need to
be in any allocated section, though. The code merely asserts that the
symbol exists in the global scope. Something like this is enough:
@@ -25710,8 +25708,8 @@ File: gawk.info, Node: Extension Mechanism Outline,
Next: Extension API Descri
17.3 How It Works at a High Level
=================================
-Communication between 'gawk' and an extension is two-way. First, when
-an extension is loaded, 'gawk' passes it a pointer to a 'struct' whose
+Communication between âgawkâ and an extension is two-way. First, when
+an extension is loaded, âgawkâ passes it a pointer to a âstructâ whose
fields are function pointers. This is shown in *note Figure 17.1:
figure-load-extension.
@@ -25743,10 +25741,10 @@ figure-load-extension.
Figure 17.1: Loading the extension
- The extension can call functions inside 'gawk' through these function
-pointers, at runtime, without needing (link-time) access to 'gawk''s
+ The extension can call functions inside âgawkâ through these function
+pointers, at runtime, without needing (link-time) access to âgawkââs
symbols. One of these function pointers is to a function for
-"registering" new functions. This is shown in *note Figure 17.2:
+âregisteringâ new functions. This is shown in *note Figure 17.2:
figure-register-new-function.
@@ -25766,8 +25764,8 @@ figure-register-new-function.
Figure 17.2: Registering a new function
In the other direction, the extension registers its new functions
-with 'gawk' by passing function pointers to the functions that provide
-the new feature ('do_chdir()', for example). 'gawk' associates the
+with âgawkâ by passing function pointers to the functions that provide
+the new feature (âdo_chdir()â, for example). âgawkâ associates the
function pointer with a name and can then call it, using a defined
calling convention. This is shown in *note Figure 17.3:
figure-call-new-function.
@@ -25789,9 +25787,9 @@ figure-call-new-function.
Figure 17.3: Calling the new function
- The 'do_XXX()' function, in turn, then uses the function pointers in
-the API 'struct' to do its work, such as updating variables or arrays,
-printing messages, setting 'ERRNO', and so on.
+ The âdo_XXX()â function, in turn, then uses the function pointers in
+the API âstructâ to do its work, such as updating variables or arrays,
+printing messages, setting âERRNOâ, and so on.
Convenience macros make calling through the function pointers look
like regular function calls so that extension code is quite readable and
@@ -25799,20 +25797,20 @@ understandable.
Although all of this sounds somewhat complicated, the result is that
extension code is quite straightforward to write and to read. You can
-see this in the sample extension 'filefuncs.c' (*note Extension
-Example::) and also in the 'testext.c' code for testing the APIs.
+see this in the sample extension âfilefuncs.câ (*note Extension
+Example::) and also in the âtestext.câ code for testing the APIs.
Some other bits and pieces:
- * The API provides access to 'gawk''s 'do_XXX' values, reflecting
- command-line options, like 'do_lint', 'do_profiling', and so on
+ ⢠The API provides access to âgawkââs âdo_XXXâ values,
reflecting
+ command-line options, like âdo_lintâ, âdo_profilingâ, and so on
(*note Extension API Variables::). These are informational: an
- extension cannot affect their values inside 'gawk'. In addition,
+ extension cannot affect their values inside âgawkâ. In addition,
attempting to assign to them produces a compile-time error.
- * The API also provides major and minor version numbers, so that an
- extension can check if the 'gawk' it is loaded with supports the
- facilities it was compiled with. (Version mismatches "shouldn't"
+ ⢠The API also provides major and minor version numbers, so that an
+ extension can check if the âgawkâ it is loaded with supports the
+ facilities it was compiled with. (Version mismatches âshouldnâtâ
happen, but we all know how _that_ goes.) *Note Extension
Versioning:: for details.
@@ -25822,9 +25820,9 @@ File: gawk.info, Node: Extension API Description,
Next: Finding Extensions, P
17.4 API Description
====================
-C or C++ code for an extension must include the header file 'gawkapi.h',
+C or C++ code for an extension must include the header file âgawkapi.hâ,
which declares the functions and defines the data types used to
-communicate with 'gawk'. This (rather large) minor node describes the
+communicate with âgawkâ. This (rather large) minor node describes the
API in detail.
* Menu:
@@ -25835,9 +25833,9 @@ API in detail.
* Constructor Functions:: Functions for creating values.
* API Ownership of MPFR and GMP Values:: Managing MPFR and GMP Values.
* Registration Functions:: Functions to register things with
- 'gawk'.
+ âgawkâ.
* Printing Messages:: Functions for printing messages.
-* Updating ERRNO:: Functions for updating 'ERRNO'.
+* Updating ERRNO:: Functions for updating âERRNOâ.
* Requesting Values:: How to get a value.
* Accessing Parameters:: Functions for accessing parameters.
* Symbol Table Access:: Functions for accessing global
@@ -25855,144 +25853,144 @@ File: gawk.info, Node: Extension API Functions
Introduction, Next: General Dat
17.4.1 Introduction
-------------------
-Access to facilities within 'gawk' is achieved by calling through
+Access to facilities within âgawkâ is achieved by calling through
function pointers passed into your extension.
API function pointers are provided for the following kinds of
operations:
- * Allocating, reallocating, and releasing memory.
+ ⢠Allocating, reallocating, and releasing memory.
- * Registration functions. You may register:
+ ⢠Registration functions. You may register:
- - Extension functions
- - Exit callbacks
- - A version string
- - Input parsers
- - Output wrappers
- - Two-way processors
+ â Extension functions
+ â Exit callbacks
+ â A version string
+ â Input parsers
+ â Output wrappers
+ â Two-way processors
All of these are discussed in detail later in this major node.
- * Printing fatal, warning, and "lint" warning messages.
+ ⢠Printing fatal, warning, and âlintâ warning messages.
- * Updating 'ERRNO', or unsetting it.
+ ⢠Updating âERRNOâ, or unsetting it.
- * Accessing parameters, including converting an undefined parameter
+ ⢠Accessing parameters, including converting an undefined parameter
into an array.
- * Symbol table access: retrieving a global variable, creating one, or
+ ⢠Symbol table access: retrieving a global variable, creating one, or
changing one.
- * Creating and releasing cached values; this provides an efficient
+ ⢠Creating and releasing cached values; this provides an efficient
way to use values for multiple variables and can be a big
performance win.
- * Manipulating arrays:
+ ⢠Manipulating arrays:
- - Retrieving, adding, deleting, and modifying elements
+ â Retrieving, adding, deleting, and modifying elements
- - Getting the count of elements in an array
+ â Getting the count of elements in an array
- - Creating a new array
+ â Creating a new array
- - Clearing an array
+ â Clearing an array
- - Flattening an array for easy C-style looping over all its
+ â Flattening an array for easy C-style looping over all its
indices and elements
- * Accessing and manipulating redirections.
+ ⢠Accessing and manipulating redirections.
Some points about using the API:
- * The following types, macros, and/or functions are referenced in
- 'gawkapi.h'. For correct use, you must therefore include the
- corresponding standard header file _before_ including 'gawkapi.h'.
+ ⢠The following types, macros, and/or functions are referenced in
+ âgawkapi.hâ. For correct use, you must therefore include the
+ corresponding standard header file _before_ including âgawkapi.hâ.
The list of macros and related header files is shown in *note Table
17.1: table-api-std-headers.
C entity Header file
-------------------------------------------
- 'EOF' '<stdio.h>'
- Values for 'errno' '<errno.h>'
- 'FILE' '<stdio.h>'
- 'NULL' '<stddef.h>'
- 'memcpy()' '<string.h>'
- 'memset()' '<string.h>'
- 'size_t' '<sys/types.h>'
- 'struct stat' '<sys/stat.h>'
+ âEOFâ â<stdio.h>â
+ Values for âerrnoâ â<errno.h>â
+ âFILEâ â<stdio.h>â
+ âNULLâ â<stddef.h>â
+ âmemcpy()â â<string.h>â
+ âmemset()â â<string.h>â
+ âsize_tâ â<sys/types.h>â
+ âstruct statâ â<sys/stat.h>â
Table 17.1: Standard header files needed by API
Due to portability concerns, especially to systems that are not
fully standards-compliant, it is your responsibility to include the
correct files in the correct way. This requirement is necessary in
- order to keep 'gawkapi.h' clean, instead of becoming a portability
- hodge-podge as can be seen in some parts of the 'gawk' source code.
+ order to keep âgawkapi.hâ clean, instead of becoming a portability
+ hodge-podge as can be seen in some parts of the âgawkâ source code.
- * If your extension uses MPFR facilities, and you wish to receive
- such values from 'gawk' and/or pass such values to it, you must
- include the '<mpfr.h>' header before including '<gawkapi.h>'.
+ ⢠If your extension uses MPFR facilities, and you wish to receive
+ such values from âgawkâ and/or pass such values to it, you must
+ include the â<mpfr.h>â header before including â<gawkapi.h>â.
- * The 'gawkapi.h' file may be included more than once without ill
+ ⢠The âgawkapi.hâ file may be included more than once without ill
effect. Doing so, however, is poor coding practice.
- * Although the API only uses ISO C 90 features, there is an
- exception; the "constructor" functions use the 'inline' keyword.
+ ⢠Although the API only uses ISO C 90 features, there is an
+ exception; the âconstructorâ functions use the âinlineâ keyword.
If your compiler does not support this keyword, you should either
- place '-Dinline=''' on your command line or use the GNU Autotools
- and include a 'config.h' file in your extensions.
+ place â-Dinline=''â on your command line or use the GNU Autotools
+ and include a âconfig.hâ file in your extensions.
- * All pointers filled in by 'gawk' point to memory managed by 'gawk'
+ ⢠All pointers filled in by âgawkâ point to memory managed by
âgawkâ
and should be treated by the extension as read-only.
- Memory for _all_ strings passed into 'gawk' from the extension
- _must_ come from calling one of 'gawk_malloc()', 'gawk_calloc()',
- or 'gawk_realloc()', and is managed by 'gawk' from then on.
+ Memory for _all_ strings passed into âgawkâ from the extension
+ _must_ come from calling one of âgawk_malloc()â, âgawk_calloc()â,
+ or âgawk_realloc()â, and is managed by âgawkâ from then on.
- Memory for MPFR/GMP values that come from 'gawk' should also be
+ Memory for MPFR/GMP values that come from âgawkâ should also be
treated as read-only. However, unlike strings, memory for MPFR/GMP
- values allocated by an extension and passed into 'gawk' is _copied_
- by 'gawk'; the extension should then free the values itself to
+ values allocated by an extension and passed into âgawkâ is _copied_
+ by âgawkâ; the extension should then free the values itself to
avoid memory leaks. This is discussed further in *API Ownership of
MPFR and GMP Values*.
- * The API defines several simple 'struct's that map values as seen
- from 'awk'. A value can be a 'double', a string, or an array (as
+ ⢠The API defines several simple âstructâs that map values as seen
+ from âawkâ. A value can be a âdoubleâ, a string, or an array (as
in multidimensional arrays, or when creating a new array).
String values maintain both pointer and length, because embedded
NUL characters are allowed.
- NOTE: By intent, 'gawk' maintains strings using the current
- multibyte encoding (as defined by 'LC_XXX' environment
+ NOTE: By intent, âgawkâ maintains strings using the current
+ multibyte encoding (as defined by âLC_XXXâ environment
variables) and not using wide characters. This matches how
- 'gawk' stores strings internally and also how characters are
+ âgawkâ stores strings internally and also how characters are
likely to be input into and output from files.
- NOTE: String values passed to an extension by 'gawk' are
+ NOTE: String values passed to an extension by âgawkâ are
always NUL-terminated. Thus it is safe to pass such string
values to standard library and system routines. However,
- because 'gawk' allows embedded NUL characters in string data,
+ because âgawkâ allows embedded NUL characters in string data,
before using the data as a regular C string, you should check
that the length for that string passed to the extension
- matches the return value of 'strlen()' for it.
+ matches the return value of âstrlen()â for it.
- * When retrieving a value (such as a parameter or that of a global
+ ⢠When retrieving a value (such as a parameter or that of a global
variable or array element), the extension requests a specific type
- (number, string, scalar, value cookie, array, or "undefined").
- When the request is "undefined," the returned value will have the
+ (number, string, scalar, value cookie, array, or âundefinedâ).
+ When the request is âundefined,â the returned value will have the
real underlying type.
- However, if the request and actual type don't match, the access
- function returns "false" and fills in the type of the actual value
+ However, if the request and actual type donât match, the access
+ function returns âfalseâ and fills in the type of the actual value
that is there, so that the extension can, e.g., print an error
- message (such as "scalar passed where array expected").
+ message (such as âscalar passed where array expectedâ).
You may call the API functions by using the function pointers
directly, but the interface is not so pretty. To make extension code
-look more like regular code, the 'gawkapi.h' header file defines several
+look more like regular code, the âgawkapi.hâ header file defines several
macros that you should use in your code. This minor node presents the
macros as if they were functions.
@@ -26003,11 +26001,11 @@ File: gawk.info, Node: General Data Types, Next:
Memory Allocation Functions,
---------------------------------
I have a true love/hate relationship with unions.
- -- _Arnold Robbins_
+ â _Arnold Robbins_
- That's the thing about unions: the compiler will arrange things so
+ Thatâs the thing about unions: the compiler will arrange things so
they can accommodate both love and hate.
- -- _Chet Ramey_
+ â _Chet Ramey_
The extension API defines a number of simple types and structures for
general-purpose use. Additional, more specialized, data structures are
@@ -26016,193 +26014,193 @@ use them.
The general-purpose types and structures are as follows:
-'typedef void *awk_ext_id_t;'
- A value of this type is received from 'gawk' when an extension is
- loaded. That value must then be passed back to 'gawk' as the first
+âtypedef void *awk_ext_id_t;â
+ A value of this type is received from âgawkâ when an extension is
+ loaded. That value must then be passed back to âgawkâ as the first
parameter of each API function.
-'#define awk_const ...'
- This macro expands to 'const' when compiling an extension, and to
- nothing when compiling 'gawk' itself. This makes certain fields in
+â#define awk_const ...â
+ This macro expands to âconstâ when compiling an extension, and to
+ nothing when compiling âgawkâ itself. This makes certain fields in
the API data structures unwritable from extension code, while
- allowing 'gawk' to use them as it needs to.
+ allowing âgawkâ to use them as it needs to.
-'typedef enum awk_bool {'
-' awk_false = 0,'
-' awk_true'
-'} awk_bool_t;'
+âtypedef enum awk_bool {â
+â awk_false = 0,â
+â awk_trueâ
+â} awk_bool_t;â
A simple Boolean type.
-'typedef struct awk_string {'
-' char *str; /* data */'
-' size_t len; /* length thereof, in chars */'
-'} awk_string_t;'
- This represents a mutable string. 'gawk' owns the memory pointed
+âtypedef struct awk_string {â
+â char *str; /* data */â
+â size_t len; /* length thereof, in chars */â
+â} awk_string_t;â
+ This represents a mutable string. âgawkâ owns the memory pointed
to if it supplied the value. Otherwise, it takes ownership of the
memory pointed to. _Such memory must come from calling one of the
- 'gawk_malloc()', 'gawk_calloc()', or 'gawk_realloc()' functions!_
+ âgawk_malloc()â, âgawk_calloc()â, or âgawk_realloc()â
functions!_
As mentioned earlier, strings are maintained using the current
multibyte encoding.
-'typedef enum {'
-' AWK_UNDEFINED,'
-' AWK_NUMBER,'
-' AWK_STRING,'
-' AWK_REGEX,'
-' AWK_STRNUM,'
-' AWK_ARRAY,'
-' AWK_SCALAR, /* opaque access to a variable */'
-' AWK_VALUE_COOKIE, /* for updating a previously created value */'
-' AWK_BOOL'
-'} awk_valtype_t;'
- This 'enum' indicates the type of a value. It is used in the
- following 'struct'.
-
-'typedef struct awk_value {'
-' awk_valtype_t val_type;'
-' union {'
-' awk_string_t s;'
-' awknum_t n;'
-' awk_array_t a;'
-' awk_scalar_t scl;'
-' awk_value_cookie_t vc;'
-' awk_bool_t b;'
-' } u;'
-'} awk_value_t;'
- An "'awk' value." The 'val_type' member indicates what kind of
- value the 'union' holds, and each member is of the appropriate
+âtypedef enum {â
+â AWK_UNDEFINED,â
+â AWK_NUMBER,â
+â AWK_STRING,â
+â AWK_REGEX,â
+â AWK_STRNUM,â
+â AWK_ARRAY,â
+â AWK_SCALAR, /* opaque access to a variable */â
+â AWK_VALUE_COOKIE, /* for updating a previously created value */â
+â AWK_BOOLâ
+â} awk_valtype_t;â
+ This âenumâ indicates the type of a value. It is used in the
+ following âstructâ.
+
+âtypedef struct awk_value {â
+â awk_valtype_t val_type;â
+â union {â
+â awk_string_t s;â
+â awknum_t n;â
+â awk_array_t a;â
+â awk_scalar_t scl;â
+â awk_value_cookie_t vc;â
+â awk_bool_t b;â
+â } u;â
+â} awk_value_t;â
+ An ââawkâ value.â The âval_typeâ member indicates what kind of
+ value the âunionâ holds, and each member is of the appropriate
type.
-'#define str_value u.s'
-'#define strnum_value str_value'
-'#define regex_value str_value'
-'#define num_value u.n.d'
-'#define num_type u.n.type'
-'#define num_ptr u.n.ptr'
-'#define array_cookie u.a'
-'#define scalar_cookie u.scl'
-'#define value_cookie u.vc'
-'#define bool_value u.b'
- Using these macros makes accessing the fields of the 'awk_value_t'
+â#define str_value u.sâ
+â#define strnum_value str_valueâ
+â#define regex_value str_valueâ
+â#define num_value u.n.dâ
+â#define num_type u.n.typeâ
+â#define num_ptr u.n.ptrâ
+â#define array_cookie u.aâ
+â#define scalar_cookie u.sclâ
+â#define value_cookie u.vcâ
+â#define bool_value u.bâ
+ Using these macros makes accessing the fields of the âawk_value_tâ
more readable.
-'enum AWK_NUMBER_TYPE {'
-' AWK_NUMBER_TYPE_DOUBLE,'
-' AWK_NUMBER_TYPE_MPFR,'
-' AWK_NUMBER_TYPE_MPZ'
-'};'
- This 'enum' is used in the following structure for defining the
+âenum AWK_NUMBER_TYPE {â
+â AWK_NUMBER_TYPE_DOUBLE,â
+â AWK_NUMBER_TYPE_MPFR,â
+â AWK_NUMBER_TYPE_MPZâ
+â};â
+ This âenumâ is used in the following structure for defining the
type of numeric value that is being worked with. It is declared at
the top level of the file so that it works correctly for C++ as
well as for C.
-'typedef struct awk_number {'
-' double d;'
-' enum AWK_NUMBER_TYPE type;'
-' void *ptr;'
-'} awk_number_t;'
- This represents a numeric value. Internally, 'gawk' stores every
- number as either a C 'double', a GMP integer, or an MPFR
+âtypedef struct awk_number {â
+â double d;â
+â enum AWK_NUMBER_TYPE type;â
+â void *ptr;â
+â} awk_number_t;â
+ This represents a numeric value. Internally, âgawkâ stores every
+ number as either a C âdoubleâ, a GMP integer, or an MPFR
arbitrary-precision floating-point value. In order to allow
extensions to also support GMP and MPFR values, numeric values are
passed in this structure.
- The double-precision 'd' element is always populated in data
- received from 'gawk'. In addition, by examining the 'type' member,
- an extension can determine if the 'ptr' member is either a GMP
- integer (type 'mpz_ptr'), or an MPFR floating-point value (type
- 'mpfr_ptr_t'), and cast it appropriately.
+ The double-precision âdâ element is always populated in data
+ received from âgawkâ. In addition, by examining the âtypeâ
member,
+ an extension can determine if the âptrâ member is either a GMP
+ integer (type âmpz_ptrâ), or an MPFR floating-point value (type
+ âmpfr_ptr_tâ), and cast it appropriately.
CAUTION: Any MPFR or MPZ values that you create and pass to
- 'gawk' to save are _copied_. This means you are responsible
- to release the storage once you're done with it. See the
- sample 'intdiv' extension for some example code.
+ âgawkâ to save are _copied_. This means you are responsible
+ to release the storage once youâre done with it. See the
+ sample âintdivâ extension for some example code.
-'typedef void *awk_scalar_t;'
+âtypedef void *awk_scalar_t;â
Scalars can be represented as an opaque type. These values are
- obtained from 'gawk' and then passed back into it. This is
+ obtained from âgawkâ and then passed back into it. This is
discussed in a general fashion in the text following this list, and
in more detail in *note Symbol table by cookie::.
-'typedef void *awk_value_cookie_t;'
- A "value cookie" is an opaque type representing a cached value.
+âtypedef void *awk_value_cookie_t;â
+ A âvalue cookieâ is an opaque type representing a cached value.
This is also discussed in a general fashion in the text following
this list, and in more detail in *note Cached values::.
- Scalar values in 'awk' are numbers, strings, strnums, or typed
-regexps. The 'awk_value_t' struct represents values. The 'val_type'
-member indicates what is in the 'union'.
+ Scalar values in âawkâ are numbers, strings, strnums, or typed
+regexps. The âawk_value_tâ struct represents values. The âval_typeâ
+member indicates what is in the âunionâ.
- Representing numbers is easy--the API uses a C 'double'. Strings
-require more work. Because 'gawk' allows embedded NUL bytes in string
+ Representing numbers is easyâthe API uses a C âdoubleâ. Strings
+require more work. Because âgawkâ allows embedded NUL bytes in string
values, a string must be represented as a pair containing a data pointer
-and length. This is the 'awk_string_t' type.
+and length. This is the âawk_string_tâ type.
A strnum (numeric string) value is represented as a string and
consists of user input data that appears to be numeric. When an
extension creates a strnum value, the result is a string flagged as user
-input. Subsequent parsing by 'gawk' then determines whether it looks
+input. Subsequent parsing by âgawkâ then determines whether it looks
like a number and should be treated as a strnum, or as a regular string.
This is useful in cases where an extension function would like to do
-something comparable to the 'split()' function which sets the strnum
+something comparable to the âsplit()â function which sets the strnum
attribute on the array elements it creates. For example, an extension
that implements CSV splitting would want to use this feature. This is
also useful for a function that retrieves a data item from a database.
-The PostgreSQL 'PQgetvalue()' function, for example, returns a string
+The PostgreSQL âPQgetvalue()â function, for example, returns a string
that may be numeric or textual depending on the contents.
Typed regexp values (*note Strong Regexp Constants::) are not of much
-use to extension functions. Extension functions can tell that they've
+use to extension functions. Extension functions can tell that theyâve
received them, and create them for scalar values. Otherwise, they can
-examine the text of the regexp through 'regex_value.str' and
-'regex_value.len'.
+examine the text of the regexp through âregex_value.strâ and
+âregex_value.lenâ.
Identifiers (i.e., the names of global variables) can be associated
-with either scalar values or with arrays. In addition, 'gawk' provides
+with either scalar values or with arrays. In addition, âgawkâ provides
true arrays of arrays, where any given array element can itself be an
array. Discussion of arrays is delayed until *note Array
Manipulation::.
The various macros listed earlier make it easier to use the elements
-of the 'union' as if they were fields in a 'struct'; this is a common
+of the âunionâ as if they were fields in a âstructâ; this is a common
coding practice in C. Such code is easier to write and to read, but it
-remains _your_ responsibility to make sure that the 'val_type' member
-correctly reflects the type of the value in the 'awk_value_t' struct.
+remains _your_ responsibility to make sure that the âval_typeâ member
+correctly reflects the type of the value in the âawk_value_tâ struct.
- Conceptually, the first three members of the 'union' (number, string,
-and array) are all that is needed for working with 'awk' values.
+ Conceptually, the first three members of the âunionâ (number, string,
+and array) are all that is needed for working with âawkâ values.
However, because the API provides routines for accessing and changing
-the value of a global scalar variable only by using the variable's name,
-there is a performance penalty: 'gawk' must find the variable each time
+the value of a global scalar variable only by using the variableâs name,
+there is a performance penalty: âgawkâ must find the variable each time
it is accessed and changed. This turns out to be a real issue, not just
a theoretical one.
Thus, if you know that your extension will spend considerable time
reading and/or changing the value of one or more scalar variables, you
-can obtain a "scalar cookie"(1) object for that variable, and then use
-the cookie for getting the variable's value or for changing the
-variable's value. The 'awk_scalar_t' type holds a scalar cookie, and
-the 'scalar_cookie' macro provides access to the value of that type in
-the 'awk_value_t' struct. Given a scalar cookie, 'gawk' can directly
+can obtain a âscalar cookieâ(1) object for that variable, and then use
+the cookie for getting the variableâs value or for changing the
+variableâs value. The âawk_scalar_tâ type holds a scalar cookie, and
+the âscalar_cookieâ macro provides access to the value of that type in
+the âawk_value_tâ struct. Given a scalar cookie, âgawkâ can directly
retrieve or modify the value, as required, without having to find it
first.
- The 'awk_value_cookie_t' type and 'value_cookie' macro are similar.
+ The âawk_value_cookie_tâ type and âvalue_cookieâ macro are similar.
If you know that you wish to use the same numeric or string _value_ for
-one or more variables, you can create the value once, retaining a "value
-cookie" for it, and then pass in that value cookie whenever you wish to
+one or more variables, you can create the value once, retaining a âvalue
+cookieâ for it, and then pass in that value cookie whenever you wish to
set the value of a variable. This saves storage space within the
-running 'gawk' process and reduces the time needed to create the value.
+running âgawkâ process and reduces the time needed to create the value.
---------- Footnotes ----------
- (1) See the "cookie" entry in the Jargon file
+ (1) See the âcookieâ entry in the Jargon file
(http://catb.org/jargon/html/C/cookie.html) for a definition of
-"cookie", and the "magic cookie" entry in the Jargon file
+âcookieâ, and the âmagic cookieâ entry in the Jargon file
(http://catb.org/jargon/html/M/magic-cookie.html) for a nice example.
-See also the entry for "Cookie" in the *note Glossary::.
+See also the entry for âCookieâ in the *note Glossary::.
File: gawk.info, Node: Memory Allocation Functions, Next: Constructor
Functions, Prev: General Data Types, Up: Extension API Description
@@ -26210,54 +26208,54 @@ File: gawk.info, Node: Memory Allocation Functions,
Next: Constructor Function
17.4.3 Memory Allocation Functions and Convenience Macros
---------------------------------------------------------
-The API provides a number of "memory allocation" functions for
-allocating memory that can be passed to 'gawk', as well as a number of
+The API provides a number of âmemory allocationâ functions for
+allocating memory that can be passed to âgawkâ, as well as a number of
convenience macros. This node presents them all as function prototypes,
in the way that extension code would use them:
-'void *gawk_malloc(size_t size);'
- Call the correct version of 'malloc()' to allocate storage that may
- be passed to 'gawk'.
+âvoid *gawk_malloc(size_t size);â
+ Call the correct version of âmalloc()â to allocate storage that may
+ be passed to âgawkâ.
-'void *gawk_calloc(size_t nmemb, size_t size);'
- Call the correct version of 'calloc()' to allocate storage that may
- be passed to 'gawk'.
+âvoid *gawk_calloc(size_t nmemb, size_t size);â
+ Call the correct version of âcalloc()â to allocate storage that may
+ be passed to âgawkâ.
-'void *gawk_realloc(void *ptr, size_t size);'
- Call the correct version of 'realloc()' to allocate storage that
- may be passed to 'gawk'.
+âvoid *gawk_realloc(void *ptr, size_t size);â
+ Call the correct version of ârealloc()â to allocate storage that
+ may be passed to âgawkâ.
-'void gawk_free(void *ptr);'
- Call the correct version of 'free()' to release storage that was
- allocated with 'gawk_malloc()', 'gawk_calloc()', or
- 'gawk_realloc()'.
+âvoid gawk_free(void *ptr);â
+ Call the correct version of âfree()â to release storage that was
+ allocated with âgawk_malloc()â, âgawk_calloc()â, or
+ âgawk_realloc()â.
The API has to provide these functions because it is possible for an
extension to be compiled and linked against a different version of the C
-library than was used for the 'gawk' executable.(1) If 'gawk' were to
-use its version of 'free()' when the memory came from an unrelated
-version of 'malloc()', unexpected behavior would likely result.
+library than was used for the âgawkâ executable.(1) If âgawkâ were to
+use its version of âfree()â when the memory came from an unrelated
+version of âmalloc()â, unexpected behavior would likely result.
Three convenience macros may be used for allocating storage from
-'gawk_malloc()', 'gawk_calloc', and 'gawk_realloc()'. If the allocation
-fails, they cause 'gawk' to exit with a fatal error message. They
+âgawk_malloc()â, âgawk_callocâ, and âgawk_realloc()â. If the
allocation
+fails, they cause âgawkâ to exit with a fatal error message. They
should be used as if they were procedure calls that do not return a
value:
-'#define emalloc(pointer, type, size, message) ...'
+â#define emalloc(pointer, type, size, message) ...â
The arguments to this macro are as follows:
- 'pointer'
+ âpointerâ
The pointer variable to point at the allocated storage.
- 'type'
+ âtypeâ
The type of the pointer variable. This is used to create a
- cast for the call to 'gawk_malloc()'.
+ cast for the call to âgawk_malloc()â.
- 'size'
+ âsizeâ
The total number of bytes to be allocated.
- 'message'
+ âmessageâ
A message to be prefixed to the fatal error message.
Typically this is the name of the function using the macro.
@@ -26273,15 +26271,15 @@ value:
-'#define ezalloc(pointer, type, size, message) ...'
- This is like 'emalloc()', but it calls 'gawk_calloc()' instead of
- 'gawk_malloc()'. The arguments are the same as for the 'emalloc()'
+â#define ezalloc(pointer, type, size, message) ...â
+ This is like âemalloc()â, but it calls âgawk_calloc()â instead of
+ âgawk_malloc()â. The arguments are the same as for the
âemalloc()â
macro, but this macro guarantees that the memory returned is
initialized to zero.
-'#define erealloc(pointer, type, size, message) ...'
- This is like 'emalloc()', but it calls 'gawk_realloc()' instead of
- 'gawk_malloc()'. The arguments are the same as for the 'emalloc()'
+â#define erealloc(pointer, type, size, message) ...â
+ This is like âemalloc()â, but it calls âgawk_realloc()â instead of
+ âgawk_malloc()â. The arguments are the same as for the
âemalloc()â
macro.
Two additional functions allocate MPFR and GMP objects for use by
@@ -26293,27 +26291,27 @@ extension functions that need to create and then
return such values.
The functions are:
-'void *get_mpfr_ptr();'
+âvoid *get_mpfr_ptr();â
Allocate and initialize an MPFR object and return a pointer to it.
- If the allocation fails, 'gawk' exits with a fatal "out of memory"
- error. If 'gawk' was compiled without MPFR support, calling this
+ If the allocation fails, âgawkâ exits with a fatal âout of memoryâ
+ error. If âgawkâ was compiled without MPFR support, calling this
function causes a fatal error.
-'void *get_mpz_ptr();'
+âvoid *get_mpz_ptr();â
Allocate and initialize a GMP object and return a pointer to it.
- If the allocation fails, 'gawk' exits with a fatal "out of memory"
- error. If 'gawk' was compiled without MPFR support, calling this
+ If the allocation fails, âgawkâ exits with a fatal âout of memoryâ
+ error. If âgawkâ was compiled without MPFR support, calling this
function causes a fatal error.
- Both of these functions return 'void *', since the 'gawkapi.h' header
-file should not have dependency upon '<mpfr.h>' (and '<gmp.h>', which is
-included from '<mpfr.h>'). The actual return values are of types
-'mpfr_ptr' and 'mpz_ptr' respectively, and you should cast the return
+ Both of these functions return âvoid *â, since the âgawkapi.hâ
header
+file should not have dependency upon â<mpfr.h>â (and â<gmp.h>â, which
is
+included from â<mpfr.h>â). The actual return values are of types
+âmpfr_ptrâ and âmpz_ptrâ respectively, and you should cast the return
values appropriately before assigning the results to variables of the
correct types.
The memory allocated by these functions should be freed with
-'gawk_free()'.
+âgawk_free()â.
---------- Footnotes ----------
@@ -26326,78 +26324,78 @@ File: gawk.info, Node: Constructor Functions, Next:
API Ownership of MPFR and
17.4.4 Constructor Functions
----------------------------
-The API provides a number of "constructor" functions for creating string
+The API provides a number of âconstructorâ functions for creating string
and numeric values, as well as a number of convenience macros. This
node presents them all as function prototypes, in the way that extension
code would use them:
-'static inline awk_value_t *'
-'make_const_string(const char *string, size_t length, awk_value_t *result);'
- This function creates a string value in the 'awk_value_t' variable
- pointed to by 'result'. It expects 'string' to be a C string
+âstatic inline awk_value_t *â
+âmake_const_string(const char *string, size_t length, awk_value_t
*result);â
+ This function creates a string value in the âawk_value_tâ variable
+ pointed to by âresultâ. It expects âstringâ to be a C string
constant (or other string data), and automatically creates a _copy_
- of the data for storage in 'result'. It returns 'result'.
-
-'static inline awk_value_t *'
-'make_malloced_string(const char *string, size_t length, awk_value_t *result);'
- This function creates a string value in the 'awk_value_t' variable
- pointed to by 'result'. It expects 'string' to be a 'char *' value
- pointing to data previously obtained from 'gawk_malloc()',
- 'gawk_calloc()', or 'gawk_realloc()'. The idea here is that the
- data is passed directly to 'gawk', which assumes responsibility for
- it. It returns 'result'.
-
-'static inline awk_value_t *'
-'make_null_string(awk_value_t *result);'
- This specialized function creates a null string (the "undefined"
- value) in the 'awk_value_t' variable pointed to by 'result'. It
- returns 'result'.
-
-'static inline awk_value_t *'
-'make_number(double num, awk_value_t *result);'
- This function simply creates a numeric value in the 'awk_value_t'
- variable pointed to by 'result'.
-
-'static inline awk_value_t *'
-'make_number_mpz(void *mpz, awk_value_t *result);'
- This function creates a GMP number value in 'result'. The 'mpz'
- must be from a call to 'get_mpz_ptr()' (and thus be of real
- underlying type 'mpz_ptr').
-
-'static inline awk_value_t *'
-'make_number_mpfr(void *mpfr, awk_value_t *result);'
- This function creates an MPFR number value in 'result'. The 'mpfr'
- must be from a call to 'get_mpfr_ptr()'.
-
-'static inline awk_value_t *'
-'make_const_user_input(const char *string, size_t length, awk_value_t
*result);'
- This function is identical to 'make_const_string()', but the string
+ of the data for storage in âresultâ. It returns âresultâ.
+
+âstatic inline awk_value_t *â
+âmake_malloced_string(const char *string, size_t length, awk_value_t
*result);â
+ This function creates a string value in the âawk_value_tâ variable
+ pointed to by âresultâ. It expects âstringâ to be a âchar *â
value
+ pointing to data previously obtained from âgawk_malloc()â,
+ âgawk_calloc()â, or âgawk_realloc()â. The idea here is that the
+ data is passed directly to âgawkâ, which assumes responsibility for
+ it. It returns âresultâ.
+
+âstatic inline awk_value_t *â
+âmake_null_string(awk_value_t *result);â
+ This specialized function creates a null string (the âundefinedâ
+ value) in the âawk_value_tâ variable pointed to by âresultâ. It
+ returns âresultâ.
+
+âstatic inline awk_value_t *â
+âmake_number(double num, awk_value_t *result);â
+ This function simply creates a numeric value in the âawk_value_tâ
+ variable pointed to by âresultâ.
+
+âstatic inline awk_value_t *â
+âmake_number_mpz(void *mpz, awk_value_t *result);â
+ This function creates a GMP number value in âresultâ. The âmpzâ
+ must be from a call to âget_mpz_ptr()â (and thus be of real
+ underlying type âmpz_ptrâ).
+
+âstatic inline awk_value_t *â
+âmake_number_mpfr(void *mpfr, awk_value_t *result);â
+ This function creates an MPFR number value in âresultâ. The
âmpfrâ
+ must be from a call to âget_mpfr_ptr()â.
+
+âstatic inline awk_value_t *â
+âmake_const_user_input(const char *string, size_t length, awk_value_t
*result);â
+ This function is identical to âmake_const_string()â, but the string
is flagged as user input that should be treated as a strnum value
if the contents of the string are numeric.
-'static inline awk_value_t *'
-'make_malloced_user_input(const char *string, size_t length, awk_value_t
*result);'
- This function is identical to 'make_malloced_string()', but the
+âstatic inline awk_value_t *â
+âmake_malloced_user_input(const char *string, size_t length, awk_value_t
*result);â
+ This function is identical to âmake_malloced_string()â, but the
string is flagged as user input that should be treated as a strnum
value if the contents of the string are numeric.
-'static inline awk_value_t *'
-'make_const_regex(const char *string, size_t length, awk_value_t *result);'
+âstatic inline awk_value_t *â
+âmake_const_regex(const char *string, size_t length, awk_value_t *result);â
This function creates a strongly typed regexp value by allocating a
- copy of the string. 'string' is the regular expression of length
- 'len'.
+ copy of the string. âstringâ is the regular expression of length
+ âlenâ.
-'static inline awk_value_t *'
-'make_malloced_regex(const char *string, size_t length, awk_value_t *result);'
- This function creates a strongly typed regexp value. 'string' is
- the regular expression of length 'len'. It expects 'string' to be
- a 'char *' value pointing to data previously obtained from
- 'gawk_malloc()', 'gawk_calloc()', or 'gawk_realloc()'.
+âstatic inline awk_value_t *â
+âmake_malloced_regex(const char *string, size_t length, awk_value_t
*result);â
+ This function creates a strongly typed regexp value. âstringâ is
+ the regular expression of length âlenâ. It expects âstringâ to be
+ a âchar *â value pointing to data previously obtained from
+ âgawk_malloc()â, âgawk_calloc()â, or âgawk_realloc()â.
-'static inline awk_value_t *'
-'make_bool(awk_bool_t boolval, awk_value_t *result);'
- This function creates a boolean value in the 'awk_value_t' variable
- pointed to by 'result'.
+âstatic inline awk_value_t *â
+âmake_bool(awk_bool_t boolval, awk_value_t *result);â
+ This function creates a boolean value in the âawk_value_tâ variable
+ pointed to by âresultâ.
File: gawk.info, Node: API Ownership of MPFR and GMP Values, Next:
Registration Functions, Prev: Constructor Functions, Up: Extension API
Description
@@ -26406,20 +26404,20 @@ File: gawk.info, Node: API Ownership of MPFR and GMP
Values, Next: Registratio
-----------------------------------
MPFR and GMP values are different from string values, where you can
-"take ownership" of the value simply by assigning pointers. For
+âtake ownershipâ of the value simply by assigning pointers. For
example:
- char *p = gawk_malloc(42); p "owns" the memory
+ char *p = gawk_malloc(42); p ``owns'' the memory
char *q = p;
- p = NULL; now q "owns" it
+ p = NULL; now q ``owns'' it
MPFR and GMP objects are indeed allocated on the stack or
dynamically, but the MPFR and GMP libraries treat these objects as
-values, the same way that you would pass an 'int' or a 'double' by
-value. There is no way to "transfer ownership" of MPFR and GMP objects.
+values, the same way that you would pass an âintâ or a âdoubleâ by
+value. There is no way to âtransfer ownershipâ of MPFR and GMP objects.
The final results of an MPFR or GMP calculation should be passed back
-to 'gawk', by value, as you would a string or a 'double'. 'gawk' will
+to âgawkâ, by value, as you would a string or a âdoubleâ. âgawkâ
will
take care of freeing the storage.
Thus, code in an extension should look like this:
@@ -26436,7 +26434,7 @@ take care of freeing the storage.
mpz_clear(part1); release intermediate values
mpz_clear(part2);
- return result; value in 'answer' managed by
'gawk'
+ return result; value in answer managed by gawk
File: gawk.info, Node: Registration Functions, Next: Printing Messages,
Prev: API Ownership of MPFR and GMP Values, Up: Extension API Description
@@ -26445,7 +26443,7 @@ File: gawk.info, Node: Registration Functions, Next:
Printing Messages, Prev:
-----------------------------
This minor node describes the API functions for registering parts of
-your extension with 'gawk'.
+your extension with âgawkâ.
* Menu:
@@ -26477,98 +26475,98 @@ Extension functions are described by the following
record:
The fields are:
-'const char *name;'
- The name of the new function. 'awk'-level code calls the function
+âconst char *name;â
+ The name of the new function. âawkâ-level code calls the function
by this name. This is a regular C string.
- Function names must obey the rules for 'awk' identifiers. That is,
+ Function names must obey the rules for âawkâ identifiers. That is,
they must begin with either an English letter or an underscore,
which may be followed by any number of letters, digits, and
underscores. Letter case in function names is significant.
-'awk_value_t *(*const function)(int num_actual_args,'
-' awk_value_t *result,'
-' struct awk_ext_func *finfo);'
- This is a pointer to the C function that provides the extension's
- functionality. The function must fill in '*result' with either a
- number, a string, or a regexp. 'gawk' takes ownership of any
+âawk_value_t *(*const function)(int num_actual_args,â
+â awk_value_t *result,â
+â struct awk_ext_func *finfo);â
+ This is a pointer to the C function that provides the extensionâs
+ functionality. The function must fill in â*resultâ with either a
+ number, a string, or a regexp. âgawkâ takes ownership of any
string memory. As mentioned earlier, string memory _must_ come
- from one of 'gawk_malloc()', 'gawk_calloc()', or 'gawk_realloc()'.
+ from one of âgawk_malloc()â, âgawk_calloc()â, or
âgawk_realloc()â.
- The 'num_actual_args' argument tells the C function how many actual
- parameters were passed from the calling 'awk' code.
+ The ânum_actual_argsâ argument tells the C function how many actual
+ parameters were passed from the calling âawkâ code.
- The 'finfo' parameter is a pointer to the 'awk_ext_func_t' for this
+ The âfinfoâ parameter is a pointer to the âawk_ext_func_tâ for
this
function. The called function may access data within it as
desired, or not.
- The function must return the value of 'result'. This is for the
- convenience of the calling code inside 'gawk'.
+ The function must return the value of âresultâ. This is for the
+ convenience of the calling code inside âgawkâ.
-'const size_t max_expected_args;'
+âconst size_t max_expected_args;â
This is the maximum number of arguments the function expects to
receive. If called with more arguments than this, and if lint
- checking has been enabled, then 'gawk' prints a warning message.
- For more information, see the entry for 'suppress_lint', later in
+ checking has been enabled, then âgawkâ prints a warning message.
+ For more information, see the entry for âsuppress_lintâ, later in
this list.
-'const size_t min_required_args;'
+âconst size_t min_required_args;â
This is the minimum number of arguments the function expects to
- receive. If called with fewer arguments, 'gawk' prints a fatal
+ receive. If called with fewer arguments, âgawkâ prints a fatal
error message and exits.
-'awk_bool_t suppress_lint;'
- This flag tells 'gawk' not to print a lint message if lint checking
+âawk_bool_t suppress_lint;â
+ This flag tells âgawkâ not to print a lint message if lint checking
has been enabled and if more arguments were supplied in the call
- than expected. An extension function can tell if 'gawk' already
- printed at least one such message by checking if 'num_actual_args >
- finfo->max_expected_args'. If so, and the function does not want
+ than expected. An extension function can tell if âgawkâ already
+ printed at least one such message by checking if ânum_actual_args >
+ finfo->max_expected_argsâ. If so, and the function does not want
more lint messages to be printed, it should set
- 'finfo->suppress_lint' to 'awk_true'.
+ âfinfo->suppress_lintâ to âawk_trueâ.
-'void *data;'
+âvoid *data;â
This is an opaque pointer to any data that an extension function
may wish to have available when called. Passing the
- 'awk_ext_func_t' structure to the extension function, and having
+ âawk_ext_func_tâ structure to the extension function, and having
this pointer available in it enable writing a single C or C++
- function that implements multiple 'awk'-level extension functions.
+ function that implements multiple âawkâ-level extension functions.
Once you have a record representing your extension function, you
-register it with 'gawk' using this API function:
+register it with âgawkâ using this API function:
-'awk_bool_t add_ext_func(const char *name_space, awk_ext_func_t *func);'
+âawk_bool_t add_ext_func(const char *name_space, awk_ext_func_t *func);â
This function returns true upon success, false otherwise. The
- 'name_space' parameter is the namespace in which to place the
- function (*note Namespaces::). Use an empty string ('""') or
- '"awk"' to place the function in the default 'awk' namespace. The
- 'func' pointer is the address of a 'struct' representing your
+ âname_spaceâ parameter is the namespace in which to place the
+ function (*note Namespaces::). Use an empty string (â""â) or
+ â"awk"â to place the function in the default âawkâ namespace. The
+ âfuncâ pointer is the address of a âstructâ representing your
function, as just described.
- 'gawk' does not modify what 'func' points to, but the extension
+ âgawkâ does not modify what âfuncâ points to, but the extension
function itself receives this pointer and can modify what it points
- to, thus it is purposely not declared to be 'const'.
+ to, thus it is purposely not declared to be âconstâ.
- The combination of 'min_required_args', 'max_expected_args', and
-'suppress_lint' may be confusing. Here is how you should set things up.
+ The combination of âmin_required_argsâ, âmax_expected_argsâ, and
+âsuppress_lintâ may be confusing. Here is how you should set things up.
Any number of arguments is valid
- Set 'min_required_args' and 'max_expected_args' to zero and set
- 'suppress_lint' to 'awk_true'.
+ Set âmin_required_argsâ and âmax_expected_argsâ to zero and set
+ âsuppress_lintâ to âawk_trueâ.
A minimum number of arguments is required, no limit on maximum number of
arguments
- Set 'min_required_args' to the minimum required. Set
- 'max_expected_args' to zero and set 'suppress_lint' to 'awk_true'.
+ Set âmin_required_argsâ to the minimum required. Set
+ âmax_expected_argsâ to zero and set âsuppress_lintâ to
âawk_trueâ.
A minimum number of arguments is required, a maximum number is expected
- Set 'min_required_args' to the minimum required. Set
- 'max_expected_args' to the maximum expected. Set 'suppress_lint'
- to 'awk_false'.
+ Set âmin_required_argsâ to the minimum required. Set
+ âmax_expected_argsâ to the maximum expected. Set âsuppress_lintâ
+ to âawk_falseâ.
A minimum number of arguments is required, and no more than a maximum is
allowed
- Set 'min_required_args' to the minimum required. Set
- 'max_expected_args' to the maximum expected. Set 'suppress_lint'
- to 'awk_false'. In your extension function, check that
- 'num_actual_args' does not exceed 'f->max_expected_args'. If it
+ Set âmin_required_argsâ to the minimum required. Set
+ âmax_expected_argsâ to the maximum expected. Set âsuppress_lintâ
+ to âawk_falseâ. In your extension function, check that
+ ânum_actual_argsâ does not exceed âf->max_expected_argsâ. If it
does, issue a fatal error message.
@@ -26577,29 +26575,29 @@ File: gawk.info, Node: Exit Callback Functions,
Next: Extension Version String
17.4.6.2 Registering An Exit Callback Function
..............................................
-An "exit callback" function is a function that 'gawk' calls before it
-exits. Such functions are useful if you have general "cleanup" tasks
+An âexit callbackâ function is a function that âgawkâ calls before it
+exits. Such functions are useful if you have general âcleanupâ tasks
that should be performed in your extension (such as closing database
connections or other resource deallocations). You can register such a
-function with 'gawk' using the following function:
+function with âgawkâ using the following function:
-'void awk_atexit(void (*funcp)(void *data, int exit_status),'
-' void *arg0);'
+âvoid awk_atexit(void (*funcp)(void *data, int exit_status),â
+â void *arg0);â
The parameters are:
- 'funcp'
- A pointer to the function to be called before 'gawk' exits.
- The 'data' parameter will be the original value of 'arg0'.
- The 'exit_status' parameter is the exit status value that
- 'gawk' intends to pass to the 'exit()' system call.
+ âfuncpâ
+ A pointer to the function to be called before âgawkâ exits.
+ The âdataâ parameter will be the original value of âarg0â.
+ The âexit_statusâ parameter is the exit status value that
+ âgawkâ intends to pass to the âexit()â system call.
- 'arg0'
- A pointer to private data that 'gawk' saves in order to pass
- to the function pointed to by 'funcp'.
+ âarg0â
+ A pointer to private data that âgawkâ saves in order to pass
+ to the function pointed to by âfuncpâ.
Exit callback functions are called in last-in, first-out (LIFO)
-order--that is, in the reverse order in which they are registered with
-'gawk'.
+orderâthat is, in the reverse order in which they are registered with
+âgawkâ.
File: gawk.info, Node: Extension Version String, Next: Input Parsers, Prev:
Exit Callback Functions, Up: Registration Functions
@@ -26608,15 +26606,15 @@ File: gawk.info, Node: Extension Version String,
Next: Input Parsers, Prev: E
................................................
You can register a version string that indicates the name and version of
-your extension with 'gawk', as follows:
+your extension with âgawkâ, as follows:
-'void register_ext_version(const char *version);'
- Register the string pointed to by 'version' with 'gawk'. Note that
- 'gawk' does _not_ copy the 'version' string, so it should not be
+âvoid register_ext_version(const char *version);â
+ Register the string pointed to by âversionâ with âgawkâ. Note
that
+ âgawkâ does _not_ copy the âversionâ string, so it should not be
changed.
- 'gawk' prints all registered extension version strings when it is
-invoked with the '--version' option.
+ âgawkâ prints all registered extension version strings when it is
+invoked with the â--versionâ option.
File: gawk.info, Node: Input Parsers, Next: Output Wrappers, Prev:
Extension Version String, Up: Registration Functions
@@ -26624,37 +26622,37 @@ File: gawk.info, Node: Input Parsers, Next: Output
Wrappers, Prev: Extension
17.4.6.4 Customized Input Parsers
.................................
-By default, 'gawk' reads text files as its input. It uses the value of
-'RS' to find the end of the record, and then uses 'FS' (or 'FIELDWIDTHS'
-or 'FPAT') to split it into fields (*note Reading Files::).
-Additionally, it sets the value of 'RT' (*note Built-in Variables::).
+By default, âgawkâ reads text files as its input. It uses the value of
+âRSâ to find the end of the record, and then uses âFSâ (or
âFIELDWIDTHSâ
+or âFPATâ) to split it into fields (*note Reading Files::).
+Additionally, it sets the value of âRTâ (*note Built-in Variables::).
If you want, you can provide your own custom input parser. An input
-parser's job is to return a record to the 'gawk' record-processing code,
+parserâs job is to return a record to the âgawkâ record-processing code,
along with indicators for the value and length of the data to be used
-for 'RT', if any.
+for âRTâ, if any.
To provide an input parser, you must first provide two functions
(where XXX is a prefix name for your extension):
-'awk_bool_t XXX_can_take_file(const awk_input_buf_t *iobuf);'
- This function examines the information available in 'iobuf' (which
+âawk_bool_t XXX_can_take_file(const awk_input_buf_t *iobuf);â
+ This function examines the information available in âiobufâ (which
we discuss shortly). Based on the information there, it decides if
the input parser should be used for this file. If so, it should
return true. Otherwise, it should return false. It should not
- change any state (variable values, etc.) within 'gawk'.
+ change any state (variable values, etc.) within âgawkâ.
-'awk_bool_t XXX_take_control_of(awk_input_buf_t *iobuf);'
- When 'gawk' decides to hand control of the file over to the input
+âawk_bool_t XXX_take_control_of(awk_input_buf_t *iobuf);â
+ When âgawkâ decides to hand control of the file over to the input
parser, it calls this function. This function in turn must fill in
- certain fields in the 'awk_input_buf_t' structure and ensure that
+ certain fields in the âawk_input_buf_tâ structure and ensure that
certain conditions are true. It should then return true. If an
error of some kind occurs, it should not fill in any fields and
- should return false; then 'gawk' will not use the input parser.
+ should return false; then âgawkâ will not use the input parser.
The details are presented shortly.
Your extension should package these functions inside an
-'awk_input_parser_t', which looks like this:
+âawk_input_parser_tâ, which looks like this:
typedef struct awk_input_parser {
const char *name; /* name of parser */
@@ -26665,29 +26663,29 @@ for 'RT', if any.
The fields are:
-'const char *name;'
+âconst char *name;â
The name of the input parser. This is a regular C string.
-'awk_bool_t (*can_take_file)(const awk_input_buf_t *iobuf);'
- A pointer to your 'XXX_can_take_file()' function.
+âawk_bool_t (*can_take_file)(const awk_input_buf_t *iobuf);â
+ A pointer to your âXXX_can_take_file()â function.
-'awk_bool_t (*take_control_of)(awk_input_buf_t *iobuf);'
- A pointer to your 'XXX_take_control_of()' function.
+âawk_bool_t (*take_control_of)(awk_input_buf_t *iobuf);â
+ A pointer to your âXXX_take_control_of()â function.
-'awk_const struct input_parser *awk_const next;'
- This is for use by 'gawk'; therefore it is marked 'awk_const' so
+âawk_const struct input_parser *awk_const next;â
+ This is for use by âgawkâ; therefore it is marked âawk_constâ so
that the extension cannot modify it.
The steps are as follows:
- 1. Create a 'static awk_input_parser_t' variable and initialize it
+ 1. Create a âstatic awk_input_parser_tâ variable and initialize it
appropriately.
2. When your extension is loaded, register your input parser with
- 'gawk' using the 'register_input_parser()' API function (described
+ âgawkâ using the âregister_input_parser()â API function (described
next).
- An 'awk_input_buf_t' looks like this:
+ An âawk_input_buf_tâ looks like this:
typedef struct awk_input {
const char *name; /* filename */
@@ -26703,161 +26701,161 @@ for 'RT', if any.
} awk_input_buf_t;
The fields can be divided into two categories: those for use
-(initially, at least) by 'XXX_can_take_file()', and those for use by
-'XXX_take_control_of()'. The first group of fields and their uses are
+(initially, at least) by âXXX_can_take_file()â, and those for use by
+âXXX_take_control_of()â. The first group of fields and their uses are
as follows:
-'const char *name;'
+âconst char *name;â
The name of the file.
-'int fd;'
- A file descriptor for the file. If 'gawk' was able to open the
- file, then 'fd' will _not_ be equal to 'INVALID_HANDLE'.
+âint fd;â
+ A file descriptor for the file. If âgawkâ was able to open the
+ file, then âfdâ will _not_ be equal to âINVALID_HANDLEâ.
Otherwise, it will.
-'struct stat sbuf;'
- If the file descriptor is valid, then 'gawk' will have filled in
- this structure via a call to the 'fstat()' system call.
+âstruct stat sbuf;â
+ If the file descriptor is valid, then âgawkâ will have filled in
+ this structure via a call to the âfstat()â system call.
- The 'XXX_can_take_file()' function should examine these fields and
+ The âXXX_can_take_file()â function should examine these fields and
decide if the input parser should be used for the file. The decision
-can be made based upon 'gawk' state (the value of a variable defined
-previously by the extension and set by 'awk' code), the name of the
+can be made based upon âgawkâ state (the value of a variable defined
+previously by the extension and set by âawkâ code), the name of the
file, whether or not the file descriptor is valid, the information in
-the 'struct stat', or any combination of these factors.
+the âstruct statâ, or any combination of these factors.
- Once 'XXX_can_take_file()' has returned true, and 'gawk' has decided
-to use your input parser, it calls 'XXX_take_control_of()'. That
-function then fills either the 'get_record' field or the 'read_func'
-field in the 'awk_input_buf_t'. It must also ensure that 'fd' is _not_
-set to 'INVALID_HANDLE'. The following list describes the fields that
-may be filled by 'XXX_take_control_of()':
+ Once âXXX_can_take_file()â has returned true, and âgawkâ has decided
+to use your input parser, it calls âXXX_take_control_of()â. That
+function then fills either the âget_recordâ field or the âread_funcâ
+field in the âawk_input_buf_tâ. It must also ensure that âfdâ is _not_
+set to âINVALID_HANDLEâ. The following list describes the fields that
+may be filled by âXXX_take_control_of()â:
-'void *opaque;'
+âvoid *opaque;â
This is used to hold any state information needed by the input
- parser for this file. It is "opaque" to 'gawk'. The input parser
+ parser for this file. It is âopaqueâ to âgawkâ. The input parser
is not required to use this pointer.
-'int (*get_record)(char **out,'
-' struct awk_input *iobuf,'
-' int *errcode,'
-' char **rt_start,'
-' size_t *rt_len,'
-' const awk_fieldwidth_info_t **field_width);'
+âint (*get_record)(char **out,â
+â struct awk_input *iobuf,â
+â int *errcode,â
+â char **rt_start,â
+â size_t *rt_len,â
+â const awk_fieldwidth_info_t **field_width);â
This function pointer should point to a function that creates the
input records. Said function is the core of the input parser. Its
behavior is described in the text following this list.
-'ssize_t (*read_func)();'
+âssize_t (*read_func)();â
This function pointer should point to a function that has the same
- behavior as the standard POSIX 'read()' system call. It is an
- alternative to the 'get_record' pointer. Its behavior is also
+ behavior as the standard POSIX âread()â system call. It is an
+ alternative to the âget_recordâ pointer. Its behavior is also
described in the text following this list.
-'void (*close_func)(struct awk_input *iobuf);'
+âvoid (*close_func)(struct awk_input *iobuf);â
This function pointer should point to a function that does the
- "teardown." It should release any resources allocated by
- 'XXX_take_control_of()'. It may also close the file. If it does
- so, it should set the 'fd' field to 'INVALID_HANDLE'.
+ âteardown.â It should release any resources allocated by
+ âXXX_take_control_of()â. It may also close the file. If it does
+ so, it should set the âfdâ field to âINVALID_HANDLEâ.
- If 'fd' is still not 'INVALID_HANDLE' after the call to this
- function, 'gawk' calls the regular 'close()' system call.
+ If âfdâ is still not âINVALID_HANDLEâ after the call to this
+ function, âgawkâ calls the regular âclose()â system call.
- Having a "teardown" function is optional. If your input parser
- does not need it, do not set this field. Then, 'gawk' calls the
- regular 'close()' system call on the file descriptor, so it should
+ Having a âteardownâ function is optional. If your input parser
+ does not need it, do not set this field. Then, âgawkâ calls the
+ regular âclose()â system call on the file descriptor, so it should
be valid.
- The 'XXX_get_record()' function does the work of creating input
+ The âXXX_get_record()â function does the work of creating input
records. The parameters are as follows:
-'char **out'
- This is a pointer to a 'char *' variable that is set to point to
- the record. 'gawk' makes its own copy of the data, so the
+âchar **outâ
+ This is a pointer to a âchar *â variable that is set to point to
+ the record. âgawkâ makes its own copy of the data, so the
extension must manage this storage.
-'struct awk_input *iobuf'
- This is the 'awk_input_buf_t' for the file. The fields should be
- used for reading data ('fd') and for managing private state
- ('opaque'), if any.
-
-'int *errcode'
- If an error occurs, '*errcode' should be set to an appropriate code
- from '<errno.h>'.
-
-'char **rt_start'
-'size_t *rt_len'
- If the concept of a "record terminator" makes sense, then
- '*rt_start' should be set to point to the data to be used for 'RT',
- and '*rt_len' should be set to the length of the data. Otherwise,
- '*rt_len' should be set to zero. 'gawk' makes its own copy of this
+âstruct awk_input *iobufâ
+ This is the âawk_input_buf_tâ for the file. The fields should be
+ used for reading data (âfdâ) and for managing private state
+ (âopaqueâ), if any.
+
+âint *errcodeâ
+ If an error occurs, â*errcodeâ should be set to an appropriate code
+ from â<errno.h>â.
+
+âchar **rt_startâ
+âsize_t *rt_lenâ
+ If the concept of a ârecord terminatorâ makes sense, then
+ â*rt_startâ should be set to point to the data to be used for
âRTâ,
+ and â*rt_lenâ should be set to the length of the data. Otherwise,
+ â*rt_lenâ should be set to zero. âgawkâ makes its own copy of
this
data, so the extension must manage this storage.
-'const awk_fieldwidth_info_t **field_width'
- If 'field_width' is not 'NULL', then '*field_width' will be
- initialized to 'NULL', and the function may set it to point to a
+âconst awk_fieldwidth_info_t **field_widthâ
+ If âfield_widthâ is not âNULLâ, then â*field_widthâ will be
+ initialized to âNULLâ, and the function may set it to point to a
structure supplying field width information to override the default
field parsing mechanism. Note that this structure will not be
- copied by 'gawk'; it must persist at least until the next call to
- 'get_record' or 'close_func'. Note also that 'field_width' is
- 'NULL' when 'getline' is assigning the results to a variable, thus
+ copied by âgawkâ; it must persist at least until the next call to
+ âget_recordâ or âclose_funcâ. Note also that âfield_widthâ is
+ âNULLâ when âgetlineâ is assigning the results to a variable, thus
field parsing is not needed. If the parser does set
- '*field_width', then 'gawk' uses this layout to parse the input
- record, and the 'PROCINFO["FS"]' value will be '"API"' while this
- record is active in '$0'. The 'awk_fieldwidth_info_t' data
+ â*field_widthâ, then âgawkâ uses this layout to parse the input
+ record, and the âPROCINFO["FS"]â value will be â"API"â while this
+ record is active in â$0â. The âawk_fieldwidth_info_tâ data
structure is described below.
- The return value is the length of the buffer pointed to by '*out', or
-'EOF' if end-of-file was reached or an error occurred.
+ The return value is the length of the buffer pointed to by â*outâ, or
+âEOFâ if end-of-file was reached or an error occurred.
- It is guaranteed that 'errcode' is a valid pointer, so there is no
-need to test for a 'NULL' value. 'gawk' sets '*errcode' to zero, so
+ It is guaranteed that âerrcodeâ is a valid pointer, so there is no
+need to test for a âNULLâ value. âgawkâ sets â*errcodeâ to zero,
so
there is no need to set it unless an error occurs.
- If an error does occur, the function should return 'EOF' and set
-'*errcode' to a value greater than zero. In that case, if '*errcode'
-does not equal zero, 'gawk' automatically updates the 'ERRNO' variable
-based on the value of '*errcode'. (In general, setting '*errcode =
-errno' should do the right thing.)
+ If an error does occur, the function should return âEOFâ and set
+â*errcodeâ to a value greater than zero. In that case, if â*errcodeâ
+does not equal zero, âgawkâ automatically updates the âERRNOâ variable
+based on the value of â*errcodeâ. (In general, setting â*errcode =
+errnoâ should do the right thing.)
As an alternative to supplying a function that returns an input
record, you may instead supply a function that simply reads bytes, and
-let 'gawk' parse the data into records. If you do so, the data should
+let âgawkâ parse the data into records. If you do so, the data should
be returned in the multibyte encoding of the current locale. Such a
-function should follow the same behavior as the 'read()' system call,
-and you fill in the 'read_func' pointer with its address in the
-'awk_input_buf_t' structure.
+function should follow the same behavior as the âread()â system call,
+and you fill in the âread_funcâ pointer with its address in the
+âawk_input_buf_tâ structure.
- By default, 'gawk' sets the 'read_func' pointer to point to the
-'read()' system call. So your extension need not set this field
+ By default, âgawkâ sets the âread_funcâ pointer to point to the
+âread()â system call. So your extension need not set this field
explicitly.
NOTE: You must choose one method or the other: either a function
that returns a record, or one that returns raw data. In
- particular, if you supply a function to get a record, 'gawk' will
+ particular, if you supply a function to get a record, âgawkâ will
call it, and will never call the raw read function.
- 'gawk' ships with a sample extension that reads directories,
+ âgawkâ ships with a sample extension that reads directories,
returning records for each entry in a directory (*note Extension Sample
Readdir::). You may wish to use that code as a guide for writing your
own input parser.
When writing an input parser, you should think about (and document)
-how it is expected to interact with 'awk' code. You may want it to
-always be called, and to take effect as appropriate (as the 'readdir'
+how it is expected to interact with âawkâ code. You may want it to
+always be called, and to take effect as appropriate (as the âreaddirâ
extension does). Or you may want it to take effect based upon the value
-of an 'awk' variable, as the XML extension from the 'gawkextlib' project
-does (*note gawkextlib::). In the latter case, code in a 'BEGINFILE'
-rule can look at 'FILENAME' and 'ERRNO' to decide whether or not to
+of an âawkâ variable, as the XML extension from the âgawkextlibâ
project
+does (*note gawkextlib::). In the latter case, code in a âBEGINFILEâ
+rule can look at âFILENAMEâ and âERRNOâ to decide whether or not to
activate an input parser (*note BEGINFILE/ENDFILE::).
You register your input parser with the following function:
-'void register_input_parser(awk_input_parser_t *input_parser);'
- Register the input parser pointed to by 'input_parser' with 'gawk'.
+âvoid register_input_parser(awk_input_parser_t *input_parser);â
+ Register the input parser pointed to by âinput_parserâ with
âgawkâ.
If you would like to override the default field parsing mechanism for
-a given record, then you must populate an 'awk_fieldwidth_info_t'
+a given record, then you must populate an âawk_fieldwidth_info_tâ
structure, which looks like this:
typedef struct {
@@ -26871,29 +26869,29 @@ structure, which looks like this:
The fields are:
-'awk_bool_t use_chars;'
- Set this to 'awk_true' if the field lengths are specified in terms
- of potentially multi-byte characters, and set it to 'awk_false' if
+âawk_bool_t use_chars;â
+ Set this to âawk_trueâ if the field lengths are specified in terms
+ of potentially multi-byte characters, and set it to âawk_falseâ if
the lengths are in terms of bytes. Performance will be better if
the values are supplied in terms of bytes.
-'size_t nf;'
- Set this to the number of fields in the input record, i.e. 'NF'.
+âsize_t nf;â
+ Set this to the number of fields in the input record, i.e. âNFâ.
-'struct awk_field_info fields[nf];'
+âstruct awk_field_info fields[nf];â
This is a variable-length array whose actual dimension should be
- 'nf'. For each field, the 'skip' element should be set to the
- number of characters or bytes, as controlled by the 'use_chars'
- flag, to skip before the start of this field. The 'len' element
- provides the length of the field. The values in 'fields[0]'
- provide the information for '$1', and so on through the
- 'fields[nf-1]' element containing the information for '$NF'.
-
- A convenience macro 'awk_fieldwidth_info_size(numfields)' is provided
+ ânfâ. For each field, the âskipâ element should be set to the
+ number of characters or bytes, as controlled by the âuse_charsâ
+ flag, to skip before the start of this field. The âlenâ element
+ provides the length of the field. The values in âfields[0]â
+ provide the information for â$1â, and so on through the
+ âfields[nf-1]â element containing the information for â$NFâ.
+
+ A convenience macro âawk_fieldwidth_info_size(numfields)â is provided
to calculate the appropriate size of a variable-length
-'awk_fieldwidth_info_t' structure containing 'numfields' fields. This
-can be used as an argument to 'malloc()' or in a union to allocate space
-statically. Please refer to the 'readdir_test' sample extension for an
+âawk_fieldwidth_info_tâ structure containing ânumfieldsâ fields. This
+can be used as an argument to âmalloc()â or in a union to allocate space
+statically. Please refer to the âreaddir_testâ sample extension for an
example.
@@ -26902,9 +26900,9 @@ File: gawk.info, Node: Output Wrappers, Next: Two-way
processors, Prev: Input
17.4.6.5 Customized Output Wrappers
...................................
-An "output wrapper" is the mirror image of an input parser. It allows
-an extension to take over the output to a file opened with the '>' or
-'>>' I/O redirection operators (*note Redirection::).
+An âoutput wrapperâ is the mirror image of an input parser. It allows
+an extension to take over the output to a file opened with the â>â or
+â>>â I/O redirection operators (*note Redirection::).
The output wrapper is very similar to the input parser structure:
@@ -26917,27 +26915,27 @@ an extension to take over the output to a file opened
with the '>' or
The members are as follows:
-'const char *name;'
+âconst char *name;â
This is the name of the output wrapper.
-'awk_bool_t (*can_take_file)(const awk_output_buf_t *outbuf);'
+âawk_bool_t (*can_take_file)(const awk_output_buf_t *outbuf);â
This points to a function that examines the information in the
- 'awk_output_buf_t' structure pointed to by 'outbuf'. It should
+ âawk_output_buf_tâ structure pointed to by âoutbufâ. It should
return true if the output wrapper wants to take over the file, and
false otherwise. It should not change any state (variable values,
- etc.) within 'gawk'.
+ etc.) within âgawkâ.
-'awk_bool_t (*take_control_of)(awk_output_buf_t *outbuf);'
- The function pointed to by this field is called when 'gawk' decides
+âawk_bool_t (*take_control_of)(awk_output_buf_t *outbuf);â
+ The function pointed to by this field is called when âgawkâ decides
to let the output wrapper take control of the file. It should fill
- in appropriate members of the 'awk_output_buf_t' structure, as
+ in appropriate members of the âawk_output_buf_tâ structure, as
described next, and return true if successful, false otherwise.
-'awk_const struct output_wrapper *awk_const next;'
- This is for use by 'gawk'; therefore it is marked 'awk_const' so
+âawk_const struct output_wrapper *awk_const next;â
+ This is for use by âgawkâ; therefore it is marked âawk_constâ so
that the extension cannot modify it.
- The 'awk_output_buf_t' structure looks like this:
+ The âawk_output_buf_tâ structure looks like this:
typedef struct awk_output_buf {
const char *name; /* name of output file */
@@ -26952,55 +26950,55 @@ an extension to take over the output to a file opened
with the '>' or
int (*gawk_fclose)(FILE *fp, void *opaque);
} awk_output_buf_t;
- Here too, your extension will define 'XXX_can_take_file()' and
-'XXX_take_control_of()' functions that examine and update data members
-in the 'awk_output_buf_t'. The data members are as follows:
+ Here too, your extension will define âXXX_can_take_file()â and
+âXXX_take_control_of()â functions that examine and update data members
+in the âawk_output_buf_tâ. The data members are as follows:
-'const char *name;'
+âconst char *name;â
The name of the output file.
-'const char *mode;'
+âconst char *mode;â
The mode string (as would be used in the second argument to
- 'fopen()') with which the file was opened.
+ âfopen()â) with which the file was opened.
-'FILE *fp;'
- The 'FILE' pointer from '<stdio.h>'. 'gawk' opens the file before
+âFILE *fp;â
+ The âFILEâ pointer from â<stdio.h>â. âgawkâ opens the file
before
attempting to find an output wrapper.
-'awk_bool_t redirected;'
- This field must be set to true by the 'XXX_take_control_of()'
+âawk_bool_t redirected;â
+ This field must be set to true by the âXXX_take_control_of()â
function.
-'void *opaque;'
- This pointer is opaque to 'gawk'. The extension should use it to
+âvoid *opaque;â
+ This pointer is opaque to âgawkâ. The extension should use it to
store a pointer to any private data associated with the file.
-'size_t (*gawk_fwrite)(const void *buf, size_t size, size_t count,'
-' FILE *fp, void *opaque);'
-'int (*gawk_fflush)(FILE *fp, void *opaque);'
-'int (*gawk_ferror)(FILE *fp, void *opaque);'
-'int (*gawk_fclose)(FILE *fp, void *opaque);'
+âsize_t (*gawk_fwrite)(const void *buf, size_t size, size_t count,â
+â FILE *fp, void *opaque);â
+âint (*gawk_fflush)(FILE *fp, void *opaque);â
+âint (*gawk_ferror)(FILE *fp, void *opaque);â
+âint (*gawk_fclose)(FILE *fp, void *opaque);â
These pointers should be set to point to functions that perform the
- equivalent function as the '<stdio.h>' functions do, if
- appropriate. 'gawk' uses these function pointers for all output.
- 'gawk' initializes the pointers to point to internal "pass-through"
- functions that just call the regular '<stdio.h>' functions, so an
+ equivalent function as the â<stdio.h>â functions do, if
+ appropriate. âgawkâ uses these function pointers for all output.
+ âgawkâ initializes the pointers to point to internal
âpass-throughâ
+ functions that just call the regular â<stdio.h>â functions, so an
extension only needs to redefine those functions that are
appropriate for what it does.
- The 'XXX_can_take_file()' function should make a decision based upon
-the 'name' and 'mode' fields, and any additional state (such as 'awk'
+ The âXXX_can_take_file()â function should make a decision based upon
+the ânameâ and âmodeâ fields, and any additional state (such as
âawkâ
variable values) that is appropriate.
- When 'gawk' calls 'XXX_take_control_of()', that function should fill
-in the other fields as appropriate, except for 'fp', which it should
+ When âgawkâ calls âXXX_take_control_of()â, that function should fill
+in the other fields as appropriate, except for âfpâ, which it should
just use normally.
You register your output wrapper with the following function:
-'void register_output_wrapper(awk_output_wrapper_t *output_wrapper);'
- Register the output wrapper pointed to by 'output_wrapper' with
- 'gawk'.
+âvoid register_output_wrapper(awk_output_wrapper_t *output_wrapper);â
+ Register the output wrapper pointed to by âoutput_wrapperâ with
+ âgawkâ.
File: gawk.info, Node: Two-way processors, Prev: Output Wrappers, Up:
Registration Functions
@@ -27008,9 +27006,9 @@ File: gawk.info, Node: Two-way processors, Prev:
Output Wrappers, Up: Registr
17.4.6.6 Customized Two-way Processors
......................................
-A "two-way processor" combines an input parser and an output wrapper for
-two-way I/O with the '|&' operator (*note Redirection::). It makes
-identical use of the 'awk_input_parser_t' and 'awk_output_buf_t'
+A âtwo-way processorâ combines an input parser and an output wrapper for
+two-way I/O with the â|&â operator (*note Redirection::). It makes
+identical use of the âawk_input_parser_tâ and âawk_output_buf_tâ
structures as described earlier.
A two-way processor is represented by the following structure:
@@ -27026,35 +27024,35 @@ structures as described earlier.
The fields are as follows:
-'const char *name;'
+âconst char *name;â
The name of the two-way processor.
-'awk_bool_t (*can_take_two_way)(const char *name);'
+âawk_bool_t (*can_take_two_way)(const char *name);â
The function pointed to by this field should return true if it
wants to take over two-way I/O for this file name. It should not
- change any state (variable values, etc.) within 'gawk'.
+ change any state (variable values, etc.) within âgawkâ.
-'awk_bool_t (*take_control_of)(const char *name,'
-' awk_input_buf_t *inbuf,'
-' awk_output_buf_t *outbuf);'
+âawk_bool_t (*take_control_of)(const char *name,â
+â awk_input_buf_t *inbuf,â
+â awk_output_buf_t *outbuf);â
The function pointed to by this field should fill in the
- 'awk_input_buf_t' and 'awk_output_buf_t' structures pointed to by
- 'inbuf' and 'outbuf', respectively. These structures were
+ âawk_input_buf_tâ and âawk_output_buf_tâ structures pointed to by
+ âinbufâ and âoutbufâ, respectively. These structures were
described earlier.
-'awk_const struct two_way_processor *awk_const next;'
- This is for use by 'gawk'; therefore it is marked 'awk_const' so
+âawk_const struct two_way_processor *awk_const next;â
+ This is for use by âgawkâ; therefore it is marked âawk_constâ so
that the extension cannot modify it.
- As with the input parser and output processor, you provide "yes I can
-take this" and "take over for this" functions, 'XXX_can_take_two_way()'
-and 'XXX_take_control_of()'.
+ As with the input parser and output processor, you provide âyes I can
+take thisâ and âtake over for thisâ functions,
âXXX_can_take_two_way()â
+and âXXX_take_control_of()â.
You register your two-way processor with the following function:
-'void register_two_way_processor(awk_two_way_processor_t *two_way_processor);'
- Register the two-way processor pointed to by 'two_way_processor'
- with 'gawk'.
+âvoid register_two_way_processor(awk_two_way_processor_t
*two_way_processor);â
+ Register the two-way processor pointed to by âtwo_way_processorâ
+ with âgawkâ.
File: gawk.info, Node: Printing Messages, Next: Updating ERRNO, Prev:
Registration Functions, Up: Extension API Description
@@ -27064,52 +27062,52 @@ File: gawk.info, Node: Printing Messages, Next:
Updating ERRNO, Prev: Registr
You can print different kinds of warning messages from your extension,
as described here. Note that for these functions, you must pass in the
-extension ID received from 'gawk' when the extension was loaded:(1)
+extension ID received from âgawkâ when the extension was loaded:(1)
-'void fatal(awk_ext_id_t id, const char *format, ...);'
- Print a message and then cause 'gawk' to exit immediately.
+âvoid fatal(awk_ext_id_t id, const char *format, ...);â
+ Print a message and then cause âgawkâ to exit immediately.
-'void nonfatal(awk_ext_id_t id, const char *format, ...);'
+âvoid nonfatal(awk_ext_id_t id, const char *format, ...);â
Print a nonfatal error message.
-'void warning(awk_ext_id_t id, const char *format, ...);'
+âvoid warning(awk_ext_id_t id, const char *format, ...);â
Print a warning message.
-'void lintwarn(awk_ext_id_t id, const char *format, ...);'
- Print a "lint warning." Normally this is the same as printing a
- warning message, but if 'gawk' was invoked with '--lint=fatal',
+âvoid lintwarn(awk_ext_id_t id, const char *format, ...);â
+ Print a âlint warning.â Normally this is the same as printing a
+ warning message, but if âgawkâ was invoked with â--lint=fatalâ,
then lint warnings become fatal error messages.
- All of these functions are otherwise like the C 'printf()' family of
-functions, where the 'format' parameter is a string with literal
+ All of these functions are otherwise like the C âprintf()â family of
+functions, where the âformatâ parameter is a string with literal
characters and formatting codes intermixed.
---------- Footnotes ----------
(1) Because the API uses only ISO C 90 features, it cannot make use
-of the ISO C 99 variadic macro feature to hide that parameter. More's
+of the ISO C 99 variadic macro feature to hide that parameter. Moreâs
the pity.
File: gawk.info, Node: Updating ERRNO, Next: Requesting Values, Prev:
Printing Messages, Up: Extension API Description
-17.4.8 Updating 'ERRNO'
+17.4.8 Updating âERRNOâ
-----------------------
-The following functions allow you to update the 'ERRNO' variable:
+The following functions allow you to update the âERRNOâ variable:
-'void update_ERRNO_int(int errno_val);'
- Set 'ERRNO' to the string equivalent of the error code in
- 'errno_val'. The value should be one of the defined error codes in
- '<errno.h>', and 'gawk' turns it into a (possibly translated)
- string using the C 'strerror()' function.
+âvoid update_ERRNO_int(int errno_val);â
+ Set âERRNOâ to the string equivalent of the error code in
+ âerrno_valâ. The value should be one of the defined error codes in
+ â<errno.h>â, and âgawkâ turns it into a (possibly translated)
+ string using the C âstrerror()â function.
-'void update_ERRNO_string(const char *string);'
- Set 'ERRNO' directly to the string value of 'ERRNO'. 'gawk' makes
- a copy of the value of 'string'.
+âvoid update_ERRNO_string(const char *string);â
+ Set âERRNOâ directly to the string value of âERRNOâ. âgawkâ
makes
+ a copy of the value of âstringâ.
-'void unset_ERRNO(void);'
- Unset 'ERRNO'.
+âvoid unset_ERRNO(void);â
+ Unset âERRNOâ.
File: gawk.info, Node: Requesting Values, Next: Accessing Parameters, Prev:
Updating ERRNO, Up: Extension API Description
@@ -27117,11 +27115,11 @@ File: gawk.info, Node: Requesting Values, Next:
Accessing Parameters, Prev: U
17.4.9 Requesting Values
------------------------
-All of the functions that return values from 'gawk' work in the same
-way. You pass in an 'awk_valtype_t' value to indicate what kind of
+All of the functions that return values from âgawkâ work in the same
+way. You pass in an âawk_valtype_tâ value to indicate what kind of
value you expect. If the actual value matches what you requested, the
-function returns true and fills in the 'awk_value_t' result. Otherwise,
-the function returns false, and the 'val_type' member indicates the type
+function returns true and fills in the âawk_value_tâ result. Otherwise,
+the function returns false, and the âval_typeâ member indicates the type
of the actual value. You may then print an error message or reissue the
request for the actual value type, as appropriate. This behavior is
summarized in *note Table 17.2: table-value-types-returned.
@@ -27153,21 +27151,21 @@ File: gawk.info, Node: Accessing Parameters, Next:
Symbol Table Access, Prev:
Two functions give you access to the arguments (parameters) passed to
your extension function. They are:
-'awk_bool_t get_argument(size_t count,'
-' awk_valtype_t wanted,'
-' awk_value_t *result);'
- Fill in the 'awk_value_t' structure pointed to by 'result' with the
- 'count'th argument. Return true if the actual type matches
- 'wanted', and false otherwise. In the latter case,
- 'result->val_type' indicates the actual type (*note Table 17.2:
- table-value-types-returned.). Counts are zero-based--the first
- argument is numbered zero, the second one, and so on. 'wanted'
+âawk_bool_t get_argument(size_t count,â
+â awk_valtype_t wanted,â
+â awk_value_t *result);â
+ Fill in the âawk_value_tâ structure pointed to by âresultâ with
the
+ âcountâth argument. Return true if the actual type matches
+ âwantedâ, and false otherwise. In the latter case,
+ âresult->val_typeâ indicates the actual type (*note Table 17.2:
+ table-value-types-returned.). Counts are zero-basedâthe first
+ argument is numbered zero, the second one, and so on. âwantedâ
indicates the type of value expected.
-'awk_bool_t set_argument(size_t count, awk_array_t array);'
+âawk_bool_t set_argument(size_t count, awk_array_t array);â
Convert a parameter that was undefined into an array; this provides
- call by reference for arrays. Return false if 'count' is too big,
- or if the argument's type is not undefined. *Note Array
+ call by reference for arrays. Return false if âcountâ is too big,
+ or if the argumentâs type is not undefined. *Note Array
Manipulation:: for more information on creating arrays.
@@ -27182,7 +27180,7 @@ allows you to create and release cached values.
* Menu:
* Symbol table by name:: Accessing variables by name.
-* Symbol table by cookie:: Accessing variables by "cookie".
+* Symbol table by cookie:: Accessing variables by âcookieâ.
* Cached values:: Creating and using cached values.
@@ -27192,61 +27190,61 @@ File: gawk.info, Node: Symbol table by name, Next:
Symbol table by cookie, Up
............................................
The following routines provide the ability to access and update global
-'awk'-level variables by name. In compiler terminology, identifiers of
-different kinds are termed "symbols", thus the "sym" in the routines'
+âawkâ-level variables by name. In compiler terminology, identifiers of
+different kinds are termed âsymbolsâ, thus the âsymâ in the routinesâ
names. The data structure that stores information about symbols is
-termed a "symbol table". The functions are as follows:
-
-'awk_bool_t sym_lookup(const char *name,'
-' awk_valtype_t wanted,'
-' awk_value_t *result);'
- Fill in the 'awk_value_t' structure pointed to by 'result' with the
- value of the variable named by the string 'name', which is a
- regular C string. 'wanted' indicates the type of value expected.
- Return true if the actual type matches 'wanted', and false
- otherwise. In the latter case, 'result->val_type' indicates the
+termed a âsymbol tableâ. The functions are as follows:
+
+âawk_bool_t sym_lookup(const char *name,â
+â awk_valtype_t wanted,â
+â awk_value_t *result);â
+ Fill in the âawk_value_tâ structure pointed to by âresultâ with
the
+ value of the variable named by the string ânameâ, which is a
+ regular C string. âwantedâ indicates the type of value expected.
+ Return true if the actual type matches âwantedâ, and false
+ otherwise. In the latter case, âresult->val_typeâ indicates the
actual type (*note Table 17.2: table-value-types-returned.).
-'awk_bool_t sym_lookup_ns(const char *name,'
-' const char *name_space,'
-' awk_valtype_t wanted,'
-' awk_value_t *result);'
- This is like 'sym_lookup()', but the 'name_space' parameter allows
- you to specify which namespace 'name' is part of. 'name_space'
- cannot be 'NULL'. If it is '""' or '"awk"', then 'name' is
- searched for in the default 'awk' namespace.
+âawk_bool_t sym_lookup_ns(const char *name,â
+â const char *name_space,â
+â awk_valtype_t wanted,â
+â awk_value_t *result);â
+ This is like âsym_lookup()â, but the âname_spaceâ parameter allows
+ you to specify which namespace ânameâ is part of. âname_spaceâ
+ cannot be âNULLâ. If it is â""â or â"awk"â, then ânameâ
is
+ searched for in the default âawkâ namespace.
- Note that 'namespace' is a C++ keyword. For interoperability with
+ Note that ânamespaceâ is a C++ keyword. For interoperability with
C++, you should avoid using that identifier in C code.
-'awk_bool_t sym_update(const char *name, awk_value_t *value);'
- Update the variable named by the string 'name', which is a regular
- C string. The variable is added to 'gawk''s symbol table if it is
+âawk_bool_t sym_update(const char *name, awk_value_t *value);â
+ Update the variable named by the string ânameâ, which is a regular
+ C string. The variable is added to âgawkââs symbol table if it is
not there. Return true if everything worked, and false otherwise.
Changing types (scalar to array or vice versa) of an existing
variable is _not_ allowed, nor may this routine be used to update
an array. This routine cannot be used to update any of the
- predefined variables (such as 'ARGC' or 'NF').
+ predefined variables (such as âARGCâ or âNFâ).
-'awk_bool_t sym_update_ns(const char *name_space, const char *name,
awk_value_t *value);'
- This is like 'sym_update()', but the 'name_space' parameter allows
- you to specify which namespace 'name' is part of. 'name_space'
- cannot be 'NULL'. If it is '""' or '"awk"', then 'name' is
- searched for in the default 'awk' namespace.
+âawk_bool_t sym_update_ns(const char *name_space, const char *name,
awk_value_t *value);â
+ This is like âsym_update()â, but the âname_spaceâ parameter allows
+ you to specify which namespace ânameâ is part of. âname_spaceâ
+ cannot be âNULLâ. If it is â""â or â"awk"â, then ânameâ
is
+ searched for in the default âawkâ namespace.
- An extension can look up the value of 'gawk''s special variables.
-However, with the exception of the 'PROCINFO' array, an extension cannot
+ An extension can look up the value of âgawkââs special variables.
+However, with the exception of the âPROCINFOâ array, an extension cannot
change any of those variables.
- When searching for or updating variables outside the 'awk' namespace
+ When searching for or updating variables outside the âawkâ namespace
(*note Namespaces::), function and variable names must be simple
identifiers.(1) In addition, namespace names and variable and function
names must follow the rules given in *note Naming Rules::.
---------- Footnotes ----------
- (1) Allowing both namespace plus identifier and 'foo::bar' would have
+ (1) Allowing both namespace plus identifier and âfoo::barâ would have
been too confusing to document, and to code and test.
@@ -27255,30 +27253,30 @@ File: gawk.info, Node: Symbol table by cookie,
Next: Cached values, Prev: Sym
17.4.11.2 Variable Access and Update by Cookie
..............................................
-A "scalar cookie" is an opaque handle that provides access to a global
+A âscalar cookieâ is an opaque handle that provides access to a global
variable or array. It is an optimization that avoids looking up
-variables in 'gawk''s symbol table every time access is needed. This
+variables in âgawkââs symbol table every time access is needed. This
was discussed earlier, in *note General Data Types::.
The following functions let you work with scalar cookies:
-'awk_bool_t sym_lookup_scalar(awk_scalar_t cookie,'
-' awk_valtype_t wanted,'
-' awk_value_t *result);'
+âawk_bool_t sym_lookup_scalar(awk_scalar_t cookie,â
+â awk_valtype_t wanted,â
+â awk_value_t *result);â
Retrieve the current value of a scalar cookie. Once you have
- obtained a scalar cookie using 'sym_lookup()', you can use this
+ obtained a scalar cookie using âsym_lookup()â, you can use this
function to get its value more efficiently. Return false if the
value cannot be retrieved.
-'awk_bool_t sym_update_scalar(awk_scalar_t cookie, awk_value_t *value);'
+âawk_bool_t sym_update_scalar(awk_scalar_t cookie, awk_value_t *value);â
Update the value associated with a scalar cookie. Return false if
- the new value is not of type 'AWK_STRING', 'AWK_STRNUM',
- 'AWK_REGEX', or 'AWK_NUMBER'. Here too, the predefined variables
+ the new value is not of type âAWK_STRINGâ, âAWK_STRNUMâ,
+ âAWK_REGEXâ, or âAWK_NUMBERâ. Here too, the predefined variables
may not be updated.
It is not obvious at first glance how to work with scalar cookies or
-what their raison d'être really is. In theory, the 'sym_lookup()' and
-'sym_update()' routines are all you really need to work with variables.
+what their raison dâêtre really is. In theory, the âsym_lookup()â and
+âsym_update()â routines are all you really need to work with variables.
For example, you might have code that looks up the value of a variable,
evaluates a condition, and then possibly changes the value of the
variable based on the result of that evaluation, like so:
@@ -27299,22 +27297,22 @@ variable based on the result of that evaluation, like
so:
return make_number(0.0, result);
}
-This code looks (and is) simple and straightforward. So what's the
+This code looks (and is) simple and straightforward. So whatâs the
problem?
- Well, consider what happens if 'awk'-level code associated with your
-extension calls the 'magic()' function (implemented in C by
-'do_magic()'), once per record, while processing hundreds of thousands
-or millions of records. The 'MAGIC_VAR' variable is looked up in the
+ Well, consider what happens if âawkâ-level code associated with your
+extension calls the âmagic()â function (implemented in C by
+âdo_magic()â), once per record, while processing hundreds of thousands
+or millions of records. The âMAGIC_VARâ variable is looked up in the
symbol table once or twice per function call!
The symbol table lookup is really pure overhead; it is considerably
more efficient to get a cookie that represents the variable, and use
-that to get the variable's value and update it as needed.(1)
+that to get the variableâs value and update it as needed.(1)
Thus, the way to use cookies is as follows. First, install your
-extension's variable in 'gawk''s symbol table using 'sym_update()', as
-usual. Then get a scalar cookie for the variable using 'sym_lookup()':
+extensionâs variable in âgawkââs symbol table using
âsym_update()â, as
+usual. Then get a scalar cookie for the variable using âsym_lookup()â:
static awk_scalar_t magic_var_cookie; /* cookie for MAGIC_VAR */
@@ -27335,7 +27333,7 @@ usual. Then get a scalar cookie for the variable using
'sym_lookup()':
}
Next, use the routines in this minor node for retrieving and updating
-the value through the cookie. Thus, 'do_magic()' now becomes something
+the value through the cookie. Thus, âdo_magic()â now becomes something
like this:
/* do_magic --- do something really great */
@@ -27373,29 +27371,29 @@ The routines in this minor node allow you to create
and release cached
values. Like scalar cookies, in theory, cached values are not
necessary. You can create numbers and strings using the functions in
*note Constructor Functions::. You can then assign those values to
-variables using 'sym_update()' or 'sym_update_scalar()', as you like.
+variables using âsym_update()â or âsym_update_scalar()â, as you like.
However, you can understand the point of cached values if you
-remember that _every_ string value's storage _must_ come from
-'gawk_malloc()', 'gawk_calloc()', or 'gawk_realloc()'. If you have 20
+remember that _every_ string valueâs storage _must_ come from
+âgawk_malloc()â, âgawk_calloc()â, or âgawk_realloc()â. If you
have 20
variables, all of which have the same string value, you must create 20
identical copies of the string.(1)
It is clearly more efficient, if possible, to create a value once,
-and then tell 'gawk' to reuse the value for multiple variables. That is
+and then tell âgawkâ to reuse the value for multiple variables. That is
what the routines in this minor node let you do. The functions are as
follows:
-'awk_bool_t create_value(awk_value_t *value, awk_value_cookie_t *result);'
- Create a cached string or numeric value from 'value' for efficient
- later assignment. Only values of type 'AWK_NUMBER', 'AWK_REGEX',
- 'AWK_STRNUM', and 'AWK_STRING' are allowed. Any other type is
- rejected. 'AWK_UNDEFINED' could be allowed, but doing so would
+âawk_bool_t create_value(awk_value_t *value, awk_value_cookie_t *result);â
+ Create a cached string or numeric value from âvalueâ for efficient
+ later assignment. Only values of type âAWK_NUMBERâ, âAWK_REGEXâ,
+ âAWK_STRNUMâ, and âAWK_STRINGâ are allowed. Any other type is
+ rejected. âAWK_UNDEFINEDâ could be allowed, but doing so would
result in inferior performance.
-'awk_bool_t release_value(awk_value_cookie_t vc);'
+âawk_bool_t release_value(awk_value_cookie_t vc);â
Release the memory associated with a value cookie obtained from
- 'create_value()'.
+ âcreate_value()â.
You use value cookies in a fashion similar to the way you use scalar
cookies. In the extension initialization routine, you create the value
@@ -27438,27 +27436,27 @@ of variables:
}
Using value cookies in this way saves considerable storage, as all of
-'VAR1' through 'VAR100' share the same value.
+âVAR1â through âVAR100â share the same value.
- You might be wondering, "Is this sharing problematic? What happens
-if 'awk' code assigns a new value to 'VAR1'; are all the others changed
-too?"
+ You might be wondering, âIs this sharing problematic? What happens
+if âawkâ code assigns a new value to âVAR1â; are all the others changed
+too?â
- That's a great question. The answer is that no, it's not a problem.
-Internally, 'gawk' uses "reference-counted strings". This means that
-many variables can share the same string value, and 'gawk' keeps track
-of the usage. When a variable's value changes, 'gawk' simply decrements
+ Thatâs a great question. The answer is that no, itâs not a problem.
+Internally, âgawkâ uses âreference-counted stringsâ. This means that
+many variables can share the same string value, and âgawkâ keeps track
+of the usage. When a variableâs value changes, âgawkâ simply decrements
the reference count on the old value and updates the variable to use the
new value.
Finally, as part of your cleanup action (*note Exit Callback
Functions::) you should release any cached values that you created,
-using 'release_value()'.
+using ârelease_value()â.
---------- Footnotes ----------
(1) Numeric values are clearly less problematic, requiring only a C
-'double' to store. But of course, GMP and MPFR values _do_ take up more
+âdoubleâ to store. But of course, GMP and MPFR values _do_ take up more
memory.
@@ -27467,11 +27465,11 @@ File: gawk.info, Node: Array Manipulation, Next:
Redirection API, Prev: Symbo
17.4.12 Array Manipulation
--------------------------
-The primary data structure(1) in 'awk' is the associative array (*note
-Arrays::). Extensions need to be able to manipulate 'awk' arrays. The
+The primary data structure(1) in âawkâ is the associative array (*note
+Arrays::). Extensions need to be able to manipulate âawkâ arrays. The
API provides a number of data structures for working with arrays,
functions for working with individual elements, and functions for
-working with arrays as a whole. This includes the ability to "flatten"
+working with arrays as a whole. This includes the ability to âflattenâ
an array so that it is easy for C code to traverse every element in an
array. The array data structures integrate nicely with the data
structures for values to make it easy to both work with and create true
@@ -27496,63 +27494,63 @@ File: gawk.info, Node: Array Data Types, Next:
Array Functions, Up: Array Man
The data types associated with arrays are as follows:
-'typedef void *awk_array_t;'
+âtypedef void *awk_array_t;â
If you request the value of an array variable, you get back an
- 'awk_array_t' value. This value is opaque(1) to the extension; it
+ âawk_array_tâ value. This value is opaque(1) to the extension; it
uniquely identifies the array but can only be used by passing it
into API functions or receiving it from API functions. This is
- very similar to way 'FILE *' values are used with the '<stdio.h>'
+ very similar to way âFILE *â values are used with the â<stdio.h>â
library routines.
-'typedef struct awk_element {'
-' /* convenience linked list pointer, not used by gawk */'
-' struct awk_element *next;'
-' enum {'
-' AWK_ELEMENT_DEFAULT = 0, /* set by gawk */'
-' AWK_ELEMENT_DELETE = 1 /* set by extension */'
-' } flags;'
-' awk_value_t index;'
-' awk_value_t value;'
-'} awk_element_t;'
- The 'awk_element_t' is a "flattened" array element. 'awk' produces
- an array of these inside the 'awk_flat_array_t' (see the next
+âtypedef struct awk_element {â
+â /* convenience linked list pointer, not used by gawk */â
+â struct awk_element *next;â
+â enum {â
+â AWK_ELEMENT_DEFAULT = 0, /* set by gawk */â
+â AWK_ELEMENT_DELETE = 1 /* set by extension */â
+â } flags;â
+â awk_value_t index;â
+â awk_value_t value;â
+â} awk_element_t;â
+ The âawk_element_tâ is a âflattenedâ array element. âawkâ
produces
+ an array of these inside the âawk_flat_array_tâ (see the next
item). Individual elements may be marked for deletion. New
elements must be added individually, one at a time, using the
separate API for that purpose. The fields are as follows:
- 'struct awk_element *next;'
+ âstruct awk_element *next;â
This pointer is for the convenience of extension writers. It
allows an extension to create a linked list of new elements
that can then be added to an array in a loop that traverses
the list.
- 'enum { ... } flags;'
+ âenum { ... } flags;â
A set of flag values that convey information between the
- extension and 'gawk'. Currently there is only one:
- 'AWK_ELEMENT_DELETE'. Setting it causes 'gawk' to delete the
+ extension and âgawkâ. Currently there is only one:
+ âAWK_ELEMENT_DELETEâ. Setting it causes âgawkâ to delete the
element from the original array upon release of the flattened
array.
- 'index'
- 'value'
+ âindexâ
+ âvalueâ
The index and value of the element, respectively. _All_
- memory pointed to by 'index' and 'value' belongs to 'gawk'.
-
-'typedef struct awk_flat_array {'
-' awk_const void *awk_const opaque1; /* for use by gawk */'
-' awk_const void *awk_const opaque2; /* for use by gawk */'
-' awk_const size_t count; /* how many elements */'
-' awk_element_t elements[1]; /* will be extended */'
-'} awk_flat_array_t;'
+ memory pointed to by âindexâ and âvalueâ belongs to
âgawkâ.
+
+âtypedef struct awk_flat_array {â
+â awk_const void *awk_const opaque1; /* for use by gawk */â
+â awk_const void *awk_const opaque2; /* for use by gawk */â
+â awk_const size_t count; /* how many elements */â
+â awk_element_t elements[1]; /* will be extended */â
+â} awk_flat_array_t;â
This is a flattened array. When an extension gets one of these
- from 'gawk', the 'elements' array is of actual size 'count'. The
- 'opaque1' and 'opaque2' pointers are for use by 'gawk'; therefore
- they are marked 'awk_const' so that the extension cannot modify
+ from âgawkâ, the âelementsâ array is of actual size âcountâ.
The
+ âopaque1â and âopaque2â pointers are for use by âgawkâ;
therefore
+ they are marked âawk_constâ so that the extension cannot modify
them.
---------- Footnotes ----------
- (1) It is also a "cookie," but the 'gawk' developers did not wish to
+ (1) It is also a âcookie,â but the âgawkâ developers did not wish to
overuse this term.
@@ -27563,92 +27561,92 @@ File: gawk.info, Node: Array Functions, Next:
Flattening Arrays, Prev: Array
The following functions relate to individual array elements:
-'awk_bool_t get_element_count(awk_array_t a_cookie, size_t *count);'
- For the array represented by 'a_cookie', place in '*count' the
+âawk_bool_t get_element_count(awk_array_t a_cookie, size_t *count);â
+ For the array represented by âa_cookieâ, place in â*countâ the
number of elements it contains. A subarray counts as a single
element. Return false if there is an error.
-'awk_bool_t get_array_element(awk_array_t a_cookie,'
-' const awk_value_t *const index,'
-' awk_valtype_t wanted,'
-' awk_value_t *result);'
- For the array represented by 'a_cookie', return in '*result' the
- value of the element whose index is 'index'. 'wanted' specifies
- the type of value you wish to retrieve. Return false if 'wanted'
- does not match the actual type or if 'index' is not in the array
+âawk_bool_t get_array_element(awk_array_t a_cookie,â
+â const awk_value_t *const index,â
+â awk_valtype_t wanted,â
+â awk_value_t *result);â
+ For the array represented by âa_cookieâ, return in â*resultâ the
+ value of the element whose index is âindexâ. âwantedâ specifies
+ the type of value you wish to retrieve. Return false if âwantedâ
+ does not match the actual type or if âindexâ is not in the array
(*note Table 17.2: table-value-types-returned.).
- The value for 'index' can be numeric, in which case 'gawk' converts
+ The value for âindexâ can be numeric, in which case âgawkâ
converts
it to a string. Using nonintegral values is possible, but requires
that you understand how such values are converted to strings (*note
Conversion::); thus, using integral values is safest.
- As with _all_ strings passed into 'gawk' from an extension, the
- string value of 'index' must come from 'gawk_malloc()',
- 'gawk_calloc()', or 'gawk_realloc()', and 'gawk' releases the
+ As with _all_ strings passed into âgawkâ from an extension, the
+ string value of âindexâ must come from âgawk_malloc()â,
+ âgawk_calloc()â, or âgawk_realloc()â, and âgawkâ releases the
storage.
-'awk_bool_t set_array_element(awk_array_t a_cookie,'
-' const awk_value_t *const index,'
-' const awk_value_t *const value);'
- In the array represented by 'a_cookie', create or modify the
- element whose index is given by 'index'. The 'ARGV' and 'ENVIRON'
- arrays may not be changed, although the 'PROCINFO' array can be.
+âawk_bool_t set_array_element(awk_array_t a_cookie,â
+â const awk_value_t *const index,â
+â const awk_value_t *const value);â
+ In the array represented by âa_cookieâ, create or modify the
+ element whose index is given by âindexâ. The âARGVâ and
âENVIRONâ
+ arrays may not be changed, although the âPROCINFOâ array can be.
-'awk_bool_t set_array_element_by_elem(awk_array_t a_cookie,'
-' awk_element_t element);'
- Like 'set_array_element()', but take the 'index' and 'value' from
- 'element'. This is a convenience macro.
+âawk_bool_t set_array_element_by_elem(awk_array_t a_cookie,â
+â awk_element_t element);â
+ Like âset_array_element()â, but take the âindexâ and âvalueâ
from
+ âelementâ. This is a convenience macro.
-'awk_bool_t del_array_element(awk_array_t a_cookie,'
-' const awk_value_t* const index);'
+âawk_bool_t del_array_element(awk_array_t a_cookie,â
+â const awk_value_t* const index);â
Remove the element with the given index from the array represented
- by 'a_cookie'. Return true if the element was removed, or false if
+ by âa_cookieâ. Return true if the element was removed, or false if
the element did not exist in the array.
The following functions relate to arrays as a whole:
-'awk_array_t create_array(void);'
+âawk_array_t create_array(void);â
Create a new array to which elements may be added. *Note Creating
Arrays:: for a discussion of how to create a new array and add
elements to it.
-'awk_bool_t clear_array(awk_array_t a_cookie);'
- Clear the array represented by 'a_cookie'. Return false if there
+âawk_bool_t clear_array(awk_array_t a_cookie);â
+ Clear the array represented by âa_cookieâ. Return false if there
was some kind of problem, true otherwise. The array remains an
array, but after calling this function, it has no elements. This
- is equivalent to using the 'delete' statement (*note Delete::).
+ is equivalent to using the âdeleteâ statement (*note Delete::).
-'awk_bool_t destroy_array(awk_array_t a_cookie);'
- Clear the array represented by 'a_cookie' and release the array
- allocated by 'create_array'. Return false if there was some kind
+âawk_bool_t destroy_array(awk_array_t a_cookie);â
+ Clear the array represented by âa_cookieâ and release the array
+ allocated by âcreate_arrayâ. Return false if there was some kind
of problem, true otherwise. The array will no longer exist and
cannot be used again.
-'awk_bool_t flatten_array_typed(awk_array_t a_cookie,'
-' awk_flat_array_t **data,'
-' awk_valtype_t index_type,'
-' awk_valtype_t value_type);'
- For the array represented by 'a_cookie', create an
- 'awk_flat_array_t' structure and fill it in with indices and values
+âawk_bool_t flatten_array_typed(awk_array_t a_cookie,â
+â awk_flat_array_t **data,â
+â awk_valtype_t index_type,â
+â awk_valtype_t value_type);â
+ For the array represented by âa_cookieâ, create an
+ âawk_flat_array_tâ structure and fill it in with indices and values
of the requested types. Set the pointer whose address is passed as
- 'data' to point to this structure. Return true upon success, or
+ âdataâ to point to this structure. Return true upon success, or
false otherwise. *Note Flattening Arrays::, for a discussion of
how to flatten an array and work with it.
-'awk_bool_t flatten_array(awk_array_t a_cookie, awk_flat_array_t **data);'
- For the array represented by 'a_cookie', create an
- 'awk_flat_array_t' structure and fill it in with 'AWK_STRING'
- indices and 'AWK_UNDEFINED' values. This is superseded by
- 'flatten_array_typed()'. It is provided as a macro, and remains
+âawk_bool_t flatten_array(awk_array_t a_cookie, awk_flat_array_t **data);â
+ For the array represented by âa_cookieâ, create an
+ âawk_flat_array_tâ structure and fill it in with âAWK_STRINGâ
+ indices and âAWK_UNDEFINEDâ values. This is superseded by
+ âflatten_array_typed()â. It is provided as a macro, and remains
for convenience and for source code compatibility with the previous
version of the API.
-'awk_bool_t release_flattened_array(awk_array_t a_cookie,'
-' awk_flat_array_t *data);'
+âawk_bool_t release_flattened_array(awk_array_t a_cookie,â
+â awk_flat_array_t *data);â
When done with a flattened array, release the storage using this
function. You must pass in both the original array cookie and the
- address of the created 'awk_flat_array_t' structure. The function
+ address of the created âawk_flat_array_tâ structure. The function
returns true upon success, false otherwise.
@@ -27657,13 +27655,13 @@ File: gawk.info, Node: Flattening Arrays, Next:
Creating Arrays, Prev: Array
17.4.12.3 Working With All The Elements of an Array
...................................................
-To "flatten" an array is to create a structure that represents the full
+To âflattenâ an array is to create a structure that represents the full
array in a fashion that makes it easy for C code to traverse the entire
-array. Some of the code in 'extension/testext.c' does this, and also
+array. Some of the code in âextension/testext.câ does this, and also
serves as a nice example showing how to use the APIs.
We walk through that part of the code one step at a time. First, the
-'gawk' script that drives the test extension:
+âgawkâ script that drives the test extension:
@load "testext"
BEGIN {
@@ -27678,16 +27676,16 @@ serves as a nice example showing how to use the APIs.
print ""
}
-This code creates an array with 'split()' (*note String Functions::) and
-then calls 'dump_array_and_delete()'. That function looks up the array
+This code creates an array with âsplit()â (*note String Functions::) and
+then calls âdump_array_and_delete()â. That function looks up the array
whose name is passed as the first argument, and deletes the element at
-the index passed in the second argument. The 'awk' code then prints the
+the index passed in the second argument. The âawkâ code then prints the
return value and checks if the element was indeed deleted. Here is the
-C code that implements 'dump_array_and_delete()'. It has been edited
+C code that implements âdump_array_and_delete()â. It has been edited
slightly for presentation.
The first part declares variables, sets up the default return value
-in 'result', and checks that the function was called with the correct
+in âresultâ, and checks that the function was called with the correct
number of arguments:
static awk_value_t *
@@ -27729,7 +27727,7 @@ itself. If either operation fails, print an error
message and return:
}
For testing purposes and to make sure that the C code sees the same
-number of elements as the 'awk' code, the second step is to get the
+number of elements as the âawkâ code, the second step is to get the
count of elements in the array and print it:
if (! get_element_count(value2.array_cookie, & count)) {
@@ -27741,7 +27739,7 @@ count of elements in the array and print it:
(unsigned long) count);
The third step is to actually flatten the array, and then to
-double-check that the count in the 'awk_flat_array_t' is the same as the
+double-check that the count in the âawk_flat_array_tâ is the same as the
count just retrieved:
if (! flatten_array_typed(value2.array_cookie, & flat_array,
@@ -27760,7 +27758,7 @@ count just retrieved:
The fourth step is to retrieve the index of the element to be
deleted, which was passed as the second argument. Remember that
-argument counts passed to 'get_argument()' are zero-based, and thus the
+argument counts passed to âget_argument()â are zero-based, and thus the
second argument is numbered one:
if (! get_argument(1, AWK_STRING, & value3)) {
@@ -27768,11 +27766,11 @@ second argument is numbered one:
goto out;
}
- The fifth step is where the "real work" is done. The function loops
+ The fifth step is where the âreal workâ is done. The function loops
over every element in the array, printing the index and element values.
In addition, upon finding the element with the index that is supposed to
-be deleted, the function sets the 'AWK_ELEMENT_DELETE' bit in the
-'flags' field of the element. When the array is released, 'gawk'
+be deleted, the function sets the âAWK_ELEMENT_DELETEâ bit in the
+âflagsâ field of the element. When the array is released, âgawkâ
traverses the flattened array, and deletes any elements that have this
flag bit set:
@@ -27792,11 +27790,11 @@ flag bit set:
}
}
- The sixth step is to release the flattened array. This tells 'gawk'
+ The sixth step is to release the flattened array. This tells âgawkâ
that the extension is no longer using the array, and that it should
-delete any elements marked for deletion. 'gawk' also frees any storage
-that was allocated, so you should not use the pointer ('flat_array' in
-this code) once you have called 'release_flattened_array()':
+delete any elements marked for deletion. âgawkâ also frees any storage
+that was allocated, so you should not use the pointer (âflat_arrayâ in
+this code) once you have called ârelease_flattened_array()â:
if (! release_flattened_array(value2.array_cookie, flat_array)) {
printf("dump_array_and_delete: could not release flattened
array\n");
@@ -27831,14 +27829,14 @@ File: gawk.info, Node: Creating Arrays, Prev:
Flattening Arrays, Up: Array Ma
17.4.12.4 How To Create and Populate Arrays
...........................................
-Besides working with arrays created by 'awk' code, you can create arrays
-and populate them as you see fit, and then 'awk' code can access them
+Besides working with arrays created by âawkâ code, you can create arrays
+and populate them as you see fit, and then âawkâ code can access them
and manipulate them.
There are two important points about creating arrays from extension
code:
- * You must install a new array into 'gawk''s symbol table immediately
+ ⢠You must install a new array into âgawkââs symbol table
immediately
upon creating it. Once you have done so, you can then populate the
array.
@@ -27846,15 +27844,15 @@ code:
array, you must add the new array to its parent before adding any
elements to it.
- Thus, the correct way to build an array is to work "top down."
- Create the array, and immediately install it in 'gawk''s symbol
- table using 'sym_update()', or install it as an element in a
- previously existing array using 'set_array_element()'. We show
+ Thus, the correct way to build an array is to work âtop down.â
+ Create the array, and immediately install it in âgawkââs symbol
+ table using âsym_update()â, or install it as an element in a
+ previously existing array using âset_array_element()â. We show
example code shortly.
- * Due to 'gawk' internals, after using 'sym_update()' to install an
- array into 'gawk', you have to retrieve the array cookie from the
- value passed in to 'sym_update()' before doing anything else with
+ ⢠Due to âgawkâ internals, after using âsym_update()â to install
an
+ array into âgawkâ, you have to retrieve the array cookie from the
+ value passed in to âsym_update()â before doing anything else with
it, like so:
awk_value_t val;
@@ -27870,10 +27868,10 @@ code:
new_array = val.array_cookie; /* YOU MUST DO THIS */
If installing an array as a subarray, you must also retrieve the
- value of the array cookie after the call to 'set_element()'.
+ value of the array cookie after the call to âset_element()â.
The following C code is a simple test extension to create an array
-with two regular elements and with a subarray. The leading '#include'
+with two regular elements and with a subarray. The leading â#includeâ
directives and boilerplate variable declarations (*note Extension API
Boilerplate::) are omitted for brevity. The first step is to create a
new array and then install it in the symbol table:
@@ -27895,10 +27893,10 @@ new array and then install it in the symbol table:
printf("create_new_array: sym_update(\"new_array\") failed!\n");
a_cookie = value.array_cookie;
-Note how 'a_cookie' is reset from the 'array_cookie' field in the
-'value' structure.
+Note how âa_cookieâ is reset from the âarray_cookieâ field in the
+âvalueâ structure.
- The second step is to install two regular values into 'new_array':
+ The second step is to install two regular values into ânew_arrayâ:
(void) make_const_string("hello", 5, & index);
(void) make_const_string("world", 5, & value);
@@ -27957,11 +27955,11 @@ array:
Here is the result of running the script:
$ AWKLIBPATH=$PWD gawk -f subarray.awk
- -| new_array["subarray"]["foo"] = bar
- -| new_array["hello"] = world
- -| new_array["answer"] = 42
+ ⣠new_array["subarray"]["foo"] = bar
+ ⣠new_array["hello"] = world
+ ⣠new_array["answer"] = 42
-(*Note Finding Extensions:: for more information on the 'AWKLIBPATH'
+(*Note Finding Extensions:: for more information on the âAWKLIBPATHâ
environment variable.)
@@ -27973,60 +27971,60 @@ File: gawk.info, Node: Redirection API, Next:
Extension API Variables, Prev:
The following function allows extensions to access and manipulate
redirections.
-'awk_bool_t get_file(const char *name,'
-' size_t name_len,'
-' const char *filetype,'
-' int fd,'
-' const awk_input_buf_t **ibufp,'
-' const awk_output_buf_t **obufp);'
- Look up file 'name' in 'gawk''s internal redirection table. If
- 'name' is 'NULL' or 'name_len' is zero, return data for the
- currently open input file corresponding to 'FILENAME'. (This does
- not access the 'filetype' argument, so that may be undefined). If
- the file is not already open, attempt to open it. The 'filetype'
+âawk_bool_t get_file(const char *name,â
+â size_t name_len,â
+â const char *filetype,â
+â int fd,â
+â const awk_input_buf_t **ibufp,â
+â const awk_output_buf_t **obufp);â
+ Look up file ânameâ in âgawkââs internal redirection table. If
+ ânameâ is âNULLâ or âname_lenâ is zero, return data for the
+ currently open input file corresponding to âFILENAMEâ. (This does
+ not access the âfiletypeâ argument, so that may be undefined). If
+ the file is not already open, attempt to open it. The âfiletypeâ
argument must be zero-terminated and should be one of:
- '">"'
+ â">"â
A file opened for output.
- '">>"'
+ â">>"â
A file opened for append.
- '"<"'
+ â"<"â
A file opened for input.
- '"|>"'
+ â"|>"â
A pipe opened for output.
- '"|<"'
+ â"|<"â
A pipe opened for input.
- '"|&"'
+ â"|&"â
A two-way coprocess.
- On error, return 'awk_false'. Otherwise, return 'awk_true', and
- return additional information about the redirection in the 'ibufp'
- and 'obufp' pointers.
-
- For input redirections, the '*ibufp' value should be non-'NULL',
- and '*obufp' should be 'NULL'. For output redirections, the
- '*obufp' value should be non-'NULL', and '*ibufp' should be 'NULL'.
- For two-way coprocesses, both values should be non-'NULL'.
-
- In the usual case, the extension is interested in '(*ibufp)->fd'
- and/or 'fileno((*obufp)->fp)'. If the file is not already open,
- and the 'fd' argument is nonnegative, 'gawk' will use that file
- descriptor instead of opening the file in the usual way. If 'fd'
- is nonnegative, but the file exists already, 'gawk' ignores 'fd'
- and returns the existing file. It is the caller's responsibility
- to notice that neither the 'fd' in the returned 'awk_input_buf_t'
- nor the 'fd' in the returned 'awk_output_buf_t' matches the
+ On error, return âawk_falseâ. Otherwise, return âawk_trueâ, and
+ return additional information about the redirection in the âibufpâ
+ and âobufpâ pointers.
+
+ For input redirections, the â*ibufpâ value should be non-âNULLâ,
+ and â*obufpâ should be âNULLâ. For output redirections, the
+ â*obufpâ value should be non-âNULLâ, and â*ibufpâ should be
âNULLâ.
+ For two-way coprocesses, both values should be non-âNULLâ.
+
+ In the usual case, the extension is interested in â(*ibufp)->fdâ
+ and/or âfileno((*obufp)->fp)â. If the file is not already open,
+ and the âfdâ argument is nonnegative, âgawkâ will use that file
+ descriptor instead of opening the file in the usual way. If âfdâ
+ is nonnegative, but the file exists already, âgawkâ ignores âfdâ
+ and returns the existing file. It is the callerâs responsibility
+ to notice that neither the âfdâ in the returned âawk_input_buf_tâ
+ nor the âfdâ in the returned âawk_output_buf_tâ matches the
requested value.
Note that supplying a file descriptor is currently _not_ supported
for pipes. However, supplying a file descriptor should work for
input, output, append, and two-way (coprocess) sockets. If
- 'filetype' is two-way, 'gawk' assumes that it is a socket! Note
+ âfiletypeâ is two-way, âgawkâ assumes that it is a socket! Note
that in the two-way case, the input and output file descriptors may
differ. To check for success, you must check whether either
matches.
@@ -28042,15 +28040,15 @@ File: gawk.info, Node: Extension API Variables,
Next: Extension API Boilerplat
The API provides two sets of variables. The first provides information
about the version of the API (both with which the extension was
-compiled, and with which 'gawk' was compiled). The second provides
-information about how 'gawk' was invoked.
+compiled, and with which âgawkâ was compiled). The second provides
+information about how âgawkâ was invoked.
* Menu:
* Extension Versioning:: API Version information.
* Extension GMP/MPFR Versioning:: Version information about GMP and MPFR.
* Extension API Informational Variables:: Variables providing information about
- 'gawk''s invocation.
+ âgawkââs invocation.
File: gawk.info, Node: Extension Versioning, Next: Extension GMP/MPFR
Versioning, Up: Extension API Variables
@@ -28058,7 +28056,7 @@ File: gawk.info, Node: Extension Versioning, Next:
Extension GMP/MPFR Versioni
17.4.14.1 API Version Constants and Variables
.............................................
-The API provides both a "major" and a "minor" version number. The API
+The API provides both a âmajorâ and a âminorâ version number. The API
versions are available at compile time as C preprocessor defines to
support conditional compilation, and as enum constants to facilitate
debugging:
@@ -28066,28 +28064,28 @@ debugging:
API Version C Preprocessor Define enum constant
--------------------------------------------------------------------
-Major 'gawk_api_major_version' 'GAWK_API_MAJOR_VERSION'
-Minor 'gawk_api_minor_version' 'GAWK_API_MINOR_VERSION'
+Major âgawk_api_major_versionâ âGAWK_API_MAJOR_VERSIONâ
+Minor âgawk_api_minor_versionâ âGAWK_API_MINOR_VERSIONâ
Table 17.3: gawk API version constants
The minor version increases when new functions are added to the API.
-Such new functions are always added to the end of the API 'struct'.
+Such new functions are always added to the end of the API âstructâ.
The major version increases (and the minor version is reset to zero)
if any of the data types change size or member order, or if any of the
existing functions change signature.
It could happen that an extension may be compiled against one version
-of the API but loaded by a version of 'gawk' using a different version.
-For this reason, the major and minor API versions of the running 'gawk'
-are included in the API 'struct' as read-only constant integers:
+of the API but loaded by a version of âgawkâ using a different version.
+For this reason, the major and minor API versions of the running âgawkâ
+are included in the API âstructâ as read-only constant integers:
-'api->major_version'
- The major version of the running 'gawk'.
+âapi->major_versionâ
+ The major version of the running âgawkâ.
-'api->minor_version'
- The minor version of the running 'gawk'.
+âapi->minor_versionâ
+ The minor version of the running âgawkâ.
It is up to the extension to decide if there are API
incompatibilities. Typically, a check like this is enough:
@@ -28101,8 +28099,8 @@ incompatibilities. Typically, a check like this is
enough:
exit(1);
}
- Such code is included in the boilerplate 'dl_load_func()' macro
-provided in 'gawkapi.h' (discussed in *note Extension API
+ Such code is included in the boilerplate âdl_load_func()â macro
+provided in âgawkapi.hâ (discussed in *note Extension API
Boilerplate::).
@@ -28112,40 +28110,40 @@ File: gawk.info, Node: Extension GMP/MPFR
Versioning, Next: Extension API Info
..........................................
The API also includes information about the versions of GMP and MPFR
-with which the running 'gawk' was compiled (if any). They are included
-in the API 'struct' as read-only constant integers:
+with which the running âgawkâ was compiled (if any). They are included
+in the API âstructâ as read-only constant integers:
-'api->gmp_major_version'
- The major version of the GMP library used to compile 'gawk'.
+âapi->gmp_major_versionâ
+ The major version of the GMP library used to compile âgawkâ.
-'api->gmp_minor_version'
- The minor version of the GMP library used to compile 'gawk'.
+âapi->gmp_minor_versionâ
+ The minor version of the GMP library used to compile âgawkâ.
-'api->mpfr_major_version'
- The major version of the MPFR library used to compile 'gawk'.
+âapi->mpfr_major_versionâ
+ The major version of the MPFR library used to compile âgawkâ.
-'api->mpfr_minor_version'
- The minor version of the MPFR library used to compile 'gawk'.
+âapi->mpfr_minor_versionâ
+ The minor version of the MPFR library used to compile âgawkâ.
- These fields are set to zero if 'gawk' was compiled without MPFR
+ These fields are set to zero if âgawkâ was compiled without MPFR
support.
You can check if the versions of MPFR and GMP that you are using
-match those of 'gawk' with the following macro:
+match those of âgawkâ with the following macro:
-'check_mpfr_version(extension)'
- The 'extension' is the extension id passed to all the other macros
- and functions defined in 'gawkapi.h'. If you have not included the
- '<mpfr.h>' header file, then this macro will be defined to do
+âcheck_mpfr_version(extension)â
+ The âextensionâ is the extension id passed to all the other macros
+ and functions defined in âgawkapi.hâ. If you have not included the
+ â<mpfr.h>â header file, then this macro will be defined to do
nothing.
If you have included that file, then this macro compares the MPFR
and GMP major and minor versions against those of the library you
- are compiling against. If your libraries are newer than 'gawk''s,
+ are compiling against. If your libraries are newer than âgawkââs,
it produces a fatal error message.
- The 'dl_load_func()' macro (*note Extension API Boilerplate::)
- calls 'check_mpfr_version()'.
+ The âdl_load_func()â macro (*note Extension API Boilerplate::)
+ calls âcheck_mpfr_version()â.
File: gawk.info, Node: Extension API Informational Variables, Prev:
Extension GMP/MPFR Versioning, Up: Extension API Variables
@@ -28154,31 +28152,31 @@ File: gawk.info, Node: Extension API Informational
Variables, Prev: Extension
.................................
The API provides access to several variables that describe whether the
-corresponding command-line options were enabled when 'gawk' was invoked.
+corresponding command-line options were enabled when âgawkâ was invoked.
The variables are:
-'do_debug'
- This variable is true if 'gawk' was invoked with '--debug' option.
+âdo_debugâ
+ This variable is true if âgawkâ was invoked with â--debugâ option.
-'do_lint'
- This variable is true if 'gawk' was invoked with '--lint' option.
+âdo_lintâ
+ This variable is true if âgawkâ was invoked with â--lintâ option.
-'do_mpfr'
- This variable is true if 'gawk' was invoked with '--bignum' option.
+âdo_mpfrâ
+ This variable is true if âgawkâ was invoked with â--bignumâ
option.
-'do_profile'
- This variable is true if 'gawk' was invoked with '--profile'
+âdo_profileâ
+ This variable is true if âgawkâ was invoked with â--profileâ
option.
-'do_sandbox'
- This variable is true if 'gawk' was invoked with '--sandbox'
+âdo_sandboxâ
+ This variable is true if âgawkâ was invoked with â--sandboxâ
option.
-'do_traditional'
- This variable is true if 'gawk' was invoked with '--traditional'
+âdo_traditionalâ
+ This variable is true if âgawkâ was invoked with â--traditionalâ
option.
- The value of 'do_lint' can change if 'awk' code modifies the 'LINT'
+ The value of âdo_lintâ can change if âawkâ code modifies the
âLINTâ
predefined variable (*note Built-in Variables::). The others should not
change during execution.
@@ -28193,7 +28191,7 @@ definitions as presented are really macros. To use
these macros, your
extension must provide a small amount of boilerplate code (variables and
functions) toward the top of your source file, using predefined names as
described here. The boilerplate needed is also provided in comments in
-the 'gawkapi.h' header file:
+the âgawkapi.hâ header file:
/* Boilerplate code: */
int plugin_is_GPL_compatible;
@@ -28225,66 +28223,66 @@ the 'gawkapi.h' header file:
These variables and functions are as follows:
-'int plugin_is_GPL_compatible;'
+âint plugin_is_GPL_compatible;â
This asserts that the extension is compatible with the GNU GPL
- (*note Copying::). If your extension does not have this, 'gawk'
+ (*note Copying::). If your extension does not have this, âgawkâ
will not load it (*note Plugin License::).
-'static gawk_api_t *const api;'
- This global 'static' variable should be set to point to the
- 'gawk_api_t' pointer that 'gawk' passes to your 'dl_load()'
+âstatic gawk_api_t *const api;â
+ This global âstaticâ variable should be set to point to the
+ âgawk_api_tâ pointer that âgawkâ passes to your âdl_load()â
function. This variable is used by all of the macros.
-'static awk_ext_id_t ext_id;'
- This global static variable should be set to the 'awk_ext_id_t'
- value that 'gawk' passes to your 'dl_load()' function. This
+âstatic awk_ext_id_t ext_id;â
+ This global static variable should be set to the âawk_ext_id_tâ
+ value that âgawkâ passes to your âdl_load()â function. This
variable is used by all of the macros.
-'static const char *ext_version = NULL; /* or ... = "some string" */'
- This global 'static' variable should be set either to 'NULL', or to
+âstatic const char *ext_version = NULL; /* or ... = "some string" */â
+ This global âstaticâ variable should be set either to âNULLâ, or
to
point to a string giving the name and version of your extension.
-'static awk_ext_func_t func_table[] = { ... };'
- This is an array of one or more 'awk_ext_func_t' structures, as
+âstatic awk_ext_func_t func_table[] = { ... };â
+ This is an array of one or more âawk_ext_func_tâ structures, as
described earlier (*note Extension Functions::). It can then be
- looped over for multiple calls to 'add_ext_func()'.
+ looped over for multiple calls to âadd_ext_func()â.
-'static awk_bool_t (*init_func)(void) = NULL;'
-' OR'
-'static awk_bool_t init_my_extension(void) { ... }'
-'static awk_bool_t (*init_func)(void) = init_my_extension;'
+âstatic awk_bool_t (*init_func)(void) = NULL;â
+â ORâ
+âstatic awk_bool_t init_my_extension(void) { ... }â
+âstatic awk_bool_t (*init_func)(void) = init_my_extension;â
If you need to do some initialization work, you should define a
function that does it (creates variables, opens files, etc.) and
- then define the 'init_func' pointer to point to your function. The
- function should return 'awk_false' upon failure, or 'awk_true' if
+ then define the âinit_funcâ pointer to point to your function. The
+ function should return âawk_falseâ upon failure, or âawk_trueâ if
everything goes well.
- If you don't need to do any initialization, define the pointer and
- initialize it to 'NULL'.
+ If you donât need to do any initialization, define the pointer and
+ initialize it to âNULLâ.
-'dl_load_func(func_table, some_name, "name_space_in_quotes")'
- This macro expands to a 'dl_load()' function that performs all the
+âdl_load_func(func_table, some_name, "name_space_in_quotes")â
+ This macro expands to a âdl_load()â function that performs all the
necessary initializations.
- The point of all the variables and arrays is to let the 'dl_load()'
-function (from the 'dl_load_func()' macro) do all the standard work. It
+ The point of all the variables and arrays is to let the âdl_load()â
+function (from the âdl_load_func()â macro) do all the standard work. It
does the following:
1. Check the API versions. If the extension major version does not
- match 'gawk''s, or if the extension minor version is greater than
- 'gawk''s, it prints a fatal error message and exits.
+ match âgawkââs, or if the extension minor version is greater than
+ âgawkââs, it prints a fatal error message and exits.
2. Check the MPFR and GMP versions. If there is a mismatch, it prints
a fatal error message and exits.
- 3. Load the functions defined in 'func_table'. If any of them fails
+ 3. Load the functions defined in âfunc_tableâ. If any of them fails
to load, it prints a warning message but continues on.
- 4. If the 'init_func' pointer is not 'NULL', call the function it
- points to. If it returns 'awk_false', print a warning message.
+ 4. If the âinit_funcâ pointer is not âNULLâ, call the function it
+ points to. If it returns âawk_falseâ, print a warning message.
- 5. If 'ext_version' is not 'NULL', register the version string with
- 'gawk'.
+ 5. If âext_versionâ is not âNULLâ, register the version string with
+ âgawkâ.
File: gawk.info, Node: Changes from API V1, Prev: Extension API Boilerplate,
Up: Extension API Description
@@ -28294,49 +28292,49 @@ File: gawk.info, Node: Changes from API V1, Prev:
Extension API Boilerplate,
The current API is _not_ binary compatible with version 1 of the API.
You will have to recompile your extensions in order to use them with the
-current version of 'gawk'.
+current version of âgawkâ.
Fortunately, at the possible expense of some compile-time warnings,
-the API remains source-code-compatible with the previous API. The major
-differences are the additional members in the 'awk_ext_func_t'
+the API remains source-codeâcompatible with the previous API. The major
+differences are the additional members in the âawk_ext_func_tâ
structure, and the addition of the third argument to the C
implementation function (*note Extension Functions::).
Here is a list of individual features that changed from version 1 to
version 2 of the API:
- * Numeric values can now have MPFR/MPZ variants (*note General Data
+ ⢠Numeric values can now have MPFR/MPZ variants (*note General Data
Types::).
- * There are new string types: 'AWK_REGEX' and 'AWK_STRNUM' (*note
+ ⢠There are new string types: âAWK_REGEXâ and âAWK_STRNUMâ (*note
General Data Types::).
- * The 'ezalloc()' macro is new (*note Memory Allocation Functions::).
+ ⢠The âezalloc()â macro is new (*note Memory Allocation Functions::).
- * The 'awk_ext_func_t' structure changed. Instead of
- 'num_expected_args', it now has 'max_expected' and 'min_required'
+ ⢠The âawk_ext_func_tâ structure changed. Instead of
+ ânum_expected_argsâ, it now has âmax_expectedâ and
âmin_requiredâ
(*note Extension Functions::).
- * For 'get_record()', an input parser can now specify field widths
+ ⢠For âget_record()â, an input parser can now specify field widths
(*note Input Parsers::).
- * Extensions can now produce nonfatal error messages (*note Printing
+ ⢠Extensions can now produce nonfatal error messages (*note Printing
Messages::).
- * When flattening an array, you can now specify the index and value
+ ⢠When flattening an array, you can now specify the index and value
types (*note Array Functions::).
- * The 'get_file()' API is new (*note Redirection API::).
+ ⢠The âget_file()â API is new (*note Redirection API::).
File: gawk.info, Node: Finding Extensions, Next: Extension Example, Prev:
Extension API Description, Up: Dynamic Extensions
-17.5 How 'gawk' Finds Extensions
+17.5 How âgawkâ Finds Extensions
================================
-Compiled extensions have to be installed in a directory where 'gawk' can
-find them. If 'gawk' is configured and built in the default fashion,
-the directory in which to find extensions is '/usr/local/lib/gawk'. You
+Compiled extensions have to be installed in a directory where âgawkâ can
+find them. If âgawkâ is configured and built in the default fashion,
+the directory in which to find extensions is â/usr/local/lib/gawkâ. You
can also specify a search path with a list of directories to search for
compiled extensions. *Note AWKLIBPATH Variable:: for more information.
@@ -28347,12 +28345,12 @@ File: gawk.info, Node: Extension Example, Next:
Extension Samples, Prev: Find
=================================
No matter where you go, there you are.
- -- _Buckaroo Banzai_
+ â _Buckaroo Banzai_
- Two useful functions that are not in 'awk' are 'chdir()' (so that an
-'awk' program can change its directory) and 'stat()' (so that an 'awk'
+ Two useful functions that are not in âawkâ are âchdir()â (so that an
+âawkâ program can change its directory) and âstat()â (so that an
âawkâ
program can gather information about a file). In order to illustrate
-the API in action, this minor node implements these functions for 'gawk'
+the API in action, this minor node implements these functions for âgawkâ
in an extension.
* Menu:
@@ -28364,12 +28362,12 @@ in an extension.
File: gawk.info, Node: Internal File Description, Next: Internal File Ops,
Up: Extension Example
-17.6.1 Using 'chdir()' and 'stat()'
+17.6.1 Using âchdir()â and âstat()â
-----------------------------------
-This minor node shows how to use the new functions at the 'awk' level
-once they've been integrated into the running 'gawk' interpreter. Using
-'chdir()' is very straightforward. It takes one argument, the new
+This minor node shows how to use the new functions at the âawkâ level
+once theyâve been integrated into the running âgawkâ interpreter. Using
+âchdir()â is very straightforward. It takes one argument, the new
directory to change to:
@load "filefuncs"
@@ -28382,12 +28380,12 @@ directory to change to:
}
...
- The return value is negative if the 'chdir()' failed, and 'ERRNO'
+ The return value is negative if the âchdir()â failed, and âERRNOâ
(*note Built-in Variables::) is set to a string indicating the error.
- Using 'stat()' is a bit more complicated. The C 'stat()' function
+ Using âstat()â is a bit more complicated. The C âstat()â function
fills in a structure that has a fair amount of information. The right
-way to model this in 'awk' is to fill in an associative array with the
+way to model this in âawkâ is to fill in an associative array with the
appropriate information:
file = "/home/arnold/.profile"
@@ -28399,94 +28397,94 @@ appropriate information:
}
printf("size of %s is %d bytes\n", file, fdata["size"])
- The 'stat()' function always clears the data array, even if the
-'stat()' fails. It fills in the following elements:
+ The âstat()â function always clears the data array, even if the
+âstat()â fails. It fills in the following elements:
-'"name"'
- The name of the file that was 'stat()'ed.
+â"name"â
+ The name of the file that was âstat()âed.
-'"dev"'
-'"ino"'
- The file's device and inode numbers, respectively.
+â"dev"â
+â"ino"â
+ The fileâs device and inode numbers, respectively.
-'"mode"'
- The file's mode, as a numeric value. This includes both the file's
+â"mode"â
+ The fileâs mode, as a numeric value. This includes both the fileâs
type and its permissions.
-'"nlink"'
+â"nlink"â
The number of hard links (directory entries) the file has.
-'"uid"'
-'"gid"'
- The numeric user and group ID numbers of the file's owner.
+â"uid"â
+â"gid"â
+ The numeric user and group ID numbers of the fileâs owner.
-'"size"'
+â"size"â
The size in bytes of the file.
-'"blocks"'
+â"blocks"â
The number of disk blocks the file actually occupies. This may not
- be a function of the file's size if the file has holes.
+ be a function of the fileâs size if the file has holes.
-'"atime"'
-'"mtime"'
-'"ctime"'
- The file's last access, modification, and inode update times,
+â"atime"â
+â"mtime"â
+â"ctime"â
+ The fileâs last access, modification, and inode update times,
respectively. These are numeric timestamps, suitable for
- formatting with 'strftime()' (*note Time Functions::).
+ formatting with âstrftime()â (*note Time Functions::).
-'"pmode"'
- The file's "printable mode." This is a string representation of
- the file's type and permissions, such as is produced by 'ls
- -l'--for example, '"drwxr-xr-x"'.
+â"pmode"â
+ The fileâs âprintable mode.â This is a string representation of the
+ fileâs type and permissions, such as is produced by âls -lââfor
+ example, â"drwxr-xr-x"â.
-'"type"'
- A printable string representation of the file's type. The value is
+â"type"â
+ A printable string representation of the fileâs type. The value is
one of the following:
- '"blockdev"'
- '"chardev"'
- The file is a block or character device ("special file").
+ â"blockdev"â
+ â"chardev"â
+ The file is a block or character device (âspecial fileâ).
- '"directory"'
+ â"directory"â
The file is a directory.
- '"fifo"'
+ â"fifo"â
The file is a named pipe (also known as a FIFO).
- '"file"'
+ â"file"â
The file is just a regular file.
- '"socket"'
- The file is an 'AF_UNIX' ("Unix domain") socket in the
+ â"socket"â
+ The file is an âAF_UNIXâ (âUnix domainâ) socket in the
filesystem.
- '"symlink"'
+ â"symlink"â
The file is a symbolic link.
-'"devbsize"'
- The size of a block for the element indexed by '"blocks"'. This
- information is derived from either the 'DEV_BSIZE' constant defined
- in '<sys/param.h>' on most systems, or the 'S_BLKSIZE' constant in
- '<sys/stat.h>' on BSD systems. For some other systems, "a priori"
+â"devbsize"â
+ The size of a block for the element indexed by â"blocks"â. This
+ information is derived from either the âDEV_BSIZEâ constant defined
+ in â<sys/param.h>â on most systems, or the âS_BLKSIZEâ constant in
+ â<sys/stat.h>â on BSD systems. For some other systems, âa prioriâ
knowledge is used to provide a value. Where no value can be
determined, it defaults to 512.
Several additional elements may be present, depending upon the
operating system and the type of the file. You can test for them in
-your 'awk' program by using the 'in' operator (*note Reference to
+your âawkâ program by using the âinâ operator (*note Reference to
Elements::):
-'"blksize"'
+â"blksize"â
The preferred block size for I/O to the file. This field is not
- present on all POSIX-like systems in the C 'stat' structure.
+ present on all POSIX-like systems in the C âstatâ structure.
-'"linkval"'
+â"linkval"â
If the file is a symbolic link, this element is the name of the
file the link points to (i.e., the value of the link).
-'"rdev"'
-'"major"'
-'"minor"'
+â"rdev"â
+â"major"â
+â"minor"â
If the file is a block or character device file, then these values
represent the numeric device number and the major and minor
components of that number, respectively.
@@ -28494,13 +28492,13 @@ Elements::):
File: gawk.info, Node: Internal File Ops, Next: Using Internal File Ops,
Prev: Internal File Description, Up: Extension Example
-17.6.2 C Code for 'chdir()' and 'stat()'
+17.6.2 C Code for âchdir()â and âstat()â
----------------------------------------
Here is the C code for these extensions.(1)
The file includes a number of standard header files, and then
-includes the 'gawkapi.h' header file, which provides the API
+includes the âgawkapi.hâ header file, which provides the API
definitions. Those are followed by the necessary variable declarations
to make use of the API macros and boilerplate code (*note Extension API
Boilerplate::):
@@ -28536,11 +28534,11 @@ Boilerplate::):
int plugin_is_GPL_compatible;
- By convention, for an 'awk' function 'foo()', the C function that
-implements it is called 'do_foo()'. The function should have two
-arguments. The first is an 'int', usually called 'nargs', that
+ By convention, for an âawkâ function âfoo()â, the C function that
+implements it is called âdo_foo()â. The function should have two
+arguments. The first is an âintâ, usually called ânargsâ, that
represents the number of actual arguments for the function. The second
-is a pointer to an 'awk_value_t' structure, usually named 'result':
+is a pointer to an âawk_value_tâ structure, usually named âresultâ:
/* do_chdir --- provide dynamically loaded chdir() function for gawk */
@@ -28552,13 +28550,13 @@ is a pointer to an 'awk_value_t' structure, usually
named 'result':
assert(result != NULL);
- The 'newdir' variable represents the new directory to change to,
-which is retrieved with 'get_argument()'. Note that the first argument
+ The ânewdirâ variable represents the new directory to change to,
+which is retrieved with âget_argument()â. Note that the first argument
is numbered zero.
If the argument is retrieved successfully, the function calls the
-'chdir()' system call. Otherwise, if the 'chdir()' fails, it updates
-'ERRNO':
+âchdir()â system call. Otherwise, if the âchdir()â fails, it updates
+âERRNOâ:
if (get_argument(0, AWK_STRING, & newdir)) {
ret = chdir(newdir.str_value.str);
@@ -28566,14 +28564,14 @@ is numbered zero.
update_ERRNO_int(errno);
}
- Finally, the function returns the return value to the 'awk' level:
+ Finally, the function returns the return value to the âawkâ level:
return make_number(ret, result);
}
- The 'stat()' extension is more involved. First comes a function that
-turns a numeric mode into a printable representation (e.g., octal '0644'
-becomes '-rw-r--r--'). This is omitted here for brevity:
+ The âstat()â extension is more involved. First comes a function that
+turns a numeric mode into a printable representation (e.g., octal â0644â
+becomes â-rw-r--r--â). This is omitted here for brevity:
/* format_mode --- turn a stat mode field into something readable */
@@ -28596,7 +28594,7 @@ omitted here for brevity:
}
Two helper functions simplify entering values in the array that will
-contain the result of the 'stat()':
+contain the result of the âstat()â:
/* array_set --- set an array element */
@@ -28622,9 +28620,9 @@ contain the result of the 'stat()':
}
The following function does most of the work to fill in the
-'awk_array_t' result array with values obtained from a valid 'struct
-stat'. This work is done in a separate function to support the 'stat()'
-function for 'gawk' and also to support the 'fts()' extension, which is
+âawk_array_tâ result array with values obtained from a valid âstruct
+statâ. This work is done in a separate function to support the âstat()â
+function for âgawkâ and also to support the âfts()â extension, which is
included in the same file but whose code is not shown here (*note
Extension Sample File Functions::).
@@ -28663,7 +28661,7 @@ table to map file types to strings:
int j, k;
The destination array is cleared, and then code fills in various
-elements based on values in the 'struct stat':
+elements based on values in the âstruct statâ:
/* empty out the array */
clear_array(array);
@@ -28731,15 +28729,15 @@ and/or the type of the file. It then returns zero,
for success:
return 0;
}
- The third argument to 'stat()' was not discussed previously. This
-argument is optional. If present, it causes 'do_stat()' to use the
-'stat()' system call instead of the 'lstat()' system call. This is done
-by using a function pointer: 'statfunc'. 'statfunc' is initialized to
-point to 'lstat()' (instead of 'stat()') to get the file information, in
+ The third argument to âstat()â was not discussed previously. This
+argument is optional. If present, it causes âdo_stat()â to use the
+âstat()â system call instead of the âlstat()â system call. This is
done
+by using a function pointer: âstatfuncâ. âstatfuncâ is initialized to
+point to âlstat()â (instead of âstat()â) to get the file information,
in
case the file is a symbolic link. However, if the third argument is
-included, 'statfunc' is set to point to 'stat()', instead.
+included, âstatfuncâ is set to point to âstat()â, instead.
- Here is the 'do_stat()' function, which starts with variable
+ Here is the âdo_stat()â function, which starts with variable
declarations and argument checking:
/* do_stat --- provide a stat() function for gawk */
@@ -28759,7 +28757,7 @@ declarations and argument checking:
Then comes the actual work. First, the function gets the arguments.
Next, it gets the information for the file. If the called function
-('lstat()' or 'stat()') returns an error, the code sets 'ERRNO' and
+(âlstat()â or âstat()â) returns an error, the code sets âERRNOâ and
returns:
/* file is first arg, array to hold results is second */
@@ -28786,18 +28784,18 @@ returns:
return make_number(ret, result);
}
- The tedious work is done by 'fill_stat_array()', shown earlier. When
-done, the function returns the result from 'fill_stat_array()':
+ The tedious work is done by âfill_stat_array()â, shown earlier. When
+done, the function returns the result from âfill_stat_array()â:
ret = fill_stat_array(name, array, & sbuf);
return make_number(ret, result);
}
- Finally, it's necessary to provide the "glue" that loads the new
-function(s) into 'gawk'.
+ Finally, itâs necessary to provide the âglueâ that loads the new
+function(s) into âgawkâ.
- The 'filefuncs' extension also provides an 'fts()' function, which we
+ The âfilefuncsâ extension also provides an âfts()â function, which
we
omit here (*note Extension Sample File Functions::). For its sake,
there is an initialization function:
@@ -28809,8 +28807,8 @@ there is an initialization function:
...
}
- We are almost done. We need an array of 'awk_ext_func_t' structures
-for loading each function into 'gawk':
+ We are almost done. We need an array of âawk_ext_func_tâ structures
+for loading each function into âgawkâ:
static awk_ext_func_t func_table[] = {
{ "chdir", do_chdir, 1, 1, awk_false, NULL },
@@ -28818,20 +28816,20 @@ for loading each function into 'gawk':
...
};
- Each extension must have a routine named 'dl_load()' to load
+ Each extension must have a routine named âdl_load()â to load
everything that needs to be loaded. It is simplest to use the
-'dl_load_func()' macro in 'gawkapi.h':
+âdl_load_func()â macro in âgawkapi.hâ:
/* define the dl_load() function using the boilerplate macro */
dl_load_func(func_table, filefuncs, "")
- And that's it!
+ And thatâs it!
---------- Footnotes ----------
(1) This version is edited slightly for presentation. See
-'extension/filefuncs.c' in the 'gawk' distribution for the complete
+âextension/filefuncs.câ in the âgawkâ distribution for the complete
version.
@@ -28841,15 +28839,15 @@ File: gawk.info, Node: Using Internal File Ops,
Prev: Internal File Ops, Up:
---------------------------------
Now that the code is written, it must be possible to add it at runtime
-to the running 'gawk' interpreter. First, the code must be compiled.
-Assuming that the functions are in a file named 'filefuncs.c', and IDIR
-is the location of the 'gawkapi.h' header file, the following steps(1)
+to the running âgawkâ interpreter. First, the code must be compiled.
+Assuming that the functions are in a file named âfilefuncs.câ, and IDIR
+is the location of the âgawkapi.hâ header file, the following steps(1)
create a GNU/Linux shared library:
$ gcc -fPIC -shared -DHAVE_CONFIG_H -c -O -g -IIDIR filefuncs.c
$ gcc -o filefuncs.so -shared filefuncs.o
- Once the library exists, it is loaded by using the '@load' keyword:
+ Once the library exists, it is loaded by using the â@loadâ keyword:
# file testff.awk
@load "filefuncs"
@@ -28878,71 +28876,71 @@ create a GNU/Linux shared library:
print "JUNK modified:", strftime("%m %d %Y %H:%M:%S", data["mtime"])
}
- The 'AWKLIBPATH' environment variable tells 'gawk' where to find
+ The âAWKLIBPATHâ environment variable tells âgawkâ where to find
extensions (*note Finding Extensions::). We set it to the current
directory and run the program:
$ AWKLIBPATH=$PWD gawk -f testff.awk
- -| /tmp
- -| Info for testff.awk
- -| ret = 0
- -| data["blksize"] = 4096
- -| data["devbsize"] = 512
- -| data["mtime"] = 1412004710
- -| data["mode"] = 33204
- -| data["type"] = file
- -| data["dev"] = 2053
- -| data["gid"] = 1000
- -| data["ino"] = 10358899
- -| data["ctime"] = 1412004710
- -| data["blocks"] = 8
- -| data["nlink"] = 1
- -| data["name"] = testff.awk
- -| data["atime"] = 1412004716
- -| data["pmode"] = -rw-rw-r--
- -| data["size"] = 666
- -| data["uid"] = 1000
- -| testff.awk modified: 09 29 2014 18:31:50
- -|
- -| Info for JUNK
- -| ret = -1
- -| JUNK modified: 01 01 1970 02:00:00
+ ⣠/tmp
+ ⣠Info for testff.awk
+ ⣠ret = 0
+ ⣠data["blksize"] = 4096
+ ⣠data["devbsize"] = 512
+ ⣠data["mtime"] = 1412004710
+ ⣠data["mode"] = 33204
+ ⣠data["type"] = file
+ ⣠data["dev"] = 2053
+ ⣠data["gid"] = 1000
+ ⣠data["ino"] = 10358899
+ ⣠data["ctime"] = 1412004710
+ ⣠data["blocks"] = 8
+ ⣠data["nlink"] = 1
+ ⣠data["name"] = testff.awk
+ ⣠data["atime"] = 1412004716
+ ⣠data["pmode"] = -rw-rw-r--
+ ⣠data["size"] = 666
+ ⣠data["uid"] = 1000
+ ⣠testff.awk modified: 09 29 2014 18:31:50
+ â£
+ ⣠Info for JUNK
+ ⣠ret = -1
+ ⣠JUNK modified: 01 01 1970 02:00:00
---------- Footnotes ----------
(1) In practice, you would probably want to use the GNU Autotools
-(Automake, Autoconf, Libtool, and 'gettext') to configure and build your
+(Automake, Autoconf, Libtool, and âgettextâ) to configure and build your
libraries. Instructions for doing so are beyond the scope of this Info
file. *Note gawkextlib:: for Internet links to the tools.
File: gawk.info, Node: Extension Samples, Next: gawkextlib, Prev: Extension
Example, Up: Dynamic Extensions
-17.7 The Sample Extensions in the 'gawk' Distribution
+17.7 The Sample Extensions in the âgawkâ Distribution
=====================================================
This minor node provides a brief overview of the sample extensions that
-come in the 'gawk' distribution. Some of them are intended for
-production use (e.g., the 'filefuncs', 'readdir', and 'inplace'
+come in the âgawkâ distribution. Some of them are intended for
+production use (e.g., the âfilefuncsâ, âreaddirâ, and âinplaceâ
extensions). Others mainly provide example code that shows how to use
the extension API.
* Menu:
* Extension Sample File Functions:: The file functions sample.
-* Extension Sample Fnmatch:: An interface to 'fnmatch()'.
-* Extension Sample Fork:: An interface to 'fork()' and other
+* Extension Sample Fnmatch:: An interface to âfnmatch()â.
+* Extension Sample Fork:: An interface to âfork()â and other
process functions.
* Extension Sample Inplace:: Enabling in-place file editing.
* Extension Sample Ord:: Character to value to character
conversions.
-* Extension Sample Readdir:: An interface to 'readdir()'.
+* Extension Sample Readdir:: An interface to âreaddir()â.
* Extension Sample Revout:: Reversing output sample output wrapper.
* Extension Sample Rev2way:: Reversing data sample two-way processor.
* Extension Sample Read write array:: Serializing an array to a file.
* Extension Sample Readfile:: Reading an entire file into a string.
-* Extension Sample Time:: An interface to 'gettimeofday()'
- and 'sleep()'.
+* Extension Sample Time:: An interface to âgettimeofday()â
+ and âsleep()â.
* Extension Sample API Tests:: Tests for the API.
@@ -28951,68 +28949,68 @@ File: gawk.info, Node: Extension Sample File
Functions, Next: Extension Sample
17.7.1 File-Related Functions
-----------------------------
-The 'filefuncs' extension provides three different functions, as
+The âfilefuncsâ extension provides three different functions, as
follows. The usage is:
-'@load "filefuncs"'
+â@load "filefuncs"â
This is how you load the extension.
-'result = chdir("/some/directory")'
- The 'chdir()' function is a direct hook to the 'chdir()' system
+âresult = chdir("/some/directory")â
+ The âchdir()â function is a direct hook to the âchdir()â system
call to change the current directory. It returns zero upon success
or a value less than zero upon error. In the latter case, it
- updates 'ERRNO'.
+ updates âERRNOâ.
-'result = stat("/some/path", statdata' [', follow']')'
- The 'stat()' function provides a hook into the 'stat()' system
+âresult = stat("/some/path", statdataâ [â, followâ]â)â
+ The âstat()â function provides a hook into the âstat()â system
call. It returns zero upon success or a value less than zero upon
- error. In the latter case, it updates 'ERRNO'.
+ error. In the latter case, it updates âERRNOâ.
- By default, it uses the 'lstat()' system call. However, if passed
- a third argument, it uses 'stat()' instead.
+ By default, it uses the âlstat()â system call. However, if passed
+ a third argument, it uses âstat()â instead.
- In all cases, it clears the 'statdata' array. When the call is
- successful, 'stat()' fills the 'statdata' array with information
+ In all cases, it clears the âstatdataâ array. When the call is
+ successful, âstat()â fills the âstatdataâ array with information
retrieved from the filesystem, as follows:
- Subscript Field in 'struct stat' File type
+ Subscript Field in âstruct statâ File type
----------------------------------------------------------------
- '"name"' The file name All
- '"dev"' 'st_dev' All
- '"ino"' 'st_ino' All
- '"mode"' 'st_mode' All
- '"nlink"' 'st_nlink' All
- '"uid"' 'st_uid' All
- '"gid"' 'st_gid' All
- '"size"' 'st_size' All
- '"atime"' 'st_atime' All
- '"mtime"' 'st_mtime' All
- '"ctime"' 'st_ctime' All
- '"rdev"' 'st_rdev' Device files
- '"major"' 'st_major' Device files
- '"minor"' 'st_minor' Device files
- '"blksize"' 'st_blksize' All
- '"pmode"' A human-readable version of the All
+ â"name"â The file name All
+ â"dev"â âst_devâ All
+ â"ino"â âst_inoâ All
+ â"mode"â âst_modeâ All
+ â"nlink"â âst_nlinkâ All
+ â"uid"â âst_uidâ All
+ â"gid"â âst_gidâ All
+ â"size"â âst_sizeâ All
+ â"atime"â âst_atimeâ All
+ â"mtime"â âst_mtimeâ All
+ â"ctime"â âst_ctimeâ All
+ â"rdev"â âst_rdevâ Device files
+ â"major"â âst_majorâ Device files
+ â"minor"â âst_minorâ Device files
+ â"blksize"â âst_blksizeâ All
+ â"pmode"â A human-readable version of the All
mode value, like that printed by
- 'ls' (for example, '"-rwxr-xr-x"')
- '"linkval"' The value of the symbolic link Symbolic
+ âlsâ (for example, â"-rwxr-xr-x"â)
+ â"linkval"â The value of the symbolic link Symbolic
links
- '"type"' The type of the file as a All
- string--one of '"file"',
- '"blockdev"', '"chardev"',
- '"directory"', '"socket"',
- '"fifo"', '"symlink"', '"door"',
- or '"unknown"' (not all systems
+ â"type"â The type of the file as a All
+ stringâone of â"file"â,
+ â"blockdev"â, â"chardev"â,
+ â"directory"â, â"socket"â,
+ â"fifo"â, â"symlink"â, â"door"â,
+ or â"unknown"â (not all systems
support all file types)
-'flags = or(FTS_PHYSICAL, ...)'
-'result = fts(pathlist, flags, filedata)'
- Walk the file trees provided in 'pathlist' and fill in the
- 'filedata' array, as described next. 'flags' is the bitwise OR of
+âflags = or(FTS_PHYSICAL, ...)â
+âresult = fts(pathlist, flags, filedata)â
+ Walk the file trees provided in âpathlistâ and fill in the
+ âfiledataâ array, as described next. âflagsâ is the bitwise OR of
several predefined values, also described in a moment. Return zero
- if there were no errors, otherwise return -1.
+ if there were no errors, otherwise return â1.
- The 'fts()' function provides a hook to the C library 'fts()'
+ The âfts()â function provides a hook to the C library âfts()â
routines for traversing file hierarchies. Instead of returning data
about one file at a time in a stream, it fills in a multidimensional
array with data about each file and directory encountered in the
@@ -29020,70 +29018,70 @@ requested hierarchies.
The arguments are as follows:
-'pathlist'
+âpathlistâ
An array of file names. The element values are used; the index
values are ignored.
-'flags'
+âflagsâ
This should be the bitwise OR of one or more of the following
- predefined constant flag values. At least one of 'FTS_LOGICAL' or
- 'FTS_PHYSICAL' must be provided; otherwise 'fts()' returns an error
- value and sets 'ERRNO'. The flags are:
+ predefined constant flag values. At least one of âFTS_LOGICALâ or
+ âFTS_PHYSICALâ must be provided; otherwise âfts()â returns an
error
+ value and sets âERRNOâ. The flags are:
- 'FTS_LOGICAL'
- Do a "logical" file traversal, where the information returned
+ âFTS_LOGICALâ
+ Do a âlogicalâ file traversal, where the information returned
for a symbolic link refers to the linked-to file, and not to
the symbolic link itself. This flag is mutually exclusive
- with 'FTS_PHYSICAL'.
+ with âFTS_PHYSICALâ.
- 'FTS_PHYSICAL'
- Do a "physical" file traversal, where the information returned
+ âFTS_PHYSICALâ
+ Do a âphysicalâ file traversal, where the information returned
for a symbolic link refers to the symbolic link itself. This
- flag is mutually exclusive with 'FTS_LOGICAL'.
+ flag is mutually exclusive with âFTS_LOGICALâ.
- 'FTS_NOCHDIR'
- As a performance optimization, the C library 'fts()' routines
+ âFTS_NOCHDIRâ
+ As a performance optimization, the C library âfts()â routines
change directory as they traverse a file hierarchy. This flag
disables that optimization.
- 'FTS_COMFOLLOW'
- Immediately follow a symbolic link named in 'pathlist',
- whether or not 'FTS_LOGICAL' is set.
+ âFTS_COMFOLLOWâ
+ Immediately follow a symbolic link named in âpathlistâ,
+ whether or not âFTS_LOGICALâ is set.
- 'FTS_SEEDOT'
- By default, the C library 'fts()' routines do not return
- entries for '.' (dot) and '..' (dot-dot). This option causes
+ âFTS_SEEDOTâ
+ By default, the C library âfts()â routines do not return
+ entries for â.â (dot) and â..â (dot-dot). This option causes
entries for dot-dot to also be included. (The extension
always includes an entry for dot; more on this in a moment.)
- 'FTS_XDEV'
+ âFTS_XDEVâ
During a traversal, do not cross onto a different mounted
filesystem.
-'filedata'
- The 'filedata' array holds the results. 'fts()' first clears it.
- Then it creates an element in 'filedata' for every element in
- 'pathlist'. The index is the name of the directory or file given
- in 'pathlist'. The element for this index is itself an array.
+âfiledataâ
+ The âfiledataâ array holds the results. âfts()â first clears it.
+ Then it creates an element in âfiledataâ for every element in
+ âpathlistâ. The index is the name of the directory or file given
+ in âpathlistâ. The element for this index is itself an array.
There are two cases:
_The path is a file_
In this case, the array contains two or three elements:
- '"path"'
- The full path to this file, starting from the "root" that
- was given in the 'pathlist' array.
+ â"path"â
+ The full path to this file, starting from the ârootâ that
+ was given in the âpathlistâ array.
- '"stat"'
+ â"stat"â
This element is itself an array, containing the same
- information as provided by the 'stat()' function
- described earlier for its 'statdata' argument. The
- element may not be present if the 'stat()' system call
+ information as provided by the âstat()â function
+ described earlier for its âstatdataâ argument. The
+ element may not be present if the âstat()â system call
for the file failed.
- '"error"'
+ â"error"â
If some kind of error was encountered, the array will
- also contain an element named '"error"', which is a
+ also contain an element named â"error"â, which is a
string describing the error.
_The path is a directory_
@@ -29091,72 +29089,72 @@ requested hierarchies.
the directory. If an entry is a file, that element is the
same as for files, just described. If the entry is a
directory, that element is (recursively) an array describing
- the subdirectory. If 'FTS_SEEDOT' was provided in the flags,
- then there will also be an element named '".."'. This element
- will be an array containing the data as provided by 'stat()'.
+ the subdirectory. If âFTS_SEEDOTâ was provided in the flags,
+ then there will also be an element named â".."â. This element
+ will be an array containing the data as provided by âstat()â.
- In addition, there will be an element whose index is '"."'.
+ In addition, there will be an element whose index is â"."â.
This element is an array containing the same two or three
- elements as for a file: '"path"', '"stat"', and '"error"'.
+ elements as for a file: â"path"â, â"stat"â, and
â"error"â.
- The 'fts()' function returns zero if there were no errors.
-Otherwise, it returns -1.
+ The âfts()â function returns zero if there were no errors.
+Otherwise, it returns â1.
- NOTE: The 'fts()' extension does not exactly mimic the interface of
- the C library 'fts()' routines, choosing instead to provide an
+ NOTE: The âfts()â extension does not exactly mimic the interface of
+ the C library âfts()â routines, choosing instead to provide an
interface that is based on associative arrays, which is more
- comfortable to use from an 'awk' program. This includes the lack
- of a comparison function, because 'gawk' already provides powerful
- array sorting facilities. Although an 'fts_read()'-like interface
+ comfortable to use from an âawkâ program. This includes the lack
+ of a comparison function, because âgawkâ already provides powerful
+ array sorting facilities. Although an âfts_read()â-like interface
could have been provided, this felt less natural than simply
creating a multidimensional array to represent the file hierarchy
and its information.
- See 'test/fts.awk' in the 'gawk' distribution for an example use of
-the 'fts()' extension function.
+ See âtest/fts.awkâ in the âgawkâ distribution for an example use of
+the âfts()â extension function.
File: gawk.info, Node: Extension Sample Fnmatch, Next: Extension Sample
Fork, Prev: Extension Sample File Functions, Up: Extension Samples
-17.7.2 Interface to 'fnmatch()'
+17.7.2 Interface to âfnmatch()â
-------------------------------
-This extension provides an interface to the C library 'fnmatch()'
+This extension provides an interface to the C library âfnmatch()â
function. The usage is:
-'@load "fnmatch"'
+â@load "fnmatch"â
This is how you load the extension.
-'result = fnmatch(pattern, string, flags)'
- The return value is zero on success, 'FNM_NOMATCH' if the string
+âresult = fnmatch(pattern, string, flags)â
+ The return value is zero on success, âFNM_NOMATCHâ if the string
did not match the pattern, or a different nonzero value if an error
occurred.
- In addition to the 'fnmatch()' function, the 'fnmatch' extension adds
-one constant ('FNM_NOMATCH'), and an array of flag values named 'FNM'.
+ In addition to the âfnmatch()â function, the âfnmatchâ extension
adds
+one constant (âFNM_NOMATCHâ), and an array of flag values named âFNMâ.
- The arguments to 'fnmatch()' are:
+ The arguments to âfnmatch()â are:
-'pattern'
+âpatternâ
The file name wildcard to match
-'string'
+âstringâ
The file name string
-'flag'
+âflagâ
Either zero, or the bitwise OR of one or more of the flags in the
- 'FNM' array
+ âFNMâ array
The flags are as follows:
-Array element Corresponding flag defined by 'fnmatch()'
+Array element Corresponding flag defined by âfnmatch()â
--------------------------------------------------------------------------
-'FNM["CASEFOLD"]' 'FNM_CASEFOLD'
-'FNM["FILE_NAME"]' 'FNM_FILE_NAME'
-'FNM["LEADING_DIR"]''FNM_LEADING_DIR'
-'FNM["NOESCAPE"]' 'FNM_NOESCAPE'
-'FNM["PATHNAME"]' 'FNM_PATHNAME'
-'FNM["PERIOD"]' 'FNM_PERIOD'
+âFNM["CASEFOLD"]â âFNM_CASEFOLDâ
+âFNM["FILE_NAME"]â âFNM_FILE_NAMEâ
+âFNM["LEADING_DIR"]ââFNM_LEADING_DIRâ
+âFNM["NOESCAPE"]â âFNM_NOESCAPEâ
+âFNM["PATHNAME"]â âFNM_PATHNAMEâ
+âFNM["PERIOD"]â âFNM_PERIODâ
Here is an example:
@@ -29169,30 +29167,30 @@ Array element Corresponding flag defined by
'fnmatch()'
File: gawk.info, Node: Extension Sample Fork, Next: Extension Sample
Inplace, Prev: Extension Sample Fnmatch, Up: Extension Samples
-17.7.3 Interface to 'fork()', 'wait()', and 'waitpid()'
+17.7.3 Interface to âfork()â, âwait()â, and âwaitpid()â
-------------------------------------------------------
-The 'fork' extension adds three functions, as follows:
+The âforkâ extension adds three functions, as follows:
-'@load "fork"'
+â@load "fork"â
This is how you load the extension.
-'pid = fork()'
+âpid = fork()â
This function creates a new process. The return value is zero in
the child and the process ID number of the child in the parent, or
- -1 upon error. In the latter case, 'ERRNO' indicates the problem.
- In the child, 'PROCINFO["pid"]' and 'PROCINFO["ppid"]' are updated
+ â1 upon error. In the latter case, âERRNOâ indicates the problem.
+ In the child, âPROCINFO["pid"]â and âPROCINFO["ppid"]â are updated
to reflect the correct values.
-'ret = waitpid(pid)'
+âret = waitpid(pid)â
This function takes a numeric argument, which is the process ID to
- wait for. The return value is that of the 'waitpid()' system call.
+ wait for. The return value is that of the âwaitpid()â system call.
-'ret = wait()'
+âret = wait()â
This function waits for the first child to die. The return value
- is that of the 'wait()' system call.
+ is that of the âwait()â system call.
- There is no corresponding 'exec()' function.
+ There is no corresponding âexec()â function.
Here is an example:
@@ -29209,11 +29207,11 @@ File: gawk.info, Node: Extension Sample Inplace,
Next: Extension Sample Ord,
17.7.4 Enabling In-Place File Editing
-------------------------------------
-The 'inplace' extension emulates GNU 'sed''s '-i' option, which performs
-"in-place" editing of each input file. It uses the bundled
-'inplace.awk' include file to invoke the extension properly. This
+The âinplaceâ extension emulates GNU âsedââs â-iâ option, which
performs
+âin-placeâ editing of each input file. It uses the bundled
+âinplace.awkâ include file to invoke the extension properly. This
extension makes use of the namespace facility to place all the variables
-and functions in the 'inplace' namespace (*note Namespaces::):
+and functions in the âinplaceâ namespace (*note Namespaces::):
# inplace --- load and invoke the inplace extension.
@@ -29260,18 +29258,18 @@ and functions in the 'inplace' namespace (*note
Namespaces::):
standard output to a temporary file configured to have the same owner
and permissions as the original. After the file has been processed, the
extension restores standard output to its original destination. If
-'inplace::suffix' is not an empty string, the original file is linked to
+âinplace::suffixâ is not an empty string, the original file is linked to
a backup file name created by appending that suffix. Finally, the
temporary file is renamed to the original file name.
Note that the use of this feature can be controlled by placing
-'inplace::enable=0' on the command-line prior to listing files that
+âinplace::enable=0â on the command-line prior to listing files that
should not be processed this way. You can reenable inplace editing by
-adding an 'inplace::enable=1' argument prior to files that should be
+adding an âinplace::enable=1â argument prior to files that should be
subject to inplace editing.
- The 'inplace::filename' variable serves to keep track of the current
-file name so as to not invoke 'inplace::end()' before processing the
+ The âinplace::filenameâ variable serves to keep track of the current
+file name so as to not invoke âinplace::end()â before processing the
first file.
If any error occurs, the extension issues a fatal error to terminate
@@ -29296,21 +29294,21 @@ signal is received, a temporary file may be left
behind.
File: gawk.info, Node: Extension Sample Ord, Next: Extension Sample Readdir,
Prev: Extension Sample Inplace, Up: Extension Samples
-17.7.5 Character and Numeric values: 'ord()' and 'chr()'
+17.7.5 Character and Numeric values: âord()â and âchr()â
--------------------------------------------------------
-The 'ordchr' extension adds two functions, named 'ord()' and 'chr()', as
+The âordchrâ extension adds two functions, named âord()â and
âchr()â, as
follows:
-'@load "ordchr"'
+â@load "ordchr"â
This is how you load the extension.
-'number = ord(string)'
- Return the numeric value of the first character in 'string'.
+ânumber = ord(string)â
+ Return the numeric value of the first character in âstringâ.
-'char = chr(number)'
+âchar = chr(number)â
Return a string whose first character is that represented by
- 'number'.
+ ânumberâ.
These functions are inspired by the Pascal language functions of the
same name. Here is an example:
@@ -29326,13 +29324,13 @@ File: gawk.info, Node: Extension Sample Readdir,
Next: Extension Sample Revout
17.7.6 Reading Directories
--------------------------
-The 'readdir' extension adds an input parser for directories. The usage
+The âreaddirâ extension adds an input parser for directories. The usage
is as follows:
@load "readdir"
When this extension is in use, instead of skipping directories named
-on the command line (or with 'getline'), they are read, with each entry
+on the command line (or with âgetlineâ), they are read, with each entry
returned as a record.
The record consists of three fields. The first two are the inode
@@ -29345,28 +29343,28 @@ file types are shown in *note Table 17.4:
table-readdir-file-types.
Letter File type
--------------------------------------------------------------------------
-'b' Block device
-'c' Character device
-'d' Directory
-'f' Regular file
-'l' Symbolic link
-'p' Named pipe (FIFO)
-'s' Socket
-'u' Anything else (unknown)
+âbâ Block device
+âcâ Character device
+âdâ Directory
+âfâ Regular file
+âlâ Symbolic link
+âpâ Named pipe (FIFO)
+âsâ Socket
+âuâ Anything else (unknown)
-Table 17.4: File types returned by the 'readdir' extension
+Table 17.4: File types returned by the âreaddirâ extension
On systems without the file type information, the third field is
-always 'u'.
+always âuâ.
- NOTE: On GNU/Linux systems, there are filesystems that don't
- support the 'd_type' entry (see the readdir(3) manual page), and so
- the file type is always 'u'. You can use the 'filefuncs' extension
- to call 'stat()' in order to get correct type information.
+ NOTE: On GNU/Linux systems, there are filesystems that donât
+ support the âd_typeâ entry (see the readdir(3) manual page), and so
+ the file type is always âuâ. You can use the âfilefuncsâ
extension
+ to call âstat()â in order to get correct type information.
By default, if a directory cannot be opened (due to permission
-problems, for example), 'gawk' will exit. As with regular files, this
-situation can be handled using a 'BEGINFILE' rule that checks 'ERRNO'
+problems, for example), âgawkâ will exit. As with regular files, this
+situation can be handled using a âBEGINFILEâ rule that checks âERRNOâ
and prints an error or otherwise handles the problem.
Here is an example:
@@ -29382,7 +29380,7 @@ File: gawk.info, Node: Extension Sample Revout, Next:
Extension Sample Rev2way
17.7.7 Reversing Output
-----------------------
-The 'revoutput' extension adds a simple output wrapper that reverses the
+The ârevoutputâ extension adds a simple output wrapper that reverses the
characters in each output line. Its main purpose is to show how to
write an output wrapper, although it may be mildly amusing for the
unwary. Here is an example:
@@ -29394,7 +29392,7 @@ unwary. Here is an example:
print "don't panic" > "/dev/stdout"
}
- The output from this program is 'cinap t'nod'.
+ The output from this program is âcinap t'nodâ.
File: gawk.info, Node: Extension Sample Rev2way, Next: Extension Sample Read
write array, Prev: Extension Sample Revout, Up: Extension Samples
@@ -29402,8 +29400,8 @@ File: gawk.info, Node: Extension Sample Rev2way,
Next: Extension Sample Read w
17.7.8 Two-Way I/O Example
--------------------------
-The 'revtwoway' extension adds a simple two-way processor that reverses
-the characters in each line sent to it for reading back by the 'awk'
+The ârevtwowayâ extension adds a simple two-way processor that reverses
+the characters in each line sent to it for reading back by the âawkâ
program. Its main purpose is to show how to write a two-way processor,
although it may also be mildly amusing. The following example shows how
to use it:
@@ -29418,7 +29416,7 @@ to use it:
close(cmd)
}
- The output from this program is: 'cinap t'nod'.
+ The output from this program is: âcinap t'nodâ.
File: gawk.info, Node: Extension Sample Read write array, Next: Extension
Sample Readfile, Prev: Extension Sample Rev2way, Up: Extension Samples
@@ -29426,31 +29424,31 @@ File: gawk.info, Node: Extension Sample Read write
array, Next: Extension Samp
17.7.9 Dumping and Restoring an Array
-------------------------------------
-The 'rwarray' extension adds four functions, named 'writea()',
-'reada()', 'writeall()' and 'readall()', as follows:
+The ârwarrayâ extension adds four functions, named âwritea()â,
+âreada()â, âwriteall()â and âreadall()â, as follows:
-'@load "rwarray"'
+â@load "rwarray"â
This is how you load the extension.
-'ret = writea(file, array)'
+âret = writea(file, array)â
This function takes a string argument, which is the name of the
file to which to dump the array, and the array itself as the second
- argument. 'writea()' understands arrays of arrays. It returns one
+ argument. âwritea()â understands arrays of arrays. It returns one
on success, or zero upon failure.
-'ret = reada(file, array)'
- 'reada()' is the inverse of 'writea()'; it reads the file named as
+âret = reada(file, array)â
+ âreada()â is the inverse of âwritea()â; it reads the file named as
its first argument, filling in the array named as the second
argument. It clears the array first. Here too, the return value
is one on success, or zero upon failure.
-'ret = writeall(file)'
+âret = writeall(file)â
This function takes a string argument, which is the name of the
file to which to dump the state of all variables. Calling this
- function is completely equivalent to calling 'writea(file,
- SYMTAB)'. It returns one on success, or zero upon failure
+ function is completely equivalent to calling âwritea(file,
+ SYMTAB)â. It returns one on success, or zero upon failure
-'ret = readall(file)'
+âret = readall(file)â
This function takes a string argument, which is the name of the
file from which to read the contents of various global variables.
For each variable in the file, the data is loaded unless the
@@ -29458,13 +29456,13 @@ The 'rwarray' extension adds four functions, named
'writea()',
that case, the data for that variable in the file is ignored. It
returns one on success, or zero upon failure.
- The array created by 'reada()' is identical to that written by
-'writea()' in the sense that the contents are the same. However, due to
+ The array created by âreada()â is identical to that written by
+âwritea()â in the sense that the contents are the same. However, due to
implementation issues, the array traversal order of the re-created array
is likely to be different from that of the original array. As array
-traversal order in 'awk' is by default undefined, this is (technically)
+traversal order in âawkâ is by default undefined, this is (technically)
not a problem. If you need to guarantee a particular traversal order,
-use the array sorting features in 'gawk' to do so (*note Array
+use the array sorting features in âgawkâ to do so (*note Array
Sorting::).
The file contains binary data. All integral values are written in
@@ -29473,12 +29471,12 @@ written as native binary data. Thus, arrays
containing only string data
can theoretically be dumped on systems with one byte order and restored
on systems with a different one, but this has not been tried.
- Note that the 'writeall()' and 'readall()' functions provide a
+ Note that the âwriteall()â and âreadall()â functions provide a
mechanism for maintaining persistent state across repeated invocations
of a program. If, for example, a program calculates some statistics
based on the data in a series of files, it could save state using
-'writeall()' after processing N files, and then reload the state using
-'readall()' when the N+1st file arrives to update the results.
+âwriteall()â after processing N files, and then reload the state using
+âreadall()â when the N+1st file arrives to update the results.
Here is an example:
@@ -29498,21 +29496,21 @@ File: gawk.info, Node: Extension Sample Readfile,
Next: Extension Sample Time,
17.7.10 Reading an Entire File
------------------------------
-The 'readfile' extension adds a single function named 'readfile()', and
+The âreadfileâ extension adds a single function named âreadfile()â, and
an input parser:
-'@load "readfile"'
+â@load "readfile"â
This is how you load the extension.
-'result = readfile("/some/path")'
+âresult = readfile("/some/path")â
The argument is the name of the file to read. The return value is
a string containing the entire contents of the requested file.
- Upon error, the function returns the empty string and sets 'ERRNO'.
+ Upon error, the function returns the empty string and sets âERRNOâ.
-'BEGIN { PROCINFO["readfile"] = 1 }'
+âBEGIN { PROCINFO["readfile"] = 1 }â
In addition, the extension adds an input parser that is activated
- if 'PROCINFO["readfile"]' exists. When activated, each input file
- is returned in its entirety as '$0'. 'RT' is set to the null
+ if âPROCINFO["readfile"]â exists. When activated, each input file
+ is returned in its entirety as â$0â. âRTâ is set to the null
string.
Here is an example:
@@ -29531,38 +29529,38 @@ File: gawk.info, Node: Extension Sample Time, Next:
Extension Sample API Tests
17.7.11 Extension Time Functions
--------------------------------
- CAUTION: As 'gawk' version 5.1.0, this extension is considered to
- be obsolete. It is replaced by the 'timex' extension in
- 'gawkextlib' (*note gawkextlib::).
+ CAUTION: As âgawkâ version 5.1.0, this extension is considered to
+ be obsolete. It is replaced by the âtimexâ extension in
+ âgawkextlibâ (*note gawkextlib::).
For version 5.1, no warning will be issued if this extension is
used. For the next major release, a warning will be issued. In
the release after that this extension will be removed from the
distribution.
- The 'time' extension adds two functions, named 'gettimeofday()' and
-'sleep()', as follows:
+ The âtimeâ extension adds two functions, named âgettimeofday()â and
+âsleep()â, as follows:
-'@load "time"'
+â@load "time"â
This is how you load the extension.
-'the_time = gettimeofday()'
+âthe_time = gettimeofday()â
Return the time in seconds that has elapsed since 1970-01-01 UTC as
a floating-point value. If the time is unavailable on this
- platform, return -1 and set 'ERRNO'. The returned time should have
+ platform, return â1 and set âERRNOâ. The returned time should have
sub-second precision, but the actual precision may vary based on
- the platform. If the standard C 'gettimeofday()' system call is
+ the platform. If the standard C âgettimeofday()â system call is
available on this platform, then it simply returns the value.
Otherwise, if on MS-Windows, it tries to use
- 'GetSystemTimeAsFileTime()'.
+ âGetSystemTimeAsFileTime()â.
-'result = sleep(SECONDS)'
+âresult = sleep(SECONDS)â
Attempt to sleep for SECONDS seconds. If SECONDS is negative, or
- the attempt to sleep fails, return -1 and set 'ERRNO'. Otherwise,
+ the attempt to sleep fails, return â1 and set âERRNOâ. Otherwise,
return zero after sleeping for the indicated amount of time. Note
that SECONDS may be a floating-point (nonintegral) value.
Implementation details: depending on platform availability, this
- function tries to use 'nanosleep()' or 'select()' to implement the
+ function tries to use ânanosleep()â or âselect()â to implement the
delay.
@@ -29571,51 +29569,51 @@ File: gawk.info, Node: Extension Sample API Tests,
Prev: Extension Sample Time
17.7.12 API Tests
-----------------
-The 'testext' extension exercises parts of the extension API that are
-not tested by the other samples. The 'extension/testext.c' file
-contains both the C code for the extension and 'awk' test code inside C
-comments that run the tests. The testing framework extracts the 'awk'
+The âtestextâ extension exercises parts of the extension API that are
+not tested by the other samples. The âextension/testext.câ file
+contains both the C code for the extension and âawkâ test code inside C
+comments that run the tests. The testing framework extracts the âawkâ
code and runs the tests. See the source file for more information.
File: gawk.info, Node: gawkextlib, Next: Extension summary, Prev: Extension
Samples, Up: Dynamic Extensions
-17.8 The 'gawkextlib' Project
+17.8 The âgawkextlibâ Project
=============================
-The 'gawkextlib' (https://sourceforge.net/projects/gawkextlib/) project
-provides a number of 'gawk' extensions, including one for processing XML
-files. This is the evolution of the original 'xgawk' (XML 'gawk')
+The âgawkextlibâ (https://sourceforge.net/projects/gawkextlib/) project
+provides a number of âgawkâ extensions, including one for processing XML
+files. This is the evolution of the original âxgawkâ (XML âgawkâ)
project.
There are a number of extensions. Some of the more interesting ones
are:
- * 'abort' extension. It allows you to exit immediately from your
- 'awk' program without running the 'END' rules.
+ ⢠âabortâ extension. It allows you to exit immediately from your
+ âawkâ program without running the âENDâ rules.
- * 'json' extension. This serializes a multidimensional array into a
- JSON string, and can deserialize a JSON string into a 'gawk' array.
+ ⢠âjsonâ extension. This serializes a multidimensional array into a
+ JSON string, and can deserialize a JSON string into a âgawkâ array.
This extension is interesting since it is written in C++ instead of
C.
- * MPFR library extension. This provides access to a number of MPFR
- functions that 'gawk''s native MPFR support does not.
+ ⢠MPFR library extension. This provides access to a number of MPFR
+ functions that âgawkââs native MPFR support does not.
- * Select extension. It provides functionality based on the
- 'select()' system call.
+ ⢠Select extension. It provides functionality based on the
+ âselect()â system call.
- * XML parser extension, using the Expat
+ ⢠XML parser extension, using the Expat
(https://expat.sourceforge.net) XML parsing library
- You can check out the code for the 'gawkextlib' project using the Git
+ You can check out the code for the âgawkextlibâ project using the Git
(https://git-scm.com) distributed source code control system. The
command is as follows:
git clone git://git.code.sf.net/p/gawkextlib/code gawkextlib-code
You will need to have the RapidJson (http://www.rapidjson.org) JSON
-parser library installed in order to build and use the 'json' extension.
+parser library installed in order to build and use the âjsonâ extension.
You will need to have the Expat (https://expat.sourceforge.net) XML
parser library installed in order to build and use the XML extension.
@@ -29623,11 +29621,11 @@ parser library installed in order to build and use
the XML extension.
In addition, you must have the GNU Autotools installed (Autoconf
(https://www.gnu.org/software/autoconf), Automake
(https://www.gnu.org/software/automake), Libtool
-(https://www.gnu.org/software/libtool), and GNU 'gettext'
+(https://www.gnu.org/software/libtool), and GNU âgettextâ
(https://www.gnu.org/software/gettext)).
- The simple recipe for building and testing 'gawkextlib' is as
-follows. First, build and install 'gawk':
+ The simple recipe for building and testing âgawkextlibâ is as
+follows. First, build and install âgawkâ:
cd .../path/to/gawk/code
./configure --prefix=/tmp/newgawk Install in /tmp/newgawk for now
@@ -29635,16 +29633,16 @@ follows. First, build and install 'gawk':
make install Install gawk
Next, go to <https://sourceforge.net/projects/gawkextlib/files> to
-download 'gawkextlib' and any extensions that you would like to build.
-The 'README' file at that site explains how to build the code. If you
-installed 'gawk' in a non-standard location, you will need to specify
-'./configure --with-gawk=/PATH/TO/GAWK' to find it. You may need to use
-the 'sudo' utility to install both 'gawk' and 'gawkextlib', depending
+download âgawkextlibâ and any extensions that you would like to build.
+The âREADMEâ file at that site explains how to build the code. If you
+installed âgawkâ in a non-standard location, you will need to specify
+â./configure --with-gawk=/PATH/TO/GAWKâ to find it. You may need to use
+the âsudoâ utility to install both âgawkâ and âgawkextlibâ,
depending
upon how your system works.
- If you write an extension that you wish to share with other 'gawk'
-users, consider doing so through the 'gawkextlib' project. See the
-project's website for more information.
+ If you write an extension that you wish to share with other âgawkâ
+users, consider doing so through the âgawkextlibâ project. See the
+projectâs website for more information.
File: gawk.info, Node: Extension summary, Next: Extension Exercises, Prev:
gawkextlib, Up: Dynamic Extensions
@@ -29652,86 +29650,86 @@ File: gawk.info, Node: Extension summary, Next:
Extension Exercises, Prev: ga
17.9 Summary
============
- * You can write extensions (sometimes called plug-ins) for 'gawk' in
+ ⢠You can write extensions (sometimes called plug-ins) for âgawkâ in
C or C++ using the application programming interface (API) defined
- by the 'gawk' developers.
+ by the âgawkâ developers.
- * Extensions must have a license compatible with the GNU General
+ ⢠Extensions must have a license compatible with the GNU General
Public License (GPL), and they must assert that fact by declaring a
- variable named 'plugin_is_GPL_compatible'.
+ variable named âplugin_is_GPL_compatibleâ.
- * Communication between 'gawk' and an extension is two-way. 'gawk'
- passes a 'struct' to the extension that contains various data
+ ⢠Communication between âgawkâ and an extension is two-way.
âgawkâ
+ passes a âstructâ to the extension that contains various data
fields and function pointers. The extension can then call into
- 'gawk' via the supplied function pointers to accomplish certain
+ âgawkâ via the supplied function pointers to accomplish certain
tasks.
- * One of these tasks is to "register" the name and implementation of
- new 'awk'-level functions with 'gawk'. The implementation takes
+ ⢠One of these tasks is to âregisterâ the name and implementation of
+ new âawkâ-level functions with âgawkâ. The implementation takes
the form of a C function pointer with a defined signature. By
- convention, implementation functions are named 'do_XXXX()' for some
- 'awk'-level function 'XXXX()'.
+ convention, implementation functions are named âdo_XXXX()â for some
+ âawkâ-level function âXXXX()â.
- * The API is defined in a header file named 'gawkapi.h'. You must
+ ⢠The API is defined in a header file named âgawkapi.hâ. You must
include a number of standard header files _before_ including it in
your source file.
- * API function pointers are provided for the following kinds of
+ ⢠API function pointers are provided for the following kinds of
operations:
- * Allocating, reallocating, and releasing memory
+ ⢠Allocating, reallocating, and releasing memory
- * Registration functions (you may register extension functions,
+ ⢠Registration functions (you may register extension functions,
exit callbacks, a version string, input parsers, output
wrappers, and two-way processors)
- * Printing fatal, nonfatal, warning, and "lint" warning messages
+ ⢠Printing fatal, nonfatal, warning, and âlintâ warning messages
- * Updating 'ERRNO', or unsetting it
+ ⢠Updating âERRNOâ, or unsetting it
- * Accessing parameters, including converting an undefined
+ ⢠Accessing parameters, including converting an undefined
parameter into an array
- * Symbol table access (retrieving a global variable, creating
+ ⢠Symbol table access (retrieving a global variable, creating
one, or changing one)
- * Creating and releasing cached values; this provides an
+ ⢠Creating and releasing cached values; this provides an
efficient way to use values for multiple variables and can be
a big performance win
- * Manipulating arrays (retrieving, adding, deleting, and
+ ⢠Manipulating arrays (retrieving, adding, deleting, and
modifying elements; getting the count of elements in an array;
creating a new array; clearing an array; and flattening an
array for easy C-style looping over all its indices and
elements)
- * The API defines a number of standard data types for representing
- 'awk' values, array elements, and arrays.
+ ⢠The API defines a number of standard data types for representing
+ âawkâ values, array elements, and arrays.
- * The API provides convenience functions for constructing values. It
+ ⢠The API provides convenience functions for constructing values. It
also provides memory management functions to ensure compatibility
- between memory allocated by 'gawk' and memory allocated by an
+ between memory allocated by âgawkâ and memory allocated by an
extension.
- * _All_ memory passed from 'gawk' to an extension must be treated as
+ ⢠_All_ memory passed from âgawkâ to an extension must be treated as
read-only by the extension.
- * _All_ memory passed from an extension to 'gawk' must come from the
- API's memory allocation functions. 'gawk' takes responsibility for
+ ⢠_All_ memory passed from an extension to âgawkâ must come from the
+ APIâs memory allocation functions. âgawkâ takes responsibility for
the memory and releases it when appropriate.
- * The API provides information about the running version of 'gawk' so
- that an extension can make sure it is compatible with the 'gawk'
+ ⢠The API provides information about the running version of âgawkâ so
+ that an extension can make sure it is compatible with the âgawkâ
that loaded it.
- * It is easiest to start a new extension by copying the boilerplate
- code described in this major node. Macros in the 'gawkapi.h'
+ ⢠It is easiest to start a new extension by copying the boilerplate
+ code described in this major node. Macros in the âgawkapi.hâ
header file make this easier to do.
- * The 'gawk' distribution includes a number of small but useful
- sample extensions. The 'gawkextlib' project includes several more
+ ⢠The âgawkâ distribution includes a number of small but useful
+ sample extensions. The âgawkextlibâ project includes several more
(larger) extensions. If you wish to write an extension and
- contribute it to the community of 'gawk' users, the 'gawkextlib'
+ contribute it to the community of âgawkâ users, the âgawkextlibâ
project is the place to do so.
@@ -29740,17 +29738,17 @@ File: gawk.info, Node: Extension Exercises, Prev:
Extension summary, Up: Dyna
17.10 Exercises
===============
- 1. Add functions to implement system calls such as 'chown()',
- 'chmod()', and 'umask()' to the file operations extension presented
+ 1. Add functions to implement system calls such as âchown()â,
+ âchmod()â, and âumask()â to the file operations extension
presented
in *note Internal File Ops::.
2. Write an input parser that prints a prompt if the input is a from a
- "terminal" device. You can use the 'isatty()' function to tell if
+ âterminalâ device. You can use the âisatty()â function to tell if
the input file is a terminal. (Hint: this function is usually
expensive to call; try to call it just once.) The content of the
- prompt should come from a variable settable by 'awk'-level code.
+ prompt should come from a variable settable by âawkâ-level code.
You can write the prompt to standard error. However, for best
- results, open a new file descriptor (or file pointer) on '/dev/tty'
+ results, open a new file descriptor (or file pointer) on â/dev/ttyâ
and print the prompt there, in case standard error has been
redirected.
@@ -29758,24 +29756,24 @@ File: gawk.info, Node: Extension Exercises, Prev:
Extension summary, Up: Dyna
writing the prompt? Which reading mechanism should you replace,
the one to get a record, or the one to read raw bytes?
- 3. Write a wrapper script that provides an interface similar to 'sed
- -i' for the "inplace" extension presented in *note Extension Sample
+ 3. Write a wrapper script that provides an interface similar to âsed
+ -iâ for the âinplaceâ extension presented in *note Extension Sample
Inplace::.
File: gawk.info, Node: Language History, Next: Installation, Prev: Dynamic
Extensions, Up: Top
-Appendix A The Evolution of the 'awk' Language
+Appendix A The Evolution of the âawkâ Language
**********************************************
-This Info file describes the GNU implementation of 'awk', which follows
-the POSIX specification. Many longtime 'awk' users learned 'awk'
-programming with the original 'awk' implementation in Version 7 Unix.
-(This implementation was the basis for 'awk' in Berkeley Unix, through
+This Info file describes the GNU implementation of âawkâ, which follows
+the POSIX specification. Many longtime âawkâ users learned âawkâ
+programming with the original âawkâ implementation in Version 7 Unix.
+(This implementation was the basis for âawkâ in Berkeley Unix, through
4.3-Reno. Subsequent versions of Berkeley Unix, and, for a while, some
-systems derived from 4.4BSD-Lite, used various versions of 'gawk' for
-their 'awk'.) This major node briefly describes the evolution of the
-'awk' language, with cross-references to other parts of the Info file
+systems derived from 4.4BSD-Lite, used various versions of âgawkâ for
+their âawkâ.) This major node briefly describes the evolution of the
+âawkâ language, with cross-references to other parts of the Info file
where you can find more information.
* Menu:
@@ -29785,14 +29783,14 @@ where you can find more information.
* SVR4:: Minor changes between System V Releases 3.1
and 4.
* POSIX:: New features from the POSIX standard.
-* BTL:: New features from Brian Kernighan's version of
- 'awk'.
-* POSIX/GNU:: The extensions in 'gawk' not in POSIX
- 'awk'.
-* Feature History:: The history of the features in 'gawk'.
+* BTL:: New features from Brian Kernighanâs version
of
+ âawkâ.
+* POSIX/GNU:: The extensions in âgawkâ not in POSIX
+ âawkâ.
+* Feature History:: The history of the features in âgawkâ.
* Common Extensions:: Common Extensions Summary.
* Ranges and Locales:: How locales used to affect regexp ranges.
-* Contributors:: The major contributors to 'gawk'.
+* Contributors:: The major contributors to âgawkâ.
* History summary:: History summary.
@@ -29801,62 +29799,62 @@ File: gawk.info, Node: V7/SVR3.1, Next: SVR4, Up:
Language History
A.1 Major Changes Between V7 and SVR3.1
=======================================
-The 'awk' language evolved considerably between the release of Version 7
+The âawkâ language evolved considerably between the release of Version 7
Unix (1978) and the new version that was first made generally available
in System V Release 3.1 (1987). This minor node summarizes the changes,
with cross-references to further details:
- * The requirement for ';' to separate rules on a line (*note
+ ⢠The requirement for â;â to separate rules on a line (*note
Statements/Lines::)
- * User-defined functions and the 'return' statement (*note
+ ⢠User-defined functions and the âreturnâ statement (*note
User-defined::)
- * The 'delete' statement (*note Delete::)
+ ⢠The âdeleteâ statement (*note Delete::)
- * The 'do'-'while' statement (*note Do Statement::)
+ ⢠The âdoâ-âwhileâ statement (*note Do Statement::)
- * The built-in functions 'atan2()', 'cos()', 'sin()', 'rand()', and
- 'srand()' (*note Numeric Functions::)
+ ⢠The built-in functions âatan2()â, âcos()â, âsin()â,
ârand()â, and
+ âsrand()â (*note Numeric Functions::)
- * The built-in functions 'gsub()', 'sub()', and 'match()' (*note
+ ⢠The built-in functions âgsub()â, âsub()â, and âmatch()â
(*note
String Functions::)
- * The built-in functions 'close()' and 'system()' (*note I/O
+ ⢠The built-in functions âclose()â and âsystem()â (*note I/O
Functions::)
- * The 'ARGC', 'ARGV', 'FNR', 'RLENGTH', 'RSTART', and 'SUBSEP'
+ ⢠The âARGCâ, âARGVâ, âFNRâ, âRLENGTHâ, âRSTARTâ, and
âSUBSEPâ
predefined variables (*note Built-in Variables::)
- * Assignable '$0' (*note Changing Fields::)
+ ⢠Assignable â$0â (*note Changing Fields::)
- * The conditional expression using the ternary operator '?:' (*note
+ ⢠The conditional expression using the ternary operator â?:â (*note
Conditional Exp::)
- * The expression 'INDX in ARRAY' outside of 'for' statements (*note
+ ⢠The expression âINDX in ARRAYâ outside of âforâ statements
(*note
Reference to Elements::)
- * The exponentiation operator '^' (*note Arithmetic Ops::) and its
- assignment operator form '^=' (*note Assignment Ops::)
+ ⢠The exponentiation operator â^â (*note Arithmetic Ops::) and its
+ assignment operator form â^=â (*note Assignment Ops::)
- * C-compatible operator precedence, which breaks some old 'awk'
+ ⢠C-compatible operator precedence, which breaks some old âawkâ
programs (*note Precedence::)
- * Regexps as the value of 'FS' (*note Field Separators::) and as the
- third argument to the 'split()' function (*note String
- Functions::), rather than using only the first character of 'FS'
+ ⢠Regexps as the value of âFSâ (*note Field Separators::) and as the
+ third argument to the âsplit()â function (*note String
+ Functions::), rather than using only the first character of âFSâ
- * Dynamic regexps as operands of the '~' and '!~' operators (*note
+ ⢠Dynamic regexps as operands of the â~â and â!~â operators (*note
Computed Regexps::)
- * The escape sequences '\b', '\f', and '\r' (*note Escape
+ ⢠The escape sequences â\bâ, â\fâ, and â\râ (*note Escape
Sequences::)
- * Redirection of input for the 'getline' function (*note Getline::)
+ ⢠Redirection of input for the âgetlineâ function (*note Getline::)
- * Multiple 'BEGIN' and 'END' rules (*note BEGIN/END::)
+ ⢠Multiple âBEGINâ and âENDâ rules (*note BEGIN/END::)
- * Multidimensional arrays (*note Multidimensional::)
+ ⢠Multidimensional arrays (*note Multidimensional::)
File: gawk.info, Node: SVR4, Next: POSIX, Prev: V7/SVR3.1, Up: Language
History
@@ -29864,74 +29862,74 @@ File: gawk.info, Node: SVR4, Next: POSIX, Prev:
V7/SVR3.1, Up: Language Hist
A.2 Changes Between SVR3.1 and SVR4
===================================
-The System V Release 4 (1989) version of Unix 'awk' added these features
-(some of which originated in 'gawk'):
+The System V Release 4 (1989) version of Unix âawkâ added these features
+(some of which originated in âgawkâ):
- * The 'ENVIRON' array (*note Built-in Variables::)
+ ⢠The âENVIRONâ array (*note Built-in Variables::)
- * Multiple '-f' options on the command line (*note Options::)
+ ⢠Multiple â-fâ options on the command line (*note Options::)
- * The '-v' option for assigning variables before program execution
+ ⢠The â-vâ option for assigning variables before program execution
begins (*note Options::)
- * The '--' signal for terminating command-line options
+ ⢠The â--â signal for terminating command-line options
- * The '\a', '\v', and '\x' escape sequences (*note Escape
+ ⢠The â\aâ, â\vâ, and â\xâ escape sequences (*note Escape
Sequences::)
- * A defined return value for the 'srand()' built-in function (*note
+ ⢠A defined return value for the âsrand()â built-in function (*note
Numeric Functions::)
- * The 'toupper()' and 'tolower()' built-in string functions for case
+ ⢠The âtoupper()â and âtolower()â built-in string functions for
case
translation (*note String Functions::)
- * A cleaner specification for the '%c' format-control letter in the
- 'printf' function (*note Control Letters::)
+ ⢠A cleaner specification for the â%câ format-control letter in the
+ âprintfâ function (*note Control Letters::)
- * The ability to dynamically pass the field width and precision
- ('"%*.*d"') in the argument list of 'printf' and 'sprintf()' (*note
+ ⢠The ability to dynamically pass the field width and precision
+ (â"%*.*d"â) in the argument list of âprintfâ and âsprintf()â
(*note
Control Letters::)
- * The use of regexp constants, such as '/foo/', as expressions, where
- they are equivalent to using the matching operator, as in '$0 ~
- /foo/' (*note Using Constant Regexps::)
+ ⢠The use of regexp constants, such as â/foo/â, as expressions, where
+ they are equivalent to using the matching operator, as in â$0 ~
+ /foo/â (*note Using Constant Regexps::)
- * Processing of escape sequences inside command-line variable
+ ⢠Processing of escape sequences inside command-line variable
assignments (*note Assignment Options::)
File: gawk.info, Node: POSIX, Next: BTL, Prev: SVR4, Up: Language History
-A.3 Changes Between SVR4 and POSIX 'awk'
+A.3 Changes Between SVR4 and POSIX âawkâ
========================================
-The POSIX Command Language and Utilities standard for 'awk' (1992)
+The POSIX Command Language and Utilities standard for âawkâ (1992)
introduced the following changes into the language:
- * The use of '-W' for implementation-specific options (*note
+ ⢠The use of â-Wâ for implementation-specific options (*note
Options::)
- * The use of 'CONVFMT' for controlling the conversion of numbers to
+ ⢠The use of âCONVFMTâ for controlling the conversion of numbers to
strings (*note Conversion::)
- * The concept of a numeric string and tighter comparison rules to go
+ ⢠The concept of a numeric string and tighter comparison rules to go
with it (*note Typing and Comparison::)
- * The use of predefined variables as function parameter names is
+ ⢠The use of predefined variables as function parameter names is
forbidden (*note Definition Syntax::)
- * More complete documentation of many of the previously undocumented
+ ⢠More complete documentation of many of the previously undocumented
features of the language
In 2012, a number of extensions that had been commonly available for
many years were finally added to POSIX. They are:
- * The 'fflush()' built-in function for flushing buffered output
+ ⢠The âfflush()â built-in function for flushing buffered output
(*note I/O Functions::)
- * The 'nextfile' statement (*note Nextfile Statement::)
+ ⢠The ânextfileâ statement (*note Nextfile Statement::)
- * The ability to delete all of an array at once with 'delete ARRAY'
+ ⢠The ability to delete all of an array at once with âdelete ARRAYâ
(*note Delete::)
*Note Common Extensions:: for a list of common extensions not
@@ -29943,712 +29941,712 @@ permitted by the POSIX standard.
File: gawk.info, Node: BTL, Next: POSIX/GNU, Prev: POSIX, Up: Language
History
-A.4 Extensions in Brian Kernighan's 'awk'
+A.4 Extensions in Brian Kernighanâs âawkâ
=========================================
Brian Kernighan has made his version available via his home page (*note
Other Versions::).
This minor node describes common extensions that originally appeared
-in his version of 'awk':
+in his version of âawkâ:
- * The '**' and '**=' operators (*note Arithmetic Ops:: and *note
+ ⢠The â**â and â**=â operators (*note Arithmetic Ops:: and *note
Assignment Ops::)
- * The use of 'func' as an abbreviation for 'function' (*note
+ ⢠The use of âfuncâ as an abbreviation for âfunctionâ (*note
Definition Syntax::)
- * The 'fflush()' built-in function for flushing buffered output
+ ⢠The âfflush()â built-in function for flushing buffered output
(*note I/O Functions::)
*Note Common Extensions:: for a full list of the extensions available
-in his 'awk'.
+in his âawkâ.
File: gawk.info, Node: POSIX/GNU, Next: Feature History, Prev: BTL, Up:
Language History
-A.5 Extensions in 'gawk' Not in POSIX 'awk'
+A.5 Extensions in âgawkâ Not in POSIX âawkâ
===========================================
-The GNU implementation, 'gawk', adds a large number of features. They
-can all be disabled with either the '--traditional' or '--posix' options
+The GNU implementation, âgawkâ, adds a large number of features. They
+can all be disabled with either the â--traditionalâ or â--posixâ
options
(*note Options::).
A number of features have come and gone over the years. This minor
-node summarizes the additional features over POSIX 'awk' that are in the
-current version of 'gawk'.
+node summarizes the additional features over POSIX âawkâ that are in the
+current version of âgawkâ.
- * Additional predefined variables:
+ ⢠Additional predefined variables:
- - The 'ARGIND', 'BINMODE', 'ERRNO', 'FIELDWIDTHS', 'FPAT',
- 'IGNORECASE', 'LINT', 'PROCINFO', 'RT', and 'TEXTDOMAIN'
+ â The âARGINDâ, âBINMODEâ, âERRNOâ, âFIELDWIDTHSâ,
âFPATâ,
+ âIGNORECASEâ, âLINTâ, âPROCINFOâ, âRTâ, and
âTEXTDOMAINâ
variables (*note Built-in Variables::)
- * Special files in I/O redirections:
+ ⢠Special files in I/O redirections:
- - The '/dev/stdin', '/dev/stdout', '/dev/stderr', and
- '/dev/fd/N' special file names (*note Special Files::)
+ â The â/dev/stdinâ, â/dev/stdoutâ, â/dev/stderrâ, and
+ â/dev/fd/Nâ special file names (*note Special Files::)
- - The '/inet', '/inet4', and '/inet6' special files for TCP/IP
- networking using '|&' to specify which version of the IP
+ â The â/inetâ, â/inet4â, and â/inet6â special files for
TCP/IP
+ networking using â|&â to specify which version of the IP
protocol to use (*note TCP/IP Networking::)
- * Changes and/or additions to the language:
+ ⢠Changes and/or additions to the language:
- - The '\x' escape sequence (*note Escape Sequences::)
+ â The â\xâ escape sequence (*note Escape Sequences::)
- - Full support for both POSIX and GNU regexps (*note Regexp::)
+ â Full support for both POSIX and GNU regexps (*note Regexp::)
- - The ability for 'FS' and for the third argument to 'split()'
+ â The ability for âFSâ and for the third argument to
âsplit()â
to be null strings (*note Single Character Fields::)
- - The ability for 'RS' to be a regexp (*note Records::)
+ â The ability for âRSâ to be a regexp (*note Records::)
- - The ability to use octal and hexadecimal constants in 'awk'
+ â The ability to use octal and hexadecimal constants in âawkâ
program source code (*note Nondecimal-numbers::)
- - The '|&' operator for two-way I/O to a coprocess (*note
+ â The â|&â operator for two-way I/O to a coprocess (*note
Two-way I/O::)
- - Indirect function calls (*note Indirect Calls::)
+ â Indirect function calls (*note Indirect Calls::)
- - Directories on the command line produce a warning and are
+ â Directories on the command line produce a warning and are
skipped (*note Command-line directories::)
- - Output with 'print' and 'printf' need not be fatal (*note
+ â Output with âprintâ and âprintfâ need not be fatal (*note
Nonfatal::)
- * New keywords:
+ ⢠New keywords:
- - The 'BEGINFILE' and 'ENDFILE' special patterns (*note
+ â The âBEGINFILEâ and âENDFILEâ special patterns (*note
BEGINFILE/ENDFILE::)
- - The 'switch' statement (*note Switch Statement::)
+ â The âswitchâ statement (*note Switch Statement::)
- * Changes to standard 'awk' functions:
+ ⢠Changes to standard âawkâ functions:
- - The optional second argument to 'close()' that allows closing
+ â The optional second argument to âclose()â that allows closing
one end of a two-way pipe to a coprocess (*note Two-way I/O::)
- - POSIX compliance for 'gsub()' and 'sub()' with '--posix'
+ â POSIX compliance for âgsub()â and âsub()â with
â--posixâ
- - The 'length()' function accepts an array argument and returns
+ â The âlength()â function accepts an array argument and returns
the number of elements in the array (*note String Functions::)
- - The optional third argument to the 'match()' function for
+ â The optional third argument to the âmatch()â function for
capturing text-matching subexpressions within a regexp (*note
String Functions::)
- - Positional specifiers in 'printf' formats for making
+ â Positional specifiers in âprintfâ formats for making
translations easier (*note Printf Ordering::)
- - The 'split()' function's additional optional fourth argument,
+ â The âsplit()â functionâs additional optional fourth argument,
which is an array to hold the text of the field separators
(*note String Functions::)
- * Additional functions only in 'gawk':
+ ⢠Additional functions only in âgawkâ:
- - The 'gensub()', 'patsplit()', and 'strtonum()' functions for
+ â The âgensub()â, âpatsplit()â, and âstrtonum()â
functions for
more powerful text manipulation (*note String Functions::)
- - The 'asort()' and 'asorti()' functions for sorting arrays
+ â The âasort()â and âasorti()â functions for sorting arrays
(*note Array Sorting::)
- - The 'mktime()', 'systime()', and 'strftime()' functions for
+ â The âmktime()â, âsystime()â, and âstrftime()â
functions for
working with timestamps (*note Time Functions::)
- - The 'and()', 'compl()', 'lshift()', 'or()', 'rshift()', and
- 'xor()' functions for bit manipulation (*note Bitwise
+ â The âand()â, âcompl()â, âlshift()â, âor()â,
ârshift()â, and
+ âxor()â functions for bit manipulation (*note Bitwise
Functions::)
- - The 'isarray()' function to check if a variable is an array or
+ â The âisarray()â function to check if a variable is an array or
not (*note Type Functions::)
- - The 'bindtextdomain()', 'dcgettext()', and 'dcngettext()'
+ â The âbindtextdomain()â, âdcgettext()â, and
âdcngettext()â
functions for internationalization (*note Programmer i18n::)
- * Changes and/or additions in the command-line options:
+ ⢠Changes and/or additions in the command-line options:
- - The 'AWKPATH' environment variable for specifying a path
- search for the '-f' command-line option (*note Options::)
+ â The âAWKPATHâ environment variable for specifying a path
+ search for the â-fâ command-line option (*note Options::)
- - The 'AWKLIBPATH' environment variable for specifying a path
- search for the '-l' command-line option (*note Options::)
+ â The âAWKLIBPATHâ environment variable for specifying a path
+ search for the â-lâ command-line option (*note Options::)
- - The '-b', '-c', '-C', '-d', '-D', '-e', '-E', '-g', '-h',
- '-i', '-l', '-L', '-M', '-n', '-N', '-o', '-O', '-p', '-P',
- '-r', '-s', '-S', '-t', and '-V' short options. Also, the
+ â The â-bâ, â-câ, â-Câ, â-dâ, â-Dâ, â-eâ,
â-Eâ, â-gâ, â-hâ,
+ â-iâ, â-lâ, â-Lâ, â-Mâ, â-nâ, â-Nâ,
â-oâ, â-Oâ, â-pâ, â-Pâ,
+ â-râ, â-sâ, â-Sâ, â-tâ, and â-Vâ short options.
Also, the
ability to use GNU-style long-named options that start with
- '--', and the '--assign', '--bignum', '--characters-as-bytes',
- '--copyright', '--debug', '--dump-variables', '--exec',
- '--field-separator', '--file', '--gen-pot', '--help',
- '--include', '--lint', '--lint-old', '--load',
- '--non-decimal-data', '--optimize', '--no-optimize',
- '--posix', '--pretty-print', '--profile', '--re-interval',
- '--sandbox', '--source', '--traditional', '--use-lc-numeric',
- and '--version' long options (*note Options::).
+ â--â, and the â--assignâ, â--bignumâ,
â--characters-as-bytesâ,
+ â--copyrightâ, â--debugâ, â--dump-variablesâ,
â--execâ,
+ â--field-separatorâ, â--fileâ, â--gen-potâ, â--helpâ,
+ â--includeâ, â--lintâ, â--lint-oldâ, â--loadâ,
+ â--non-decimal-dataâ, â--optimizeâ, â--no-optimizeâ,
+ â--posixâ, â--pretty-printâ, â--profileâ,
â--re-intervalâ,
+ â--sandboxâ, â--sourceâ, â--traditionalâ,
â--use-lc-numericâ,
+ and â--versionâ long options (*note Options::).
- * Support for the following obsolete systems was removed from the
- code and the documentation for 'gawk' version 4.0:
+ ⢠Support for the following obsolete systems was removed from the
+ code and the documentation for âgawkâ version 4.0:
- - Amiga
+ â Amiga
- - Atari
+ â Atari
- - BeOS
+ â BeOS
- - Cray
+ â Cray
- - MIPS RiscOS
+ â MIPS RiscOS
- - MS-DOS with the Microsoft Compiler
+ â MS-DOS with the Microsoft Compiler
- - MS-Windows with the Microsoft Compiler
+ â MS-Windows with the Microsoft Compiler
- - NeXT
+ â NeXT
- - SunOS 3.x, Sun 386 (Road Runner)
+ â SunOS 3.x, Sun 386 (Road Runner)
- - Tandem (non-POSIX)
+ â Tandem (non-POSIX)
- - Prestandard VAX C compiler for VAX/VMS
+ â Prestandard VAX C compiler for VAX/VMS
- - GCC for Alpha has not been tested for a while.
+ â GCC for Alpha has not been tested for a while.
- * Support for the following obsolete system was removed from the code
- for 'gawk' version 4.1:
+ ⢠Support for the following obsolete system was removed from the code
+ for âgawkâ version 4.1:
- - Ultrix
+ â Ultrix
- * Support for the following systems was removed from the code for
- 'gawk' version 4.2:
+ ⢠Support for the following systems was removed from the code for
+ âgawkâ version 4.2:
- - MirBSD
+ â MirBSD
- - GNU/Linux on Alpha
+ â GNU/Linux on Alpha
- * Support for the following systems was removed from the code for
- 'gawk' version 5.2:
+ ⢠Support for the following systems was removed from the code for
+ âgawkâ version 5.2:
- - OS/2
+ â OS/2
- - DJGPP
+ â DJGPP
- - VAX/VMS
+ â VAX/VMS
File: gawk.info, Node: Feature History, Next: Common Extensions, Prev:
POSIX/GNU, Up: Language History
-A.6 History of 'gawk' Features
+A.6 History of âgawkâ Features
==============================
-This minor node describes the features in 'gawk' over and above those in
-POSIX 'awk', in the order they were added to 'gawk'.
+This minor node describes the features in âgawkâ over and above those in
+POSIX âawkâ, in the order they were added to âgawkâ.
- Version 2.10 of 'gawk' introduced the following features:
+ Version 2.10 of âgawkâ introduced the following features:
- * The 'AWKPATH' environment variable for specifying a path search for
- the '-f' command-line option (*note Options::).
+ ⢠The âAWKPATHâ environment variable for specifying a path search for
+ the â-fâ command-line option (*note Options::).
- * The 'IGNORECASE' variable and its effects (*note
+ ⢠The âIGNORECASEâ variable and its effects (*note
Case-sensitivity::).
- * The '/dev/stdin', '/dev/stdout', '/dev/stderr' and '/dev/fd/N'
+ ⢠The â/dev/stdinâ, â/dev/stdoutâ, â/dev/stderrâ and
â/dev/fd/Nâ
special file names (*note Special Files::).
- Version 2.13 of 'gawk' introduced the following features:
+ Version 2.13 of âgawkâ introduced the following features:
- * The 'FIELDWIDTHS' variable and its effects (*note Constant Size::).
+ ⢠The âFIELDWIDTHSâ variable and its effects (*note Constant Size::).
- * The 'systime()' and 'strftime()' built-in functions for obtaining
+ ⢠The âsystime()â and âstrftime()â built-in functions for
obtaining
and printing timestamps (*note Time Functions::).
- * Additional command-line options (*note Options::):
+ ⢠Additional command-line options (*note Options::):
- - The '-W lint' option to provide error and portability checking
+ â The â-W lintâ option to provide error and portability checking
for both the source code and at runtime.
- - The '-W compat' option to turn off the GNU extensions.
+ â The â-W compatâ option to turn off the GNU extensions.
- - The '-W posix' option for full POSIX compliance.
+ â The â-W posixâ option for full POSIX compliance.
- Version 2.14 of 'gawk' introduced the following feature:
+ Version 2.14 of âgawkâ introduced the following feature:
- * The 'next file' statement for skipping to the next data file (*note
+ ⢠The ânext fileâ statement for skipping to the next data file (*note
Nextfile Statement::).
- Version 2.15 of 'gawk' introduced the following features:
+ Version 2.15 of âgawkâ introduced the following features:
- * New variables (*note Built-in Variables::):
+ ⢠New variables (*note Built-in Variables::):
- - 'ARGIND', which tracks the movement of 'FILENAME' through
- 'ARGV'.
+ â âARGINDâ, which tracks the movement of âFILENAMEâ through
+ âARGVâ.
- - 'ERRNO', which contains the system error message when
- 'getline' returns -1 or 'close()' fails.
+ â âERRNOâ, which contains the system error message when
+ âgetlineâ returns â1 or âclose()â fails.
- * The '/dev/pid', '/dev/ppid', '/dev/pgrpid', and '/dev/user' special
+ ⢠The â/dev/pidâ, â/dev/ppidâ, â/dev/pgrpidâ, and
â/dev/userâ special
file names. These have since been removed.
- * The ability to delete all of an array at once with 'delete ARRAY'
+ ⢠The ability to delete all of an array at once with âdelete ARRAYâ
(*note Delete::).
- * Command-line option changes (*note Options::):
+ ⢠Command-line option changes (*note Options::):
- - The ability to use GNU-style long-named options that start
- with '--'.
+ â The ability to use GNU-style long-named options that start
+ with â--â.
- - The '--source' option for mixing command-line and library-file
+ â The â--sourceâ option for mixing command-line and library-file
source code.
- Version 3.0 of 'gawk' introduced the following features:
+ Version 3.0 of âgawkâ introduced the following features:
- * New or changed variables:
+ ⢠New or changed variables:
- - 'IGNORECASE' changed, now applying to string comparison as
+ â âIGNORECASEâ changed, now applying to string comparison as
well as regexp operations (*note Case-sensitivity::).
- - 'RT', which contains the input text that matched 'RS' (*note
+ â âRTâ, which contains the input text that matched âRSâ
(*note
Records::).
- * Full support for both POSIX and GNU regexps (*note Regexp::).
+ ⢠Full support for both POSIX and GNU regexps (*note Regexp::).
- * The 'gensub()' function for more powerful text manipulation (*note
+ ⢠The âgensub()â function for more powerful text manipulation (*note
String Functions::).
- * The 'strftime()' function acquired a default time format, allowing
+ ⢠The âstrftime()â function acquired a default time format, allowing
it to be called with no arguments (*note Time Functions::).
- * The ability for 'FS' and for the third argument to 'split()' to be
+ ⢠The ability for âFSâ and for the third argument to âsplit()â to
be
null strings (*note Single Character Fields::).
- * The ability for 'RS' to be a regexp (*note Records::).
+ ⢠The ability for âRSâ to be a regexp (*note Records::).
- * The 'next file' statement became 'nextfile' (*note Nextfile
+ ⢠The ânext fileâ statement became ânextfileâ (*note Nextfile
Statement::).
- * The 'fflush()' function from BWK 'awk' (then at Bell Laboratories;
+ ⢠The âfflush()â function from BWK âawkâ (then at Bell
Laboratories;
*note I/O Functions::).
- * New command-line options:
+ ⢠New command-line options:
- - The '--lint-old' option to warn about constructs that are not
- available in the original Version 7 Unix version of 'awk'
+ â The â--lint-oldâ option to warn about constructs that are not
+ available in the original Version 7 Unix version of âawkâ
(*note V7/SVR3.1::).
- - The '-m' option from BWK 'awk'. (Brian was still at Bell
+ â The â-mâ option from BWK âawkâ. (Brian was still at Bell
Laboratories at the time.) This was later removed from both
- his 'awk' and from 'gawk'.
+ his âawkâ and from âgawkâ.
- - The '--re-interval' option to provide interval expressions in
+ â The â--re-intervalâ option to provide interval expressions in
regexps (*note Regexp Operators::).
- - The '--traditional' option was added as a better name for
- '--compat' (*note Options::).
+ â The â--traditionalâ option was added as a better name for
+ â--compatâ (*note Options::).
- * The use of GNU Autoconf to control the configuration process (*note
+ ⢠The use of GNU Autoconf to control the configuration process (*note
Quick Installation::).
- * Amiga support. This has since been removed.
+ ⢠Amiga support. This has since been removed.
- Version 3.1 of 'gawk' introduced the following features:
+ Version 3.1 of âgawkâ introduced the following features:
- * New variables (*note Built-in Variables::):
+ ⢠New variables (*note Built-in Variables::):
- - 'BINMODE', for non-POSIX systems, which allows binary I/O for
+ â âBINMODEâ, for non-POSIX systems, which allows binary I/O for
input and/or output files (*note PC Using::).
- - 'LINT', which dynamically controls lint warnings.
+ â âLINTâ, which dynamically controls lint warnings.
- - 'PROCINFO', an array for providing process-related
+ â âPROCINFOâ, an array for providing process-related
information.
- - 'TEXTDOMAIN', for setting an application's
+ â âTEXTDOMAINâ, for setting an applicationâs
internationalization text domain (*note
Internationalization::).
- * The ability to use octal and hexadecimal constants in 'awk' program
+ ⢠The ability to use octal and hexadecimal constants in âawkâ program
source code (*note Nondecimal-numbers::).
- * The '|&' operator for two-way I/O to a coprocess (*note Two-way
+ ⢠The â|&â operator for two-way I/O to a coprocess (*note Two-way
I/O::).
- * The '/inet' special files for TCP/IP networking using '|&' (*note
+ ⢠The â/inetâ special files for TCP/IP networking using â|&â
(*note
TCP/IP Networking::).
- * The optional second argument to 'close()' that allows closing one
+ ⢠The optional second argument to âclose()â that allows closing one
end of a two-way pipe to a coprocess (*note Two-way I/O::).
- * The optional third argument to the 'match()' function for capturing
+ ⢠The optional third argument to the âmatch()â function for capturing
text-matching subexpressions within a regexp (*note String
Functions::).
- * Positional specifiers in 'printf' formats for making translations
+ ⢠Positional specifiers in âprintfâ formats for making translations
easier (*note Printf Ordering::).
- * A number of new built-in functions:
+ ⢠A number of new built-in functions:
- - The 'asort()' and 'asorti()' functions for sorting arrays
+ â The âasort()â and âasorti()â functions for sorting arrays
(*note Array Sorting::).
- - The 'bindtextdomain()', 'dcgettext()' and 'dcngettext()'
+ â The âbindtextdomain()â, âdcgettext()â and
âdcngettext()â
functions for internationalization (*note Programmer i18n::).
- - The 'extension()' function and the ability to add new built-in
+ â The âextension()â function and the ability to add new built-in
functions dynamically. This has seen removed. It was
replaced by the new extension mechanism. *Note Dynamic
Extensions::.
- - The 'mktime()' function for creating timestamps (*note Time
+ â The âmktime()â function for creating timestamps (*note Time
Functions::).
- - The 'and()', 'or()', 'xor()', 'compl()', 'lshift()',
- 'rshift()', and 'strtonum()' functions (*note Bitwise
+ â The âand()â, âor()â, âxor()â, âcompl()â,
âlshift()â,
+ ârshift()â, and âstrtonum()â functions (*note Bitwise
Functions::).
- * The support for 'next file' as two words was removed completely
+ ⢠The support for ânext fileâ as two words was removed completely
(*note Nextfile Statement::).
- * Additional command-line options (*note Options::):
+ ⢠Additional command-line options (*note Options::):
- - The '--dump-variables' option to print a list of all global
+ â The â--dump-variablesâ option to print a list of all global
variables.
- - The '--exec' option, for use in CGI scripts.
+ â The â--execâ option, for use in CGI scripts.
- - The '--gen-po' command-line option and the use of a leading
+ â The â--gen-poâ command-line option and the use of a leading
underscore to mark strings that should be translated (*note
String Extraction::).
- - The '--non-decimal-data' option to allow non-decimal input
+ â The â--non-decimal-dataâ option to allow non-decimal input
data (*note Nondecimal Data::).
- - The '--profile' option and 'pgawk', the profiling version of
- 'gawk', for producing execution profiles of 'awk' programs
+ â The â--profileâ option and âpgawkâ, the profiling version
of
+ âgawkâ, for producing execution profiles of âawkâ programs
(*note Profiling::).
- - The '--use-lc-numeric' option to force 'gawk' to use the
- locale's decimal point for parsing input data (*note
+ â The â--use-lc-numericâ option to force âgawkâ to use the
+ localeâs decimal point for parsing input data (*note
Conversion::).
- * The use of GNU Automake to help in standardizing the configuration
+ ⢠The use of GNU Automake to help in standardizing the configuration
process (*note Quick Installation::).
- * The use of GNU 'gettext' for 'gawk''s own message output (*note
+ ⢠The use of GNU âgettextâ for âgawkââs own message output
(*note
Gawk I18N::).
- * BeOS support. This was later removed.
+ ⢠BeOS support. This was later removed.
- * Tandem support. This was later removed.
+ ⢠Tandem support. This was later removed.
- * The Atari port became officially unsupported and was later removed
+ ⢠The Atari port became officially unsupported and was later removed
entirely.
- * The source code changed to use ISO C standard-style function
+ ⢠The source code changed to use ISO C standard-style function
definitions.
- * POSIX compliance for 'sub()' and 'gsub()' (*note Gory Details::).
+ ⢠POSIX compliance for âsub()â and âgsub()â (*note Gory
Details::).
- * The 'length()' function was extended to accept an array argument
+ ⢠The âlength()â function was extended to accept an array argument
and return the number of elements in the array (*note String
Functions::).
- * The 'strftime()' function acquired a third argument to enable
+ ⢠The âstrftime()â function acquired a third argument to enable
printing times as UTC (*note Time Functions::).
- Version 4.0 of 'gawk' introduced the following features:
+ Version 4.0 of âgawkâ introduced the following features:
- * Variable additions:
+ ⢠Variable additions:
- - 'FPAT', which allows you to specify a regexp that matches the
+ â âFPATâ, which allows you to specify a regexp that matches the
fields, instead of matching the field separator (*note
Splitting By Content::).
- - If 'PROCINFO["sorted_in"]' exists, 'for (iggy in foo)' loops
+ â If âPROCINFO["sorted_in"]â exists, âfor (iggy in foo)â
loops
sort the indices before looping over them. The value of this
element provides control over how the indices are sorted
before the loop traversal starts (*note Controlling
Scanning::).
- - 'PROCINFO["strftime"]', which holds the default format for
- 'strftime()' (*note Time Functions::).
+ â âPROCINFO["strftime"]â, which holds the default format for
+ âstrftime()â (*note Time Functions::).
- * The special files '/dev/pid', '/dev/ppid', '/dev/pgrpid' and
- '/dev/user' were removed.
+ ⢠The special files â/dev/pidâ, â/dev/ppidâ, â/dev/pgrpidâ and
+ â/dev/userâ were removed.
- * Support for IPv6 was added via the '/inet6' special file. '/inet4'
- forces IPv4 and '/inet' chooses the system default, which is
+ ⢠Support for IPv6 was added via the â/inet6â special file.
â/inet4â
+ forces IPv4 and â/inetâ chooses the system default, which is
probably IPv4 (*note TCP/IP Networking::).
- * The use of '\s' and '\S' escape sequences in regular expressions
+ ⢠The use of â\sâ and â\Sâ escape sequences in regular expressions
(*note GNU Regexp Operators::).
- * Interval expressions became part of default regular expressions
+ ⢠Interval expressions became part of default regular expressions
(*note Regexp Operators::).
- * POSIX character classes work even with '--traditional' (*note
+ ⢠POSIX character classes work even with â--traditionalâ (*note
Regexp Operators::).
- * 'break' and 'continue' became invalid outside a loop, even with
- '--traditional' (*note Break Statement::, and also see *note
+ ⢠âbreakâ and âcontinueâ became invalid outside a loop, even with
+ â--traditionalâ (*note Break Statement::, and also see *note
Continue Statement::).
- * 'fflush()', 'nextfile', and 'delete ARRAY' are allowed if '--posix'
- or '--traditional', since they are all now part of POSIX.
+ ⢠âfflush()â, ânextfileâ, and âdelete ARRAYâ are allowed if
â--posixâ
+ or â--traditionalâ, since they are all now part of POSIX.
- * An optional third argument to 'asort()' and 'asorti()', specifying
+ ⢠An optional third argument to âasort()â and âasorti()â,
specifying
how to sort (*note String Functions::).
- * The behavior of 'fflush()' changed to match BWK 'awk' and for
- POSIX; now both 'fflush()' and 'fflush("")' flush all open output
+ ⢠The behavior of âfflush()â changed to match BWK âawkâ and for
+ POSIX; now both âfflush()â and âfflush("")â flush all open output
redirections (*note I/O Functions::).
- * The 'isarray()' function which distinguishes if an item is an array
+ ⢠The âisarray()â function which distinguishes if an item is an array
or not, to make it possible to traverse arrays of arrays (*note
Type Functions::).
- * The 'patsplit()' function which gives the same capability as
- 'FPAT', for splitting (*note String Functions::).
+ ⢠The âpatsplit()â function which gives the same capability as
+ âFPATâ, for splitting (*note String Functions::).
- * An optional fourth argument to the 'split()' function, which is an
+ ⢠An optional fourth argument to the âsplit()â function, which is an
array to hold the values of the separators (*note String
Functions::).
- * Arrays of arrays (*note Arrays of Arrays::).
+ ⢠Arrays of arrays (*note Arrays of Arrays::).
- * The 'BEGINFILE' and 'ENDFILE' special patterns (*note
+ ⢠The âBEGINFILEâ and âENDFILEâ special patterns (*note
BEGINFILE/ENDFILE::).
- * Indirect function calls (*note Indirect Calls::).
+ ⢠Indirect function calls (*note Indirect Calls::).
- * 'switch' / 'case' are enabled by default (*note Switch
+ ⢠âswitchâ / âcaseâ are enabled by default (*note Switch
Statement::).
- * Command-line option changes (*note Options::):
+ ⢠Command-line option changes (*note Options::):
- - The '-b' and '--characters-as-bytes' options which prevent
- 'gawk' from treating input as a multibyte string.
+ â The â-bâ and â--characters-as-bytesâ options which prevent
+ âgawkâ from treating input as a multibyte string.
- - The redundant '--compat', '--copyleft', and '--usage' long
+ â The redundant â--compatâ, â--copyleftâ, and â--usageâ
long
options were removed.
- - The '--gen-po' option was finally renamed to the correct
- '--gen-pot'.
+ â The â--gen-poâ option was finally renamed to the correct
+ â--gen-potâ.
- - The '--sandbox' option which disables certain features.
+ â The â--sandboxâ option which disables certain features.
- - All long options acquired corresponding short options, for use
- in '#!' scripts.
+ â All long options acquired corresponding short options, for use
+ in â#!â scripts.
- * Directories named on the command line now produce a warning, not a
- fatal error, unless '--posix' or '--traditional' are used (*note
+ ⢠Directories named on the command line now produce a warning, not a
+ fatal error, unless â--posixâ or â--traditionalâ are used (*note
Command-line directories::).
- * The 'gawk' internals were rewritten, bringing the 'dgawk' debugger
+ ⢠The âgawkâ internals were rewritten, bringing the âdgawkâ
debugger
and possibly improved performance (*note Debugger::).
- * Per the GNU Coding Standards, dynamic extensions must now define a
+ ⢠Per the GNU Coding Standards, dynamic extensions must now define a
global symbol indicating that they are GPL-compatible (*note Plugin
License::).
- * In POSIX mode, string comparisons use 'strcoll()' / 'wcscoll()'
+ ⢠In POSIX mode, string comparisons use âstrcoll()â / âwcscoll()â
(*note POSIX String Comparison::).
- * The option for raw sockets was removed, since it was never
+ ⢠The option for raw sockets was removed, since it was never
implemented (*note TCP/IP Networking::).
- * Ranges of the form '[d-h]' are treated as if they were in the C
+ ⢠Ranges of the form â[d-h]â are treated as if they were in the C
locale, no matter what kind of regexp is being used, and even if
- '--posix' (*note Ranges and Locales::).
+ â--posixâ (*note Ranges and Locales::).
- * Support was removed for the following systems:
+ ⢠Support was removed for the following systems:
- - Atari
+ â Atari
- - Amiga
+ â Amiga
- - BeOS
+ â BeOS
- - Cray
+ â Cray
- - MIPS RiscOS
+ â MIPS RiscOS
- - MS-DOS with the Microsoft Compiler
+ â MS-DOS with the Microsoft Compiler
- - MS-Windows with the Microsoft Compiler
+ â MS-Windows with the Microsoft Compiler
- - NeXT
+ â NeXT
- - SunOS 3.x, Sun 386 (Road Runner)
+ â SunOS 3.x, Sun 386 (Road Runner)
- - Tandem (non-POSIX)
+ â Tandem (non-POSIX)
- - Prestandard VAX C compiler for VAX/VMS
+ â Prestandard VAX C compiler for VAX/VMS
- Version 4.1 of 'gawk' introduced the following features:
+ Version 4.1 of âgawkâ introduced the following features:
- * Three new arrays: 'SYMTAB', 'FUNCTAB', and
- 'PROCINFO["identifiers"]' (*note Auto-set::).
+ ⢠Three new arrays: âSYMTABâ, âFUNCTABâ, and
+ âPROCINFO["identifiers"]â (*note Auto-set::).
- * The three executables 'gawk', 'pgawk', and 'dgawk', were merged
- into one, named just 'gawk'. As a result the command-line options
+ ⢠The three executables âgawkâ, âpgawkâ, and âdgawkâ, were
merged
+ into one, named just âgawkâ. As a result the command-line options
changed.
- * Command-line option changes (*note Options::):
+ ⢠Command-line option changes (*note Options::):
- - The '-D' option invokes the debugger.
+ â The â-Dâ option invokes the debugger.
- - The '-i' and '--include' options load 'awk' library files.
+ â The â-iâ and â--includeâ options load âawkâ library
files.
- - The '-l' and '--load' options load compiled dynamic
+ â The â-lâ and â--loadâ options load compiled dynamic
extensions.
- - The '-M' and '--bignum' options enable MPFR.
+ â The â-Mâ and â--bignumâ options enable MPFR.
- - The '-o' option only does pretty-printing.
+ â The â-oâ option only does pretty-printing.
- - The '-p' option is used for profiling.
+ â The â-pâ option is used for profiling.
- - The '-R' option was removed.
+ â The â-Râ option was removed.
- * Support for high precision arithmetic with MPFR (*note Arbitrary
+ ⢠Support for high precision arithmetic with MPFR (*note Arbitrary
Precision Arithmetic::).
- * The 'and()', 'or()' and 'xor()' functions changed to allow any
+ ⢠The âand()â, âor()â and âxor()â functions changed to allow
any
number of arguments, with a minimum of two (*note Bitwise
Functions::).
- * The dynamic extension interface was completely redone (*note
+ ⢠The dynamic extension interface was completely redone (*note
Dynamic Extensions::).
- * Redirected 'getline' became allowed inside 'BEGINFILE' and
- 'ENDFILE' (*note BEGINFILE/ENDFILE::).
+ ⢠Redirected âgetlineâ became allowed inside âBEGINFILEâ and
+ âENDFILEâ (*note BEGINFILE/ENDFILE::).
- * The 'where' command was added to the debugger (*note Execution
+ ⢠The âwhereâ command was added to the debugger (*note Execution
Stack::).
- * Support for Ultrix was removed.
+ ⢠Support for Ultrix was removed.
- Version 4.2 of 'gawk' introduced the following changes:
+ Version 4.2 of âgawkâ introduced the following changes:
- * Changes to 'ENVIRON' are reflected into 'gawk''s environment and
+ ⢠Changes to âENVIRONâ are reflected into âgawkââs environment
and
that of programs that it runs. *Note Auto-set::.
- * 'FIELDWIDTHS' was enhanced to allow skipping characters before
+ ⢠âFIELDWIDTHSâ was enhanced to allow skipping characters before
assigning a value to a field (*note Splitting By Content::).
- * The 'PROCINFO["argv"]' array. *Note Auto-set::.
+ ⢠The âPROCINFO["argv"]â array. *Note Auto-set::.
- * The maximum number of hexadecimal digits in '\x' escapes is now
+ ⢠The maximum number of hexadecimal digits in â\xâ escapes is now
two. *Note Escape Sequences::.
- * Strongly typed regexp constants of the form '@/.../' (*note Strong
+ ⢠Strongly typed regexp constants of the form â@/.../â (*note Strong
Regexp Constants::).
- * The bitwise functions changed, making negative arguments into a
+ ⢠The bitwise functions changed, making negative arguments into a
fatal error (*note Bitwise Functions::).
- * The 'mktime()' function now accepts an optional second argument
+ ⢠The âmktime()â function now accepts an optional second argument
(*note Time Functions::).
- * The 'typeof()' function (*note Type Functions::).
+ ⢠The âtypeof()â function (*note Type Functions::).
- * Optimizations are enabled by default. Use '-s' / '--no-optimize'
+ ⢠Optimizations are enabled by default. Use â-sâ /
â--no-optimizeâ
to disable optimizations.
- * For many years, POSIX specified that default field splitting only
- allowed spaces and tabs to separate fields, and this was how 'gawk'
- behaved with '--posix'. As of 2013, the standard restored
- historical behavior, and now default field splitting with '--posix'
+ ⢠For many years, POSIX specified that default field splitting only
+ allowed spaces and tabs to separate fields, and this was how âgawkâ
+ behaved with â--posixâ. As of 2013, the standard restored
+ historical behavior, and now default field splitting with â--posixâ
also allows newlines to separate fields.
- * Nonfatal output with 'print' and 'printf'. *Note Nonfatal::.
+ ⢠Nonfatal output with âprintâ and âprintfâ. *Note Nonfatal::.
- * Retryable I/O via 'PROCINFO[INPUT-FILE, "RETRY"]'; (*note Retrying
+ ⢠Retryable I/O via âPROCINFO[INPUT-FILE, "RETRY"]â; (*note Retrying
Input::).
- * Changes to the pretty-printer (*note Profiling::):
+ ⢠Changes to the pretty-printer (*note Profiling::):
- - The '--pretty-print' option no longer runs the 'awk' program
+ â The â--pretty-printâ option no longer runs the âawkâ
program
too.
- - Comments in the source program are preserved and placed into
+ â Comments in the source program are preserved and placed into
the output file.
- - Explicit parentheses for expressions in the input are
+ â Explicit parentheses for expressions in the input are
preserved in the generated output.
- * Improvements to the extension API (*note Dynamic Extensions::):
+ ⢠Improvements to the extension API (*note Dynamic Extensions::):
- - The 'get_file()' function to access open redirections.
+ â The âget_file()â function to access open redirections.
- - The 'nonfatal()' function for generating nonfatal error
+ â The ânonfatal()â function for generating nonfatal error
messages.
- - Support for GMP and MPFR values.
+ â Support for GMP and MPFR values.
- - Input parsers can now override the default field parsing
+ â Input parsers can now override the default field parsing
mechanism by specifying explicit locations.
- * Shell startup files are supplied with the distribution and
- installed by 'make install' (*note Shell Startup Files::).
+ ⢠Shell startup files are supplied with the distribution and
+ installed by âmake installâ (*note Shell Startup Files::).
- * The 'igawk' program and its manual page are no longer installed
- when 'gawk' is built. *Note Igawk Program::.
+ ⢠The âigawkâ program and its manual page are no longer installed
+ when âgawkâ is built. *Note Igawk Program::.
- * Support for MirBSD was removed.
+ ⢠Support for MirBSD was removed.
- * Support for GNU/Linux on Alpha was removed.
+ ⢠Support for GNU/Linux on Alpha was removed.
Version 5.0 added the following features:
- * The 'PROCINFO["platform"]' array element, which allows you to write
+ ⢠The âPROCINFO["platform"]â array element, which allows you to write
code that takes the operating system / platform into account.
- Version 5.1 was created to release 'gawk' with a correct major
+ Version 5.1 was created to release âgawkâ with a correct major
version number for the API. This was overlooked for version 5.0,
unfortunately. It added the following features:
- * The index for this manual was completely reworked.
+ ⢠The index for this manual was completely reworked.
- * Support was added for MSYS2.
+ ⢠Support was added for MSYS2.
- * 'asort()' and 'asorti()' were changed to allow 'FUNCTAB' and
- 'SYMTAB' as the first argument if a second destination array is
+ ⢠âasort()â and âasorti()â were changed to allow âFUNCTABâ and
+ âSYMTABâ as the first argument if a second destination array is
supplied (*note String Functions::).
- * The '-I'/'--trace' options were added to print a trace of the byte
+ ⢠The â-Iâ/â--traceâ options were added to print a trace of the
byte
codes as they execute (*note Options::).
- * '$0' and the fields are now cleared before starting a 'BEGINFILE'
+ ⢠â$0â and the fields are now cleared before starting a
âBEGINFILEâ
rule (*note BEGINFILE/ENDFILE::).
- * Several example programs in the manual were updated to their modern
+ ⢠Several example programs in the manual were updated to their modern
POSIX equivalents.
- * The "no effect" lint warnings from '--lint' were fixed up and now
+ ⢠The âno effectâ lint warnings from â--lintâ were fixed up and
now
behave more sanely (*note Options::).
- * Handling of Infinity and NaN values were improved. *Note Math
+ ⢠Handling of Infinity and NaN values were improved. *Note Math
Definitions::, and also see *note POSIX Floating Point Problems::.
Version 5.2 added the following features:
- * The 'mkbool()' built-in function (*note Boolean Functions::).
+ ⢠The âmkbool()â built-in function (*note Boolean Functions::).
- * Interval expressions in regular expressions are enabled by default
+ ⢠Interval expressions in regular expressions are enabled by default
(*note Interval Expressions::).
- * Support for the FNV1-A hash algorithm for its hash function (*note
+ ⢠Support for the FNV1-A hash algorithm for its hash function (*note
Other Environment Variables::).
- * The 'gawkbug' script for reporting bugs (*note Bug address::).
+ ⢠The âgawkbugâ script for reporting bugs (*note Bug address::).
- * Terence Kelly's persistent memory allocator (PMA) was added,
+ ⢠Terence Kellyâs persistent memory allocator (PMA) was added,
allowing the use of persistent data on certain systems (*note
Persistent Memory::).
- * 'PROCINFO["pma"]' exists if the PMA allocator is compiled in (*note
+ ⢠âPROCINFO["pma"]â exists if the PMA allocator is compiled in (*note
Auto-set::).
@@ -30658,24 +30656,24 @@ A.7 Common Extensions Summary
=============================
The following table summarizes the common extensions supported by
-'gawk', Brian Kernighan's 'awk', and 'mawk', the three most widely used
-freely available versions of 'awk' (*note Other Versions::).
+âgawkâ, Brian Kernighanâs âawkâ, and âmawkâ, the three most
widely used
+freely available versions of âawkâ (*note Other Versions::).
-Feature BWK 'awk' 'mawk' 'gawk' Now standard
+Feature BWK âawkâ âmawkâ âgawkâ Now
standard
--------------------------------------------------------------------------
-'\x' escape sequence X X X
-'FS' as null string X X X
-'/dev/stdin' special file X X X
-'/dev/stdout' special file X X X
-'/dev/stderr' special file X X X
-'delete' without subscript X X X X
-'fflush()' function X X X X
-'length()' of an array X X X
-'nextfile' statement X X X X
-'**' and '**=' operators X X
-'func' keyword X X
-'BINMODE' variable X X
-'RS' as regexp X X X
+â\xâ escape sequence X X X
+âFSâ as null string X X X
+â/dev/stdinâ special file X X X
+â/dev/stdoutâ special file X X X
+â/dev/stderrâ special file X X X
+âdeleteâ without subscript X X X X
+âfflush()â function X X X X
+âlength()â of an array X X X
+ânextfileâ statement X X X X
+â**â and â**=â operators X X
+âfuncâ keyword X X
+âBINMODEâ variable X X
+âRSâ as regexp X X X
Time-related functions X X
@@ -30686,22 +30684,22 @@ A.8 Regexp Ranges and Locales: A Long Sad Story
This minor node describes the confusing history of ranges within regular
expressions and their interactions with locales, and how this affected
-different versions of 'gawk'.
+different versions of âgawkâ.
The original Unix tools that worked with regular expressions defined
-character ranges (such as '[a-z]') to match any character between the
+character ranges (such as â[a-z]â) to match any character between the
first character in the range and the last character in the range,
inclusive. Ordering was based on the numeric value of each character in
-the machine's native character set. Thus, on ASCII-based systems,
-'[a-z]' matched all the lowercase letters, and only the lowercase
-letters, as the numeric values for the letters from 'a' through 'z' were
-contiguous. (On an EBCDIC system, the range '[a-z]' includes additional
+the machineâs native character set. Thus, on ASCII-based systems,
+â[a-z]â matched all the lowercase letters, and only the lowercase
+letters, as the numeric values for the letters from âaâ through âzâ
were
+contiguous. (On an EBCDIC system, the range â[a-z]â includes additional
nonalphabetic characters as well.)
Almost all introductory Unix literature explained range expressions
as working in this fashion, and in particular, would teach that the
-"correct" way to match lowercase letters was with '[a-z]', and that
-'[A-Z]' was the "correct" way to match uppercase letters. And indeed,
+âcorrectâ way to match lowercase letters was with â[a-z]â, and that
+â[A-Z]â was the âcorrectâ way to match uppercase letters. And indeed,
this was true.(1)
The 1992 POSIX standard introduced the idea of locales (*note
@@ -30712,63 +30710,63 @@ different kinds of characters besides the traditional
ones in the ASCII
character set.
However, the standard _changed_ the interpretation of range
-expressions. In the '"C"' and '"POSIX"' locales, a range expression
-like '[a-dx-z]' is still equivalent to '[abcdxyz]', as in ASCII. But
+expressions. In the â"C"â and â"POSIX"â locales, a range expression
+like â[a-dx-z]â is still equivalent to â[abcdxyz]â, as in ASCII. But
outside those locales, the ordering was defined to be based on
-"collation order".
+âcollation orderâ.
- What does that mean? In many locales, 'A' and 'a' are both less than
-'B'. In other words, these locales sort characters in dictionary order,
-and '[a-dx-z]' is typically not equivalent to '[abcdxyz]'; instead, it
-might be equivalent to '[ABCXYabcdxyz]', for example.
+ What does that mean? In many locales, âAâ and âaâ are both less
than
+âBâ. In other words, these locales sort characters in dictionary order,
+and â[a-dx-z]â is typically not equivalent to â[abcdxyz]â; instead, it
+might be equivalent to â[ABCXYabcdxyz]â, for example.
This point needs to be emphasized: much literature teaches that you
-should use '[a-z]' to match a lowercase character. But on systems with
+should use â[a-z]â to match a lowercase character. But on systems with
non-ASCII locales, this also matches all of the uppercase characters
-except 'A' or 'Z'! This was a continuous cause of confusion, even well
+except âAâ or âZâ! This was a continuous cause of confusion, even well
into the twenty-first century.
- To demonstrate these issues, the following example uses the 'sub()'
+ To demonstrate these issues, the following example uses the âsub()â
function, which does text replacement (*note String Functions::). Here,
the intent is to remove trailing uppercase characters:
$ echo something1234abc | gawk-3.1.8 '{ sub("[A-Z]*$", ""); print }'
- -| something1234a
+ ⣠something1234a
-This output is unexpected, as the 'bc' at the end of 'something1234abc'
-should not normally match '[A-Z]*'. This result is due to the locale
+This output is unexpected, as the âbcâ at the end of âsomething1234abcâ
+should not normally match â[A-Z]*â. This result is due to the locale
setting (and thus you may not see it on your system).
- Similar considerations apply to other ranges. For example, '["-/]'
+ Similar considerations apply to other ranges. For example, â["-/]â
is perfectly valid in ASCII, but is not valid in many Unicode locales,
-such as 'en_US.UTF-8'.
+such as âen_US.UTF-8â.
- Early versions of 'gawk' used regexp matching code that was not
+ Early versions of âgawkâ used regexp matching code that was not
locale-aware, so ranges had their traditional interpretation.
- When 'gawk' switched to using locale-aware regexp matchers, the
+ When âgawkâ switched to using locale-aware regexp matchers, the
problems began; especially as both GNU/Linux and commercial Unix vendors
started implementing non-ASCII locales, _and making them the default_.
-Perhaps the most frequently asked question became something like, "Why
-does '[A-Z]' match lowercase letters?!?"
+Perhaps the most frequently asked question became something like, âWhy
+does â[A-Z]â match lowercase letters?!?â
This situation existed for close to 10 years, if not more, and the
-'gawk' maintainer grew weary of trying to explain that 'gawk' was being
-nicely standards-compliant, and that the issue was in the user's locale.
-During the development of version 4.0, he modified 'gawk' to always
-treat ranges in the original, pre-POSIX fashion, unless '--posix' was
+âgawkâ maintainer grew weary of trying to explain that âgawkâ was being
+nicely standards-compliant, and that the issue was in the userâs locale.
+During the development of version 4.0, he modified âgawkâ to always
+treat ranges in the original, pre-POSIX fashion, unless â--posixâ was
used (*note Options::).(2)
- Fortunately, shortly before the final release of 'gawk' 4.0, the
+ Fortunately, shortly before the final release of âgawkâ 4.0, the
maintainer learned that the 2008 standard had changed the definition of
-ranges, such that outside the '"C"' and '"POSIX"' locales, the meaning
+ranges, such that outside the â"C"â and â"POSIX"â locales, the meaning
of range expressions was _undefined_.(3)
By using this lovely technical term, the standard gives license to
implementers to implement ranges in whatever way they choose. The
-'gawk' maintainer chose to apply the pre-POSIX meaning both with the
-default regexp matching and when '--traditional' or '--posix' are used.
-In all cases 'gawk' remains POSIX-compliant.
+âgawkâ maintainer chose to apply the pre-POSIX meaning both with the
+default regexp matching and when â--traditionalâ or â--posixâ are used.
+In all cases âgawkâ remains POSIX-compliant.
---------- Footnotes ----------
@@ -30776,8 +30774,8 @@ In all cases 'gawk' remains POSIX-compliant.
(2) And thus was born the Campaign for Rational Range Interpretation
(or RRI). A number of GNU tools have already implemented this change, or
-will soon. Thanks to Karl Berry for coining the phrase "Rational Range
-Interpretation."
+will soon. Thanks to Karl Berry for coining the phrase âRational Range
+Interpretation.â
(3) See the standard
(https://pubs.opengroup.org/onlinepubs/9699919799/basedefs/V1_chap09.html#tag_09_03_05)
@@ -30787,158 +30785,158 @@ and its rationale
File: gawk.info, Node: Contributors, Next: History summary, Prev: Ranges
and Locales, Up: Language History
-A.9 Major Contributors to 'gawk'
+A.9 Major Contributors to âgawkâ
================================
Always give credit where credit is due.
- -- _Anonymous_
+ â _Anonymous_
- This minor node names the major contributors to 'gawk' and/or this
+ This minor node names the major contributors to âgawkâ and/or this
Info file, in approximate chronological order:
- * Dr. Alfred V. Aho, Dr. Peter J. Weinberger, and Dr. Brian W.
+ ⢠Dr. Alfred V. Aho, Dr. Peter J. Weinberger, and Dr. Brian W.
Kernighan, all of Bell Laboratories, designed and implemented Unix
- 'awk', from which 'gawk' gets the majority of its feature set.
+ âawkâ, from which âgawkâ gets the majority of its feature set.
- * Paul Rubin did the initial design and implementation in 1986, and
+ ⢠Paul Rubin did the initial design and implementation in 1986, and
wrote the first draft (around 40 pages) of this Info file.
- * Jay Fenlason finished the initial implementation.
+ ⢠Jay Fenlason finished the initial implementation.
- * Diane Close revised the first draft of this Info file, bringing it
+ ⢠Diane Close revised the first draft of this Info file, bringing it
to around 90 pages.
- * Richard Stallman helped finish the implementation and the initial
+ ⢠Richard Stallman helped finish the implementation and the initial
draft of this Info file. He is also the founder of the FSF and the
GNU Project.
- * John Woods contributed parts of the code (mostly fixes) in the
- initial version of 'gawk'.
+ ⢠John Woods contributed parts of the code (mostly fixes) in the
+ initial version of âgawkâ.
- * In 1988, David Trueman took over primary maintenance of 'gawk',
- making it compatible with "new" 'awk', and greatly improving its
+ ⢠In 1988, David Trueman took over primary maintenance of âgawkâ,
+ making it compatible with ânewâ âawkâ, and greatly improving its
performance.
- * Conrad Kwok, Scott Garfinkle, and Kent Williams did the initial
+ ⢠Conrad Kwok, Scott Garfinkle, and Kent Williams did the initial
ports to MS-DOS with various versions of MSC.
- * Pat Rankin provided the VMS port and its documentation.
+ ⢠Pat Rankin provided the VMS port and its documentation.
- * Hal Peterson provided help in porting 'gawk' to Cray systems.
+ ⢠Hal Peterson provided help in porting âgawkâ to Cray systems.
(This is no longer supported.)
- * Kai Uwe Rommel provided the initial port to OS/2 and its
+ ⢠Kai Uwe Rommel provided the initial port to OS/2 and its
documentation.
- * Michal Jaegermann provided the port to Atari systems and its
+ ⢠Michal Jaegermann provided the port to Atari systems and its
documentation. (This port is no longer supported.) He continues
to provide portability checking, and has done a lot of work to make
- sure 'gawk' works on non-32-bit systems.
+ sure âgawkâ works on non-32-bit systems.
- * Fred Fish provided the port to Amiga systems and its documentation.
- (With Fred's sad passing, this is no longer supported.)
+ ⢠Fred Fish provided the port to Amiga systems and its documentation.
+ (With Fredâs sad passing, this is no longer supported.)
- * Scott Deifik formerly maintained the MS-DOS port using DJGPP.
+ ⢠Scott Deifik formerly maintained the MS-DOS port using DJGPP.
- * Eli Zaretskii currently maintains the MS-Windows port using MinGW.
+ ⢠Eli Zaretskii currently maintains the MS-Windows port using MinGW.
- * Juan Grigera provided a port to Windows32 systems. (This is no
+ ⢠Juan Grigera provided a port to Windows32 systems. (This is no
longer supported.)
- * For many years, Dr. Darrel Hankerson acted as coordinator for the
+ ⢠For many years, Dr. Darrel Hankerson acted as coordinator for the
various ports to different PC platforms and created binary
distributions for various PC operating systems. He was also
instrumental in keeping the documentation up to date for the
various PC platforms.
- * Christos Zoulas provided the 'extension()' built-in function for
- dynamically adding new functions. (This was obsoleted at 'gawk'
+ ⢠Christos Zoulas provided the âextension()â built-in function for
+ dynamically adding new functions. (This was obsoleted at âgawkâ
4.1.)
- * Jürgen Kahrs contributed the initial version of the TCP/IP
+ ⢠Jürgen Kahrs contributed the initial version of the TCP/IP
networking code and documentation, and motivated the inclusion of
- the '|&' operator.
+ the â|&â operator.
- * Stephen Davies provided the initial port to Tandem systems and its
+ ⢠Stephen Davies provided the initial port to Tandem systems and its
documentation. (However, this is no longer supported.) He was
also instrumental in the initial work to integrate the byte-code
- internals into the 'gawk' code base. Additionally, he did most of
+ internals into the âgawkâ code base. Additionally, he did most of
the work enabling the pretty-printer to preserve and output
comments.
- * Matthew Woehlke provided improvements for Tandem's POSIX-compliant
+ ⢠Matthew Woehlke provided improvements for Tandemâs POSIX-compliant
systems.
- * Martin Brown provided the port to BeOS and its documentation.
+ ⢠Martin Brown provided the port to BeOS and its documentation.
(This is no longer supported.)
- * Arno Peters did the initial work to convert 'gawk' to use GNU
- Automake and GNU 'gettext'.
+ ⢠Arno Peters did the initial work to convert âgawkâ to use GNU
+ Automake and GNU âgettextâ.
- * Alan J. Broder provided the initial version of the 'asort()'
+ ⢠Alan J. Broder provided the initial version of the âasort()â
function as well as the code for the optional third argument to the
- 'match()' function.
+ âmatch()â function.
- * Andreas Buening updated the 'gawk' port for OS/2.
+ ⢠Andreas Buening updated the âgawkâ port for OS/2.
- * Isamu Hasegawa, of IBM in Japan, contributed support for multibyte
+ ⢠Isamu Hasegawa, of IBM in Japan, contributed support for multibyte
characters.
- * Michael Benzinger contributed the initial code for 'switch'
+ ⢠Michael Benzinger contributed the initial code for âswitchâ
statements.
- * Patrick T.J. McPhee contributed the code for dynamic loading in
+ ⢠Patrick T.J. McPhee contributed the code for dynamic loading in
Windows32 environments. (This is no longer supported.)
- * Anders Wallin helped keep the VMS port going for several years.
+ ⢠Anders Wallin helped keep the VMS port going for several years.
- * Assaf Gordon contributed the initial code to implement the
- '--sandbox' option.
+ ⢠Assaf Gordon contributed the initial code to implement the
+ â--sandboxâ option.
- * John Haque made the following contributions:
+ ⢠John Haque made the following contributions:
- - The modifications to convert 'gawk' into a byte-code
+ â The modifications to convert âgawkâ into a byte-code
interpreter, including the debugger
- - The addition of true arrays of arrays
+ â The addition of true arrays of arrays
- - The additional modifications for support of
+ â The additional modifications for support of
arbitrary-precision arithmetic
- - The initial text of *note Arbitrary Precision Arithmetic::
+ â The initial text of *note Arbitrary Precision Arithmetic::
- - The work to merge the three versions of 'gawk' into one, for
+ â The work to merge the three versions of âgawkâ into one, for
the 4.1 release
- - Improved array internals for arrays indexed by integers
+ â Improved array internals for arrays indexed by integers
- - The improved array sorting features were also driven by John,
+ â The improved array sorting features were also driven by John,
together with Pat Rankin
- * Panos Papadopoulos contributed the original text for *note Include
+ ⢠Panos Papadopoulos contributed the original text for *note Include
Files::.
- * Efraim Yawitz contributed the original text for *note Debugger::.
+ ⢠Efraim Yawitz contributed the original text for *note Debugger::.
- * The development of the extension API first released with 'gawk' 4.1
+ ⢠The development of the extension API first released with âgawkâ 4.1
was driven primarily by Arnold Robbins and Andrew Schorr, with
notable contributions from the rest of the development team.
- * John Malmberg contributed significant improvements to the OpenVMS
+ ⢠John Malmberg contributed significant improvements to the OpenVMS
port and the related documentation.
- * Antonio Giovanni Colombo rewrote a number of examples in the early
+ ⢠Antonio Giovanni Colombo rewrote a number of examples in the early
chapters that were severely dated, for which I am incredibly
grateful. He also provided and maintains the Italian translation.
- * Marco Curreli, together with Antonio Colombo, translated this Info
- file into Italian. It is included in the 'gawk' distribution.
+ ⢠Marco Curreli, together with Antonio Colombo, translated this Info
+ file into Italian. It is included in the âgawkâ distribution.
- * Juan Manuel Guerrero took over maintenance of the DJGPP port.
+ ⢠Juan Manuel Guerrero took over maintenance of the DJGPP port.
- * "Jannick" provided support for MSYS2.
+ ⢠âJannickâ provided support for MSYS2.
- * Arnold Robbins has been working on 'gawk' since 1988, at first
+ ⢠Arnold Robbins has been working on âgawkâ since 1988, at first
helping David Trueman, and as the primary maintainer since around
1994.
@@ -30948,38 +30946,38 @@ File: gawk.info, Node: History summary, Prev:
Contributors, Up: Language Hist
A.10 Summary
============
- * The 'awk' language has evolved over time. The first release was
+ ⢠The âawkâ language has evolved over time. The first release was
with V7 Unix, circa 1978. In 1987, for System V Release 3.1, major
additions, including user-defined functions, were made to the
language. Additional changes were made for System V Release 4, in
1989. Since then, further minor changes have happened under the
auspices of the POSIX standard.
- * Brian Kernighan's 'awk' provides a small number of extensions that
- are implemented in common with other versions of 'awk'.
+ ⢠Brian Kernighanâs âawkâ provides a small number of extensions that
+ are implemented in common with other versions of âawkâ.
- * 'gawk' provides a large number of extensions over POSIX 'awk'.
- They can be disabled with either the '--traditional' or '--posix'
+ ⢠âgawkâ provides a large number of extensions over POSIX âawkâ.
+ They can be disabled with either the â--traditionalâ or â--posixâ
options.
- * The interaction of POSIX locales and regexp matching in 'gawk' has
- been confusing over the years. Today, 'gawk' implements Rational
- Range Interpretation, where ranges of the form '[a-z]' match _only_
- the characters numerically between 'a' through 'z' in the machine's
+ ⢠The interaction of POSIX locales and regexp matching in âgawkâ has
+ been confusing over the years. Today, âgawkâ implements Rational
+ Range Interpretation, where ranges of the form â[a-z]â match _only_
+ the characters numerically between âaâ through âzâ in the
machineâs
native character set. Usually this is ASCII, but it can be EBCDIC
on IBM S/390 systems.
- * Many people have contributed to 'gawk' development over the years.
+ ⢠Many people have contributed to âgawkâ development over the years.
We hope that the list provided in this major node is complete and
gives the appropriate credit where credit is due.
File: gawk.info, Node: Installation, Next: Notes, Prev: Language History,
Up: Top
-Appendix B Installing 'gawk'
+Appendix B Installing âgawkâ
****************************
-This appendix provides instructions for installing 'gawk' on the various
+This appendix provides instructions for installing âgawkâ on the various
platforms that are supported by the developers. The primary developer
supports GNU/Linux (and Unix), whereas the other ports are contributed.
*Note Bugs:: for the email addresses of the people who maintain the
@@ -30987,22 +30985,22 @@ respective ports.
* Menu:
-* Gawk Distribution:: What is in the 'gawk' distribution.
-* Unix Installation:: Installing 'gawk' under various
+* Gawk Distribution:: What is in the âgawkâ distribution.
+* Unix Installation:: Installing âgawkâ under various
versions of Unix.
* Non-Unix Installation:: Installation on Other Operating Systems.
* Bugs:: Reporting Problems and Bugs.
-* Other Versions:: Other freely available 'awk'
+* Other Versions:: Other freely available âawkâ
implementations.
* Installation summary:: Summary of installation.
File: gawk.info, Node: Gawk Distribution, Next: Unix Installation, Up:
Installation
-B.1 The 'gawk' Distribution
+B.1 The âgawkâ Distribution
===========================
-This minor node describes how to get the 'gawk' distribution, how to
+This minor node describes how to get the âgawkâ distribution, how to
extract it, and then what is in the various files and subdirectories.
* Menu:
@@ -31014,16 +31012,16 @@ extract it, and then what is in the various files and
subdirectories.
File: gawk.info, Node: Getting, Next: Extracting, Up: Gawk Distribution
-B.1.1 Getting the 'gawk' Distribution
+B.1.1 Getting the âgawkâ Distribution
-------------------------------------
There are two ways to get GNU software:
- * Copy it from someone else who already has it.
+ ⢠Copy it from someone else who already has it.
- * Retrieve 'gawk' from the Internet host 'ftp.gnu.org', in the
- directory '/gnu/gawk'. Both anonymous 'ftp' and 'http' access are
- supported. If you have the 'wget' program, you can use a command
+ ⢠Retrieve âgawkâ from the Internet host âftp.gnu.orgâ, in the
+ directory â/gnu/gawkâ. Both anonymous âftpâ and âhttpâ
access are
+ supported. If you have the âwgetâ program, you can use a command
like the following:
wget https://ftp.gnu.org/gnu/gawk/gawk-5.2.2.tar.gz
@@ -31034,7 +31032,7 @@ up-to-date list of mirror sites is available from the
main FSF website
they will be less busy, and you can usually find one closer to your
site.
- You may also retrieve the 'gawk' source code from the official Git
+ You may also retrieve the âgawkâ source code from the official Git
repository; for more information see *note Accessing The Source::.
@@ -31043,275 +31041,275 @@ File: gawk.info, Node: Extracting, Next:
Distribution contents, Prev: Getting
B.1.2 Extracting the Distribution
---------------------------------
-'gawk' is distributed as several 'tar' files compressed with different
-compression programs: 'gzip', 'bzip2', and 'xz'. For simplicity, the
+âgawkâ is distributed as several âtarâ files compressed with different
+compression programs: âgzipâ, âbzip2â, and âxzâ. For simplicity,
the
rest of these instructions assume you are using the one compressed with
-the GNU Gzip program ('gzip').
+the GNU Gzip program (âgzipâ).
- Once you have the distribution (e.g., 'gawk-5.2.2.tar.gz'), use
-'gzip' to expand the file and then use 'tar' to extract it. You can use
-the following pipeline to produce the 'gawk' distribution:
+ Once you have the distribution (e.g., âgawk-5.2.2.tar.gzâ), use
+âgzipâ to expand the file and then use âtarâ to extract it. You can
use
+the following pipeline to produce the âgawkâ distribution:
gzip -d -c gawk-5.2.2.tar.gz | tar -xvpf -
- On a system with GNU 'tar', you can let 'tar' do the decompression
+ On a system with GNU âtarâ, you can let âtarâ do the decompression
for you:
tar -xvpzf gawk-5.2.2.tar.gz
-Extracting the archive creates a directory named 'gawk-5.2.2' in the
+Extracting the archive creates a directory named âgawk-5.2.2â in the
current directory.
- The distribution file name is of the form 'gawk-V.R.P.tar.gz'. The V
-represents the major version of 'gawk', the R represents the current
-release of version V, and the P represents a "patch level", meaning that
+ The distribution file name is of the form âgawk-V.R.P.tar.gzâ. The V
+represents the major version of âgawkâ, the R represents the current
+release of version V, and the P represents a âpatch levelâ, meaning that
minor bugs have been fixed in the release. The current patch level is
2, but when retrieving distributions, you should get the version with
the highest version, release, and patch level. (Note, however, that
-patch levels greater than or equal to 60 denote "beta" or nonproduction
-software; you might not want to retrieve such a version unless you don't
+patch levels greater than or equal to 60 denote âbetaâ or nonproduction
+software; you might not want to retrieve such a version unless you donât
mind experimenting.) If you are not on a Unix or GNU/Linux system, you
-need to make other arrangements for getting and extracting the 'gawk'
+need to make other arrangements for getting and extracting the âgawkâ
distribution. You should consult a local expert.
File: gawk.info, Node: Distribution contents, Prev: Extracting, Up: Gawk
Distribution
-B.1.3 Contents of the 'gawk' Distribution
+B.1.3 Contents of the âgawkâ Distribution
-----------------------------------------
-The 'gawk' distribution has a number of C source files, documentation
+The âgawkâ distribution has a number of C source files, documentation
files, subdirectories, and files related to the configuration process
(*note Unix Installation::), as well as several subdirectories related
to different non-Unix operating systems:
-Various '.c', '.y', and '.h' files
- These files contain the actual 'gawk' source code.
+Various â.câ, â.yâ, and â.hâ files
+ These files contain the actual âgawkâ source code.
-'support/*'
- C header and source files for routines that 'gawk' uses, but that
+âsupport/*â
+ C header and source files for routines that âgawkâ uses, but that
are not part of its core functionality. For example, argument
parsing, regular expression matching, and random number generating
routines are all kept here.
-'ABOUT-NLS'
- A file containing information about GNU 'gettext' and translations.
+âABOUT-NLSâ
+ A file containing information about GNU âgettextâ and translations.
-'AUTHORS'
- A file with some information about the authorship of 'gawk'. It
+âAUTHORSâ
+ A file with some information about the authorship of âgawkâ. It
exists only to satisfy the pedants at the Free Software Foundation.
-'README'
-'README_d/README.*'
- Descriptive files: 'README' for 'gawk' under Unix and the rest for
+âREADMEâ
+âREADME_d/README.*â
+ Descriptive files: âREADMEâ for âgawkâ under Unix and the rest for
the various hardware and software combinations.
-'INSTALL'
+âINSTALLâ
A file providing an overview of the configuration and installation
process.
-'ChangeLog'
+âChangeLogâ
A detailed list of source code changes as bugs are fixed or
improvements made. There are similar files in all of the
subdirectories.
-'ChangeLog.0'
-'ChangeLog.1'
+âChangeLog.0â
+âChangeLog.1â
Older lists of source code changes. There are similar files in all
of the subdirectories.
-'NEWS'
- A list of changes to 'gawk' since the last release or patch. There
+âNEWSâ
+ A list of changes to âgawkâ since the last release or patch. There
may be similar files in other subdirectories.
-'NEWS.0'
-'NEWS.1'
- Older lists of changes to 'gawk'. There may be similar files in
+âNEWS.0â
+âNEWS.1â
+ Older lists of changes to âgawkâ. There may be similar files in
other subdirectories.
-'COPYING'
+âCOPYINGâ
The GNU General Public License.
-'POSIX.STD'
- A description of behaviors in the POSIX standard for 'awk' that are
- left undefined, or where 'gawk' may not comply fully, as well as a
+âPOSIX.STDâ
+ A description of behaviors in the POSIX standard for âawkâ that are
+ left undefined, or where âgawkâ may not comply fully, as well as a
list of things that the POSIX standard should describe but does
not.
-'doc/awkforai.txt'
+âdoc/awkforai.txtâ
Pointers to the original draft of a short article describing why
- 'gawk' is a good language for artificial intelligence (AI)
+ âgawkâ is a good language for artificial intelligence (AI)
programming.
-'doc/bc_notes'
- A brief description of 'gawk''s "byte code" internals.
-
-'doc/README.card'
-'doc/ad.block'
-'doc/awkcard.in'
-'doc/cardfonts'
-'doc/colors'
-'doc/macros'
-'doc/no.colors'
-'doc/setter.outline'
- The 'troff' source for a five-color 'awk' reference card. A modern
- version of 'troff' such as GNU 'troff' ('groff') is needed to
- produce the color version. See the file 'README.card' for
- instructions if you have an older 'troff'.
-
-'doc/gawk.1'
- The 'troff' source for a manual page describing 'gawk'. This is
+âdoc/bc_notesâ
+ A brief description of âgawkââs âbyte codeâ internals.
+
+âdoc/README.cardâ
+âdoc/ad.blockâ
+âdoc/awkcard.inâ
+âdoc/cardfontsâ
+âdoc/colorsâ
+âdoc/macrosâ
+âdoc/no.colorsâ
+âdoc/setter.outlineâ
+ The âtroffâ source for a five-color âawkâ reference card. A
modern
+ version of âtroffâ such as GNU âtroffâ (âgroffâ) is needed to
+ produce the color version. See the file âREADME.cardâ for
+ instructions if you have an older âtroffâ.
+
+âdoc/gawk.1â
+ The âtroffâ source for a manual page describing âgawkâ. This is
distributed for the convenience of Unix users.
-'doc/gawktexi.in'
-'doc/sidebar.awk'
+âdoc/gawktexi.inâ
+âdoc/sidebar.awkâ
The Texinfo source file for this Info file. It should be processed
- by 'doc/sidebar.awk' before processing with 'texi2dvi' or
- 'texi2pdf' to produce a printed document, and with 'makeinfo' to
- produce an Info or HTML file. The 'Makefile' takes care of this
- processing and produces printable output via 'texi2dvi' or
- 'texi2pdf'.
+ by âdoc/sidebar.awkâ before processing with âtexi2dviâ or
+ âtexi2pdfâ to produce a printed document, and with âmakeinfoâ to
+ produce an Info or HTML file. The âMakefileâ takes care of this
+ processing and produces printable output via âtexi2dviâ or
+ âtexi2pdfâ.
-'doc/gawk.texi'
- The file produced after processing 'gawktexi.in' with
- 'sidebar.awk'.
+âdoc/gawk.texiâ
+ The file produced after processing âgawktexi.inâ with
+ âsidebar.awkâ.
-'doc/gawk.info'
+âdoc/gawk.infoâ
The generated Info file for this Info file.
-'doc/gawkinet.texi'
+âdoc/gawkinet.texiâ
The Texinfo source file for *note General Introduction:
- (gawkinet)Top. It should be processed with TeX (via 'texi2dvi' or
- 'texi2pdf') to produce a printed document and with 'makeinfo' to
+ (gawkinet)Top. It should be processed with TeX (via âtexi2dviâ or
+ âtexi2pdfâ) to produce a printed document and with âmakeinfoâ to
produce an Info or HTML file.
-'doc/gawkinet.info'
- The generated Info file for 'TCP/IP Internetworking with 'gawk''.
+âdoc/gawkinet.infoâ
+ The generated Info file for âTCP/IP Internetworking with âgawkââ.
-'doc/gawkworkflow.texi'
+âdoc/gawkworkflow.texiâ
The Texinfo source file for *note General Introduction:
- (gawkworkflow)Top. It should be processed with TeX (via 'texi2dvi'
- or 'texi2pdf') to produce a printed document and with 'makeinfo' to
+ (gawkworkflow)Top. It should be processed with TeX (via âtexi2dviâ
+ or âtexi2pdfâ) to produce a printed document and with âmakeinfoâ
to
produce an Info or HTML file.
-'doc/gawkworkflow.info'
- The generated Info file for 'Participating in 'gawk' Development'.
+âdoc/gawkworkflow.infoâ
+ The generated Info file for âParticipating in âgawkâ Developmentâ.
-'doc/pm-gawk.texi'
+âdoc/pm-gawk.texiâ
The Texinfo source file for *note General Introduction:
- (pm-gawk)Top. It should be processed with TeX (via 'texi2dvi' or
- 'texi2pdf') to produce a printed document and with 'makeinfo' to
+ (pm-gawk)Top. It should be processed with TeX (via âtexi2dviâ or
+ âtexi2pdfâ) to produce a printed document and with âmakeinfoâ to
produce an Info or HTML file.
-'doc/pm-gawk.info'
- The generated Info file for 'Persistent-Memory 'gawk' User Manual'.
+âdoc/pm-gawk.infoâ
+ The generated Info file for âPersistent-Memory âgawkâ User
Manualâ.
-'doc/pm-gawk.1'
- The 'troff' source for a manual page describing the the persistent
+âdoc/pm-gawk.1â
+ The âtroffâ source for a manual page describing the the persistent
memory features presented in *note Persistent Memory::.
-'doc/igawk.1'
- The 'troff' source for a manual page describing the 'igawk' program
- presented in *note Igawk Program::. (Since 'gawk' can do its own
- '@include' processing, neither 'igawk' nor 'igawk.1' are
+âdoc/igawk.1â
+ The âtroffâ source for a manual page describing the âigawkâ
program
+ presented in *note Igawk Program::. (Since âgawkâ can do its own
+ â@includeâ processing, neither âigawkâ nor âigawk.1â are
installed.)
-'doc/it/*'
+âdoc/it/*â
Files for the Italian translation of this Info file, produced and
contributed by Antonio Colombo and Marco Curreli.
-'doc/Makefile.in'
+âdoc/Makefile.inâ
The input file used during the configuration process to generate
- the actual 'Makefile' for creating the documentation.
+ the actual âMakefileâ for creating the documentation.
-'Makefile.am'
-'*/Makefile.am'
+âMakefile.amâ
+â*/Makefile.amâ
Files used by the GNU Automake software for generating the
- 'Makefile.in' files used by Autoconf and 'configure'.
-
-'Makefile.in'
-'aclocal.m4'
-'build-aux/*'
-'configh.in'
-'configure.ac'
-'configure'
-'custom.h'
-'missing_d/*'
-'m4/*'
+ âMakefile.inâ files used by Autoconf and âconfigureâ.
+
+âMakefile.inâ
+âaclocal.m4â
+âbuild-aux/*â
+âconfigh.inâ
+âconfigure.acâ
+âconfigureâ
+âcustom.hâ
+âmissing_d/*â
+âm4/*â
These files and subdirectories are used when configuring and
- compiling 'gawk' for various Unix systems. Most of them are
+ compiling âgawkâ for various Unix systems. Most of them are
explained in *note Unix Installation::. The rest are there to
support the main infrastructure.
-'po/*'
- The 'po' library contains message translations.
+âpo/*â
+ The âpoâ library contains message translations.
-'awklib/extract.awk'
-'awklib/Makefile.am'
-'awklib/Makefile.in'
-'awklib/eg/*'
- The 'awklib' directory contains a copy of 'extract.awk' (*note
+âawklib/extract.awkâ
+âawklib/Makefile.amâ
+âawklib/Makefile.inâ
+âawklib/eg/*â
+ The âawklibâ directory contains a copy of âextract.awkâ (*note
Extract Program::), which can be used to extract the sample
programs from the Texinfo source file for this Info file. It also
- contains a 'Makefile.in' file, which 'configure' uses to generate a
- 'Makefile'. 'Makefile.am' is used by GNU Automake to create
- 'Makefile.in'. The library functions from *note Library
- Functions::, are included as ready-to-use files in the 'gawk'
+ contains a âMakefile.inâ file, which âconfigureâ uses to generate
a
+ âMakefileâ. âMakefile.amâ is used by GNU Automake to create
+ âMakefile.inâ. The library functions from *note Library
+ Functions::, are included as ready-to-use files in the âgawkâ
distribution. They are installed as part of the installation
process. The rest of the programs in this Info file are available
- in appropriate subdirectories of 'awklib/eg'.
+ in appropriate subdirectories of âawklib/egâ.
-'extension/*'
+âextension/*â
The source code, manual pages, and infrastructure files for the
- sample extensions included with 'gawk'. *Note Dynamic
+ sample extensions included with âgawkâ. *Note Dynamic
Extensions::, for more information.
-'extras/*'
+âextras/*â
Additional non-essential files. Currently, this directory contains
- some shell startup files to be installed in '/etc/profile.d' to aid
- in manipulating the 'AWKPATH' and 'AWKLIBPATH' environment
+ some shell startup files to be installed in â/etc/profile.dâ to aid
+ in manipulating the âAWKPATHâ and âAWKLIBPATHâ environment
variables. *Note Shell Startup Files::, for more information.
-'posix/*'
- Files needed for building 'gawk' on POSIX-compliant systems.
+âposix/*â
+ Files needed for building âgawkâ on POSIX-compliant systems.
-'pc/*'
- Files needed for building 'gawk' under MS-Windows (*note PC
+âpc/*â
+ Files needed for building âgawkâ under MS-Windows (*note PC
Installation:: for details).
-'vms/*'
- Files needed for building 'gawk' under OpenVMS (*note OpenVMS
+âvms/*â
+ Files needed for building âgawkâ under OpenVMS (*note OpenVMS
Installation:: for details).
-'test/*'
- A test suite for 'gawk'. You can use 'make check' from the
- top-level 'gawk' directory to run your version of 'gawk' against
- the test suite. If 'gawk' successfully passes 'make check', then
+âtest/*â
+ A test suite for âgawkâ. You can use âmake checkâ from the
+ top-level âgawkâ directory to run your version of âgawkâ against
+ the test suite. If âgawkâ successfully passes âmake checkâ, then
you can be confident of a successful port.
File: gawk.info, Node: Unix Installation, Next: Non-Unix Installation,
Prev: Gawk Distribution, Up: Installation
-B.2 Compiling and Installing 'gawk' on Unix-Like Systems
+B.2 Compiling and Installing âgawkâ on Unix-Like Systems
========================================================
-Usually, you can compile and install 'gawk' by typing only two commands.
-However, if you use an unusual system, you may need to configure 'gawk'
+Usually, you can compile and install âgawkâ by typing only two commands.
+However, if you use an unusual system, you may need to configure âgawkâ
for your system yourself.
* Menu:
-* Quick Installation:: Compiling 'gawk' under Unix.
+* Quick Installation:: Compiling âgawkâ under Unix.
* Shell Startup Files:: Shell convenience functions.
* Additional Configuration Options:: Other compile-time options.
-* Configuration Philosophy:: How it's all supposed to work.
+* Configuration Philosophy:: How itâs all supposed to work.
* Compiling from Git:: Compiling from Git.
* Building the Documentation:: Building the Documentation.
File: gawk.info, Node: Quick Installation, Next: Shell Startup Files, Up:
Unix Installation
-B.2.1 Compiling 'gawk' for Unix-Like Systems
+B.2.1 Compiling âgawkâ for Unix-Like Systems
--------------------------------------------
* Menu:
@@ -31322,50 +31320,50 @@ The normal installation steps should work on all
modern commercial
Unix-derived systems, GNU/Linux, BSD-based systems, and the Cygwin
environment for MS-Windows.
- After you have extracted the 'gawk' distribution, 'cd' to
-'gawk-5.2.2'. As with most GNU software, you configure 'gawk' for your
-system by running the 'configure' program. This program is a Bourne
+ After you have extracted the âgawkâ distribution, âcdâ to
+âgawk-5.2.2â. As with most GNU software, you configure âgawkâ for your
+system by running the âconfigureâ program. This program is a Bourne
shell script that is generated automatically using GNU Autoconf. (The
Autoconf software is described fully starting with *note Autoconf:
(autoconf)Top.)
- To configure 'gawk', simply run 'configure':
+ To configure âgawkâ, simply run âconfigureâ:
sh ./configure
- This produces a 'Makefile' and 'config.h' tailored to your system.
-The 'config.h' file describes various facts about your system. You
-might want to edit the 'Makefile' to change the 'CFLAGS' variable, which
+ This produces a âMakefileâ and âconfig.hâ tailored to your system.
+The âconfig.hâ file describes various facts about your system. You
+might want to edit the âMakefileâ to change the âCFLAGSâ variable,
which
controls the command-line options that are passed to the C compiler
(such as optimization levels or compiling for debugging).
- Alternatively, you can add your own values for most 'make' variables
-on the command line, such as 'CC' and 'CFLAGS', when running
-'configure':
+ Alternatively, you can add your own values for most âmakeâ variables
+on the command line, such as âCCâ and âCFLAGSâ, when running
+âconfigureâ:
CC=cc CFLAGS=-g sh ./configure
-See the file 'INSTALL' in the 'gawk' distribution for all the details.
+See the file âINSTALLâ in the âgawkâ distribution for all the details.
- After you have run 'configure' and possibly edited the 'Makefile',
+ After you have run âconfigureâ and possibly edited the âMakefileâ,
type:
make
-Shortly thereafter, you should have an executable version of 'gawk'.
-That's all there is to it! To verify that 'gawk' is working properly,
-run 'make check'. All of the tests should succeed. If these steps do
-not work, or if any of the tests fail, check the files in the 'README_d'
-directory to see if you've found a known problem. If the failure is not
+Shortly thereafter, you should have an executable version of âgawkâ.
+Thatâs all there is to it! To verify that âgawkâ is working properly,
+run âmake checkâ. All of the tests should succeed. If these steps do
+not work, or if any of the tests fail, check the files in the âREADME_dâ
+directory to see if youâve found a known problem. If the failure is not
described there, send in a bug report (*note Bugs::).
- Of course, once you've built 'gawk', it is likely that you will wish
-to install it. To do so, you need to run the command 'make install', as
+ Of course, once youâve built âgawkâ, it is likely that you will wish
+to install it. To do so, you need to run the command âmake installâ, as
a user with the appropriate permissions. How to do this varies by
-system, but on many systems you can use the 'sudo' command to do so.
-The command then becomes 'sudo make install'. It is likely that you
+system, but on many systems you can use the âsudoâ command to do so.
+The command then becomes âsudo make installâ. It is likely that you
will be asked for your password, and you will have to have been set up
-previously as a user who is allowed to run the 'sudo' command.
+previously as a user who is allowed to run the âsudoâ command.
File: gawk.info, Node: Compiling with MPFR, Up: Quick Installation
@@ -31373,12 +31371,12 @@ File: gawk.info, Node: Compiling with MPFR, Up:
Quick Installation
B.2.1.1 Building With MPFR
..........................
-Use of the MPFR library with 'gawk' is an optional feature: if you have
+Use of the MPFR library with âgawkâ is an optional feature: if you have
the MPFR and GMP libraries already installed when you configure and
-build 'gawk', 'gawk' automatically will be able to use them.
+build âgawkâ, âgawkâ automatically will be able to use them.
You can install these libraries from source code by fetching them
-from the GNU distribution site at 'ftp.gnu.org'.
+from the GNU distribution site at âftp.gnu.orgâ.
Most modern systems provide package managers which save you the
trouble of building from source. They fetch and install the library
@@ -31391,31 +31389,31 @@ File: gawk.info, Node: Shell Startup Files, Next:
Additional Configuration Opt
B.2.2 Shell Startup Files
-------------------------
-The distribution contains shell startup files 'gawk.sh' and 'gawk.csh',
-containing functions to aid in manipulating the 'AWKPATH' and
-'AWKLIBPATH' environment variables. On a Fedora GNU/Linux system, these
-files should be installed in '/etc/profile.d'; on other platforms, the
+The distribution contains shell startup files âgawk.shâ and âgawk.cshâ,
+containing functions to aid in manipulating the âAWKPATHâ and
+âAWKLIBPATHâ environment variables. On a Fedora GNU/Linux system, these
+files should be installed in â/etc/profile.dâ; on other platforms, the
appropriate location may be different.
-'gawkpath_default'
- Reset the 'AWKPATH' environment variable to its default value.
+âgawkpath_defaultâ
+ Reset the âAWKPATHâ environment variable to its default value.
-'gawkpath_prepend'
- Add the argument to the front of the 'AWKPATH' environment
+âgawkpath_prependâ
+ Add the argument to the front of the âAWKPATHâ environment
variable.
-'gawkpath_append'
- Add the argument to the end of the 'AWKPATH' environment variable.
+âgawkpath_appendâ
+ Add the argument to the end of the âAWKPATHâ environment variable.
-'gawklibpath_default'
- Reset the 'AWKLIBPATH' environment variable to its default value.
+âgawklibpath_defaultâ
+ Reset the âAWKLIBPATHâ environment variable to its default value.
-'gawklibpath_prepend'
- Add the argument to the front of the 'AWKLIBPATH' environment
+âgawklibpath_prependâ
+ Add the argument to the front of the âAWKLIBPATHâ environment
variable.
-'gawklibpath_append'
- Add the argument to the end of the 'AWKLIBPATH' environment
+âgawklibpath_appendâ
+ Add the argument to the end of the âAWKLIBPATHâ environment
variable.
@@ -31424,28 +31422,28 @@ File: gawk.info, Node: Additional Configuration
Options, Next: Configuration P
B.2.3 Additional Configuration Options
--------------------------------------
-There are several additional options you may use on the 'configure'
-command line when compiling 'gawk' from scratch, including:
+There are several additional options you may use on the âconfigureâ
+command line when compiling âgawkâ from scratch, including:
-'--disable-extensions'
- Disable the extension mechanism within 'gawk'. With this option,
+â--disable-extensionsâ
+ Disable the extension mechanism within âgawkâ. With this option,
it is not possible to use dynamic extensions. This also disables
- configuring and building the sample extensions in the 'extension'
+ configuring and building the sample extensions in the âextensionâ
directory.
This option may be useful for cross-compiling. The default action
is to dynamically check if the extensions can be configured and
compiled.
-'--disable-lint'
- Disable all lint checking within 'gawk'. The '--lint' and
- '--lint-old' options (*note Options::) are accepted, but silently
- do nothing. Similarly, setting the 'LINT' variable (*note
- User-modified::) has no effect on the running 'awk' program.
+â--disable-lintâ
+ Disable all lint checking within âgawkâ. The â--lintâ and
+ â--lint-oldâ options (*note Options::) are accepted, but silently
+ do nothing. Similarly, setting the âLINTâ variable (*note
+ User-modified::) has no effect on the running âawkâ program.
- When used with the GNU Compiler Collection's (GCC's) automatic
+ When used with the GNU Compiler Collectionâs (GCCâs) automatic
dead-code-elimination, this option cuts almost 23K bytes off the
- size of the 'gawk' executable on GNU/Linux x86_64 systems. Results
+ size of the âgawkâ executable on GNU/Linux x86_64 systems. Results
on other systems and with other compilers are likely to vary.
Using this option may bring you some slight performance
improvement.
@@ -31454,24 +31452,24 @@ command line when compiling 'gawk' from scratch,
including:
test suite to fail. This option may be removed at a later
date.
-'--disable-mpfr'
+â--disable-mpfrâ
Skip checking for the MPFR and GMP libraries. This is useful
mainly for the developers, to make sure nothing breaks if MPFR
support is not available.
-'--disable-nls'
+â--disable-nlsâ
Disable all message-translation facilities. This is usually not
desirable, but it may bring you some slight performance
improvement.
-'--enable-versioned-extension-dir'
+â--enable-versioned-extension-dirâ
Use a versioned directory for extensions. The directory name will
include the major and minor API versions in it. This makes it
possible to keep extensions for different API versions on the same
system without their conflicting with one another.
- Use the command './configure --help' to see the full list of options
-supplied by 'configure'.
+ Use the command â./configure --helpâ to see the full list of options
+supplied by âconfigureâ.
File: gawk.info, Node: Configuration Philosophy, Next: Compiling from Git,
Prev: Additional Configuration Options, Up: Unix Installation
@@ -31482,42 +31480,42 @@ B.2.4 The Configuration Process
This minor node is of interest only if you know something about using
the C language and Unix-like operating systems.
- The source code for 'gawk' generally attempts to adhere to formal
-standards wherever possible. This means that 'gawk' uses library
+ The source code for âgawkâ generally attempts to adhere to formal
+standards wherever possible. This means that âgawkâ uses library
routines that are specified by the ISO C standard and by the POSIX
-operating system interface standard. The 'gawk' source code requires
+operating system interface standard. The âgawkâ source code requires
using an ISO C compiler (the 1999 standard).
Many Unix systems do not support all of either the ISO or the POSIX
-standards. The 'missing_d' subdirectory in the 'gawk' distribution
+standards. The âmissing_dâ subdirectory in the âgawkâ distribution
contains replacement versions of those functions that are most likely to
be missing.
- The 'config.h' file that 'configure' creates contains definitions
+ The âconfig.hâ file that âconfigureâ creates contains definitions
that describe features of the particular operating system where you are
-attempting to compile 'gawk'. The three things described by this file
+attempting to compile âgawkâ. The three things described by this file
are: what header files are available, so that they can be correctly
included, what (supposedly) standard functions are actually available in
your C libraries, and various miscellaneous facts about your operating
-system. For example, there may not be an 'st_blksize' element in the
-'stat' structure. In this case, 'HAVE_STRUCT_STAT_ST_BLKSIZE' is
+system. For example, there may not be an âst_blksizeâ element in the
+âstatâ structure. In this case, âHAVE_STRUCT_STAT_ST_BLKSIZEâ is
undefined.
- It is possible for your C compiler to lie to 'configure'. It may do
+ It is possible for your C compiler to lie to âconfigureâ. It may do
so by not exiting with an error when a library function is not
-available. To get around this, edit the 'custom.h' file. Use an
-'#ifdef' that is appropriate for your system, and either '#define' any
-constants that 'configure' should have defined but didn't, or '#undef'
-any constants that 'configure' defined and should not have. The
-'custom.h' file is automatically included by the 'config.h' file.
+available. To get around this, edit the âcustom.hâ file. Use an
+â#ifdefâ that is appropriate for your system, and either â#defineâ any
+constants that âconfigureâ should have defined but didnât, or
â#undefâ
+any constants that âconfigureâ defined and should not have. The
+âcustom.hâ file is automatically included by the âconfig.hâ file.
- It is also possible that the 'configure' program generated by
+ It is also possible that the âconfigureâ program generated by
Autoconf will not work on your system in some other fashion. If you do
-have a problem, the 'configure.ac' file is the input for Autoconf. You
+have a problem, the âconfigure.acâ file is the input for Autoconf. You
may be able to change this file and generate a new version of
-'configure' that works on your system (*note Bugs:: for information on
-how to report problems in configuring 'gawk'). The same mechanism may
-be used to send in updates to 'configure.ac' and/or 'custom.h'.
+âconfigureâ that works on your system (*note Bugs:: for information on
+how to report problems in configuring âgawkâ). The same mechanism may
+be used to send in updates to âconfigure.acâ and/or âcustom.hâ.
File: gawk.info, Node: Compiling from Git, Next: Building the Documentation,
Prev: Configuration Philosophy, Up: Unix Installation
@@ -31525,7 +31523,7 @@ File: gawk.info, Node: Compiling from Git, Next:
Building the Documentation,
B.2.5 Compiling from Git
------------------------
-Building 'gawk' directly from the development source control repository
+Building âgawkâ directly from the development source control repository
is possible, but not recommended for everyday users, as the code may not
be as stable as released versions are. If you really do want to do
that, here are the steps:
@@ -31540,16 +31538,16 @@ File: gawk.info, Node: Building the Documentation,
Prev: Compiling from Git,
B.2.6 Building the Documentation
--------------------------------
-The generated Info documentation is included in the distribution 'tar'
+The generated Info documentation is included in the distribution âtarâ
files and in the Git source code repository; you should not need to
-rebuild it. However, if it needs to be done, simply running 'make' will
-do it, assuming that you have a recent enough version of 'makeinfo'
+rebuild it. However, if it needs to be done, simply running âmakeâ will
+do it, assuming that you have a recent enough version of âmakeinfoâ
installed.
If you wish to build the PDF version of the manuals, you will need to
have TeX installed, and possibly additional packages that provide the
-necessary fonts and tools, such as 'dvi2pdf' and 'ps2pdf'. You will
-also need GNU Troff ('groff') installed in order to format the reference
+necessary fonts and tools, such as âdvi2pdfâ and âps2pdfâ. You will
+also need GNU Troff (âgroffâ) installed in order to format the reference
card and the manual page (*note Distribution contents::). Managing this
process is beyond the scope of this Info file.
@@ -31562,7 +31560,7 @@ the PDF versions of the documentation:
This creates PDF versions of all three Texinfo documents included in the
distribution, as well as of the manual page and the reference card.
- Similarly, if you have a recent enough version of 'makeinfo', you can
+ Similarly, if you have a recent enough version of âmakeinfoâ, you can
make the HTML version of the manuals with:
cd doc
@@ -31577,14 +31575,14 @@ File: gawk.info, Node: Non-Unix Installation, Next:
Bugs, Prev: Unix Installa
B.3 Installation on Other Operating Systems
===========================================
-This minor node describes how to install 'gawk' on various non-Unix
+This minor node describes how to install âgawkâ on various non-Unix
systems.
* Menu:
-* PC Installation:: Installing and Compiling 'gawk' on
+* PC Installation:: Installing and Compiling âgawkâ on
Microsoft Windows.
-* OpenVMS Installation:: Installing 'gawk' on OpenVMS.
+* OpenVMS Installation:: Installing âgawkâ on OpenVMS.
File: gawk.info, Node: PC Installation, Next: OpenVMS Installation, Up:
Non-Unix Installation
@@ -31592,21 +31590,21 @@ File: gawk.info, Node: PC Installation, Next:
OpenVMS Installation, Up: Non-U
B.3.1 Installation on MS-Windows
--------------------------------
-This minor node covers installation and usage of 'gawk' on Intel
+This minor node covers installation and usage of âgawkâ on Intel
architecture machines running any version of MS-Windows. In this minor
-node, the term "Windows32" refers to any of Microsoft Windows
+node, the term âWindows32â refers to any of Microsoft Windows
95/98/ME/NT/2000/XP/Vista/7/8/10/11.
- See also the 'README_d/README.pc' file in the distribution.
+ See also the âREADME_d/README.pcâ file in the distribution.
* Menu:
* PC Binary Installation:: Installing a prepared distribution.
-* PC Compiling:: Compiling 'gawk' for Windows32.
-* PC Using:: Running 'gawk' on Windows32.
-* Cygwin:: Building and running 'gawk' for
+* PC Compiling:: Compiling âgawkâ for Windows32.
+* PC Using:: Running âgawkâ on Windows32.
+* Cygwin:: Building and running âgawkâ for
Cygwin.
-* MSYS:: Using 'gawk' In The MSYS Environment.
+* MSYS:: Using âgawkâ In The MSYS Environment.
File: gawk.info, Node: PC Binary Installation, Next: PC Compiling, Up: PC
Installation
@@ -31615,101 +31613,101 @@ B.3.1.1 Installing a Prepared Distribution for
MS-Windows Systems
.................................................................
The only supported binary distribution for MS-Windows systems is that
-provided by Eli Zaretskii's "ezwinports"
+provided by Eli Zaretskiiâs âezwinportsâ
(https://sourceforge.net/projects/ezwinports/) project. Install the
-compiled 'gawk' from there. Note that to run that port, you need to
-have the 'libgcc_s_dw2-1.dll' file installed on your system. This file
+compiled âgawkâ from there. Note that to run that port, you need to
+have the âlibgcc_s_dw2-1.dllâ file installed on your system. This file
is part of the GCC distribution, and should reside either in the same
-directory where you install 'gawk.exe' or somewhere on your system's
-'Path'. You can download this file from the MinGW site
-(https://osdn.net/projects/mingw/releases); look under the "MinGW.org
-Compiler Collection (GCC)" for the 'LibGCC-1.DLL' download.
+directory where you install âgawk.exeâ or somewhere on your systemâs
+âPathâ. You can download this file from the MinGW site
+(https://osdn.net/projects/mingw/releases); look under the âMinGW.org
+Compiler Collection (GCC)â for the âLibGCC-1.DLLâ download.
File: gawk.info, Node: PC Compiling, Next: PC Using, Prev: PC Binary
Installation, Up: PC Installation
-B.3.1.2 Compiling 'gawk' for PC Operating Systems
+B.3.1.2 Compiling âgawkâ for PC Operating Systems
.................................................
-'gawk' can be compiled for Windows32 using MinGW (Windows32). The file
-'README_d/README.pc' in the 'gawk' distribution contains additional
-notes, and 'pc/Makefile' contains important information on compilation
+âgawkâ can be compiled for Windows32 using MinGW (Windows32). The file
+âREADME_d/README.pcâ in the âgawkâ distribution contains additional
+notes, and âpc/Makefileâ contains important information on compilation
options.
- To build 'gawk' for Windows32, copy the files in the 'pc' directory
-(_except_ for 'ChangeLog') to the directory with the rest of the 'gawk'
-sources, then invoke 'make' with the appropriate target name as an
-argument to build 'gawk'. The 'Makefile' copied from the 'pc' directory
+ To build âgawkâ for Windows32, copy the files in the âpcâ directory
+(_except_ for âChangeLogâ) to the directory with the rest of the âgawkâ
+sources, then invoke âmakeâ with the appropriate target name as an
+argument to build âgawkâ. The âMakefileâ copied from the âpcâ
directory
contains a configuration section with comments and may need to be edited
-in order to work with your 'make' utility.
+in order to work with your âmakeâ utility.
- The 'Makefile' supports a number of targets for building various
-Windows32 versions. A list of targets is printed if the 'make' command
+ The âMakefileâ supports a number of targets for building various
+Windows32 versions. A list of targets is printed if the âmakeâ command
is given without a target. As an example, to build a native MS-Windows
-binary of 'gawk' using the MinGW tools, type 'make mingw32'.
+binary of âgawkâ using the MinGW tools, type âmake mingw32â.
File: gawk.info, Node: PC Using, Next: Cygwin, Prev: PC Compiling, Up: PC
Installation
-B.3.1.3 Using 'gawk' on PC Operating Systems
+B.3.1.3 Using âgawkâ on PC Operating Systems
............................................
-Information in this section applies to the MinGW port of 'gawk'. *Note
+Information in this section applies to the MinGW port of âgawkâ. *Note
Cygwin:: for information about the Cygwin port.
- Under MS-Windows, the MinGW environment supports both the '|&'
+ Under MS-Windows, the MinGW environment supports both the â|&â
operator and TCP/IP networking (*note TCP/IP Networking::).
- The MS-Windows version of 'gawk' searches for program files as
+ The MS-Windows version of âgawkâ searches for program files as
described in *note AWKPATH Variable::. However, semicolons (rather than
-colons) separate elements in the 'AWKPATH' variable. If 'AWKPATH' is
+colons) separate elements in the âAWKPATHâ variable. If âAWKPATHâ is
not set or is empty, then the default search path is
-'.;c:/lib/awk;c:/gnu/lib/awk'.
+â.;c:/lib/awk;c:/gnu/lib/awkâ.
- Under MS-Windows, 'gawk' (and many other text programs) silently
-translates end-of-line '\r\n' to '\n' on input and '\n' to '\r\n' on
-output. A special 'BINMODE' variable (c.e.) allows control over these
+ Under MS-Windows, âgawkâ (and many other text programs) silently
+translates end-of-line â\r\nâ to â\nâ on input and â\nâ to
â\r\nâ on
+output. A special âBINMODEâ variable (c.e.) allows control over these
translations and is interpreted as follows:
- * If 'BINMODE' is '"r"' or one, then binary mode is set on read
+ ⢠If âBINMODEâ is â"r"â or one, then binary mode is set on read
(i.e., no translations on reads).
- * If 'BINMODE' is '"w"' or two, then binary mode is set on write
+ ⢠If âBINMODEâ is â"w"â or two, then binary mode is set on write
(i.e., no translations on writes).
- * If 'BINMODE' is '"rw"' or '"wr"' or three, binary mode is set for
+ ⢠If âBINMODEâ is â"rw"â or â"wr"â or three, binary mode is
set for
both read and write.
- * 'BINMODE=NON-NULL-STRING' is the same as 'BINMODE=3' (i.e., no
- translations on reads or writes). However, 'gawk' issues a warning
- message if the string is not one of '"rw"' or '"wr"'.
+ ⢠âBINMODE=NON-NULL-STRINGâ is the same as âBINMODE=3â (i.e., no
+ translations on reads or writes). However, âgawkâ issues a warning
+ message if the string is not one of â"rw"â or â"wr"â.
The modes for standard input and standard output are set one time only
-(after the command line is read, but before processing any of the 'awk'
-program). Setting 'BINMODE' for standard input or standard output is
-accomplished by using an appropriate '-v BINMODE=N' option on the
-command line. 'BINMODE' is set at the time a file or pipe is opened and
+(after the command line is read, but before processing any of the âawkâ
+program). Setting âBINMODEâ for standard input or standard output is
+accomplished by using an appropriate â-v BINMODE=Nâ option on the
+command line. âBINMODEâ is set at the time a file or pipe is opened and
cannot be changed midstream.
- On POSIX-compatible systems, this variable's value has no effect.
+ On POSIX-compatible systems, this variableâs value has no effect.
Thus, if you think your program will run on multiple different systems
-and that you may need to use 'BINMODE', you should simply set it (in the
+and that you may need to use âBINMODEâ, you should simply set it (in the
program or on the command line) unconditionally, and not worry about the
operating system on which your program is running.
- The name 'BINMODE' was chosen to match 'mawk' (*note Other
-Versions::). 'mawk' and 'gawk' handle 'BINMODE' similarly; however,
-'mawk' adds a '-W BINMODE=N' option and an environment variable that can
-set 'BINMODE', 'RS', and 'ORS'. The files 'binmode[1-3].awk' (under
-'gnu/lib/awk' in some of the prepared binary distributions) have been
-chosen to match 'mawk''s '-W BINMODE=N' option. These can be changed or
-discarded; in particular, the setting of 'RS' giving the fewest
-"surprises" is open to debate. 'mawk' uses 'RS = "\r\n"' if binary mode
+ The name âBINMODEâ was chosen to match âmawkâ (*note Other
+Versions::). âmawkâ and âgawkâ handle âBINMODEâ similarly;
however,
+âmawkâ adds a â-W BINMODE=Nâ option and an environment variable that
can
+set âBINMODEâ, âRSâ, and âORSâ. The files âbinmode[1-3].awkâ
(under
+âgnu/lib/awkâ in some of the prepared binary distributions) have been
+chosen to match âmawkââs â-W BINMODE=Nâ option. These can be
changed or
+discarded; in particular, the setting of âRSâ giving the fewest
+âsurprisesâ is open to debate. âmawkâ uses âRS = "\r\n"â if
binary mode
is set on read, which is appropriate for files with the MS-DOS-style
end-of-line.
To illustrate, the following examples set binary mode on writes for
-standard output and other files, and set 'ORS' as the "usual"
+standard output and other files, and set âORSâ as the âusualâ
MS-DOS-style end-of-line:
gawk -v BINMODE=2 -v ORS="\r\n" ...
@@ -31718,8 +31716,8 @@ or:
gawk -v BINMODE=w -f binmode2.awk ...
-These give the same result as the '-W BINMODE=2' option in 'mawk'. The
-following changes the record separator to '"\r\n"' and sets binary mode
+These give the same result as the â-W BINMODE=2â option in âmawkâ. The
+following changes the record separator to â"\r\n"â and sets binary mode
on reads, but does not affect the mode on standard input:
gawk -v RS="\r\n" -e "BEGIN { BINMODE = 1 }" ...
@@ -31728,16 +31726,16 @@ or:
gawk -f binmode1.awk ...
-With proper quoting, in the first example the setting of 'RS' can be
-moved into the 'BEGIN' rule.
+With proper quoting, in the first example the setting of âRSâ can be
+moved into the âBEGINâ rule.
File: gawk.info, Node: Cygwin, Next: MSYS, Prev: PC Using, Up: PC
Installation
-B.3.1.4 Using 'gawk' In The Cygwin Environment
+B.3.1.4 Using âgawkâ In The Cygwin Environment
..............................................
-'gawk' can be built and used "out of the box" under MS-Windows if you
+âgawkâ can be built and used âout of the boxâ under MS-Windows if you
are using the Cygwin environment (http://www.cygwin.com). This
environment provides an excellent simulation of GNU/Linux, using Bash,
GCC, GNU Make, and other GNU programs. Compilation and installation for
@@ -31748,64 +31746,64 @@ Cygwin is the same as for a Unix system:
./configure
make && make check
- When compared to GNU/Linux on the same system, the 'configure' step
+ When compared to GNU/Linux on the same system, the âconfigureâ step
on Cygwin takes considerably longer. However, it does finish, and then
-the 'make' proceeds as usual.
+the âmakeâ proceeds as usual.
- You may also install 'gawk' using the regular Cygwin installer. In
+ You may also install âgawkâ using the regular Cygwin installer. In
general Cygwin supplies the latest released version.
Recent versions of Cygwin open all files in binary mode. This means
-that you should use 'RS = "\r?\n"' in order to be able to handle
+that you should use âRS = "\r?\n"â in order to be able to handle
standard MS-Windows text files with carriage-return plus line-feed line
endings.
- The Cygwin environment supports both the '|&' operator and TCP/IP
+ The Cygwin environment supports both the â|&â operator and TCP/IP
networking (*note TCP/IP Networking::).
File: gawk.info, Node: MSYS, Prev: Cygwin, Up: PC Installation
-B.3.1.5 Using 'gawk' In The MSYS Environment
+B.3.1.5 Using âgawkâ In The MSYS Environment
............................................
-In the MSYS environment under MS-Windows, 'gawk' automatically uses
+In the MSYS environment under MS-Windows, âgawkâ automatically uses
binary mode for reading and writing files. Thus, there is no need to
-use the 'BINMODE' variable.
+use the âBINMODEâ variable.
This can cause problems with other Unix-like components that have
-been ported to MS-Windows that expect 'gawk' to do automatic translation
-of '"\r\n"', because it won't.
+been ported to MS-Windows that expect âgawkâ to do automatic translation
+of â"\r\n"â, because it wonât.
- Under MSYS2, compilation using the standard './configure && make'
-recipe works "out of the box."
+ Under MSYS2, compilation using the standard â./configure && makeâ
+recipe works âout of the box.â
File: gawk.info, Node: OpenVMS Installation, Prev: PC Installation, Up:
Non-Unix Installation
-B.3.2 Compiling and Installing 'gawk' on OpenVMS
+B.3.2 Compiling and Installing âgawkâ on OpenVMS
------------------------------------------------
-This node describes how to compile and install 'gawk' under OpenVMS.
+This node describes how to compile and install âgawkâ under OpenVMS.
* Menu:
-* OpenVMS Compilation:: How to compile 'gawk' under OpenVMS.
-* OpenVMS Dynamic Extensions:: Compiling 'gawk' dynamic extensions
+* OpenVMS Compilation:: How to compile âgawkâ under OpenVMS.
+* OpenVMS Dynamic Extensions:: Compiling âgawkâ dynamic extensions
on OpenVMS.
-* OpenVMS Installation Details:: How to install 'gawk' under OpenVMS.
-* OpenVMS Running:: How to run 'gawk' under OpenVMS.
+* OpenVMS Installation Details:: How to install âgawkâ under OpenVMS.
+* OpenVMS Running:: How to run âgawkâ under OpenVMS.
* OpenVMS GNV:: The OpenVMS GNV Project.
File: gawk.info, Node: OpenVMS Compilation, Next: OpenVMS Dynamic
Extensions, Up: OpenVMS Installation
-B.3.2.1 Compiling 'gawk' on OpenVMS
+B.3.2.1 Compiling âgawkâ on OpenVMS
...................................
-To compile 'gawk' under OpenVMS, there is a 'DCL' command procedure that
-issues all the necessary 'CC' and 'LINK' commands. There is also a
-'Makefile' for use with the 'MMS' and 'MMK' utilities. From the source
+To compile âgawkâ under OpenVMS, there is a âDCLâ command procedure
that
+issues all the necessary âCCâ and âLINKâ commands. There is also a
+âMakefileâ for use with the âMMSâ and âMMKâ utilities. From the
source
directory, use either:
$ @[.vms]vmsbuild.com
@@ -31818,37 +31816,37 @@ or:
$ MMK/DESCRIPTION=[.vms]descrip.mms gawk
- Note that the 'vmsbuild.com' method of building is no longer being
+ Note that the âvmsbuild.comâ method of building is no longer being
maintained and is planned to be removed in the future.
- 'MMK' is an open source, free, near-clone of 'MMS' and can better
-handle ODS-5 volumes with upper- and lowercase file names. 'MMK' is
+ âMMKâ is an open source, free, near-clone of âMMSâ and can better
+handle ODS-5 volumes with upper- and lowercase file names. âMMKâ is
available from <https://github.com/endlesssoftware/mmk>.
With ODS-5 volumes and extended parsing enabled, the case of the
target parameter may need to be exact.
- 'gawk' has been tested using these VMS Software, Inc. Community
+ âgawkâ has been tested using these VMS Software, Inc. Community
editions:
- * HP C V7.3-010 on OpenVMS Alpha V8.4-2L1.
+ ⢠HP C V7.3-010 on OpenVMS Alpha V8.4-2L1.
- * HP C V7.3-020 on OpenVMS IA64 V8.4-2L3.(1)
+ ⢠HP C V7.3-020 on OpenVMS IA64 V8.4-2L3.(1)
Due to HPE cancelling the Hobbyist licensing program, no more testing
is being done on older releases of OpenVMS.
- *Note OpenVMS GNV:: for information on building 'gawk' as a PCSI kit
+ *Note OpenVMS GNV:: for information on building âgawkâ as a PCSI kit
that is compatible with the GNV product.
---------- Footnotes ----------
- (1) The IA64 architecture is also known as "Itanium."
+ (1) The IA64 architecture is also known as âItanium.â
File: gawk.info, Node: OpenVMS Dynamic Extensions, Next: OpenVMS
Installation Details, Prev: OpenVMS Compilation, Up: OpenVMS Installation
-B.3.2.2 Compiling 'gawk' Dynamic Extensions on OpenVMS
+B.3.2.2 Compiling âgawkâ Dynamic Extensions on OpenVMS
......................................................
The extensions that have been ported to OpenVMS can be built using one
@@ -31860,12 +31858,12 @@ or:
$ MMK/DESCRIPTION=[.vms]descrip.mms extensions
- 'gawk' uses 'AWKLIBPATH' as either an environment variable or a
+ âgawkâ uses âAWKLIBPATHâ as either an environment variable or a
logical name to find the dynamic extensions.
Dynamic extensions need to be compiled with the same compiler options
for floating-point, pointer size, and symbol name handling as were used
-to compile 'gawk' itself. Alpha and Itanium should use IEEE floating
+to compile âgawkâ itself. Alpha and Itanium should use IEEE floating
point. The pointer size is 32 bits, and the symbol name handling should
be exact case with CRC shortening for symbols longer than 32 bits.
@@ -31886,77 +31884,77 @@ OpenVMS-supplied header file is included, as follows:
#endif
If you are writing your own extensions to run on OpenVMS, you must
-supply these definitions yourself. The 'config.h' file created when
-building 'gawk' on OpenVMS does this for you; if instead you use that
+supply these definitions yourself. The âconfig.hâ file created when
+building âgawkâ on OpenVMS does this for you; if instead you use that
file or a similar one, then you must remember to include it before any
OpenVMS-supplied header files.
File: gawk.info, Node: OpenVMS Installation Details, Next: OpenVMS Running,
Prev: OpenVMS Dynamic Extensions, Up: OpenVMS Installation
-B.3.2.3 Installing 'gawk' on OpenVMS
+B.3.2.3 Installing âgawkâ on OpenVMS
....................................
-To use 'gawk', all you need is a "foreign" command, which is a 'DCL'
+To use âgawkâ, all you need is a âforeignâ command, which is a
âDCLâ
symbol whose value begins with a dollar sign. For example:
$ GAWK :== $disk1:[gnubin]gawk
-Substitute the actual location of 'gawk.exe' for '$disk1:[gnubin]'. The
-symbol should be placed in the 'login.com' of any user who wants to run
-'gawk', so that it is defined every time the user logs on.
-Alternatively, the symbol may be placed in the system-wide 'sylogin.com'
-procedure, which allows all users to run 'gawk'.
+Substitute the actual location of âgawk.exeâ for â$disk1:[gnubin]â.
The
+symbol should be placed in the âlogin.comâ of any user who wants to run
+âgawkâ, so that it is defined every time the user logs on.
+Alternatively, the symbol may be placed in the system-wide âsylogin.comâ
+procedure, which allows all users to run âgawkâ.
- If your 'gawk' was installed by a PCSI kit into the 'GNV$GNU:'
-directory tree, the program will be known as 'GNV$GNU:[bin]gnv$gawk.exe'
-and the help file will be 'GNV$GNU:[vms_help]gawk.hlp'.
+ If your âgawkâ was installed by a PCSI kit into the âGNV$GNU:â
+directory tree, the program will be known as âGNV$GNU:[bin]gnv$gawk.exeâ
+and the help file will be âGNV$GNU:[vms_help]gawk.hlpâ.
- The PCSI kit also installs a 'GNV$GNU:[vms_bin]gawk_verb.cld' file
-that can be used to add 'gawk' and 'awk' as DCL commands.
+ The PCSI kit also installs a âGNV$GNU:[vms_bin]gawk_verb.cldâ file
+that can be used to add âgawkâ and âawkâ as DCL commands.
For just the current process you can use:
$ set command gnv$gnu:[vms_bin]gawk_verb.cld
- Or the system manager can use 'GNV$GNU:[vms_bin]gawk_verb.cld' to add
-the 'gawk' and 'awk' commands to the system-wide 'DCLTABLES'.
+ Or the system manager can use âGNV$GNU:[vms_bin]gawk_verb.cldâ to add
+the âgawkâ and âawkâ commands to the system-wide âDCLTABLESâ.
- The DCL syntax is documented in the 'gawk.hlp' file.
+ The DCL syntax is documented in the âgawk.hlpâ file.
- Optionally, the 'gawk.hlp' entry can be loaded into an OpenVMS help
+ Optionally, the âgawk.hlpâ entry can be loaded into an OpenVMS help
library:
$ LIBRARY/HELP sys$help:helplib [.vms]gawk.hlp
(You may want to substitute a site-specific help library rather than the
-standard OpenVMS library 'HELPLIB'.) After loading the help text, the
+standard OpenVMS library âHELPLIBâ.) After loading the help text, the
command:
$ HELP GAWK
-provides information about both the 'gawk' implementation and the 'awk'
+provides information about both the âgawkâ implementation and the âawkâ
programming language.
- The logical name 'AWK_LIBRARY' can designate a default location for
-'awk' program files. For the '-f' option, if the specified file name
-has no device or directory path information in it, 'gawk' looks in the
+ The logical name âAWK_LIBRARYâ can designate a default location for
+âawkâ program files. For the â-fâ option, if the specified file name
+has no device or directory path information in it, âgawkâ looks in the
current directory first, then in the directory specified by the
-translation of 'AWK_LIBRARY' if the file is not found. If, after
-searching in both directories, the file still is not found, 'gawk'
-appends the suffix '.awk' to the file name and retries the file search.
-If 'AWK_LIBRARY' has no definition, a default value of 'SYS$LIBRARY:' is
+translation of âAWK_LIBRARYâ if the file is not found. If, after
+searching in both directories, the file still is not found, âgawkâ
+appends the suffix â.awkâ to the file name and retries the file search.
+If âAWK_LIBRARYâ has no definition, a default value of âSYS$LIBRARY:â
is
used for it.
File: gawk.info, Node: OpenVMS Running, Next: OpenVMS GNV, Prev: OpenVMS
Installation Details, Up: OpenVMS Installation
-B.3.2.4 Running 'gawk' on OpenVMS
+B.3.2.4 Running âgawkâ on OpenVMS
.................................
Command-line parsing and quoting conventions are significantly different
on OpenVMS, so examples in this Info file or from other sources often
-need minor changes. They _are_ minor though, and all 'awk' programs
+need minor changes. They _are_ minor though, and all âawkâ programs
should run correctly.
Here are a couple of trivial tests:
@@ -31967,51 +31965,51 @@ should run correctly.
Note that uppercase and mixed-case text must be quoted.
- The OpenVMS port of 'gawk' includes a 'DCL'-style interface in
+ The OpenVMS port of âgawkâ includes a âDCLâ-style interface in
addition to the original shell-style interface (see the help entry for
details). One side effect of dual command-line parsing is that if there
is only a single parameter (as in the quoted program string), the
command becomes ambiguous. To work around this, the normally optional
-'--' flag is required to force Unix-style parsing rather than 'DCL'
+â--â flag is required to force Unix-style parsing rather than âDCLâ
parsing. If any other dash-type options (or multiple parameters such as
-data files to process) are present, there is no ambiguity and '--' can
+data files to process) are present, there is no ambiguity and â--â can
be omitted.
- The 'exit' value is a Unix-style value and is encoded into an OpenVMS
+ The âexitâ value is a Unix-style value and is encoded into an OpenVMS
exit status value when the program exits.
- The OpenVMS severity bits will be set based on the 'exit' value. A
-failure is indicated by 1, and OpenVMS sets the 'ERROR' status. A fatal
-error is indicated by 2, and OpenVMS sets the 'FATAL' status. All other
-values will have the 'SUCCESS' status. The exit value is encoded to
-comply with OpenVMS coding standards and will have the 'C_FACILITY_NO'
-of '0x350000' with the constant '0xA000' added to the number shifted
+ The OpenVMS severity bits will be set based on the âexitâ value. A
+failure is indicated by 1, and OpenVMS sets the âERRORâ status. A fatal
+error is indicated by 2, and OpenVMS sets the âFATALâ status. All other
+values will have the âSUCCESSâ status. The exit value is encoded to
+comply with OpenVMS coding standards and will have the âC_FACILITY_NOâ
+of â0x350000â with the constant â0xA000â added to the number shifted
over by 3 bits to make room for the severity codes.
- To extract the actual 'gawk' exit code from the OpenVMS status, use:
+ To extract the actual âgawkâ exit code from the OpenVMS status, use:
unix_status = (vms_status .and. %x7f8) / 8
-A C program that uses 'exec()' to call 'gawk' will get the original
+A C program that uses âexec()â to call âgawkâ will get the original
Unix-style exit value.
OpenVMS reports time values in GMT unless one of the
-'SYS$TIMEZONE_RULE' or 'TZ' logical names is set.
+âSYS$TIMEZONE_RULEâ or âTZâ logical names is set.
- The default search path, when looking for 'awk' program files
-specified by the '-f' option, is '"SYS$DISK:[],AWK_LIBRARY:"'. The
-logical name 'AWKPATH' can be used to override this default. The format
-of 'AWKPATH' is a comma-separated list of directory specifications.
+ The default search path, when looking for âawkâ program files
+specified by the â-fâ option, is â"SYS$DISK:[],AWK_LIBRARY:"â. The
+logical name âAWKPATHâ can be used to override this default. The format
+of âAWKPATHâ is a comma-separated list of directory specifications.
When defining it, the value should be quoted so that it retains a single
-translation and not a multitranslation 'RMS' searchlist.
+translation and not a multitranslation âRMSâ searchlist.
- This restriction also applies to running 'gawk' under GNV, as
+ This restriction also applies to running âgawkâ under GNV, as
redirection is always to a DCL command.
If you are redirecting data to an OpenVMS command or utility, the
current implementation requires setting up an OpenVMS foreign command
-that runs a command file before invoking 'gawk'. (This restriction may
-be removed in a future release of 'gawk' on OpenVMS.)
+that runs a command file before invoking âgawkâ. (This restriction may
+be removed in a future release of âgawkâ on OpenVMS.)
Without this command file, the input data will also appear prepended
to the output data.
@@ -32019,8 +32017,8 @@ to the output data.
This also allows simulating POSIX commands that are not found on
OpenVMS or the use of GNV utilities.
- The example below is for 'gawk' redirecting data to the OpenVMS
-'sort' command.
+ The example below is for âgawkâ redirecting data to the OpenVMS
+âsortâ command.
$ sort = "@device:[dir]vms_gawk_sort.com"
@@ -32032,12 +32030,12 @@ the output. It must be in the format in the example.
The next line creates a foreign command that overrides the outer
foreign command which prevents an infinite recursion of command files.
- The next to the last command redirects 'sys$input' to be
-'sys$command', in order to pick up the data that is being redirected to
+ The next to the last command redirects âsys$inputâ to be
+âsys$commandâ, in order to pick up the data that is being redirected to
the command.
The last line runs the actual command. It must be the last command
-as the data redirected from 'gawk' will be read when the command file
+as the data redirected from âgawkâ will be read when the command file
ends.
$!'f$verify(0,0)'
@@ -32052,15 +32050,15 @@ B.3.2.5 The OpenVMS GNV Project
...............................
The OpenVMS GNV package provides a build environment similar to POSIX
-with ports of a collection of open source tools. The 'gawk' found in
+with ports of a collection of open source tools. The âgawkâ found in
the GNV base kit is an older port. Currently, the GNV project is being
reorganized to supply individual PCSI packages for each component. See
<https://sourceforge.net/p/gnv/wiki/InstallingGNVPackages/>.
- The normal build procedure for 'gawk' produces a program that is
+ The normal build procedure for âgawkâ produces a program that is
suitable for use with GNV.
- The file 'vms/gawk_build_steps.txt' in the distribution documents the
+ The file âvms/gawk_build_steps.txtâ in the distribution documents the
procedure for building an OpenVMS PCSI kit that is compatible with GNV.
@@ -32070,9 +32068,9 @@ B.4 Reporting Problems and Bugs
===============================
There is nothing more dangerous than a bored archaeologist.
- -- _Douglas Adams, 'The Hitchhiker's Guide to the Galaxy'_
+ â _Douglas Adams, âThe Hitchhikerâs Guide to the Galaxyâ_
- If you have problems with 'gawk' or think that you have found a bug,
+ If you have problems with âgawkâ or think that you have found a bug,
report it to the developers; we cannot promise to do anything, but we
might well want to fix it.
@@ -32092,82 +32090,82 @@ File: gawk.info, Node: Bug definition, Next: Bug
address, Up: Bugs
B.4.1 Defining What Is and What Is Not A Bug
--------------------------------------------
-Before talking about reporting bugs, let's define what is a bug, and
+Before talking about reporting bugs, letâs define what is a bug, and
what is not.
A bug is:
- * When 'gawk' behaves differently from what's described in the POSIX
+ ⢠When âgawkâ behaves differently from whatâs described in the POSIX
standard, and that difference is not mentioned in this Info file as
being done on purpose.
- * When 'gawk' behaves differently from what's described in this Info
+ ⢠When âgawkâ behaves differently from whatâs described in this Info
file.
- * When 'gawk' behaves differently from other 'awk' implementations in
+ ⢠When âgawkâ behaves differently from other âawkâ
implementations in
particular circumstances, and that behavior cannot be attributed to
- an additional feature in 'gawk'.
+ an additional feature in âgawkâ.
- * Something that is obviously wrong, such as a core dump.
+ ⢠Something that is obviously wrong, such as a core dump.
- * When this Info file is unclear or ambiguous about a particular
- feature's behavior.
+ ⢠When this Info file is unclear or ambiguous about a particular
+ featureâs behavior.
The following things are _not_ bugs, and should not be reported to
-the bug mailing list. You can ask about them on the "help" mailing list
-(*note Asking for help::), but don't be surprised if you get an answer
-of the form "that's how 'gawk' behaves and it isn't going to change."
-Here's the list:
+the bug mailing list. You can ask about them on the âhelpâ mailing list
+(*note Asking for help::), but donât be surprised if you get an answer
+of the form âthatâs how âgawkâ behaves and it isnât going to
change.â
+Hereâs the list:
- * Missing features, for any definition of "feature". For example,
+ ⢠Missing features, for any definition of âfeatureâ. For example,
additional built-in arithmetic functions, or additional ways to
split fields or records, or anything else.
- The number of features that 'gawk' does _not_ have is by definition
+ The number of features that âgawkâ does _not_ have is by definition
infinite. It cannot be all things to all people. In short, just
- because 'gawk' doesn't do what _you_ think it should, it's not
+ because âgawkâ doesnât do what _you_ think it should, itâs not
necessarily a bug.
- * Behaviors that are defined by the POSIX standard and/or for
- historical compatibility with Unix 'awk'. Even if you happen to
- dislike those behaviors, they're not going to change: changing them
- would break millions of existing 'awk' programs.
+ ⢠Behaviors that are defined by the POSIX standard and/or for
+ historical compatibility with Unix âawkâ. Even if you happen to
+ dislike those behaviors, theyâre not going to change: changing them
+ would break millions of existing âawkâ programs.
- * Behaviors that differ from how it's done in other languages. 'awk'
- and 'gawk' stand on their own and do not have to follow the crowd.
+ ⢠Behaviors that differ from how itâs done in other languages.
âawkâ
+ and âgawkâ stand on their own and do not have to follow the crowd.
This is particularly true when the requested behavior change would
break backwards compatibility.
- This applies also to differences in behavior between 'gawk' and
+ This applies also to differences in behavior between âgawkâ and
other language compilers and interpreters, such as wishes for more
detailed descriptions of what the problem is when a syntax error is
encountered.
- * Documentation issues of the form "the manual doesn't tell me how to
- do XYZ." The manual is not a cookbook to solve every little problem
+ ⢠Documentation issues of the form âthe manual doesnât tell me how to
+ do XYZ.â The manual is not a cookbook to solve every little problem
you may have. Its purpose is to teach you how to solve your
problems on your own.
- * General questions and discussion about 'awk' programming or why
- 'gawk' behaves the way it does. For that use the "help" mailing
+ ⢠General questions and discussion about âawkâ programming or why
+ âgawkâ behaves the way it does. For that use the âhelpâ mailing
list: see *note Asking for help::.
- For more information, see 'Fork My Code, Please!--An Open Letter To
-Those of You Who Are Unhappy' (http://www.skeeve.com/fork-my-code.html),
+ For more information, see âFork My Code, Please!âAn Open Letter To
+Those of You Who Are Unhappyâ (http://www.skeeve.com/fork-my-code.html),
by Arnold Robbins and Chet Ramey.
A Note About Fuzzers
- In recent years, people have been running "fuzzers" to generate
-invalid 'awk' programs in order to find and report (so-called) bugs in
-'gawk'.
+ In recent years, people have been running âfuzzersâ to generate
+invalid âawkâ programs in order to find and report (so-called) bugs in
+âgawkâ.
In general, such reports are not of much practical use. The programs
they create are not realistic and the bugs found are generally from some
kind of memory corruption that is fatal anyway.
- So, if you want to run a fuzzer against 'gawk' and report the
-results, you may do so, but be aware that such reports don't carry the
+ So, if you want to run a fuzzer against âgawkâ and report the
+results, you may do so, but be aware that such reports donât carry the
same weight as reports of real bugs do.
@@ -32182,36 +32180,36 @@ Before reporting a bug, make sure you have really
found a genuine bug.
make both your life and the lives of the maintainers much easier.
1. Make sure that what you want to report is appropriate. *Note Bug
- definition::. If it's not, you are wasting your time and ours.
+ definition::. If itâs not, you are wasting your time and ours.
- 2. Verify that you have the latest version of 'gawk'. Many bugs
+ 2. Verify that you have the latest version of âgawkâ. Many bugs
(usually subtle ones) are fixed at each release, and if yours is
out-of-date, the problem may already have been solved.
- 3. Please see if setting the environment variable 'LC_ALL' to
- 'LC_ALL=C' causes things to behave as you expect. If so, it's a
+ 3. Please see if setting the environment variable âLC_ALLâ to
+ âLC_ALL=Câ causes things to behave as you expect. If so, itâs a
locale issue, and may or may not really be a bug.
4. Carefully reread the documentation and see if it says you can do
- what you're trying to do. If it's not clear whether you should be
- able to do something or not, report that too; it's a bug in the
+ what youâre trying to do. If itâs not clear whether you should be
+ able to do something or not, report that too; itâs a bug in the
documentation!
5. Before reporting a bug or trying to fix it yourself, try to isolate
- it to the smallest possible 'awk' program and input data file that
+ it to the smallest possible âawkâ program and input data file that
reproduce the problem.
- 6. Use the 'gawkbug' program to submit the bug report. This program
+ 6. Use the âgawkbugâ program to submit the bug report. This program
sets up a bug report template and opens it in your editor. You
then need to edit it appropriately to include:
- * The program and data file.
+ ⢠The program and data file.
- * The exact results 'gawk' gave you. Also say what you expected
+ ⢠The exact results âgawkâ gave you. Also say what you expected
to occur; this helps us decide whether the problem is really
in the documentation.
- * A fix if you have one.
+ ⢠A fix if you have one.
7. Do _not_ send screenshots. Instead, use copy/paste to send text,
or send files.
@@ -32222,27 +32220,27 @@ make both your life and the lives of the maintainers
much easier.
9. _All email must be in English. This is the only language
understood in common by all the maintainers._
- The 'gawkbug' program sends email to <bug-gawk@gnu.org>.
+ The âgawkbugâ program sends email to <bug-gawk@gnu.org>.
- The 'gawk' maintainers subscribe to this address, and thus they will
+ The âgawkâ maintainers subscribe to this address, and thus they will
receive your bug report. Do _not_ send mail to the maintainers
directly; the bug reporting address is preferred because the email list
is archived at the GNU Project.
- If you are using OpenVMS or the MinGW build of 'gawk', the 'gawkbug'
-script won't be available. Please send the previously listed
+ If you are using OpenVMS or the MinGW build of âgawkâ, the âgawkbugâ
+script wonât be available. Please send the previously listed
information directly in an email to the bug list. Please send any test
program or data files as attachments, instead of inline in the email, to
avoid their being mangled by various mail systems.
NOTE: Many distributions of GNU/Linux and the various BSD-based
operating systems have their own bug reporting systems. If you
- report a bug using your distribution's bug reporting system, you
+ report a bug using your distributionâs bug reporting system, you
should also send a copy to <bug-gawk@gnu.org>.
This is for two reasons. First, although some distributions
- forward bug reports "upstream" to the GNU mailing list, many don't,
- so there is a good chance that the 'gawk' maintainers won't even
+ forward bug reports âupstreamâ to the GNU mailing list, many donât,
+ so there is a good chance that the âgawkâ maintainers wonât even
see the bug report! Second, mail to the GNU list is archived, and
having everything at the GNU Project keeps things self-contained
and not dependent on other organizations.
@@ -32254,27 +32252,27 @@ correspondence on the list (as well as off of it).
File: gawk.info, Node: Usenet, Next: Performance bugs, Prev: Bug address,
Up: Bugs
-B.4.3 Please Don't Post Bug Reports to USENET
+B.4.3 Please Donât Post Bug Reports to USENET
---------------------------------------------
- I gave up on Usenet a couple of years ago and haven't really looked
- back. It's like sports talk radio--you feel smarter for not having
+ I gave up on Usenet a couple of years ago and havenât really looked
+ back. Itâs like sports talk radioâyou feel smarter for not having
read it.
- -- _Chet Ramey_
+ â _Chet Ramey_
- Please do _not_ try to report bugs in 'gawk' by posting to the
-Usenet/Internet newsgroup 'comp.lang.awk'. Although some of the 'gawk'
-developers occasionally read this news group, the primary 'gawk'
-maintainer no longer does. Thus it's virtually guaranteed that he will
+ Please do _not_ try to report bugs in âgawkâ by posting to the
+Usenet/Internet newsgroup âcomp.lang.awkâ. Although some of the âgawkâ
+developers occasionally read this news group, the primary âgawkâ
+maintainer no longer does. Thus itâs virtually guaranteed that he will
_not_ see your posting.
- If you really don't care about the previous paragraph and continue to
-post bug reports in 'comp.lang.awk', then understand that you're not
-reporting bugs, you're just whining.
+ If you really donât care about the previous paragraph and continue to
+post bug reports in âcomp.lang.awkâ, then understand that youâre not
+reporting bugs, youâre just whining.
Similarly, posting bug reports or questions in web forums (such as
Stack Overflow (https://stackoverflow.com/)) may get you an answer, but
-it won't be from the 'gawk' maintainers, who do not spend their time in
+it wonât be from the âgawkâ maintainers, who do not spend their time in
web forums. The steps described here are the only officially recognized
way for reporting bugs. Really.
@@ -32284,57 +32282,57 @@ File: gawk.info, Node: Performance bugs, Next:
Asking for help, Prev: Usenet,
B.4.4 What To Do If You Think There Is A Performance Issue
----------------------------------------------------------
-If you think that 'gawk' is too slow at doing a particular task, you
+If you think that âgawkâ is too slow at doing a particular task, you
should investigate before sending in a bug report. Here are the steps
to follow:
- 1. Run 'gawk' with the '--profile' option (*note Options::) to see
+ 1. Run âgawkâ with the â--profileâ option (*note Options::) to see
what your program is doing. It may be that you have written it in
an inefficient manner. For example, you may be doing something for
every record that could be done just once, for every file. (Use a
- 'BEGINFILE' rule; *note BEGINFILE/ENDFILE::.) Or you may be doing
+ âBEGINFILEâ rule; *note BEGINFILE/ENDFILE::.) Or you may be doing
something for every file that only needs to be done once per run of
- the program. (Use a 'BEGIN' rule; *note BEGIN/END::.)
+ the program. (Use a âBEGINâ rule; *note BEGIN/END::.)
- 2. If profiling at the 'awk' level doesn't help, then you will need to
- compile 'gawk' itself for profiling at the C language level.
+ 2. If profiling at the âawkâ level doesnât help, then you will need to
+ compile âgawkâ itself for profiling at the C language level.
- To do that, start with the latest released version of 'gawk'.
+ To do that, start with the latest released version of âgawkâ.
Unpack the source code in a new directory, and configure it:
$ tar -xpzvf gawk-X.Y.Z.tar.gz
- -| ... Output omitted
+ ⣠... Output omitted
$ cd gawk-X.Y.Z
$ ./configure
- -| ... Output omitted
+ ⣠... Output omitted
- 3. Edit the files 'Makefile' and 'support/Makefile'. Change every
- instance of '-O2' or '-O' to '-pg'. This causes 'gawk' to be
+ 3. Edit the files âMakefileâ and âsupport/Makefileâ. Change every
+ instance of â-O2â or â-Oâ to â-pgâ. This causes âgawkâ
to be
compiled for profiling.
- 4. Compile the program by running the 'make' command:
+ 4. Compile the program by running the âmakeâ command:
$ make
- -| ... Output omitted
+ ⣠... Output omitted
- 5. Run the freshly compiled 'gawk' on a _real_ program, using _real_
+ 5. Run the freshly compiled âgawkâ on a _real_ program, using _real_
data. Using an artificial program to try to time one particular
- feature of 'gawk' is useless; real 'awk' programs generally spend
+ feature of âgawkâ is useless; real âawkâ programs generally spend
most of their time doing I/O, not computing. If you want to prove
that something is slow, it _must_ be done using a real program and
real data.
Use a data file that is large enough for the statistical profiling
- to measure where 'gawk' spends its time. It should be at least 100
+ to measure where âgawkâ spends its time. It should be at least 100
megabytes in size.
$ ./gawk -f realprogram.awk realdata > /dev/null
6. When done, you should have a file in the current directory named
- 'gmon.out'. Run the command 'gprof gawk gmon.out > gprof.out'.
+ âgmon.outâ. Run the command âgprof gawk gmon.out > gprof.outâ.
7. Submit a bug report explaining what you think is slow. Include the
- 'gprof.out' file with it.
+ âgprof.outâ file with it.
Preferably, you should also submit the program and the data, or
else indicate where to get the data if the file is large.
@@ -32344,7 +32342,7 @@ to follow:
patches were effective.
If you are incapable or unwilling to do the steps listed above, then
-you will just have to live with 'gawk' as it is.
+you will just have to live with âgawkâ as it is.
File: gawk.info, Node: Asking for help, Next: Maintainers, Prev:
Performance bugs, Up: Bugs
@@ -32352,8 +32350,8 @@ File: gawk.info, Node: Asking for help, Next:
Maintainers, Prev: Performance
B.4.5 Where To Send Non-bug Questions
-------------------------------------
-If you have questions related to 'awk' programming, or why 'gawk'
-behaves a certain way, or any other 'awk'- or 'gawk'-related issue,
+If you have questions related to âawkâ programming, or why âgawkâ
+behaves a certain way, or any other âawkâ- or âgawkâ-related issue,
please _do not_ send it to the bug reporting address.
As of July, 2021, there is a separate mailing list for this purpose:
@@ -32376,7 +32374,7 @@ Proulx:
_Subscribe by email_
Send an email message to <help-gawk-request@gnu.org> with
- "subscribe" in the body of the message. The subject does not
+ âsubscribeâ in the body of the message. The subject does not
matter and is not used.
_Subscribe by web form_
@@ -32384,7 +32382,7 @@ _Subscribe by web form_
To use the web interface visit the list information page
(https://lists.gnu.org/mailman/listinfo/help-gawk). Use the
subscribe form to fill out your email address and submit using the
- 'Subscribe' button.
+ âSubscribeâ button.
_Reply to the confirmation message_
@@ -32404,13 +32402,13 @@ File: gawk.info, Node: Maintainers, Prev: Asking
for help, Up: Bugs
B.4.6 Reporting Problems with Non-Unix Ports
--------------------------------------------
-If you find bugs in one of the non-Unix ports of 'gawk', send an email
+If you find bugs in one of the non-Unix ports of âgawkâ, send an email
to the bug list, with a copy to the person who maintains that port. The
-maintainers are named in the following list, as well as in the 'README'
-file in the 'gawk' distribution. Information in the 'README' file
+maintainers are named in the following list, as well as in the âREADMEâ
+file in the âgawkâ distribution. Information in the âREADMEâ file
should be considered authoritative if it conflicts with this Info file.
- The people maintaining the various 'gawk' ports are:
+ The people maintaining the various âgawkâ ports are:
Unix and POSIX Arnold Robbins, <arnold@skeeve.com>
systems
@@ -32426,108 +32424,108 @@ report to the <bug-gawk@gnu.org> email list as well.
File: gawk.info, Node: Other Versions, Next: Installation summary, Prev:
Bugs, Up: Installation
-B.5 Other Freely Available 'awk' Implementations
+B.5 Other Freely Available âawkâ Implementations
================================================
- It's kind of fun to put comments like this in your awk code:
- '// Do C++ comments work? answer: yes! of course'
- -- _Michael Brennan_
+ Itâs kind of fun to put comments like this in your awk code:
+ â// Do C++ comments work? answer: yes! of courseâ
+ â _Michael Brennan_
- There are a number of other freely available 'awk' implementations.
+ There are a number of other freely available âawkâ implementations.
This minor node briefly describes where to get them:
-Unix 'awk'
- Brian Kernighan, one of the original designers of Unix 'awk', has
- made his implementation of 'awk' freely available. You can
+Unix âawkâ
+ Brian Kernighan, one of the original designers of Unix âawkâ, has
+ made his implementation of âawkâ freely available. You can
retrieve it from GitHub:
git clone https://github.com/onetrueawk/awk bwkawk
This command creates a copy of the Git (https://git-scm.com)
- repository in a directory named 'bwkawk'. If you omit the last
- argument from the 'git' command line, the repository copy is
- created in a directory named 'awk'.
+ repository in a directory named âbwkawkâ. If you omit the last
+ argument from the âgitâ command line, the repository copy is
+ created in a directory named âawkâ.
This version requires an ISO C (1990 standard) compiler; the C
compiler from GCC (the GNU Compiler Collection) works quite nicely.
- To build it, review the settings in the 'makefile', and then just
- run 'make'. Note that the result of compilation is named 'a.out';
+ To build it, review the settings in the âmakefileâ, and then just
+ run âmakeâ. Note that the result of compilation is named âa.outâ;
you will have to rename it to something reasonable.
- *Note Common Extensions:: for a list of extensions in this 'awk'
- that are not in POSIX 'awk'.
+ *Note Common Extensions:: for a list of extensions in this âawkâ
+ that are not in POSIX âawkâ.
As a side note, Dan Bornstein has created a Git repository tracking
- all the versions of BWK 'awk' that he could find. It's available
+ all the versions of BWK âawkâ that he could find. Itâs available
at <https://github.com/danfuzz/one-true-awk>.
-'mawk'
- Michael Brennan wrote an independent implementation of 'awk',
- called 'mawk'. It is available under the GPL (*note Copying::),
- just as 'gawk' is.
+âmawkâ
+ Michael Brennan wrote an independent implementation of âawkâ,
+ called âmawkâ. It is available under the GPL (*note Copying::),
+ just as âgawkâ is.
- The original distribution site for the 'mawk' source code no longer
+ The original distribution site for the âmawkâ source code no longer
has it. A copy is available at
<http://www.skeeve.com/gawk/mawk1.3.3.tar.gz>.
- In 2009, Thomas Dickey took on 'mawk' maintenance. Basic
- information is available on the project's web page
+ In 2009, Thomas Dickey took on âmawkâ maintenance. Basic
+ information is available on the projectâs web page
(http://www.invisible-island.net/mawk). The download URL is
<http://invisible-island.net/datafiles/release/mawk.tar.gz>.
- Once you have it, 'gunzip' may be used to decompress this file.
- Installation is similar to 'gawk''s (*note Unix Installation::).
+ Once you have it, âgunzipâ may be used to decompress this file.
+ Installation is similar to âgawkââs (*note Unix Installation::).
- *Note Common Extensions:: for a list of extensions in 'mawk' that
- are not in POSIX 'awk'.
+ *Note Common Extensions:: for a list of extensions in âmawkâ that
+ are not in POSIX âawkâ.
-'mawk' 2.0
- In 2016, Michael Brennan resumed 'mawk' development. His
- development snapshots are available via Git from the project's
+âmawkâ 2.0
+ In 2016, Michael Brennan resumed âmawkâ development. His
+ development snapshots are available via Git from the projectâs
GitHub page (https://github.com/mikebrennan000/mawk-2).
-'awka'
- Written by Andrew Sumner, 'awka' translates 'awk' programs into C,
+âawkaâ
+ Written by Andrew Sumner, âawkaâ translates âawkâ programs into C,
compiles them, and links them with a library of functions that
- provide the core 'awk' functionality. It also has a number of
+ provide the core âawkâ functionality. It also has a number of
extensions.
- Both the 'awk' translator and the library are released under the
+ Both the âawkâ translator and the library are released under the
GPL.
- To get 'awka', go to <https://sourceforge.net/projects/awka>.
+ To get âawkaâ, go to <https://sourceforge.net/projects/awka>.
The project seems to be frozen; no new code changes have been made
since approximately 2001.
Revive Awka
This project, available at <https://github.com/noyesno/awka>,
- intends to fix bugs in 'awka' and add more features.
+ intends to fix bugs in âawkaâ and add more features.
-'pawk'
- Nelson H.F. Beebe at the University of Utah has modified BWK 'awk'
+âpawkâ
+ Nelson H.F. Beebe at the University of Utah has modified BWK âawkâ
to provide timing and profiling information. It is different from
- 'gawk' with the '--profile' option (*note Profiling::) in that it
+ âgawkâ with the â--profileâ option (*note Profiling::) in that it
uses CPU-based profiling, not line-count profiling. You may find
it at either
<ftp://ftp.math.utah.edu/pub/pawk/pawk-20030606.tar.gz> or
<http://www.math.utah.edu/pub/pawk/pawk-20030606.tar.gz>.
-BusyBox 'awk'
+BusyBox âawkâ
BusyBox is a GPL-licensed program providing small versions of many
applications within a single executable. It is aimed at embedded
- systems. It includes a full implementation of POSIX 'awk'. When
- building it, be careful not to do 'make install' as it will
- overwrite copies of other applications in your '/usr/local/bin'.
- For more information, see the project's home page
+ systems. It includes a full implementation of POSIX âawkâ. When
+ building it, be careful not to do âmake installâ as it will
+ overwrite copies of other applications in your â/usr/local/binâ.
+ For more information, see the projectâs home page
(https://busybox.net).
-The OpenSolaris POSIX 'awk'
- The versions of 'awk' in '/usr/xpg4/bin' and '/usr/xpg6/bin' on
+The OpenSolaris POSIX âawkâ
+ The versions of âawkâ in â/usr/xpg4/binâ and â/usr/xpg6/binâ
on
Solaris are more or less POSIX-compliant. They are based on the
- 'awk' from Mortice Kern Systems for PCs. We were able to make this
- code compile and work under GNU/Linux with 1-2 hours of work.
+ âawkâ from Mortice Kern Systems for PCs. We were able to make this
+ code compile and work under GNU/Linux with 1â2 hours of work.
Making it more generally portable (using GNU Autoconf and/or
Automake) would take more work, and this has not been done, at
least to our knowledge.
@@ -32540,69 +32538,69 @@ The OpenSolaris POSIX 'awk'
from
<https://github.com/joyent/illumos-joyent/blob/master/usr/src/cmd/awk_xpg4>.
-'frawk'
- This is a language for writing short programs. "To a first
+âfrawkâ
+ This is a language for writing short programs. âTo a first
approximation, it is an implementation of the AWK language; many
- common 'awk' programs produce equivalent output when passed to
- 'frawk'." However, it has a number of important additional
+ common âawkâ programs produce equivalent output when passed to
+ âfrawkâ.â However, it has a number of important additional
features. The code is available at
<https://github.com/ezrosent/frawk>.
-'goawk'
- This is an 'awk' interpreter written in the Go programming language
- (https://golang.org/). It implements POSIX 'awk', with a few minor
+âgoawkâ
+ This is an âawkâ interpreter written in the Go programming language
+ (https://golang.org/). It implements POSIX âawkâ, with a few minor
extensions. Source code is available from
<https://github.com/benhoyt/goawk>. The author wrote a nice
article (https://benhoyt.com/writings/goawk/) describing the
implementation.
-'AWKgo'
- This is an 'awk' to Go translator. It was written by the author of
- 'goawk'. (See the previous entry in this list.) Source code is
+âAWKgoâ
+ This is an âawkâ to Go translator. It was written by the author of
+ âgoawkâ. (See the previous entry in this list.) Source code is
available from
- <https://github.com/benhoyt/goawk/tree/master/awkgo>. The author's
+ <https://github.com/benhoyt/goawk/tree/master/awkgo>. The authorâs
article about it is at <https://benhoyt.com/writings/awkgo/>.
-'jawk'
- This is an interpreter for 'awk' written in Java. It claims to be
+âjawkâ
+ This is an interpreter for âawkâ written in Java. It claims to be
a full interpreter, although because it uses Java facilities for
I/O and for regexp matching, the language it supports is different
- from POSIX 'awk'. More information is available on the project's
+ from POSIX âawkâ. More information is available on the projectâs
home page (http://jawk.sourceforge.net).
-Hoijui's 'jawk'
+Hoijuiâs âjawkâ
This project, available at <https://github.com/hoijui/Jawk>, is
- another 'awk' interpreter written in Java. It uses modern Java
+ another âawkâ interpreter written in Java. It uses modern Java
build tools.
Libmawk
- This is an embeddable 'awk' interpreter derived from 'mawk'. For
+ This is an embeddable âawkâ interpreter derived from âmawkâ. For
more information, see <http://repo.hu/projects/libmawk/>.
-Mircea Neacsu's Embeddable 'awk'
- Mircea Neacsu has created an embeddable 'awk' interpreter, based on
- BWK awk. It's available at <https://github.com/neacsum/awk>.
+Mircea Neacsuâs Embeddable âawkâ
+ Mircea Neacsu has created an embeddable âawkâ interpreter, based on
+ BWK awk. Itâs available at <https://github.com/neacsum/awk>.
-'pawk'
- This is a Python module that claims to bring 'awk'-like features to
+âpawkâ
+ This is a Python module that claims to bring âawkâ-like features to
Python. See <https://github.com/alecthomas/pawk> for more
- information. (This is not related to Nelson Beebe's modified
- version of BWK 'awk', described earlier.)
+ information. (This is not related to Nelson Beebeâs modified
+ version of BWK âawkâ, described earlier.)
-'awkcc'
- This is an early adaptation of Unix 'awk' that translates 'awk'
+âawkccâ
+ This is an early adaptation of Unix âawkâ that translates âawkâ
into C code. It was done by J. Christopher Ramming at Bell Labs,
- circa 1988. It's available at <https://github.com/nokia/awkcc>.
+ circa 1988. Itâs available at <https://github.com/nokia/awkcc>.
Bringing this up to date would be an interesting software
engineering exercise.
-QSE 'awk'
- This is an embeddable 'awk' interpreter. For more information, see
+QSE âawkâ
+ This is an embeddable âawkâ interpreter. For more information, see
<https://code.google.com/p/qse/>.
-'QTawk'
- This is an independent implementation of 'awk' distributed under
- the GPL. It has a large number of extensions over standard 'awk'
+âQTawkâ
+ This is an independent implementation of âawkâ distributed under
+ the GPL. It has a large number of extensions over standard âawkâ
and may not be 100% syntactically compatible with it. See
<http://www.quiktrim.org/QTawk.html> for more information,
including the manual. The download link there is out of date; see
@@ -32613,15 +32611,15 @@ QSE 'awk'
since approximately 2014.
Other versions
- See also the "Versions and implementations" section of the
+ See also the âVersions and implementationsâ section of the
Wikipedia article
(https://en.wikipedia.org/wiki/Awk_language#Versions_and_implementations)
- on 'awk' for information on additional versions.
+ on âawkâ for information on additional versions.
An interesting collection of library functions is available at
<https://github.com/e36freak/awk-libs>.
- An interesting collection of 'gawk' extensions is available
+ An interesting collection of âgawkâ extensions is available
<https://github.com/su8/gawk-extensions>.
@@ -32630,33 +32628,33 @@ File: gawk.info, Node: Installation summary, Prev:
Other Versions, Up: Instal
B.6 Summary
===========
- * The 'gawk' distribution is available from the GNU Project's main
- distribution site, 'ftp.gnu.org'. The canonical build recipe is:
+ ⢠The âgawkâ distribution is available from the GNU Projectâs main
+ distribution site, âftp.gnu.orgâ. The canonical build recipe is:
wget https://ftp.gnu.org/gnu/gawk/gawk-5.2.2.tar.gz
tar -xvpzf gawk-5.2.2.tar.gz
cd gawk-5.2.2
./configure && make && make check
- NOTE: Because of the 'https://' URL, you may have to supply
- the '--no-check-certificate' option to 'wget' to download the
+ NOTE: Because of the âhttps://â URL, you may have to supply
+ the â--no-check-certificateâ option to âwgetâ to download the
file.
- * 'gawk' may be built on non-POSIX systems as well. The currently
+ ⢠âgawkâ may be built on non-POSIX systems as well. The currently
supported systems are MS-Windows using MSYS, MSYS2, MinGW, and
Cygwin, and OpenVMS. Instructions for each system are included in
this major node.
- * Bug reports should be sent via email to <bug-gawk@gnu.org>. Bug
+ ⢠Bug reports should be sent via email to <bug-gawk@gnu.org>. Bug
reports should be in English and should include the version of
- 'gawk', how it was compiled, and a short program and data file that
+ âgawkâ, how it was compiled, and a short program and data file that
demonstrate the problem.
- * Non-bug emails should be sent to <help-gawk@gnu.org>. Repeatedly
+ ⢠Non-bug emails should be sent to <help-gawk@gnu.org>. Repeatedly
sending non-bug emails to the bug list will get you blacklisted
from it.
- * There are a number of other freely available 'awk' implementations.
+ ⢠There are a number of other freely available âawkâ implementations.
Many are POSIX-compliant; others are less so.
@@ -32666,14 +32664,14 @@ Appendix C Implementation Notes
*******************************
This appendix contains information mainly of interest to implementers
-and maintainers of 'gawk'. Everything in it applies specifically to
-'gawk' and not to other implementations.
+and maintainers of âgawkâ. Everything in it applies specifically to
+âgawkâ and not to other implementations.
* Menu:
-* Compatibility Mode:: How to disable certain 'gawk'
+* Compatibility Mode:: How to disable certain âgawkâ
extensions.
-* Additions:: Making Additions To 'gawk'.
+* Additions:: Making Additions To âgawkâ.
* Future Extensions:: New features that may be implemented one day.
* Implementation Limitations:: Some limitations of the implementation.
* Extension Design:: Design notes about the extension API.
@@ -32685,43 +32683,43 @@ File: gawk.info, Node: Compatibility Mode, Next:
Additions, Up: Notes
C.1 Downward Compatibility and Debugging
========================================
-*Note POSIX/GNU::, for a summary of the GNU extensions to the 'awk'
+*Note POSIX/GNU::, for a summary of the GNU extensions to the âawkâ
language and program. All of these features can be turned off by
-invoking 'gawk' with the '--traditional' option or with the '--posix'
+invoking âgawkâ with the â--traditionalâ option or with the
â--posixâ
option.
- If 'gawk' is compiled for debugging with '-DDEBUG', then there is one
+ If âgawkâ is compiled for debugging with â-DDEBUGâ, then there is
one
more option available on the command line:
-'-Y'
-'--parsedebug'
+â-Yâ
+â--parsedebugâ
Print out the parse stack information as the program is being
parsed.
- This option is intended only for serious 'gawk' developers and not
+ This option is intended only for serious âgawkâ developers and not
for the casual user. It probably has not even been compiled into your
-version of 'gawk', since it slows down execution.
+version of âgawkâ, since it slows down execution.
File: gawk.info, Node: Additions, Next: Future Extensions, Prev:
Compatibility Mode, Up: Notes
-C.2 Making Additions to 'gawk'
+C.2 Making Additions to âgawkâ
==============================
-If you find that you want to enhance 'gawk' in a significant fashion,
+If you find that you want to enhance âgawkâ in a significant fashion,
you are perfectly free to do so. That is the point of having free
software; the source code is available and you are free to change it as
you want (*note Copying::).
- This minor node discusses the ways you might want to change 'gawk' as
+ This minor node discusses the ways you might want to change âgawkâ as
well as any considerations you should bear in mind.
* Menu:
* Accessing The Source:: Accessing the Git repository.
* Adding Code:: Adding code to the main body of
- 'gawk'.
-* New Ports:: Porting 'gawk' to a new operating
+ âgawkâ.
+* New Ports:: Porting âgawkâ to a new operating
system.
* Derived Files:: Why derived files are kept in the Git
repository.
@@ -32729,35 +32727,35 @@ well as any considerations you should bear in mind.
File: gawk.info, Node: Accessing The Source, Next: Adding Code, Up:
Additions
-C.2.1 Accessing The 'gawk' Git Repository
+C.2.1 Accessing The âgawkâ Git Repository
-----------------------------------------
-As 'gawk' is Free Software, the source code is always available. *note
+As âgawkâ is Free Software, the source code is always available. *note
Gawk Distribution:: describes how to get and build the formal, released
-versions of 'gawk'.
+versions of âgawkâ.
- However, if you want to modify 'gawk' and contribute back your
+ However, if you want to modify âgawkâ and contribute back your
changes, you will probably wish to work with the development version.
-To do so, you will need to access the 'gawk' source code repository.
+To do so, you will need to access the âgawkâ source code repository.
The code is maintained using the Git distributed version control system
(https://git-scm.com). You will need to install it if your system
-doesn't have it. Once you have done so, use the command:
+doesnât have it. Once you have done so, use the command:
git clone git://git.savannah.gnu.org/gawk.git
-This clones the 'gawk' repository. If you are behind a firewall that
+This clones the âgawkâ repository. If you are behind a firewall that
does not allow you to use the Git native protocol, you can still access
the repository using:
git clone https://git.savannah.gnu.org/r/gawk.git
-(Using the 'https' URL is considered to be more secure.)
+(Using the âhttpsâ URL is considered to be more secure.)
- Once you have made changes, you can use 'git diff' to produce a
-patch, and send that to the 'gawk' maintainer; see *note Bugs::, for how
+ Once you have made changes, you can use âgit diffâ to produce a
+patch, and send that to the âgawkâ maintainer; see *note Bugs::, for how
to do that.
- Once upon a time there was Git-CVS gateway for use by people who
+ Once upon a time there was GitâCVS gateway for use by people who
could not install Git. However, this gateway no longer works, so you
may have better luck using a more modern version control system like
Bazaar, that has a Git plug-in for working with Git repositories.
@@ -32768,18 +32766,18 @@ File: gawk.info, Node: Adding Code, Next: New
Ports, Prev: Accessing The Sour
C.2.2 Adding New Features
-------------------------
-You are free to add any new features you like to 'gawk'. However, if
-you want your changes to be incorporated into the 'gawk' distribution,
+You are free to add any new features you like to âgawkâ. However, if
+you want your changes to be incorporated into the âgawkâ distribution,
there are several steps that you need to take in order to make it
possible to include them:
- 1. Discuss the proposed new feature with the 'gawk' maintainer. The
- bug list may be used for this. Even if I don't wish to include
+ 1. Discuss the proposed new feature with the âgawkâ maintainer. The
+ bug list may be used for this. Even if I donât wish to include
your feature, be aware that you are still free to add it and
- distribute your own "fork" of 'gawk'.
+ distribute your own âforkâ of âgawkâ.
- 2. Before building the new feature into 'gawk' itself, consider
- writing it as an extension (*note Dynamic Extensions::). If that's
+ 2. Before building the new feature into âgawkâ itself, consider
+ writing it as an extension (*note Dynamic Extensions::). If thatâs
not possible, continue with the rest of the steps in this list.
3. Be prepared to sign the appropriate paperwork. In order for the
@@ -32792,130 +32790,130 @@ possible to include them:
4. Get the latest version. It is much easier for me to integrate
changes if they are relative to the most recent distributed version
- of 'gawk', or better yet, relative to the latest code in the Git
- repository. If your version of 'gawk' is very old, I may not be
+ of âgawkâ, or better yet, relative to the latest code in the Git
+ repository. If your version of âgawkâ is very old, I may not be
able to integrate your changes at all. (*Note Getting::, for
- information on getting the latest version of 'gawk'.)
+ information on getting the latest version of âgawkâ.)
5. *Note Version: (standards)Top. This document describes how GNU
- software should be written. If you haven't read it, please do so,
- preferably _before_ starting to modify 'gawk'. (The 'GNU Coding
- Standards' are available from the GNU Project's website
+ software should be written. If you havenât read it, please do so,
+ preferably _before_ starting to modify âgawkâ. (The âGNU Coding
+ Standardsâ are available from the GNU Projectâs website
(https://www.gnu.org/prep/standards/). Texinfo, Info, and DVI
versions are also available.)
- 6. Use the 'gawk' coding style. The C code for 'gawk' follows the
- instructions in the 'GNU Coding Standards', with minor exceptions.
- The code is formatted using the traditional "K&R" style,
+ 6. Use the âgawkâ coding style. The C code for âgawkâ follows the
+ instructions in the âGNU Coding Standardsâ, with minor exceptions.
+ The code is formatted using the traditional âK&Râ style,
particularly as regards to the placement of braces and the use of
- TABs. In brief, the coding rules for 'gawk' are as follows:
+ TABs. In brief, the coding rules for âgawkâ are as follows:
- * Use ANSI/ISO style (prototype) function headers when defining
+ ⢠Use ANSI/ISO style (prototype) function headers when defining
functions.
- * Put the name of the function at the beginning of its own line.
+ ⢠Put the name of the function at the beginning of its own line.
- * Use '#elif' instead of nesting '#if' inside '#else'.
+ ⢠Use â#elifâ instead of nesting â#ifâ inside â#elseâ.
- * Put the return type of the function, even if it is 'int', on
+ ⢠Put the return type of the function, even if it is âintâ, on
the line above the line with the name and arguments of the
function.
- * Put spaces around parentheses used in control structures
- ('if', 'while', 'for', 'do', and 'switch').
+ ⢠Put spaces around parentheses used in control structures
+ (âifâ, âwhileâ, âforâ, âdoâ, and âswitchâ).
- * Do not parenthesize the expression used with 'return'.
+ ⢠Do not parenthesize the expression used with âreturnâ.
- * Do not put spaces in front of parentheses used in function
+ ⢠Do not put spaces in front of parentheses used in function
calls.
- * Put spaces around all C operators and after commas in function
+ ⢠Put spaces around all C operators and after commas in function
calls.
- * Do not use the comma operator to produce multiple side
- effects, except in 'for' loop initialization and increment
+ ⢠Do not use the comma operator to produce multiple side
+ effects, except in âforâ loop initialization and increment
parts, and in macro bodies.
- * Use real TABs for indenting, not spaces.
+ ⢠Use real TABs for indenting, not spaces.
- * Use the "K&R" brace layout style.
+ ⢠Use the âK&Râ brace layout style.
- * Use comparisons against 'NULL' and ''\0'' in the conditions of
- 'if', 'while', and 'for' statements, as well as in the 'case's
- of 'switch' statements, instead of just the plain pointer or
+ ⢠Use comparisons against âNULLâ and â'\0'â in the
conditions of
+ âifâ, âwhileâ, and âforâ statements, as well as in the
âcaseâs
+ of âswitchâ statements, instead of just the plain pointer or
character value.
- * Do not, _under any circumstances_, use the '-1 == foo' or '0
- >= bar' style of comparison expressions. I have known about
+ ⢠Do not, _under any circumstances_, use the â-1 == fooâ or â0
+ >= barâ style of comparison expressions. I have known about
it for decades, and I understand why some people like it.
Nonetheless, I abhor it with a passion, and code that uses it
will never be accepted.
- * Use 'true' and 'false' for 'bool' values, the 'NULL' symbolic
- constant for pointer values, and the character constant ''\0''
- where appropriate, instead of '1' and '0'.
+ ⢠Use âtrueâ and âfalseâ for âboolâ values, the
âNULLâ symbolic
+ constant for pointer values, and the character constant â'\0'â
+ where appropriate, instead of â1â and â0â.
- * Provide one-line descriptive comments for each function.
+ ⢠Provide one-line descriptive comments for each function.
- * Do not use the 'alloca()' function for allocating memory off
+ ⢠Do not use the âalloca()â function for allocating memory off
the stack. Its use causes more portability trouble than is
worth the minor benefit of not having to free the storage.
- Instead, use 'malloc()' and 'free()'.
+ Instead, use âmalloc()â and âfree()â.
- * Do not use comparisons of the form '! strcmp(a, b)' or
- similar. As Henry Spencer once said, "'strcmp()' is not a
- boolean!" Instead, use 'strcmp(a, b) == 0'.
+ ⢠Do not use comparisons of the form â! strcmp(a, b)â or
+ similar. As Henry Spencer once said, ââstrcmp()â is not a
+ boolean!â Instead, use âstrcmp(a, b) == 0â.
- * If adding new bit flag values, use explicit hexadecimal
- constants ('0x001', '0x002', '0x004', and so on) instead of
- shifting one left by successive amounts ('(1<<0)', '(1<<1)',
+ ⢠If adding new bit flag values, use explicit hexadecimal
+ constants (â0x001â, â0x002â, â0x004â, and so on) instead
of
+ shifting one left by successive amounts (â(1<<0)â, â(1<<1)â,
and so on).
NOTE: If I have to reformat your code to follow the coding
- style used in 'gawk', I may not bother to integrate your
+ style used in âgawkâ, I may not bother to integrate your
changes at all.
7. Update the documentation. Along with your new code, please supply
new sections and/or chapters for this Info file. If at all
possible, please use real Texinfo, instead of just supplying
unformatted ASCII text (although even that is better than no
- documentation at all). Conventions to be followed in 'GAWK:
- Effective AWK Programming' are provided after the '@bye' at the end
- of the Texinfo source file. If possible, please update the 'man'
+ documentation at all). Conventions to be followed in âGAWK:
+ Effective AWK Programmingâ are provided after the â@byeâ at the end
+ of the Texinfo source file. If possible, please update the âmanâ
page as well.
You will also have to sign paperwork for your documentation
changes.
- 8. Submit changes as unified diffs. Use 'diff -u -r -N' to compare
- the original 'gawk' source tree with your version. I recommend
- using the GNU version of 'diff', or best of all, 'git diff' or 'git
- format-patch'. Send the output produced by 'diff' to me when you
+ 8. Submit changes as unified diffs. Use âdiff -u -r -Nâ to compare
+ the original âgawkâ source tree with your version. I recommend
+ using the GNU version of âdiffâ, or best of all, âgit diffâ or
âgit
+ format-patchâ. Send the output produced by âdiffâ to me when you
submit your changes. (*Note Bugs::, for the electronic mail
information.)
Using this format makes it easy for me to apply your changes to the
- master version of the 'gawk' source code (using 'patch'). If I
+ master version of the âgawkâ source code (using âpatchâ). If I
have to apply the changes manually, using a text editor, I may not
do so, particularly if there are lots of changes.
- 9. Include an entry for the 'ChangeLog' file with your submission.
+ 9. Include an entry for the âChangeLogâ file with your submission.
This helps further minimize the amount of work I have to do, making
it easier for me to accept patches. It is simplest if you just
make this part of your diff.
Although this sounds like a lot of work, please remember that while
you may write the new code, I have to maintain it and support it. If it
-isn't possible for me to do that with a minimum of extra work, then I
+isnât possible for me to do that with a minimum of extra work, then I
probably will not.
File: gawk.info, Node: New Ports, Next: Derived Files, Prev: Adding Code,
Up: Additions
-C.2.3 Porting 'gawk' to a New Operating System
+C.2.3 Porting âgawkâ to a New Operating System
----------------------------------------------
-If you want to port 'gawk' to a new operating system, there are several
+If you want to port âgawkâ to a new operating system, there are several
steps:
1. Follow the guidelines in *note Adding Code::, concerning coding
@@ -32929,9 +32927,9 @@ steps:
questions, please contact me, or <gnu@gnu.org>.
3. When doing a port, bear in mind that your code must coexist
- peacefully with the rest of 'gawk' and the other ports. Avoid
+ peacefully with the rest of âgawkâ and the other ports. Avoid
gratuitous changes to the system-independent parts of the code. If
- at all possible, avoid sprinkling '#ifdef's just for your port
+ at all possible, avoid sprinkling â#ifdefâs just for your port
throughout the code.
If the changes needed for a particular system affect too much of
@@ -32939,43 +32937,43 @@ steps:
can, of course, distribute your changes on your own, as long as you
comply with the GPL (*note Copying::).
- 4. A number of the files that come with 'gawk' are maintained by other
+ 4. A number of the files that come with âgawkâ are maintained by other
people. Thus, you should not change them unless it is for a very
good reason; i.e., changes are not out of the question, but changes
to these files are scrutinized extra carefully. These are all the
- files in the 'support' directory within the 'gawk' distribution.
+ files in the âsupportâ directory within the âgawkâ distribution.
See there.
5. A number of other files are provided by the GNU Autotools
- (Autoconf, Automake, and GNU 'gettext'). You should not change
+ (Autoconf, Automake, and GNU âgettextâ). You should not change
them either, unless it is for a very good reason. The files are
- 'ABOUT-NLS', 'config.guess', 'config.rpath', 'config.sub',
- 'depcomp', 'INSTALL', 'install-sh', 'missing', 'mkinstalldirs', and
- 'ylwrap'.
+ âABOUT-NLSâ, âconfig.guessâ, âconfig.rpathâ, âconfig.subâ,
+ âdepcompâ, âINSTALLâ, âinstall-shâ, âmissingâ,
âmkinstalldirsâ, and
+ âylwrapâ.
6. Be willing to continue to maintain the port. Non-Unix operating
systems are supported by volunteers who maintain the code needed to
- compile and run 'gawk' on their systems. If no-one volunteers to
+ compile and run âgawkâ on their systems. If no-one volunteers to
maintain a port, it becomes unsupported and it may be necessary to
remove it from the distribution.
- 7. Supply an appropriate 'gawkmisc.???' file. Each port has its own
- 'gawkmisc.???' that implements certain operating system specific
- functions. This is cleaner than a plethora of '#ifdef's scattered
- throughout the code. The 'gawkmisc.c' in the main source directory
- includes the appropriate 'gawkmisc.???' file from each
+ 7. Supply an appropriate âgawkmisc.???â file. Each port has its own
+ âgawkmisc.???â that implements certain operating system specific
+ functions. This is cleaner than a plethora of â#ifdefâs scattered
+ throughout the code. The âgawkmisc.câ in the main source directory
+ includes the appropriate âgawkmisc.???â file from each
subdirectory. Be sure to update it as well.
- Each port's 'gawkmisc.???' file has a suffix reminiscent of the
- machine or operating system for the port--for example,
- 'pc/gawkmisc.pc' and 'vms/gawkmisc.vms'. The use of separate
- suffixes, instead of plain 'gawkmisc.c', makes it possible to move
- files from a port's subdirectory into the main subdirectory,
- without accidentally destroying the real 'gawkmisc.c' file.
+ Each portâs âgawkmisc.???â file has a suffix reminiscent of the
+ machine or operating system for the portâfor example,
+ âpc/gawkmisc.pcâ and âvms/gawkmisc.vmsâ. The use of separate
+ suffixes, instead of plain âgawkmisc.câ, makes it possible to move
+ files from a portâs subdirectory into the main subdirectory,
+ without accidentally destroying the real âgawkmisc.câ file.
(Currently, this is only an issue for the PC operating system
ports.)
- 8. Supply a 'Makefile' as well as any other C source and header files
+ 8. Supply a âMakefileâ as well as any other C source and header files
that are necessary for your operating system. All your code should
be in a separate subdirectory, with a name that is the same as, or
reminiscent of, either your operating system or the computer
@@ -32987,10 +32985,10 @@ steps:
9. Update the documentation. Please write a section (or sections) for
this Info file describing the installation and compilation steps
- needed to compile and/or install 'gawk' for your system.
+ needed to compile and/or install âgawkâ for your system.
Following these steps makes it much easier to integrate your changes
-into 'gawk' and have them coexist happily with other operating systems'
+into âgawkâ and have them coexist happily with other operating systemsâ
code that is already there.
In the code that you supply and maintain, feel free to use a coding
@@ -33002,17 +33000,17 @@ File: gawk.info, Node: Derived Files, Prev: New
Ports, Up: Additions
C.2.4 Why Generated Files Are Kept In Git
-----------------------------------------
-If you look at the 'gawk' source in the Git repository, you will notice
+If you look at the âgawkâ source in the Git repository, you will notice
that it includes files that are automatically generated by GNU
-infrastructure tools, such as 'Makefile.in' from Automake and even
-'configure' from Autoconf.
+infrastructure tools, such as âMakefile.inâ from Automake and even
+âconfigureâ from Autoconf.
This is different from many Free Software projects that do not store
the derived files, because that keeps the repository less cluttered, and
it is easier to see the substantive changes when comparing versions and
trying to understand what changed between commits.
- However, there are several reasons why the 'gawk' maintainer likes to
+ However, there are several reasons why the âgawkâ maintainer likes to
have everything in the repository.
First, because it is then easy to reproduce any given version
@@ -33020,30 +33018,30 @@ completely, without relying upon the availability of
(older, likely
obsolete, and maybe even impossible to find) other tools.
As an extreme example, if you ever even think about trying to
-compile, oh, say, the V7 'awk', you will discover that not only do you
-have to bootstrap the V7 'yacc' to do so, but you also need the V7
-'lex'. And the latter is pretty much impossible to bring up on a modern
+compile, oh, say, the V7 âawkâ, you will discover that not only do you
+have to bootstrap the V7 âyaccâ to do so, but you also need the V7
+âlexâ. And the latter is pretty much impossible to bring up on a modern
GNU/Linux system.(1)
- (Or, let's say 'gawk' 1.2 required 'bison' whatever-it-was in 1989
-and that there was no 'awkgram.c' file in the repository. Is there a
-guarantee that we could find that 'bison' version? Or that _it_ would
+ (Or, letâs say âgawkâ 1.2 required âbisonâ whatever-it-was in 1989
+and that there was no âawkgram.câ file in the repository. Is there a
+guarantee that we could find that âbisonâ version? Or that _it_ would
build?)
- If the repository has all the generated files, then it's easy to just
+ If the repository has all the generated files, then itâs easy to just
check them out and build. (Or _easier_, depending upon how far back we
go.)
And that brings us to the second (and stronger) reason why all the
files really need to be in Git. It boils down to who do you cater
-to--the 'gawk' developer(s), or the user who just wants to check out a
+toâthe âgawkâ developer(s), or the user who just wants to check out a
version and try it out?
- The 'gawk' maintainer wants it to be possible for any interested
-'awk' user in the world to just clone the repository, check out the
+ The âgawkâ maintainer wants it to be possible for any interested
+âawkâ user in the world to just clone the repository, check out the
branch of interest and build it, without their having to have the
correct version(s) of the autotools.(2) That is the point of the
-'bootstrap.sh' file. It touches the various other files in the right
+âbootstrap.shâ file. It touches the various other files in the right
order such that
# The canonical incantation for building GNU software:
@@ -33051,48 +33049,48 @@ order such that
will _just work_.
- This is extremely important for the 'master' and 'gawk-X.Y-stable'
+ This is extremely important for the âmasterâ and âgawk-X.Y-stableâ
branches.
- Further, the 'gawk' maintainer would argue that it's also important
-for the 'gawk' developers. When he tried to check out the 'xgawk'
-branch(3) to build it, he couldn't. (No 'ltmain.sh' file, and he had no
+ Further, the âgawkâ maintainer would argue that itâs also important
+for the âgawkâ developers. When he tried to check out the âxgawkâ
+branch(3) to build it, he couldnât. (No âltmain.shâ file, and he had no
idea how to create it, and that was not the only problem.)
He felt _extremely_ frustrated. With respect to that branch, the
maintainer is no different than Jane User who wants to try to build
-'gawk-4.1-stable' or 'master' from the repository.
+âgawk-4.1-stableâ or âmasterâ from the repository.
- Thus, the maintainer thinks that it's not just important, but
+ Thus, the maintainer thinks that itâs not just important, but
critical, that for any given branch, the above incantation _just works_.
- A third reason to have all the files is that without them, using 'git
-bisect' to try to find the commit that introduced a bug is exceedingly
+ A third reason to have all the files is that without them, using âgit
+bisectâ to try to find the commit that introduced a bug is exceedingly
difficult. The maintainer tried to do that on another project that
-requires running bootstrapping scripts just to create 'configure' and so
+requires running bootstrapping scripts just to create âconfigureâ and so
on; it was really painful. When the repository is self-contained, using
-'git bisect' in it is very easy.
+âgit bisectâ in it is very easy.
What are some of the consequences and/or actions to take?
- 1. We don't mind that there are differing files in the different
+ 1. We donât mind that there are differing files in the different
branches as a result of different versions of the autotools.
- A. It's the maintainer's job to merge them and he will deal with
+ A. Itâs the maintainerâs job to merge them and he will deal with
it.
- B. He is really good at 'git diff x y > /tmp/diff1 ; gvim
- /tmp/diff1' to remove the diffs that aren't of interest in
+ B. He is really good at âgit diff x y > /tmp/diff1 ; gvim
+ /tmp/diff1â to remove the diffs that arenât of interest in
order to review code.
2. It would certainly help if everyone used the same versions of the
GNU tools as he does, which in general are the latest released
- versions of Automake, Autoconf, 'bison', GNU 'gettext', and
+ versions of Automake, Autoconf, âbisonâ, GNU âgettextâ, and
Libtool.
- Installing from source is quite easy. It's how the maintainer
- worked for years (and still works). He had '/usr/local/bin' at the
- front of his 'PATH' and just did:
+ Installing from source is quite easy. Itâs how the maintainer
+ worked for years (and still works). He had â/usr/local/binâ at the
+ front of his âPATHâ and just did:
wget https://ftp.gnu.org/gnu/PACKAGE/PACKAGE-X.Y.Z.tar.gz
tar -xpzvf PACKAGE-X.Y.Z.tar.gz
@@ -33100,23 +33098,23 @@ on; it was really painful. When the repository is
self-contained, using
./configure && make && make check
make install # as root
- NOTE: Because of the 'https://' URL, you may have to supply
- the '--no-check-certificate' option to 'wget' to download the
+ NOTE: Because of the âhttps://â URL, you may have to supply
+ the â--no-check-certificateâ option to âwgetâ to download the
file.
Most of the above was originally written by the maintainer to other
-'gawk' developers. It raised the objection from one of the developers
-"... that anybody pulling down the source from Git is not an end user."
+âgawkâ developers. It raised the objection from one of the developers
+â... that anybody pulling down the source from Git is not an end user.â
- However, this is not true. There are "power 'awk' users" who can
-build 'gawk' (using the magic incantation shown previously) but who
-can't program in C. Thus, the major branches should be kept buildable
+ However, this is not true. There are âpower âawkâ usersâ who can
+build âgawkâ (using the magic incantation shown previously) but who
+canât program in C. Thus, the major branches should be kept buildable
all the time.
- It was then suggested that there be a 'cron' job to create nightly
-tarballs of "the source." Here, the problem is that there are source
+ It was then suggested that there be a âcronâ job to create nightly
+tarballs of âthe source.â Here, the problem is that there are source
trees, corresponding to the various branches! So, nightly tarballs
-aren't the answer, especially as the repository can go for weeks without
+arenât the answer, especially as the repository can go for weeks without
significant change being introduced.
Fortunately, the Git server can meet this need. For any given branch
@@ -33132,14 +33130,14 @@ to retrieve a snapshot of the given branch.
(2) There is one GNU program that is (in our opinion) severely
difficult to bootstrap from the Git repository. For example, on the
-author's old (but still working) PowerPC Macintosh with macOS 10.5, it
+authorâs old (but still working) PowerPC Macintosh with macOS 10.5, it
was necessary to bootstrap a ton of software, starting with Git itself,
-in order to try to work with the latest code. It's not pleasant, and
-especially on older systems, it's a big waste of time.
+in order to try to work with the latest code. Itâs not pleasant, and
+especially on older systems, itâs a big waste of time.
Starting with the latest tarball was no picnic either. The
-maintainers had dropped '.gz' and '.bz2' files and only distribute
-'.tar.xz' files. It was necessary to bootstrap 'xz' first!
+maintainers had dropped â.gzâ and â.bz2â files and only distribute
+â.tar.xzâ files. It was necessary to bootstrap âxzâ first!
(3) A branch (since removed) created by one of the other developers
that did not include the generated files.
@@ -33151,12 +33149,12 @@ C.3 Probable Future Extensions
==============================
AWK is a language similar to PERL, only considerably more elegant.
- -- _Arnold Robbins_
+ â _Arnold Robbins_
Hey!
- -- _Larry Wall_
+ â _Larry Wall_
- The 'TODO' file in the 'master' branch of the 'gawk' Git repository
+ The âTODOâ file in the âmasterâ branch of the âgawkâ Git
repository
lists possible future enhancements. Some of these relate to the source
code, and others to possible new features. Please see that file for the
list. *Note Additions::, if you are interested in tackling any of the
@@ -33168,7 +33166,7 @@ File: gawk.info, Node: Implementation Limitations,
Next: Extension Design, Pr
C.4 Some Limitations of the Implementation
==========================================
-This following table describes limits of 'gawk' on a Unix-like system
+This following table describes limits of âgawkâ on a Unix-like system
(although it is variable even then). Other systems may have different
limits.
@@ -33176,25 +33174,25 @@ Item Limit
--------------------------------------------------------------------------
Characters in a character 2^(number of bits per byte)
class
-Length of input record in 'ULONG_MAX'
+Length of input record in âULONG_MAXâ
bytes
Length of output record Unlimited
Length of source line Unlimited
-Number of fields in a 'ULONG_MAX'
+Number of fields in a âULONG_MAXâ
record
Number of file redirections Unlimited
-Number of input records in 'MAX_LONG'
+Number of input records in âMAX_LONGâ
one file
-Number of input records 'MAX_LONG'
+Number of input records âMAX_LONGâ
total
Number of pipe redirections min(number of processes per user, number
of open files)
Numeric values Double-precision floating point (if not
using MPFR)
-Size of a field in bytes 'ULONG_MAX'
-Size of a literal string in 'ULONG_MAX'
+Size of a field in bytes âULONG_MAXâ
+Size of a literal string in âULONG_MAXâ
bytes
-Size of a printf string in 'ULONG_MAX'
+Size of a printf string in âULONG_MAXâ
bytes
@@ -33206,15 +33204,15 @@ C.5 Extension API Design
This minor node documents the design of the extension API, including a
discussion of some of the history and problems that needed to be solved.
- The first version of extensions for 'gawk' was developed in the
-mid-1990s and released with 'gawk' 3.1 in the late 1990s. The basic
+ The first version of extensions for âgawkâ was developed in the
+mid-1990s and released with âgawkâ 3.1 in the late 1990s. The basic
mechanisms and design remained unchanged for close to 15 years, until
2012.
- The old extension mechanism used data types and functions from 'gawk'
-itself, with a "clever hack" to install extension functions.
+ The old extension mechanism used data types and functions from âgawkâ
+itself, with a âclever hackâ to install extension functions.
- 'gawk' included some sample extensions, of which a few were really
+ âgawkâ included some sample extensions, of which a few were really
useful. However, it was clear from the outset that the extension
mechanism was bolted onto the side and was not really well thought out.
@@ -33233,33 +33231,33 @@ C.5.1 Problems With The Old Mechanism
The old extension mechanism had several problems:
- * It depended heavily upon 'gawk' internals. Any time the 'NODE'
+ ⢠It depended heavily upon âgawkâ internals. Any time the âNODEâ
structure(1) changed, an extension would have to be recompiled.
Furthermore, to really write extensions required understanding
- something about 'gawk''s internal functions. There was some
+ something about âgawkââs internal functions. There was some
documentation in this Info file, but it was quite minimal.
- * Being able to call into 'gawk' from an extension required linker
+ ⢠Being able to call into âgawkâ from an extension required linker
facilities that are common on Unix-derived systems but that did not
work on MS-Windows systems; users wanting extensions on MS-Windows
- had to statically link them into 'gawk', even though MS-Windows
+ had to statically link them into âgawkâ, even though MS-Windows
supports dynamic loading of shared objects.
- * The API would change occasionally as 'gawk' changed; no
+ ⢠The API would change occasionally as âgawkâ changed; no
compatibility between versions was ever offered or planned for.
- Despite the drawbacks, the 'xgawk' project developers forked 'gawk'
+ Despite the drawbacks, the âxgawkâ project developers forked âgawkâ
and developed several significant extensions. They also enhanced
-'gawk''s facilities relating to file inclusion and shared object access.
+âgawkââs facilities relating to file inclusion and shared object access.
A new API was desired for a long time, but only in 2012 did the
-'gawk' maintainer and the 'xgawk' developers finally start working on it
-together. More information about the 'xgawk' project is provided in
+âgawkâ maintainer and the âxgawkâ developers finally start working on
it
+together. More information about the âxgawkâ project is provided in
*note gawkextlib::.
---------- Footnotes ----------
- (1) A critical central data structure inside 'gawk'.
+ (1) A critical central data structure inside âgawkâ.
File: gawk.info, Node: Extension New Mechanism Goals, Next: Extension Other
Design Decisions, Prev: Old Extension Problems, Up: Extension Design
@@ -33269,42 +33267,42 @@ C.5.2 Goals For A New Mechanism
Some goals for the new API were:
- * The API should be independent of 'gawk' internals. Changes in
- 'gawk' internals should not be visible to the writer of an
+ ⢠The API should be independent of âgawkâ internals. Changes in
+ âgawkâ internals should not be visible to the writer of an
extension function.
- * The API should provide _binary_ compatibility across 'gawk'
+ ⢠The API should provide _binary_ compatibility across âgawkâ
releases as long as the API itself does not change.
- * The API should enable extensions written in C or C++ to have
- roughly the same "appearance" to 'awk'-level code as 'awk'
+ ⢠The API should enable extensions written in C or C++ to have
+ roughly the same âappearanceâ to âawkâ-level code as âawkâ
functions do. This means that extensions should have:
- - The ability to access function parameters.
+ â The ability to access function parameters.
- - The ability to turn an undefined parameter into an array (call
+ â The ability to turn an undefined parameter into an array (call
by reference).
- - The ability to create, access and update global variables.
+ â The ability to create, access and update global variables.
- - Easy access to all the elements of an array at once ("array
- flattening") in order to loop over all the element in an easy
+ â Easy access to all the elements of an array at once (âarray
+ flatteningâ) in order to loop over all the element in an easy
fashion for C code.
- - The ability to create arrays (including 'gawk''s true arrays
+ â The ability to create arrays (including âgawkââs true arrays
of arrays).
Some additional important goals were:
- * The API should use only features in ISO C 90, so that extensions
+ ⢠The API should use only features in ISO C 90, so that extensions
can be written using the widest range of C and C++ compilers. The
- header should include the appropriate '#ifdef __cplusplus' and
- 'extern "C"' magic so that a C++ compiler could be used. (If using
+ header should include the appropriate â#ifdef __cplusplusâ and
+ âextern "C"â magic so that a C++ compiler could be used. (If using
C++, the runtime system has to be smart enough to call any
- constructors and destructors, as 'gawk' is a C program. As of this
+ constructors and destructors, as âgawkâ is a C program. As of this
writing, this has not been tested.)
- * The API mechanism should not require access to 'gawk''s symbols(1)
+ ⢠The API mechanism should not require access to âgawkââs symbols(1)
by the compile-time or dynamic linker, in order to enable creation
of extensions that also work on MS-Windows.
@@ -33312,28 +33310,28 @@ Some goals for the new API were:
that should be available to extensions, which were also subsequently
provided:
- * Extensions should have the ability to hook into 'gawk''s I/O
- redirection mechanism. In particular, the 'xgawk' developers
- provided a so-called "open hook" to take over reading records.
+ ⢠Extensions should have the ability to hook into âgawkââs I/O
+ redirection mechanism. In particular, the âxgawkâ developers
+ provided a so-called âopen hookâ to take over reading records.
During development, this was generalized to allow extensions to
hook into input processing, output processing, and two-way I/O.
- * An extension should be able to provide a "call back" function to
- perform cleanup actions when 'gawk' exits.
+ ⢠An extension should be able to provide a âcall backâ function to
+ perform cleanup actions when âgawkâ exits.
- * An extension should be able to provide a version string so that
- 'gawk''s '--version' option can provide information about
+ ⢠An extension should be able to provide a version string so that
+ âgawkââs â--versionâ option can provide information about
extensions as well.
- The requirement to avoid access to 'gawk''s symbols is, at first
+ The requirement to avoid access to âgawkââs symbols is, at first
glance, a difficult one to meet.
One design, apparently used by Perl and Ruby and maybe others, would
-be to make the mainline 'gawk' code into a library, with the 'gawk'
-utility a small C 'main()' function linked against the library.
+be to make the mainline âgawkâ code into a library, with the âgawkâ
+utility a small C âmain()â function linked against the library.
This seemed like the tail wagging the dog, complicating build and
-installation and making a simple copy of the 'gawk' executable from one
+installation and making a simple copy of the âgawkâ executable from one
system to another (or one place to another on the same system!) into a
chancy operation.
@@ -33342,8 +33340,8 @@ Mechanism Outline::, for the details.
---------- Footnotes ----------
- (1) The "symbols" are the variables and functions defined inside
-'gawk'. Access to these symbols by code external to 'gawk' loaded
+ (1) The âsymbolsâ are the variables and functions defined inside
+âgawkâ. Access to these symbols by code external to âgawkâ loaded
dynamically at runtime is problematic on MS-Windows.
@@ -33353,39 +33351,39 @@ C.5.3 Other Design Decisions
----------------------------
As an arbitrary design decision, extensions can read the values of
-predefined variables and arrays (such as 'ARGV' and 'FS'), but cannot
-change them, with the exception of 'PROCINFO'.
+predefined variables and arrays (such as âARGVâ and âFSâ), but cannot
+change them, with the exception of âPROCINFOâ.
The reason for this is to prevent an extension function from
-affecting the flow of an 'awk' program outside its control. While a
-real 'awk' function can do what it likes, that is at the discretion of
+affecting the flow of an âawkâ program outside its control. While a
+real âawkâ function can do what it likes, that is at the discretion of
the programmer. An extension function should provide a service or make
-a C API available for use within 'awk', and not mess with 'FS' or 'ARGC'
-and 'ARGV'.
+a C API available for use within âawkâ, and not mess with âFSâ or
âARGCâ
+and âARGVâ.
In addition, it becomes easy to start down a slippery slope. How
-much access to 'gawk' facilities do extensions need? Do they need
-'getline'? What about calling 'gsub()' or compiling regular
-expressions? What about calling into 'awk' functions? (_That_ would be
+much access to âgawkâ facilities do extensions need? Do they need
+âgetlineâ? What about calling âgsub()â or compiling regular
+expressions? What about calling into âawkâ functions? (_That_ would be
messy.)
- In order to avoid these issues, the 'gawk' developers chose to start
+ In order to avoid these issues, the âgawkâ developers chose to start
with the simplest, most basic features that are still truly useful.
- Another decision is that although 'gawk' provides nice things like
+ Another decision is that although âgawkâ provides nice things like
MPFR, and arrays indexed internally by integers, these features are not
being brought out to the API in order to keep things simple and close to
-traditional 'awk' semantics. (In fact, arrays indexed internally by
-integers are so transparent that they aren't even documented!)
+traditional âawkâ semantics. (In fact, arrays indexed internally by
+integers are so transparent that they arenât even documented!)
Additionally, all functions in the API check that their pointer input
-parameters are not 'NULL'. If they are, they return an error. (It is a
+parameters are not âNULLâ. If they are, they return an error. (It is a
good idea for extension code to verify that pointers received from
-'gawk' are not 'NULL'. Such a thing should not happen, but the 'gawk'
+âgawkâ are not âNULLâ. Such a thing should not happen, but the
âgawkâ
developers are only human, and they have been known to occasionally make
mistakes.)
- With time, the API will undoubtedly evolve; the 'gawk' developers
+ With time, the API will undoubtedly evolve; the âgawkâ developers
expect this to be driven by user needs. For now, the current API seems
to provide a minimal yet powerful set of features for creating
extensions.
@@ -33398,9 +33396,9 @@ C.5.4 Room For Future Growth
The API can later be expanded, in at least the following way:
- * 'gawk' passes an "extension id" into the extension when it first
+ ⢠âgawkâ passes an âextension idâ into the extension when it first
loads the extension. The extension then passes this id back to
- 'gawk' with each function call. This mechanism allows 'gawk' to
+ âgawkâ with each function call. This mechanism allows âgawkâ to
identify the extension calling into it, should it need to know.
Of course, as of this writing, no decisions have been made with
@@ -33412,27 +33410,27 @@ File: gawk.info, Node: Notes summary, Prev:
Extension Design, Up: Notes
C.6 Summary
===========
- * 'gawk''s extensions can be disabled with either the '--traditional'
- option or with the '--posix' option. The '--parsedebug' option is
- available if 'gawk' is compiled with '-DDEBUG'.
+ ⢠âgawkââs extensions can be disabled with either the
â--traditionalâ
+ option or with the â--posixâ option. The â--parsedebugâ option is
+ available if âgawkâ is compiled with â-DDEBUGâ.
- * The source code for 'gawk' is maintained in a publicly accessible
+ ⢠The source code for âgawkâ is maintained in a publicly accessible
Git repository. Anyone may check it out and view the source.
- * Contributions to 'gawk' are welcome. Following the steps outlined
+ ⢠Contributions to âgawkâ are welcome. Following the steps outlined
in this major node will make it easier to integrate your
contributions into the code base. This applies both to new feature
contributions and to ports to additional operating systems.
- * 'gawk' has some limits--generally those that are imposed by the
+ ⢠âgawkâ has some limitsâgenerally those that are imposed by the
machine architecture.
- * The extension API design was intended to solve a number of problems
+ ⢠The extension API design was intended to solve a number of problems
with the previous extension mechanism, enable features needed by
- the 'xgawk' project, and provide binary compatibility going
+ the âxgawkâ project, and provide binary compatibility going
forward.
- * The previous extension mechanism is no longer supported and was
+ ⢠The previous extension mechanism is no longer supported and was
removed from the code base with the 4.2 release.
@@ -33443,7 +33441,7 @@ Appendix D Basic Programming Concepts
This major node attempts to define some of the basic concepts and terms
that are used throughout the rest of this Info file. As this Info file
-is specifically about 'awk', and not about computer programming in
+is specifically about âawkâ, and not about computer programming in
general, the coverage here is by necessity fairly cursory and
simplistic. (If you need more background, there are many other
introductory texts that you should refer to instead.)
@@ -33470,9 +33468,9 @@ data and produce results. See *note Figure D.1:
figure-general-flow.
Figure D.1: General Program Flow
- The "program" in the figure can be either a compiled program(1) (such
-as 'ls'), or it may be "interpreted". In the latter case, a
-machine-executable program such as 'awk' reads your program, and then
+ The âprogramâ in the figure can be either a compiled program(1) (such
+as âlsâ), or it may be âinterpretedâ. In the latter case, a
+machine-executable program such as âawkâ reads your program, and then
uses the instructions in your program to process the data.
When you write a program, it usually consists of the following, very
@@ -33496,7 +33494,7 @@ Figure D.2: Basic Program Steps
Initialization
These are the things you do before actually starting to process
data, such as checking arguments, initializing any data you need to
- work with, and so on. This step corresponds to 'awk''s 'BEGIN'
+ work with, and so on. This step corresponds to âawkââs âBEGINâ
rule (*note BEGIN/END::).
If you were baking a cake, this might consist of laying out all the
@@ -33509,7 +33507,7 @@ Processing
In most programming languages, you have to manually manage the
reading of data, checking to see if there is more each time you
- read a chunk. 'awk''s pattern-action paradigm (*note Getting
+ read a chunk. âawkââs pattern-action paradigm (*note Getting
Started::) handles the mechanics of this for you.
In baking a cake, the processing corresponds to the actual labor:
@@ -33517,42 +33515,42 @@ Processing
then putting the cake into the oven.
Clean Up
- Once you've processed all the data, you may have things you need to
- do before exiting. This step corresponds to 'awk''s 'END' rule
+ Once youâve processed all the data, you may have things you need to
+ do before exiting. This step corresponds to âawkââs âENDâ rule
(*note BEGIN/END::).
After the cake comes out of the oven, you still have to wrap it in
plastic wrap to keep anyone from tasting it, as well as wash the
mixing bowls and utensils.
- An "algorithm" is a detailed set of instructions necessary to
+ An âalgorithmâ is a detailed set of instructions necessary to
accomplish a task, or process data. It is much the same as a recipe for
baking a cake. Programs implement algorithms. Often, it is up to you
to design the algorithm and implement it, simultaneously.
- The "logical chunks" we talked about previously are called "records",
+ The âlogical chunksâ we talked about previously are called
ârecordsâ,
similar to the records a company keeps on employees, a school keeps for
students, or a doctor keeps for patients. Each record has many
component parts, such as first and last names, date of birth, address,
-and so on. The component parts are referred to as the "fields" of the
+and so on. The component parts are referred to as the âfieldsâ of the
record.
- The act of reading data is termed "input", and that of generating
-results, not too surprisingly, is termed "output". They are often
-referred to together as "input/output," and even more often, as "I/O"
-for short. (You will also see "input" and "output" used as verbs.)
+ The act of reading data is termed âinputâ, and that of generating
+results, not too surprisingly, is termed âoutputâ. They are often
+referred to together as âinput/output,â and even more often, as âI/Oâ
+for short. (You will also see âinputâ and âoutputâ used as verbs.)
- 'awk' manages the reading of data for you, as well as the breaking it
-up into records and fields. Your program's job is to tell 'awk' what to
-do with the data. You do this by describing "patterns" in the data to
-look for, and "actions" to execute when those patterns are seen. This
-"data-driven" nature of 'awk' programs usually makes them both easier to
+ âawkâ manages the reading of data for you, as well as the breaking it
+up into records and fields. Your programâs job is to tell âawkâ what to
+do with the data. You do this by describing âpatternsâ in the data to
+look for, and âactionsâ to execute when those patterns are seen. This
+âdata-drivenâ nature of âawkâ programs usually makes them both easier
to
write and easier to read.
---------- Footnotes ----------
(1) Compiled programs are typically written in lower-level languages
-such as C, C++, or Ada, and then translated, or "compiled", into a form
+such as C, C++, or Ada, and then translated, or âcompiledâ, into a form
that the computer can execute directly.
@@ -33562,18 +33560,18 @@ D.2 Data Values in a Computer
=============================
In a program, you keep track of information and values in things called
-"variables". A variable is just a name for a given value, such as
-'first_name', 'last_name', 'address', and so on. 'awk' has several
+âvariablesâ. A variable is just a name for a given value, such as
+âfirst_nameâ, âlast_nameâ, âaddressâ, and so on. âawkâ has
several
predefined variables, and it has special names to refer to the current
input record and the fields of the record. You may also group multiple
associated values under one name, as an array.
- Data, particularly in 'awk', consists of either numeric values, such
+ Data, particularly in âawkâ, consists of either numeric values, such
as 42 or 3.1415927, or string values. String values are essentially
-anything that's not a number, such as a name. Strings are sometimes
-referred to as "character data", since they store the individual
+anything thatâs not a number, such as a name. Strings are sometimes
+referred to as âcharacter dataâ, since they store the individual
characters that comprise them. Individual variables, as well as numeric
-and string variables, are referred to as "scalar" values. Groups of
+and string variables, are referred to as âscalarâ values. Groups of
values, such as arrays, are not scalars.
*note Computer Arithmetic::, provided a basic introduction to numeric
@@ -33584,41 +33582,41 @@ presented.
While you are probably used to the idea of a number without a value
(i.e., zero), it takes a bit more getting used to the idea of
zero-length character data. Nevertheless, such a thing exists. It is
-called the "null string". The null string is character data that has no
-value. In other words, it is empty. It is written in 'awk' programs
-like this: '""'.
+called the ânull stringâ. The null string is character data that has no
+value. In other words, it is empty. It is written in âawkâ programs
+like this: â""â.
Humans are used to working in decimal; i.e., base 10. In base 10,
-numbers go from 0 to 9, and then "roll over" into the next column.
+numbers go from 0 to 9, and then âroll overâ into the next column.
(Remember grade school? 42 = 4 x 10 + 2.)
There are other number bases though. Computers commonly use base 2
-or "binary", base 8 or "octal", and base 16 or "hexadecimal". In
+or âbinaryâ, base 8 or âoctalâ, and base 16 or âhexadecimalâ. In
binary, each column represents two times the value in the column to its
right. Each column may contain either a 0 or a 1. Thus, binary 1010
represents (1 x 8) + (0 x 4) + (1 x 2) + (0 x 1), or decimal 10. Octal
and hexadecimal are discussed more in *note Nondecimal-numbers::.
At the very lowest level, computers store values as groups of binary
-digits, or "bits". Modern computers group bits into groups of eight,
-called "bytes". Advanced applications sometimes have to manipulate bits
-directly, and 'gawk' provides functions for doing so.
+digits, or âbitsâ. Modern computers group bits into groups of eight,
+called âbytesâ. Advanced applications sometimes have to manipulate bits
+directly, and âgawkâ provides functions for doing so.
Programs are written in programming languages. Hundreds, if not
thousands, of programming languages exist. One of the most popular is
the C programming language. The C language had a very strong influence
-on the design of the 'awk' language.
+on the design of the âawkâ language.
There have been several versions of C. The first is often referred to
-as "K&R" C, after the initials of Brian Kernighan and Dennis Ritchie,
+as âK&Râ C, after the initials of Brian Kernighan and Dennis Ritchie,
the authors of the first book on C. (Dennis Ritchie created the
-language, and Brian Kernighan was one of the creators of 'awk'.)
+language, and Brian Kernighan was one of the creators of âawkâ.)
In the mid-1980s, an effort began to produce an international
standard for C. This work culminated in 1989, with the production of the
ANSI standard for C. This standard became an ISO standard in 1990. In
1999, a revised ISO C standard was approved and released. Where it
-makes sense, POSIX 'awk' is compatible with 1999 ISO C.
+makes sense, POSIX âawkâ is compatible with 1999 ISO C.
File: gawk.info, Node: Glossary, Next: Copying, Prev: Basic Concepts, Up:
Top
@@ -33627,8 +33625,8 @@ Glossary
********
Action
- A series of 'awk' statements attached to a rule. If the rule's
- pattern matches an input record, 'awk' executes the rule's action.
+ A series of âawkâ statements attached to a rule. If the ruleâs
+ pattern matches an input record, âawkâ executes the ruleâs action.
Actions are always enclosed in braces. (*Note Action Overview::.)
Ada
@@ -33636,33 +33634,33 @@ Ada
Defense for embedded programming. It was designed to enforce good
Software Engineering practices.
-Amazing 'awk' Assembler
+Amazing âawkâ Assembler
Henry Spencer at the University of Toronto wrote a retargetable
- assembler completely as 'sed' and 'awk' scripts. It is thousands
+ assembler completely as âsedâ and âawkâ scripts. It is thousands
of lines long, including machine descriptions for several eight-bit
microcomputers. It is a good example of a program that would have
been better written in another language.
-Amazingly Workable Formatter ('awf')
+Amazingly Workable Formatter (âawfâ)
Henry Spencer at the University of Toronto wrote a formatter that
- accepts a large subset of the 'nroff -ms' and 'nroff -man'
- formatting commands, using 'awk' and 'sh'.
+ accepts a large subset of the ânroff -msâ and ânroff -manâ
+ formatting commands, using âawkâ and âshâ.
Anchor
- The regexp metacharacters '^' and '$', which force the match to the
+ The regexp metacharacters â^â and â$â, which force the match to
the
beginning or end of the string, respectively.
ANSI
The American National Standards Institute. This organization
produces many standards, among them the standards for the C and C++
programming languages. These standards often become international
- standards as well. See also "ISO."
+ standards as well. See also âISO.â
Argument
An argument can be two different things. It can be an option or a
file name passed to a command while invoking it from the command
- line, or it can be something passed to a "function" inside a
- program, e.g. inside 'awk'.
+ line, or it can be something passed to a âfunctionâ inside a
+ program, e.g. inside âawkâ.
In the latter case, an argument can be passed to a function in two
ways. Either it is given to the called function by value, i.e., a
@@ -33670,12 +33668,12 @@ Argument
function, but the original variable cannot be modified by the
function itself; or it is given by reference, i.e., a pointer to
the interested variable is passed to the function, which can then
- directly modify it. In 'awk' scalars are passed by value, and
- arrays are passed by reference. See "Pass By Value/Reference."
+ directly modify it. In âawkâ scalars are passed by value, and
+ arrays are passed by reference. See âPass By Value/Reference.â
Array
A grouping of multiple values under the same name. Most languages
- just provide sequential arrays. 'awk' provides associative arrays.
+ just provide sequential arrays. âawkâ provides associative arrays.
Assertion
A statement in a program that a condition is true at this point in
@@ -33683,37 +33681,37 @@ Assertion
to behave.
Assignment
- An 'awk' expression that changes the value of some 'awk' variable
+ An âawkâ expression that changes the value of some âawkâ variable
or data object. An object that you can assign to is called an
- "lvalue". The assigned values are called "rvalues". *Note
+ âlvalueâ. The assigned values are called ârvaluesâ. *Note
Assignment Ops::.
Associative Array
Arrays in which the indices may be numbers or strings, not just
sequential integers in a fixed range.
-'awk' Language
- The language in which 'awk' programs are written.
+âawkâ Language
+ The language in which âawkâ programs are written.
-'awk' Program
- An 'awk' program consists of a series of "patterns" and "actions",
- collectively known as "rules". For each input record given to the
- program, the program's rules are all processed in turn. 'awk'
+âawkâ Program
+ An âawkâ program consists of a series of âpatternsâ and
âactionsâ,
+ collectively known as ârulesâ. For each input record given to the
+ program, the programâs rules are all processed in turn. âawkâ
programs may also contain function definitions.
-'awk' Script
- Another name for an 'awk' program.
+âawkâ Script
+ Another name for an âawkâ program.
Bash
The GNU version of the standard shell (the Bourne-Again SHell).
- See also "Bourne Shell."
+ See also âBourne Shell.â
Binary
- Base-two notation, where the digits are '0'-'1'. Since electronic
- circuitry works "naturally" in base 2 (just think of Off/On),
+ Base-two notation, where the digits are â0âââ1â. Since
electronic
+ circuitry works ânaturallyâ in base 2 (just think of Off/On),
everything inside a computer is calculated using base 2. Each
digit represents the presence (or absence) of a power of 2 and is
- called a "bit". So, for example, the base-two number '10101' is
+ called a âbitâ. So, for example, the base-two number â10101â is
the same as decimal 21, ((1 x 16) + (1 x 4) + (1 x 1)).
Since base-two numbers quickly become very long to read and write,
@@ -33728,12 +33726,12 @@ Binary
numbers in their registers, but 32-bit, 16-bit and 8-bit registers
have been widely used in the past. *Note Nondecimal-numbers::.
Bit
- Short for "Binary Digit." All values in computer memory ultimately
+ Short for âBinary Digit.â All values in computer memory ultimately
reduce to binary digits: values that are either zero or one.
- Groups of bits may be interpreted differently--as integers,
+ Groups of bits may be interpreted differentlyâas integers,
floating-point numbers, character data, addresses of other memory
- objects, or other data. 'awk' lets you work with floating-point
- numbers and strings. 'gawk' lets you manipulate bit values with
+ objects, or other data. âawkâ lets you work with floating-point
+ numbers and strings. âgawkâ lets you manipulate bit values with
the built-in functions described in *note Bitwise Functions::.
Computers are often defined by how many bits they use to represent
@@ -33742,77 +33740,77 @@ Bit
essentially disappeared.
Boolean Expression
- Named after the English mathematician Boole. See also "Logical
- Expression."
+ Named after the English mathematician Boole. See also âLogical
+ Expression.â
Bourne Shell
- The standard shell ('/bin/sh') on Unix and Unix-like systems,
+ The standard shell (â/bin/shâ) on Unix and Unix-like systems,
originally written by Steven R. Bourne at Bell Laboratories. Many
- shells (Bash, 'ksh', 'pdksh', 'zsh') are generally upwardly
+ shells (Bash, âkshâ, âpdkshâ, âzshâ) are generally upwardly
compatible with the Bourne shell.
Braces
- The characters '{' and '}'. Braces are used in 'awk' for
+ The characters â{â and â}â. Braces are used in âawkâ for
delimiting actions, compound statements, and function bodies.
Bracket Expression
- Inside a "regular expression", an expression included in square
+ Inside a âregular expressionâ, an expression included in square
brackets, meant to designate a single character as belonging to a
specified character class. A bracket expression can contain a list
- of one or more characters, like '[abc]', a range of characters,
- like '[A-Z]', or a name, delimited by ':', that designates a known
- set of characters, like '[:digit:]'. The form of bracket
- expression enclosed between ':' is independent of the underlying
+ of one or more characters, like â[abc]â, a range of characters,
+ like â[A-Z]â, or a name, delimited by â:â, that designates a known
+ set of characters, like â[:digit:]â. The form of bracket
+ expression enclosed between â:â is independent of the underlying
representation of the character themselves, which could utilize the
ASCII, EBCDIC, or Unicode codesets, depending on the architecture
- of the computer system, and on localization. See also "Regular
- Expression."
+ of the computer system, and on localization. See also âRegular
+ Expression.â
Built-in Function
- The 'awk' language provides built-in functions that perform various
+ The âawkâ language provides built-in functions that perform various
numerical, I/O-related, and string computations. Examples are
- 'sqrt()' (for the square root of a number) and 'substr()' (for a
- substring of a string). 'gawk' provides functions for timestamp
+ âsqrt()â (for the square root of a number) and âsubstr()â (for a
+ substring of a string). âgawkâ provides functions for timestamp
management, bit manipulation, array sorting, type checking, and
runtime string translation. (*Note Built-in::.)
Built-in Variable
- 'ARGC', 'ARGV', 'CONVFMT', 'ENVIRON', 'FILENAME', 'FNR', 'FS',
- 'NF', 'NR', 'OFMT', 'OFS', 'ORS', 'RLENGTH', 'RSTART', 'RS', and
- 'SUBSEP' are the variables that have special meaning to 'awk'. In
- addition, 'ARGIND', 'BINMODE', 'ERRNO', 'FIELDWIDTHS', 'FPAT',
- 'IGNORECASE', 'LINT', 'PROCINFO', 'RT', and 'TEXTDOMAIN' are the
- variables that have special meaning to 'gawk'. Changing some of
- them affects 'awk''s running environment. (*Note Built-in
+ âARGCâ, âARGVâ, âCONVFMTâ, âENVIRONâ, âFILENAMEâ,
âFNRâ, âFSâ,
+ âNFâ, âNRâ, âOFMTâ, âOFSâ, âORSâ, âRLENGTHâ,
âRSTARTâ, âRSâ, and
+ âSUBSEPâ are the variables that have special meaning to âawkâ. In
+ addition, âARGINDâ, âBINMODEâ, âERRNOâ, âFIELDWIDTHSâ,
âFPATâ,
+ âIGNORECASEâ, âLINTâ, âPROCINFOâ, âRTâ, and
âTEXTDOMAINâ are the
+ variables that have special meaning to âgawkâ. Changing some of
+ them affects âawkââs running environment. (*Note Built-in
Variables::.)
C
The system programming language that most GNU software is written
- in. The 'awk' programming language has C-like syntax, and this
- Info file points out similarities between 'awk' and C when
+ in. The âawkâ programming language has C-like syntax, and this
+ Info file points out similarities between âawkâ and C when
appropriate.
- In general, 'gawk' attempts to be as similar to the 1990 version of
+ In general, âgawkâ attempts to be as similar to the 1990 version of
ISO C as makes sense.
C Shell
- The C Shell ('csh' or its improved version, 'tcsh') is a Unix shell
+ The C Shell (âcshâ or its improved version, âtcshâ) is a Unix
shell
that was created by Bill Joy in the late 1970s. The C shell was
differentiated from other shells by its interactive features and
overall style, which looks more like C. The C Shell is not backward
compatible with the Bourne Shell, so special attention is required
when converting scripts written for other Unix shells to the C
shell, especially with regard to the management of shell variables.
- See also "Bourne Shell."
+ See also âBourne Shell.â
C++
A popular object-oriented programming language derived from C.
Character Class
- See "Bracket Expression."
+ See âBracket Expression.â
Character List
- See "Bracket Expression."
+ See âBracket Expression.â
Character Set
The set of numeric codes used by a computer system to represent the
@@ -33825,55 +33823,55 @@ Character Set
used on GNU/Linux systems.
CHEM
- A preprocessor for 'pic' that reads descriptions of molecules and
- produces 'pic' input for drawing them. It was written in 'awk' by
+ A preprocessor for âpicâ that reads descriptions of molecules and
+ produces âpicâ input for drawing them. It was written in âawkâ by
Brian Kernighan and Jon Bentley, and is available from
<http://netlib.org/typesetting/chem>.
Comparison Expression
- A relation that is either true or false, such as 'a < b'.
- Comparison expressions are used in 'if', 'while', 'do', and 'for'
+ A relation that is either true or false, such as âa < bâ.
+ Comparison expressions are used in âifâ, âwhileâ, âdoâ, and
âforâ
statements, and in patterns to select which input records to
process. (*Note Typing and Comparison::.)
Compiler
A program that translates human-readable source code into
machine-executable object code. The object code is then executed
- directly by the computer. See also "Interpreter."
+ directly by the computer. See also âInterpreter.â
Complemented Bracket Expression
- The negation of a "bracket expression". All that is _not_
- described by a given bracket expression. The symbol '^' precedes
- the negated bracket expression. E.g.: '[^[:digit:]]' designates
- whatever character is not a digit. '[^bad]' designates whatever
- character is not one of the letters 'b', 'a', or 'd'. See "Bracket
- Expression."
+ The negation of a âbracket expressionâ. All that is _not_
+ described by a given bracket expression. The symbol â^â precedes
+ the negated bracket expression. E.g.: â[^[:digit:]]â designates
+ whatever character is not a digit. â[^bad]â designates whatever
+ character is not one of the letters âbâ, âaâ, or âdâ. See
âBracket
+ Expression.â
Compound Statement
- A series of 'awk' statements, enclosed in curly braces. Compound
+ A series of âawkâ statements, enclosed in curly braces. Compound
statements may be nested. (*Note Statements::.)
Computed Regexps
- See "Dynamic Regular Expressions."
+ See âDynamic Regular Expressions.â
Concatenation
Concatenating two strings means sticking them together, one after
- another, producing a new string. For example, the string 'foo'
- concatenated with the string 'bar' gives the string 'foobar'.
+ another, producing a new string. For example, the string âfooâ
+ concatenated with the string âbarâ gives the string âfoobarâ.
(*Note Concatenation::.)
Conditional Expression
- An expression using the '?:' ternary operator, such as 'EXPR1 ?
- EXPR2 : EXPR3'. The expression EXPR1 is evaluated; if the result
+ An expression using the â?:â ternary operator, such as âEXPR1 ?
+ EXPR2 : EXPR3â. The expression EXPR1 is evaluated; if the result
is true, the value of the whole expression is the value of EXPR2;
otherwise the value is EXPR3. In either case, only one of EXPR2
and EXPR3 is evaluated. (*Note Conditional Exp::.)
Control Statement
A control statement is an instruction to perform a given operation
- or a set of operations inside an 'awk' program, if a given
- condition is true. Control statements are: 'if', 'for', 'while',
- and 'do' (*note Statements::).
+ or a set of operations inside an âawkâ program, if a given
+ condition is true. Control statements are: âifâ, âforâ,
âwhileâ,
+ and âdoâ (*note Statements::).
Cookie
A peculiar goodie, token, saying or remembrance produced by or
@@ -33884,16 +33882,16 @@ Coprocess
possible.
Curly Braces
- See "Braces."
+ See âBraces.â
Dark Corner
An area in the language where specifications often were (or still
are) not clear, leading to unexpected or undesirable behavior.
- Such areas are marked in this Info file with "(d.c.)" in the text
- and are indexed under the heading "dark corner."
+ Such areas are marked in this Info file with â(d.c.)â in the text
+ and are indexed under the heading âdark corner.â
Data Driven
- A description of 'awk' programs, where you specify the data you are
+ A description of âawkâ programs, where you specify the data you are
interested in processing, and what to do when that data is seen.
Data Objects
@@ -33905,61 +33903,61 @@ Deadlock
for the other to perform an action.
Debugger
- A program used to help developers remove "bugs" from (de-bug) their
+ A program used to help developers remove âbugsâ from (de-bug) their
programs.
Double Precision
An internal representation of numbers that can have fractional
parts. Double precision numbers keep track of more digits than do
single precision numbers, but operations on them are sometimes more
- expensive. This is the way 'awk' stores numeric values. It is the
- C type 'double'.
+ expensive. This is the way âawkâ stores numeric values. It is the
+ C type âdoubleâ.
Dynamic Regular Expression
A dynamic regular expression is a regular expression written as an
ordinary expression. It could be a string constant, such as
- '"foo"', but it may also be an expression whose value can vary.
+ â"foo"â, but it may also be an expression whose value can vary.
(*Note Computed Regexps::.)
Empty String
- See "Null String."
+ See âNull String.â
Environment
- A collection of strings, of the form 'NAME=VAL', that each program
+ A collection of strings, of the form âNAME=VALâ, that each program
has available to it. Users generally place values into the
environment in order to provide information to various programs.
- Typical examples are the environment variables 'HOME' and 'PATH'.
+ Typical examples are the environment variables âHOMEâ and âPATHâ.
Epoch
- The date used as the "beginning of time" for timestamps. Time
+ The date used as the âbeginning of timeâ for timestamps. Time
values in most systems are represented as seconds since the epoch,
with library functions available for converting these values into
standard date and time formats.
The epoch on Unix and POSIX systems is 1970-01-01 00:00:00 UTC. See
- also "GMT" and "UTC."
+ also âGMTâ and âUTC.â
Escape Sequences
A special sequence of characters used for describing nonprinting
- characters, such as '\n' for newline or '\033' for the ASCII ESC
+ characters, such as â\nâ for newline or â\033â for the ASCII ESC
(Escape) character. (*Note Escape Sequences::.)
Extension
An additional feature or change to a programming language or
- utility not defined by that language's or utility's standard.
- 'gawk' has (too) many extensions over POSIX 'awk'.
+ utility not defined by that languageâs or utilityâs standard.
+ âgawkâ has (too) many extensions over POSIX âawkâ.
FDL
- See "Free Documentation License."
+ See âFree Documentation License.â
Field
- When 'awk' reads an input record, it splits the record into pieces
+ When âawkâ reads an input record, it splits the record into pieces
separated by whitespace (or by a separator regexp that you can
- change by setting the predefined variable 'FS'). Such pieces are
+ change by setting the predefined variable âFSâ). Such pieces are
called fields. If the pieces are of fixed length, you can use the
- built-in variable 'FIELDWIDTHS' to describe their lengths. If you
+ built-in variable âFIELDWIDTHSâ to describe their lengths. If you
wish to specify the contents of fields instead of the field
- separator, you can use the predefined variable 'FPAT' to do so.
+ separator, you can use the predefined variable âFPATâ to do so.
(*Note Field Separators::, *note Constant Size::, and *note
Splitting By Content::.)
@@ -33968,16 +33966,16 @@ Flag
nonexistence of some condition.
Floating-Point Number
- Often referred to in mathematical terms as a "rational" or real
+ Often referred to in mathematical terms as a ârationalâ or real
number, this is just a number that can have a fractional part. See
- also "Double Precision" and "Single Precision."
+ also âDouble Precisionâ and âSingle Precision.â
Format
- Format strings control the appearance of output in the 'strftime()'
- and 'sprintf()' functions, and in the 'printf' statement as well.
+ Format strings control the appearance of output in the âstrftime()â
+ and âsprintf()â functions, and in the âprintfâ statement as well.
Also, data conversions from numbers to strings are controlled by
- the format strings contained in the predefined variables 'CONVFMT'
- and 'OFMT'. (*Note Control Letters::.)
+ the format strings contained in the predefined variables âCONVFMTâ
+ and âOFMTâ. (*Note Control Letters::.)
Fortran
Shorthand for FORmula TRANslator, one of the first programming
@@ -33997,40 +33995,40 @@ Free Software Foundation
Emacs is the most widely used version of Emacs today.
FSF
- See "Free Software Foundation."
+ See âFree Software Foundation.â
Function
- A part of an 'awk' program that can be invoked from every point of
- the program, to perform a task. 'awk' has several built-in
+ A part of an âawkâ program that can be invoked from every point of
+ the program, to perform a task. âawkâ has several built-in
functions. Users can define their own functions in every part of
the program. Function can be recursive, i.e., they may invoke
- themselves. *Note Functions::. In 'gawk' it is also possible to
+ themselves. *Note Functions::. In âgawkâ it is also possible to
have functions shared among different programs, and included where
- required using the '@include' directive (*note Include Files::).
- In 'gawk' the name of the function that should be invoked can be
- generated at run time, i.e., dynamically. The 'gawk' extension API
+ required using the â@includeâ directive (*note Include Files::).
+ In âgawkâ the name of the function that should be invoked can be
+ generated at run time, i.e., dynamically. The âgawkâ extension API
provides constructor functions (*note Constructor Functions::).
-'gawk'
- The GNU implementation of 'awk'.
+âgawkâ
+ The GNU implementation of âawkâ.
General Public License
- This document describes the terms under which 'gawk' and its source
+ This document describes the terms under which âgawkâ and its source
code may be distributed. (*Note Copying::.)
GMT
- "Greenwich Mean Time." This is the old term for UTC. It is the
- time of day used internally for Unix and POSIX systems. See also
- "Epoch" and "UTC."
+ âGreenwich Mean Time.â This is the old term for UTC. It is the time
+ of day used internally for Unix and POSIX systems. See also
+ âEpochâ and âUTC.â
GNU
- "GNU's not Unix". An on-going project of the Free Software
+ âGNUâs not Unixâ. An on-going project of the Free Software
Foundation to create a complete, freely distributable,
POSIX-compliant computing environment.
GNU/Linux
A variant of the GNU system using the Linux kernel, instead of the
- Free Software Foundation's Hurd kernel. The Linux kernel is a
+ Free Software Foundationâs Hurd kernel. The Linux kernel is a
stable, efficient, full-featured clone of Unix that has been ported
to a variety of architectures. It is most popular on PC-class
systems, but runs well on a variety of other systems too. The
@@ -34038,21 +34036,21 @@ GNU/Linux
General Public License, which is perhaps its most important aspect.
GPL
- See "General Public License."
+ See âGeneral Public License.â
Hexadecimal
- Base 16 notation, where the digits are '0'-'9' and 'A'-'F', with
- 'A' representing 10, 'B' representing 11, and so on, up to 'F' for
- 15. Hexadecimal numbers are written in C using a leading '0x', to
- indicate their base. Thus, '0x12' is 18 ((1 x 16) + 2). *Note
+ Base 16 notation, where the digits are â0âââ9â and
âAâââFâ, with
+ âAâ representing 10, âBâ representing 11, and so on, up to
âFâ for
+ 15. Hexadecimal numbers are written in C using a leading â0xâ, to
+ indicate their base. Thus, â0x12â is 18 ((1 x 16) + 2). *Note
Nondecimal-numbers::.
I/O
- Abbreviation for "Input/Output," the act of moving data into and/or
+ Abbreviation for âInput/Output,â the act of moving data into and/or
out of a running program.
Input Record
- A single chunk of data that is read in by 'awk'. Usually, an 'awk'
+ A single chunk of data that is read in by âawkâ. Usually, an
âawkâ
input record consists of one line of text. (*Note Records::.)
Integer
@@ -34065,14 +34063,14 @@ Internationalization
Interpreter
A program that reads human-readable source code directly, and uses
- the instructions in it to process data and produce results. 'awk'
+ the instructions in it to process data and produce results. âawkâ
is typically (but not always) implemented as an interpreter. See
- also "Compiler."
+ also âCompiler.â
Interval Expression
A component of a regular expression that lets you specify repeated
matches of some part of the regexp. Interval expressions were not
- originally available in 'awk' programs.
+ originally available in âawkâ programs.
ISO
The International Organization for Standardization. This
@@ -34080,7 +34078,7 @@ ISO
including programming languages, such as C and C++. In the
computer arena, important standards like those for C, C++, and
POSIX become both American national and ISO international standards
- simultaneously. This Info file refers to Standard C as "ISO C"
+ simultaneously. This Info file refers to Standard C as âISO Câ
throughout. See the ISO website
(https://www.iso.org/iso/home/about.htm) for more information about
the name of the organization and its language-independent
@@ -34094,20 +34092,20 @@ Java
native code.
Keyword
- In the 'awk' language, a keyword is a word that has special
+ In the âawkâ language, a keyword is a word that has special
meaning. Keywords are reserved and may not be used as variable
names.
- 'gawk''s keywords are: 'BEGIN', 'BEGINFILE', 'END', 'ENDFILE',
- 'break', 'case', 'continue', 'default', 'delete', 'do...while',
- 'else', 'exit', 'for...in', 'for', 'function', 'func', 'if',
- 'next', 'nextfile', 'switch', and 'while'.
+ âgawkââs keywords are: âBEGINâ, âBEGINFILEâ, âENDâ,
âENDFILEâ,
+ âbreakâ, âcaseâ, âcontinueâ, âdefaultâ, âdeleteâ,
âdo...whileâ,
+ âelseâ, âexitâ, âfor...inâ, âforâ, âfunctionâ,
âfuncâ, âifâ,
+ ânextâ, ânextfileâ, âswitchâ, and âwhileâ.
Korn Shell
- The Korn Shell ('ksh') is a Unix shell which was developed by David
+ The Korn Shell (âkshâ) is a Unix shell which was developed by David
Korn at Bell Laboratories in the early 1980s. The Korn Shell is
backward-compatible with the Bourne shell and includes many
- features of the C shell. See also "Bourne Shell."
+ features of the C shell. See also âBourne Shell.â
Lesser General Public License
This document describes the terms under which binary library
@@ -34115,10 +34113,10 @@ Lesser General Public License
distributed.
LGPL
- See "Lesser General Public License."
+ See âLesser General Public License.â
Linux
- See "GNU/Linux."
+ See âGNU/Linux.â
Localization
The process of providing the data necessary for an
@@ -34126,19 +34124,19 @@ Localization
Logical Expression
An expression using the operators for logic, AND, OR, and NOT,
- written '&&', '||', and '!' in 'awk'. Often called "Boolean
- expressions", after the mathematician who pioneered this kind of
+ written â&&â, â||â, and â!â in âawkâ. Often called
âBoolean
+ expressionsâ, after the mathematician who pioneered this kind of
mathematical logic.
Lvalue
An expression that can appear on the left side of an assignment
operator. In most languages, lvalues can be variables or array
- elements. In 'awk', a field designator can also be used as an
+ elements. In âawkâ, a field designator can also be used as an
lvalue.
Matching
The act of testing a string against a regular expression. If the
- regexp describes the contents of the string, it is said to "match"
+ regexp describes the contents of the string, it is said to âmatchâ
it.
Metacharacters
@@ -34148,8 +34146,8 @@ Metacharacters
Nesting
Nesting is where information is organized in layers, or where
- objects contain other similar objects. In 'gawk' the '@include'
- directive can be nested. The "natural" nesting of arithmetic and
+ objects contain other similar objects. In âgawkâ the â@includeâ
+ directive can be nested. The ânaturalâ nesting of arithmetic and
logical operations can be changed using parentheses (*note
Precedence::).
@@ -34158,32 +34156,32 @@ No-op
Null String
A string with no characters in it. It is represented explicitly in
- 'awk' programs by placing two double quote characters next to each
- other ('""'). It can appear in input data by having two successive
+ âawkâ programs by placing two double quote characters next to each
+ other (â""â). It can appear in input data by having two successive
occurrences of the field separator appear next to each other.
Number
- A numeric-valued data object. Modern 'awk' implementations use
+ A numeric-valued data object. Modern âawkâ implementations use
double precision floating-point to represent numbers. Ancient
- 'awk' implementations used single precision floating-point.
+ âawkâ implementations used single precision floating-point.
Octal
- Base-eight notation, where the digits are '0'-'7'. Octal numbers
- are written in C using a leading '0', to indicate their base.
- Thus, '013' is 11 ((1 x 8) + 3). *Note Nondecimal-numbers::.
+ Base-eight notation, where the digits are â0âââ7â. Octal
numbers
+ are written in C using a leading â0â, to indicate their base.
+ Thus, â013â is 11 ((1 x 8) + 3). *Note Nondecimal-numbers::.
Output Record
- A single chunk of data that is written out by 'awk'. Usually, an
- 'awk' output record consists of one or more lines of text. *Note
+ A single chunk of data that is written out by âawkâ. Usually, an
+ âawkâ output record consists of one or more lines of text. *Note
Records::.
Pattern
- Patterns tell 'awk' which input records are interesting to which
+ Patterns tell âawkâ which input records are interesting to which
rules.
A pattern is an arbitrary conditional expression against which
input is tested. If the condition is satisfied, the pattern is
- said to "match" the input record. A typical pattern might compare
+ said to âmatchâ the input record. A typical pattern might compare
the input record against a regular expression. (*Note Pattern
Overview::.)
@@ -34193,14 +34191,14 @@ PEBKAC
Chair.)
Plug-in
- See "Extensions."
+ See âExtensions.â
POSIX
The name for a series of standards that specify a Portable
- Operating System interface. The "IX" denotes the Unix heritage of
- these standards. The main standard of interest for 'awk' users is
- 'IEEE Standard for Information Technology, Standard
- 1003.1^{TM}-2017 (Revision of IEEE Std 1003.1-2008)'. The 2018
+ Operating System interface. The âIXâ denotes the Unix heritage of
+ these standards. The main standard of interest for âawkâ users is
+ âIEEE Standard for Information Technology, Standard
+ 1003.1^{TM}-2017 (Revision of IEEE Std 1003.1-2008)â. The 2018
POSIX standard can be found online at
<https://pubs.opengroup.org/onlinepubs/9699919799/>.
@@ -34210,36 +34208,36 @@ Precedence
Private
Variables and/or functions that are meant for use exclusively by
- library functions and not for the main 'awk' program. Special care
+ library functions and not for the main âawkâ program. Special care
must be taken when naming such variables and functions. (*Note
Library Names::.)
Range (of input lines)
A sequence of consecutive lines from the input file(s). A pattern
- can specify ranges of input lines for 'awk' to process or it can
+ can specify ranges of input lines for âawkâ to process or it can
specify single lines. (*Note Pattern Overview::.)
Record
- See "Input record" and "Output record."
+ See âInput recordâ and âOutput record.â
Recursion
When a function calls itself, either directly or indirectly. If
this is clear, stop, and proceed to the next entry. Otherwise,
- refer to the entry for "recursion."
+ refer to the entry for ârecursion.â
Redirection
Redirection means performing input from something other than the
standard input stream, or performing output to something other than
the standard output stream.
- You can redirect input to the 'getline' statement using the '<',
- '|', and '|&' operators. You can redirect the output of the
- 'print' and 'printf' statements to a file or a system command,
- using the '>', '>>', '|', and '|&' operators. (*Note Getline::,
+ You can redirect input to the âgetlineâ statement using the â<â,
+ â|â, and â|&â operators. You can redirect the output of the
+ âprintâ and âprintfâ statements to a file or a system command,
+ using the â>â, â>>â, â|â, and â|&â operators. (*Note
Getline::,
and *note Redirection::.)
Reference Counts
- An internal mechanism in 'gawk' to minimize the amount of memory
+ An internal mechanism in âgawkâ to minimize the amount of memory
needed to store the value of string variables. If the value
assumed by a variable is used in more than one place, only one copy
of the value itself is kept, and the associated reference count is
@@ -34249,42 +34247,42 @@ Reference Counts
the value of the variable is freed.
Regexp
- See "Regular Expression."
+ See âRegular Expression.â
Regular Expression
- A regular expression ("regexp" for short) is a pattern that denotes
+ A regular expression (âregexpâ for short) is a pattern that denotes
a set of strings, possibly an infinite set. For example, the
- regular expression 'R.*xp' matches any string starting with the
- letter 'R' and ending with the letters 'xp'. In 'awk', regular
+ regular expression âR.*xpâ matches any string starting with the
+ letter âRâ and ending with the letters âxpâ. In âawkâ,
regular
expressions are used in patterns and in conditional expressions.
Regular expressions may contain escape sequences. (*Note
Regexp::.)
Regular Expression Constant
A regular expression constant is a regular expression written
- within slashes, such as '/foo/'. This regular expression is chosen
- when you write the 'awk' program and cannot be changed during its
+ within slashes, such as â/foo/â. This regular expression is chosen
+ when you write the âawkâ program and cannot be changed during its
execution. (*Note Regexp Usage::.)
Regular Expression Operators
- See "Metacharacters."
+ See âMetacharacters.â
Rounding
Rounding the result of an arithmetic operation can be tricky. More
- than one way of rounding exists, and in 'gawk' it is possible to
+ than one way of rounding exists, and in âgawkâ it is possible to
choose which method should be used in a program. *Note Setting the
rounding mode::.
Rule
- A segment of an 'awk' program that specifies how to process single
- input records. A rule consists of a "pattern" and an "action".
- 'awk' reads an input record; then, for each rule, if the input
- record satisfies the rule's pattern, 'awk' executes the rule's
+ A segment of an âawkâ program that specifies how to process single
+ input records. A rule consists of a âpatternâ and an âactionâ.
+ âawkâ reads an input record; then, for each rule, if the input
+ record satisfies the ruleâs pattern, âawkâ executes the ruleâs
action. Otherwise, the rule does nothing for that input record.
Rvalue
A value that can appear on the right side of an assignment
- operator. In 'awk', essentially every expression has a value.
+ operator. In âawkâ, essentially every expression has a value.
These values are rvalues.
Scalar
@@ -34292,12 +34290,12 @@ Scalar
scalars; arrays and functions are not.
Search Path
- In 'gawk', a list of directories to search for 'awk' program source
+ In âgawkâ, a list of directories to search for âawkâ program
source
files. In the shell, a list of directories to search for
executable programs.
-'sed'
- See "Stream Editor."
+âsedâ
+ See âStream Editor.â
Seed
The initial value, or starting point, for a sequence of random
@@ -34309,7 +34307,7 @@ Shell
batch files, or shell scripts.
Short-Circuit
- The nature of the 'awk' logical operators '&&' and '||'. If the
+ The nature of the âawkâ logical operators â&&â and â||â. If
the
value of the entire expression is determinable from evaluating just
the lefthand side of these operators, the righthand side is not
evaluated. (*Note Boolean Ops::.)
@@ -34325,20 +34323,20 @@ Single Precision
parts. Single precision numbers keep track of fewer digits than do
double precision numbers, but operations on them are sometimes less
expensive in terms of CPU time. This is the type used by some
- ancient versions of 'awk' to store numeric values. It is the C
- type 'float'.
+ ancient versions of âawkâ to store numeric values. It is the C
+ type âfloatâ.
Space
The character generated by hitting the space bar on the keyboard.
Special File
- A file name interpreted internally by 'gawk', instead of being
- handed directly to the underlying operating system--for example,
- '/dev/stderr'. (*Note Special Files::.)
+ A file name interpreted internally by âgawkâ, instead of being
+ handed directly to the underlying operating systemâfor example,
+ â/dev/stderrâ. (*Note Special Files::.)
Statement
- An expression inside an 'awk' program in the action part of a
- pattern-action rule, or inside an 'awk' function. A statement can
+ An expression inside an âawkâ program in the action part of a
+ patternâaction rule, or inside an âawkâ function. A statement can
be a variable assignment, an array operation, a loop, etc.
Stream Editor
@@ -34349,13 +34347,13 @@ Stream Editor
programs which require input from the user.
String
- A datum consisting of a sequence of characters, such as 'I am a
- string'. Constant strings are written with double quotes in the
- 'awk' language and may contain escape sequences. (*Note Escape
+ A datum consisting of a sequence of characters, such as âI am a
+ stringâ. Constant strings are written with double quotes in the
+ âawkâ language and may contain escape sequences. (*Note Escape
Sequences::.)
Tab
- The character generated by hitting the 'TAB' key on the keyboard.
+ The character generated by hitting the âTABâ key on the keyboard.
It usually expands to up to eight spaces upon output.
Text Domain
@@ -34363,13 +34361,13 @@ Text Domain
messages that are translated at runtime into the local language.
Timestamp
- A value in the "seconds since the epoch" format used by Unix and
- POSIX systems. Used for the 'gawk' functions 'mktime()',
- 'strftime()', and 'systime()'. See also "Epoch," "GMT," and "UTC."
+ A value in the âseconds since the epochâ format used by Unix and
+ POSIX systems. Used for the âgawkâ functions âmktime()â,
+ âstrftime()â, and âsystime()â. See also âEpoch,â âGMT,â
and âUTC.â
Unix
A computer operating system originally developed in the early
- 1970's at AT&T Bell Laboratories. It initially became popular in
+ 1970âs at AT&T Bell Laboratories. It initially became popular in
universities around the world and later moved into commercial
environments as a software development system and network server
system. There are many commercial versions of Unix, as well as
@@ -34378,13 +34376,12 @@ Unix
(https://www.freebsd.org), and OpenBSD (http://www.openbsd.org)).
UTC
- The accepted abbreviation for "Universal Coordinated Time." This
- is standard time in Greenwich, England, which is used as a
- reference time for day and date calculations. See also "Epoch" and
- "GMT."
+ The accepted abbreviation for âUniversal Coordinated Time.â This is
+ standard time in Greenwich, England, which is used as a reference
+ time for day and date calculations. See also âEpochâ and âGMT.â
Variable
- A name for a value. In 'awk', variables may be either scalars or
+ A name for a value. In âawkâ, variables may be either scalars or
arrays.
Whitespace
@@ -34399,7 +34396,7 @@ GNU General Public License
Version 3, 29 June 2007
- Copyright (C) 2007 Free Software Foundation, Inc. <https://fsf.org/>
+ Copyright © 2007 Free Software Foundation, Inc. <https://fsf.org/>
Everyone is permitted to copy and distribute verbatim copies of this
license document, but changing it is not allowed.
@@ -34413,7 +34410,7 @@ and other kinds of works.
The licenses for most software and other practical works are designed
to take away your freedom to share and change the works. By contrast,
the GNU General Public License is intended to guarantee your freedom to
-share and change all versions of a program--to make sure it remains free
+share and change all versions of a programâto make sure it remains free
software for all its users. We, the Free Software Foundation, use the
GNU General Public License for most of our software; it applies also to
any other work released this way by its authors. You can apply it to
@@ -34441,16 +34438,16 @@ know their rights.
(1) assert copyright on the software, and (2) offer you this License
giving you legal permission to copy, distribute and/or modify it.
- For the developers' and authors' protection, the GPL clearly explains
-that there is no warranty for this free software. For both users' and
-authors' sake, the GPL requires that modified versions be marked as
+ For the developersâ and authorsâ protection, the GPL clearly explains
+that there is no warranty for this free software. For both usersâ and
+authorsâ sake, the GPL requires that modified versions be marked as
changed, so that their problems will not be attributed erroneously to
authors of previous versions.
Some devices are designed to deny users access to install or run
modified versions of the software inside them, although the manufacturer
can do so. This is fundamentally incompatible with the aim of
-protecting users' freedom to change the software. The systematic
+protecting usersâ freedom to change the software. The systematic
pattern of such abuse occurs in the area of products for individuals to
use, which is precisely where it is most unacceptable. Therefore, we
have designed this version of the GPL to prohibit the practice for those
@@ -34473,25 +34470,25 @@ TERMS AND CONDITIONS
0. Definitions.
- "This License" refers to version 3 of the GNU General Public
+ âThis Licenseâ refers to version 3 of the GNU General Public
License.
- "Copyright" also means copyright-like laws that apply to other
+ âCopyrightâ also means copyright-like laws that apply to other
kinds of works, such as semiconductor masks.
- "The Program" refers to any copyrightable work licensed under this
- License. Each licensee is addressed as "you". "Licensees" and
- "recipients" may be individuals or organizations.
+ âThe Programâ refers to any copyrightable work licensed under this
+ License. Each licensee is addressed as âyouâ. âLicenseesâ and
+ ârecipientsâ may be individuals or organizations.
- To "modify" a work means to copy from or adapt all or part of the
+ To âmodifyâ a work means to copy from or adapt all or part of the
work in a fashion requiring copyright permission, other than the
- making of an exact copy. The resulting work is called a "modified
- version" of the earlier work or a work "based on" the earlier work.
+ making of an exact copy. The resulting work is called a âmodified
+ versionâ of the earlier work or a work âbased onâ the earlier work.
- A "covered work" means either the unmodified Program or a work
+ A âcovered workâ means either the unmodified Program or a work
based on the Program.
- To "propagate" a work means to do anything with it that, without
+ To âpropagateâ a work means to do anything with it that, without
permission, would make you directly or secondarily liable for
infringement under applicable copyright law, except executing it on
a computer or modifying a private copy. Propagation includes
@@ -34499,12 +34496,12 @@ TERMS AND CONDITIONS
available to the public, and in some countries other activities as
well.
- To "convey" a work means any kind of propagation that enables other
+ To âconveyâ a work means any kind of propagation that enables other
parties to make or receive copies. Mere interaction with a user
through a computer network, with no transfer of a copy, is not
conveying.
- An interactive user interface displays "Appropriate Legal Notices"
+ An interactive user interface displays âAppropriate Legal Noticesâ
to the extent that it includes a convenient and prominently visible
feature that (1) displays an appropriate copyright notice, and (2)
tells the user that there is no warranty for the work (except to
@@ -34516,33 +34513,33 @@ TERMS AND CONDITIONS
1. Source Code.
- The "source code" for a work means the preferred form of the work
- for making modifications to it. "Object code" means any non-source
+ The âsource codeâ for a work means the preferred form of the work
+ for making modifications to it. âObject codeâ means any non-source
form of a work.
- A "Standard Interface" means an interface that either is an
+ A âStandard Interfaceâ means an interface that either is an
official standard defined by a recognized standards body, or, in
the case of interfaces specified for a particular programming
language, one that is widely used among developers working in that
language.
- The "System Libraries" of an executable work include anything,
+ The âSystem Librariesâ of an executable work include anything,
other than the work as a whole, that (a) is included in the normal
form of packaging a Major Component, but which is not part of that
Major Component, and (b) serves only to enable use of the work with
that Major Component, or to implement a Standard Interface for
which an implementation is available to the public in source code
- form. A "Major Component", in this context, means a major
+ form. A âMajor Componentâ, in this context, means a major
essential component (kernel, window system, and so on) of the
specific operating system (if any) on which the executable work
runs, or a compiler used to produce the work, or an object code
interpreter used to run it.
- The "Corresponding Source" for a work in object code form means all
+ The âCorresponding Sourceâ for a work in object code form means all
the source code needed to generate, install, and (for an executable
work) run the object code and to modify the work, including scripts
to control those activities. However, it does not include the
- work's System Libraries, or general-purpose tools or generally
+ workâs System Libraries, or general-purpose tools or generally
available free programs which are used unmodified in performing
those activities but which are not part of the work. For example,
Corresponding Source includes interface definition files associated
@@ -34586,7 +34583,7 @@ TERMS AND CONDITIONS
the conditions stated below. Sublicensing is not allowed; section
10 makes it unnecessary.
- 3. Protecting Users' Legal Rights From Anti-Circumvention Law.
+ 3. Protecting Usersâ Legal Rights From Anti-Circumvention Law.
No covered work shall be deemed part of an effective technological
measure under any applicable law fulfilling obligations under
@@ -34599,12 +34596,12 @@ TERMS AND CONDITIONS
circumvention is effected by exercising rights under this License
with respect to the covered work, and you disclaim any intention to
limit operation or modification of the work as a means of
- enforcing, against the work's users, your or third parties' legal
+ enforcing, against the workâs users, your or third partiesâ legal
rights to forbid circumvention of technological measures.
4. Conveying Verbatim Copies.
- You may convey verbatim copies of the Program's source code as you
+ You may convey verbatim copies of the Programâs source code as you
receive it, in any medium, provided that you conspicuously and
appropriately publish on each copy an appropriate copyright notice;
keep intact all notices stating that this License and any
@@ -34628,7 +34625,7 @@ TERMS AND CONDITIONS
b. The work must carry prominent notices stating that it is
released under this License and any conditions added under
section 7. This requirement modifies the requirement in
- section 4 to "keep intact all notices".
+ section 4 to âkeep intact all noticesâ.
c. You must license the entire work, as a whole, under this
License to anyone who comes into possession of a copy. This
@@ -34648,9 +34645,9 @@ TERMS AND CONDITIONS
works, which are not by their nature extensions of the covered
work, and which are not combined with it such as to form a larger
program, in or on a volume of a storage or distribution medium, is
- called an "aggregate" if the compilation and its resulting
+ called an âaggregateâ if the compilation and its resulting
copyright are not used to limit the access or legal rights of the
- compilation's users beyond what the individual works permit.
+ compilationâs users beyond what the individual works permit.
Inclusion of a covered work in an aggregate does not cause this
License to apply to the other parts of the aggregate.
@@ -34708,13 +34705,13 @@ TERMS AND CONDITIONS
excluded from the Corresponding Source as a System Library, need
not be included in conveying the object code work.
- A "User Product" is either (1) a "consumer product", which means
+ A âUser Productâ is either (1) a âconsumer productâ, which means
any tangible personal property which is normally used for personal,
family, or household purposes, or (2) anything designed or sold for
incorporation into a dwelling. In determining whether a product is
a consumer product, doubtful cases shall be resolved in favor of
coverage. For a particular product received by a particular user,
- "normally used" refers to a typical or common use of that class of
+ ânormally usedâ refers to a typical or common use of that class of
product, regardless of the status of the particular user or of the
way in which the particular user actually uses, or expects or is
expected to use, the product. A product is a consumer product
@@ -34722,7 +34719,7 @@ TERMS AND CONDITIONS
industrial or non-consumer uses, unless such uses represent the
only significant mode of use of the product.
- "Installation Information" for a User Product means any methods,
+ âInstallation Informationâ for a User Product means any methods,
procedures, authorization keys, or other information required to
install and execute modified versions of a covered work in that
User Product from a modified version of its Corresponding Source.
@@ -34758,7 +34755,7 @@ TERMS AND CONDITIONS
7. Additional Terms.
- "Additional permissions" are terms that supplement the terms of
+ âAdditional permissionsâ are terms that supplement the terms of
this License by making exceptions from one or more of its
conditions. Additional permissions that are applicable to the
entire Program shall be treated as though they were included in
@@ -34803,8 +34800,8 @@ TERMS AND CONDITIONS
the recipient, for any liability that these contractual
assumptions directly impose on those licensors and authors.
- All other non-permissive additional terms are considered "further
- restrictions" within the meaning of section 10. If the Program as
+ All other non-permissive additional terms are considered âfurther
+ restrictionsâ within the meaning of section 10. If the Program as
you received it, or any part of it, contains a notice stating that
it is governed by this License along with a term that is a further
restriction, you may remove that term. If a license document
@@ -34870,12 +34867,12 @@ TERMS AND CONDITIONS
responsible for enforcing compliance by third parties with this
License.
- An "entity transaction" is a transaction transferring control of an
+ An âentity transactionâ is a transaction transferring control of an
organization, or substantially all assets of one, or subdividing an
organization, or merging organizations. If propagation of a
covered work results from an entity transaction, each party to that
transaction who receives a copy of the work also receives whatever
- licenses to the work the party's predecessor in interest had or
+ licenses to the work the partyâs predecessor in interest had or
could give under the previous paragraph, plus a right to possession
of the Corresponding Source of the work from the predecessor in
interest, if the predecessor has it or can get it with reasonable
@@ -34892,31 +34889,31 @@ TERMS AND CONDITIONS
11. Patents.
- A "contributor" is a copyright holder who authorizes use under this
+ A âcontributorâ is a copyright holder who authorizes use under this
License of the Program or a work on which the Program is based.
- The work thus licensed is called the contributor's "contributor
- version".
+ The work thus licensed is called the contributorâs âcontributor
+ versionâ.
- A contributor's "essential patent claims" are all patent claims
+ A contributorâs âessential patent claimsâ are all patent claims
owned or controlled by the contributor, whether already acquired or
hereafter acquired, that would be infringed by some manner,
permitted by this License, of making, using, or selling its
contributor version, but do not include claims that would be
infringed only as a consequence of further modification of the
- contributor version. For purposes of this definition, "control"
+ contributor version. For purposes of this definition, âcontrolâ
includes the right to grant patent sublicenses in a manner
consistent with the requirements of this License.
Each contributor grants you a non-exclusive, worldwide,
- royalty-free patent license under the contributor's essential
+ royalty-free patent license under the contributorâs essential
patent claims, to make, use, sell, offer for sale, import and
otherwise run, modify and propagate the contents of its contributor
version.
- In the following three paragraphs, a "patent license" is any
+ In the following three paragraphs, a âpatent licenseâ is any
express agreement or commitment, however denominated, not to
enforce a patent (such as an express permission to practice a
- patent or covenant not to sue for patent infringement). To "grant"
+ patent or covenant not to sue for patent infringement). To âgrantâ
such a patent license to a party means to make such an agreement or
commitment not to enforce a patent against the party.
@@ -34929,9 +34926,9 @@ TERMS AND CONDITIONS
yourself of the benefit of the patent license for this particular
work, or (3) arrange, in a manner consistent with the requirements
of this License, to extend the patent license to downstream
- recipients. "Knowingly relying" means you have actual knowledge
+ recipients. âKnowingly relyingâ means you have actual knowledge
that, but for the patent license, your conveying the covered work
- in a country, or your recipient's use of the covered work in a
+ in a country, or your recipientâs use of the covered work in a
country, would infringe one or more identifiable patents in that
country that you have reason to believe are valid.
@@ -34943,7 +34940,7 @@ TERMS AND CONDITIONS
patent license you grant is automatically extended to all
recipients of the covered work and works based on it.
- A patent license is "discriminatory" if it does not include within
+ A patent license is âdiscriminatoryâ if it does not include within
the scope of its coverage, prohibits the exercise of, or is
conditioned on the non-exercise of one or more of the rights that
are specifically granted under this License. You may not convey a
@@ -34963,7 +34960,7 @@ TERMS AND CONDITIONS
any implied license or other defenses to infringement that may
otherwise be available to you under applicable patent law.
- 12. No Surrender of Others' Freedom.
+ 12. No Surrender of Othersâ Freedom.
If conditions are imposed on you (whether by court order, agreement
or otherwise) that contradict the conditions of this License, they
@@ -34996,7 +34993,7 @@ TERMS AND CONDITIONS
Each version is given a distinguishing version number. If the
Program specifies that a certain numbered version of the GNU
- General Public License "or any later version" applies to it, you
+ General Public License âor any later versionâ applies to it, you
have the option of following the terms and conditions either of
that numbered version or of any later version published by the Free
Software Foundation. If the Program does not specify a version
@@ -35005,7 +35002,7 @@ TERMS AND CONDITIONS
If the Program specifies that a proxy can decide which future
versions of the GNU General Public License can be used, that
- proxy's public statement of acceptance of a version permanently
+ proxyâs public statement of acceptance of a version permanently
authorizes you to choose that version for the Program.
Later license versions may give you additional or different
@@ -35017,7 +35014,7 @@ TERMS AND CONDITIONS
THERE IS NO WARRANTY FOR THE PROGRAM, TO THE EXTENT PERMITTED BY
APPLICABLE LAW. EXCEPT WHEN OTHERWISE STATED IN WRITING THE
- COPYRIGHT HOLDERS AND/OR OTHER PARTIES PROVIDE THE PROGRAM "AS IS"
+ COPYRIGHT HOLDERS AND/OR OTHER PARTIES PROVIDE THE PROGRAM âAS ISâ
WITHOUT WARRANTY OF ANY KIND, EITHER EXPRESSED OR IMPLIED,
INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. THE ENTIRE
@@ -35061,7 +35058,7 @@ terms.
To do so, attach the following notices to the program. It is safest
to attach them to the start of each source file to most effectively
state the exclusion of warranty; and each file should have at least the
-"copyright" line and a pointer to where the full notice is found.
+âcopyrightâ line and a pointer to where the full notice is found.
ONE LINE TO GIVE THE PROGRAM'S NAME AND A BRIEF IDEA OF WHAT IT DOES.
Copyright (C) YEAR NAME OF AUTHOR
@@ -35086,17 +35083,17 @@ mail.
notice like this when it starts in an interactive mode:
PROGRAM Copyright (C) YEAR NAME OF AUTHOR
- This program comes with ABSOLUTELY NO WARRANTY; for details type 'show w'.
+ This program comes with ABSOLUTELY NO WARRANTY; for details type âshow
wâ.
This is free software, and you are welcome to redistribute it
- under certain conditions; type 'show c' for details.
+ under certain conditions; type âshow câ for details.
- The hypothetical commands 'show w' and 'show c' should show the
+ The hypothetical commands âshow wâ and âshow câ should show the
appropriate parts of the General Public License. Of course, your
-program's commands might be different; for a GUI interface, you would
-use an "about box".
+programâs commands might be different; for a GUI interface, you would
+use an âabout boxâ.
You should also get your employer (if you work as a programmer) or
-school, if any, to sign a "copyright disclaimer" for the program, if
+school, if any, to sign a âcopyright disclaimerâ for the program, if
necessary. For more information on this, and how to apply and follow
the GNU GPL, see <https://www.gnu.org/licenses/>.
@@ -35115,7 +35112,7 @@ GNU Free Documentation License
Version 1.3, 3 November 2008
- Copyright (C) 2000, 2001, 2002, 2007, 2008 Free Software Foundation, Inc.
+ Copyright © 2000, 2001, 2002, 2007, 2008 Free Software Foundation, Inc.
<https://fsf.org/>
Everyone is permitted to copy and distribute verbatim copies
@@ -35124,14 +35121,14 @@ GNU Free Documentation License
0. PREAMBLE
The purpose of this License is to make a manual, textbook, or other
- functional and useful document "free" in the sense of freedom: to
+ functional and useful document âfreeâ in the sense of freedom: to
assure everyone the effective freedom to copy and redistribute it,
with or without modifying it, either commercially or
noncommercially. Secondarily, this License preserves for the
author and publisher a way to get credit for their work, while not
being considered responsible for modifications made by others.
- This License is a kind of "copyleft", which means that derivative
+ This License is a kind of âcopyleftâ, which means that derivative
works of the document must themselves be free in the same sense.
It complements the GNU General Public License, which is a copyleft
license designed for free software.
@@ -35152,18 +35149,18 @@ GNU Free Documentation License
be distributed under the terms of this License. Such a notice
grants a world-wide, royalty-free license, unlimited in duration,
to use that work under the conditions stated herein. The
- "Document", below, refers to any such manual or work. Any member
- of the public is a licensee, and is addressed as "you". You accept
+ âDocumentâ, below, refers to any such manual or work. Any member
+ of the public is a licensee, and is addressed as âyouâ. You accept
the license if you copy, modify or distribute the work in a way
requiring permission under copyright law.
- A "Modified Version" of the Document means any work containing the
+ A âModified Versionâ of the Document means any work containing the
Document or a portion of it, either copied verbatim, or with
modifications and/or translated into another language.
- A "Secondary Section" is a named appendix or a front-matter section
+ A âSecondary Sectionâ is a named appendix or a front-matter section
of the Document that deals exclusively with the relationship of the
- publishers or authors of the Document to the Document's overall
+ publishers or authors of the Document to the Documentâs overall
subject (or to related matters) and contains nothing that could
fall directly within that overall subject. (Thus, if the Document
is in part a textbook of mathematics, a Secondary Section may not
@@ -35172,7 +35169,7 @@ GNU Free Documentation License
of legal, commercial, philosophical, ethical or political position
regarding them.
- The "Invariant Sections" are certain Secondary Sections whose
+ The âInvariant Sectionsâ are certain Secondary Sections whose
titles are designated, as being those of Invariant Sections, in the
notice that says that the Document is released under this License.
If a section does not fit the above definition of Secondary then it
@@ -35180,13 +35177,13 @@ GNU Free Documentation License
contain zero Invariant Sections. If the Document does not identify
any Invariant Sections then there are none.
- The "Cover Texts" are certain short passages of text that are
+ The âCover Textsâ are certain short passages of text that are
listed, as Front-Cover Texts or Back-Cover Texts, in the notice
that says that the Document is released under this License. A
Front-Cover Text may be at most 5 words, and a Back-Cover Text may
be at most 25 words.
- A "Transparent" copy of the Document means a machine-readable copy,
+ A âTransparentâ copy of the Document means a machine-readable copy,
represented in a format whose specification is available to the
general public, that is suitable for revising the document
straightforwardly with generic text editors or (for images composed
@@ -35198,7 +35195,7 @@ GNU Free Documentation License
been arranged to thwart or discourage subsequent modification by
readers is not Transparent. An image format is not Transparent if
used for any substantial amount of text. A copy that is not
- "Transparent" is called "Opaque".
+ âTransparentâ is called âOpaqueâ.
Examples of suitable formats for Transparent copies include plain
ASCII without markup, Texinfo input format, LaTeX input format,
@@ -35211,23 +35208,23 @@ GNU Free Documentation License
the machine-generated HTML, PostScript or PDF produced by some word
processors for output purposes only.
- The "Title Page" means, for a printed book, the title page itself,
+ The âTitle Pageâ means, for a printed book, the title page itself,
plus such following pages as are needed to hold, legibly, the
material this License requires to appear in the title page. For
- works in formats which do not have any title page as such, "Title
- Page" means the text near the most prominent appearance of the
- work's title, preceding the beginning of the body of the text.
+ works in formats which do not have any title page as such, âTitle
+ Pageâ means the text near the most prominent appearance of the
+ workâs title, preceding the beginning of the body of the text.
- The "publisher" means any person or entity that distributes copies
+ The âpublisherâ means any person or entity that distributes copies
of the Document to the public.
- A section "Entitled XYZ" means a named subunit of the Document
+ A section âEntitled XYZâ means a named subunit of the Document
whose title either is precisely XYZ or contains XYZ in parentheses
following text that translates XYZ in another language. (Here XYZ
stands for a specific section name mentioned below, such as
- "Acknowledgements", "Dedications", "Endorsements", or "History".)
- To "Preserve the Title" of such a section when you modify the
- Document means that it remains a section "Entitled XYZ" according
+ âAcknowledgementsâ, âDedicationsâ, âEndorsementsâ, or
âHistoryâ.)
+ To âPreserve the Titleâ of such a section when you modify the
+ Document means that it remains a section âEntitled XYZâ according
to this definition.
The Document may include Warranty Disclaimers next to the notice
@@ -35257,7 +35254,7 @@ GNU Free Documentation License
If you publish printed copies (or copies in media that commonly
have printed covers) of the Document, numbering more than 100, and
- the Document's license notice requires Cover Texts, you must
+ the Documentâs license notice requires Cover Texts, you must
enclose the copies in covers that carry, clearly and legibly, all
these Cover Texts: Front-Cover Texts on the front cover, and
Back-Cover Texts on the back cover. Both covers must also clearly
@@ -35329,15 +35326,15 @@ GNU Free Documentation License
the Addendum below.
G. Preserve in that license notice the full lists of Invariant
- Sections and required Cover Texts given in the Document's
+ Sections and required Cover Texts given in the Documentâs
license notice.
H. Include an unaltered copy of this License.
- I. Preserve the section Entitled "History", Preserve its Title,
+ I. Preserve the section Entitled âHistoryâ, Preserve its Title,
and add to it an item stating at least the title, year, new
authors, and publisher of the Modified Version as given on the
- Title Page. If there is no section Entitled "History" in the
+ Title Page. If there is no section Entitled âHistoryâ in the
Document, create one stating the title, year, authors, and
publisher of the Document as given on its Title Page, then add
an item describing the Modified Version as stated in the
@@ -35347,12 +35344,12 @@ GNU Free Documentation License
for public access to a Transparent copy of the Document, and
likewise the network locations given in the Document for
previous versions it was based on. These may be placed in the
- "History" section. You may omit a network location for a work
+ âHistoryâ section. You may omit a network location for a work
that was published at least four years before the Document
itself, or if the original publisher of the version it refers
to gives permission.
- K. For any section Entitled "Acknowledgements" or "Dedications",
+ K. For any section Entitled âAcknowledgementsâ or âDedicationsâ,
Preserve the Title of the section, and preserve in the section
all the substance and tone of each of the contributor
acknowledgements and/or dedications given therein.
@@ -35361,11 +35358,11 @@ GNU Free Documentation License
in their text and in their titles. Section numbers or the
equivalent are not considered part of the section titles.
- M. Delete any section Entitled "Endorsements". Such a section
+ M. Delete any section Entitled âEndorsementsâ. Such a section
may not be included in the Modified Version.
N. Do not retitle any existing section to be Entitled
- "Endorsements" or to conflict in title with any Invariant
+ âEndorsementsâ or to conflict in title with any Invariant
Section.
O. Preserve any Warranty Disclaimers.
@@ -35374,15 +35371,15 @@ GNU Free Documentation License
appendices that qualify as Secondary Sections and contain no
material copied from the Document, you may at your option designate
some or all of these sections as invariant. To do this, add their
- titles to the list of Invariant Sections in the Modified Version's
+ titles to the list of Invariant Sections in the Modified Versionâs
license notice. These titles must be distinct from any other
section titles.
- You may add a section Entitled "Endorsements", provided it contains
+ You may add a section Entitled âEndorsementsâ, provided it contains
nothing but endorsements of your Modified Version by various
- parties--for example, statements of peer review or that the text
- has been approved by an organization as the authoritative
- definition of a standard.
+ partiesâfor example, statements of peer review or that the text has
+ been approved by an organization as the authoritative definition of
+ a standard.
You may add a passage of up to five words as a Front-Cover Text,
and a passage of up to 25 words as a Back-Cover Text, to the end of
@@ -35420,10 +35417,10 @@ GNU Free Documentation License
combined work.
In the combination, you must combine any sections Entitled
- "History" in the various original documents, forming one section
- Entitled "History"; likewise combine any sections Entitled
- "Acknowledgements", and any sections Entitled "Dedications". You
- must delete all sections Entitled "Endorsements."
+ âHistoryâ in the various original documents, forming one section
+ Entitled âHistoryâ; likewise combine any sections Entitled
+ âAcknowledgementsâ, and any sections Entitled âDedicationsâ. You
+ must delete all sections Entitled âEndorsements.â
6. COLLECTIONS OF DOCUMENTS
@@ -35444,16 +35441,16 @@ GNU Free Documentation License
A compilation of the Document or its derivatives with other
separate and independent documents or works, in or on a volume of a
- storage or distribution medium, is called an "aggregate" if the
+ storage or distribution medium, is called an âaggregateâ if the
copyright resulting from the compilation is not used to limit the
- legal rights of the compilation's users beyond what the individual
+ legal rights of the compilationâs users beyond what the individual
works permit. When the Document is included in an aggregate, this
License does not apply to the other works in the aggregate which
are not themselves derivative works of the Document.
If the Cover Text requirement of section 3 is applicable to these
copies of the Document, then if the Document is less than one half
- of the entire aggregate, the Document's Cover Texts may be placed
+ of the entire aggregate, the Documentâs Cover Texts may be placed
on covers that bracket the Document within the aggregate, or the
electronic equivalent of covers if the Document is in electronic
form. Otherwise they must appear on printed covers that bracket
@@ -35475,8 +35472,8 @@ GNU Free Documentation License
this License or a notice or disclaimer, the original version will
prevail.
- If a section in the Document is Entitled "Acknowledgements",
- "Dedications", or "History", the requirement (section 4) to
+ If a section in the Document is Entitled âAcknowledgementsâ,
+ âDedicationsâ, or âHistoryâ, the requirement (section 4) to
Preserve its Title (section 1) will typically require changing the
actual title.
@@ -35517,7 +35514,7 @@ GNU Free Documentation License
Each version of the License is given a distinguishing version
number. If the Document specifies that a particular numbered
- version of this License "or any later version" applies to it, you
+ version of this License âor any later versionâ applies to it, you
have the option of following the terms and conditions either of
that specified version or of any later version that has been
published (not as a draft) by the Free Software Foundation. If the
@@ -35525,29 +35522,29 @@ GNU Free Documentation License
choose any version ever published (not as a draft) by the Free
Software Foundation. If the Document specifies that a proxy can
decide which future versions of this License can be used, that
- proxy's public statement of acceptance of a version permanently
+ proxyâs public statement of acceptance of a version permanently
authorizes you to choose that version for the Document.
11. RELICENSING
- "Massive Multiauthor Collaboration Site" (or "MMC Site") means any
+ âMassive Multiauthor Collaboration Siteâ (or âMMC Siteâ) means any
World Wide Web server that publishes copyrightable works and also
provides prominent facilities for anybody to edit those works. A
public wiki that anybody can edit is an example of such a server.
- A "Massive Multiauthor Collaboration" (or "MMC") contained in the
+ A âMassive Multiauthor Collaborationâ (or âMMCâ) contained in the
site means any set of copyrightable works thus published on the MMC
site.
- "CC-BY-SA" means the Creative Commons Attribution-Share Alike 3.0
+ âCC-BY-SAâ means the Creative Commons Attribution-Share Alike 3.0
license published by Creative Commons Corporation, a not-for-profit
corporation with a principal place of business in San Francisco,
California, as well as future copyleft versions of that license
published by that same organization.
- "Incorporate" means to publish or republish a Document, in whole or
+ âIncorporateâ means to publish or republish a Document, in whole or
in part, as part of another Document.
- An MMC is "eligible for relicensing" if it is licensed under this
+ An MMC is âeligible for relicensingâ if it is licensed under this
License, and if all works that were first published under this
License somewhere other than this MMC, and subsequently
incorporated in whole or in part into the MMC, (1) had no cover
@@ -35574,7 +35571,7 @@ notices just after the title page:
Free Documentation License''.
If you have Invariant Sections, Front-Cover Texts and Back-Cover
-Texts, replace the "with...Texts." line with this:
+Texts, replace the âwith...Texts.â line with this:
with the Invariant Sections being LIST THEIR TITLES, with
the Front-Cover Texts being LIST, and with the Back-Cover Texts
@@ -35781,8 +35778,8 @@ Index
* / (forward slash), /= operator <1>: Precedence. (line 94)
* / (forward slash), patterns and: Expression Patterns. (line 24)
* /= operator vs. /=.../ regexp constant: Assignment Ops. (line 150)
-* /dev/fd/N special files (gawk): Special FD. (line 48)
* /dev/... special files: Special FD. (line 48)
+* /dev/fd/N special files (gawk): Special FD. (line 48)
* /inet/... special files (gawk): TCP/IP Networking. (line 6)
* /inet4/... special files (gawk): TCP/IP Networking. (line 6)
* /inet6/... special files (gawk): TCP/IP Networking. (line 6)
@@ -36017,7 +36014,7 @@ Index
(line 6)
* arrays, unassigned elements: Reference to Elements.
(line 18)
-* arrays, elements, that don't exist: Reference to Elements.
+* arrays, elements, that donât exist: Reference to Elements.
(line 23)
* arrays, elements, assigning values: Assigning Elements. (line 6)
* arrays, example of using: Array Example. (line 6)
@@ -36356,25 +36353,25 @@ Index
* Brennan, Michael <4>: Simple Sed. (line 25)
* Brennan, Michael <5>: Other Versions. (line 6)
* Brennan, Michael <6>: Other Versions. (line 39)
-* Brian Kernighan's awk: When. (line 21)
-* Brian Kernighan's awk <1>: Escape Sequences. (line 112)
-* Brian Kernighan's awk <2>: GNU Regexp Operators.
+* Brian Kernighanâs awk: When. (line 21)
+* Brian Kernighanâs awk <1>: Escape Sequences. (line 112)
+* Brian Kernighanâs awk <2>: GNU Regexp Operators.
(line 84)
-* Brian Kernighan's awk <3>: gawk split records. (line 71)
-* Brian Kernighan's awk <4>: Regexp Field Splitting.
+* Brian Kernighanâs awk <3>: gawk split records. (line 71)
+* Brian Kernighanâs awk <4>: Regexp Field Splitting.
(line 66)
-* Brian Kernighan's awk <5>: Getline/Pipe. (line 62)
-* Brian Kernighan's awk <6>: Concatenation. (line 36)
-* Brian Kernighan's awk <7>: I/O And BEGIN/END. (line 15)
-* Brian Kernighan's awk <8>: Break Statement. (line 51)
-* Brian Kernighan's awk <9>: Continue Statement. (line 44)
-* Brian Kernighan's awk <10>: Nextfile Statement. (line 47)
-* Brian Kernighan's awk <11>: Delete. (line 51)
-* Brian Kernighan's awk <12>: String Functions. (line 510)
-* Brian Kernighan's awk <13>: Gory Details. (line 19)
-* Brian Kernighan's awk <14>: I/O Functions. (line 43)
-* Brian Kernighan's awk, extensions: BTL. (line 6)
-* Brian Kernighan's awk, source code: Other Versions. (line 13)
+* Brian Kernighanâs awk <5>: Getline/Pipe. (line 62)
+* Brian Kernighanâs awk <6>: Concatenation. (line 36)
+* Brian Kernighanâs awk <7>: I/O And BEGIN/END. (line 15)
+* Brian Kernighanâs awk <8>: Break Statement. (line 51)
+* Brian Kernighanâs awk <9>: Continue Statement. (line 44)
+* Brian Kernighanâs awk <10>: Nextfile Statement. (line 47)
+* Brian Kernighanâs awk <11>: Delete. (line 51)
+* Brian Kernighanâs awk <12>: String Functions. (line 510)
+* Brian Kernighanâs awk <13>: Gory Details. (line 19)
+* Brian Kernighanâs awk <14>: I/O Functions. (line 43)
+* Brian Kernighanâs awk, extensions: BTL. (line 6)
+* Brian Kernighanâs awk, source code: Other Versions. (line 13)
* Brini, Davide: Signature Program. (line 6)
* Brink, Jeroen: DOS Quoting. (line 10)
* Broder, Alan J.: Contributors. (line 91)
@@ -36652,7 +36649,7 @@ Index
(line 43)
* dark corner, command-line arguments: Assignment Options. (line 43)
* dark corner, CONVFMT variable: Strings And Numbers. (line 39)
-* dark corner, locale's decimal point character: Locale influences conversions.
+* dark corner, localeâs decimal point character: Locale influences
conversions.
(line 17)
* dark corner, regexp constants, /= operator and: Assignment Ops.
(line 150)
@@ -37218,9 +37215,9 @@ Index
* extensions, loadable, distributed with gawk: Extension Samples.
(line 6)
* extensions, loadable, gawkextlib project: gawkextlib. (line 6)
-* extensions, Brian Kernighan's awk: BTL. (line 6)
+* extensions, Brian Kernighanâs awk: BTL. (line 6)
* extensions, in gawk, not in POSIX awk: POSIX/GNU. (line 6)
-* extensions, Brian Kernighan's awk <1>: Common Extensions. (line 6)
+* extensions, Brian Kernighanâs awk <1>: Common Extensions. (line 6)
* extensions, mawk: Common Extensions. (line 6)
* extensions, common, BINMODE variable: PC Using. (line 18)
* extract.awk program: Extract Program. (line 79)
@@ -38245,7 +38242,7 @@ Index
* patterns, ranges in: Ranges. (line 6)
* patterns, empty: Empty. (line 6)
* patterns, counts, in a profile: Profiling. (line 118)
-* pawk (profiling version of Brian Kernighan's awk): Other Versions.
+* pawk (profiling version of Brian Kernighanâs awk): Other Versions.
(line 82)
* pawk, awk-like facilities for Python: Other Versions. (line 161)
* PC operating systems, gawk on, installing: PC Installation. (line 6)
@@ -38799,9 +38796,9 @@ Index
* sidebar, FS and IGNORECASE: Field Splitting Summary.
(line 37)
* sidebar, Piping into sh: Redirection. (line 134)
-* sidebar, Using close()'s Return Value: Close Files And Pipes.
+* sidebar, Using close()âs Return Value: Close Files And Pipes.
(line 130)
-* sidebar, A Constant's Base Does Not Affect Its Value: Nondecimal-numbers.
+* sidebar, A Constantâs Base Does Not Affect Its Value: Nondecimal-numbers.
(line 63)
* sidebar, Pre-POSIX awk Used OFMT for String Conversion: Strings And Numbers.
(line 54)
@@ -38860,10 +38857,10 @@ Index
(line 94)
* source code, mixing: Options. (line 120)
* source code, gawk: Gawk Distribution. (line 6)
-* source code, Brian Kernighan's awk: Other Versions. (line 13)
+* source code, Brian Kernighanâs awk: Other Versions. (line 13)
* source code, mawk: Other Versions. (line 39)
* source code, awka: Other Versions. (line 64)
-* source code, pawk (profiling version of Brian Kernighan's awk): Other
Versions.
+* source code, pawk (profiling version of Brian Kernighanâs awk): Other
Versions.
(line 82)
* source code, BusyBox Awk: Other Versions. (line 92)
* source code, Solaris awk: Other Versions. (line 100)
@@ -39267,618 +39264,618 @@ Index
Tag Table:
-Node: Top1200
-Node: Foreword345854
-Node: Foreword450296
-Node: Preface51828
-Ref: Preface-Footnote-154690
-Ref: Preface-Footnote-254799
-Ref: Preface-Footnote-355033
-Node: History55175
-Node: Names57527
-Ref: Names-Footnote-158631
-Node: This Manual58778
-Ref: This Manual-Footnote-165417
-Node: Conventions65517
-Node: Manual History67886
-Ref: Manual History-Footnote-170883
-Ref: Manual History-Footnote-270924
-Node: How To Contribute70998
-Node: Acknowledgments71920
-Node: Getting Started76857
-Node: Running gawk79296
-Node: One-shot80486
-Node: Read Terminal81749
-Node: Long83742
-Node: Executable Scripts85255
-Ref: Executable Scripts-Footnote-187888
-Node: Comments87991
-Node: Quoting90475
-Node: DOS Quoting96001
-Node: Sample Data Files98057
-Node: Very Simple100652
-Node: Two Rules106754
-Node: More Complex108639
-Node: Statements/Lines110971
-Ref: Statements/Lines-Footnote-1115739
-Node: Other Features116004
-Node: When116940
-Ref: When-Footnote-1118694
-Node: Intro Summary118759
-Node: Invoking Gawk119643
-Node: Command Line121157
-Node: Options121955
-Ref: Options-Footnote-1140204
-Ref: Options-Footnote-2140435
-Node: Other Arguments140460
-Node: Naming Standard Input144471
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-Node: AWKPATH Variable146239
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-Ref: AWKPATH Variable-Footnote-2149685
-Node: AWKLIBPATH Variable150056
-Ref: AWKLIBPATH Variable-Footnote-1151753
-Node: Other Environment Variables152128
-Node: Exit Status156416
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-Node: Regexp Usage167423
-Node: Escape Sequences169460
-Node: Regexp Operators175702
-Node: Regexp Operator Details176187
-Ref: Regexp Operator Details-Footnote-1183551
-Node: Interval Expressions183698
-Ref: Interval Expressions-Footnote-1185873
-Node: Bracket Expressions185971
-Ref: table-char-classes188447
-Node: Leftmost Longest191774
-Node: Computed Regexps193077
-Node: GNU Regexp Operators196504
-Node: Case-sensitivity200300
-Ref: Case-sensitivity-Footnote-1203166
-Ref: Case-sensitivity-Footnote-2203401
-Node: Regexp Summary203509
-Node: Reading Files204975
-Node: Records207244
-Node: awk split records208319
-Node: gawk split records213019
-Ref: gawk split records-Footnote-1218093
-Node: Fields218130
-Node: Nonconstant Fields220871
-Ref: Nonconstant Fields-Footnote-1223107
-Node: Changing Fields223311
-Node: Field Separators229342
-Node: Default Field Splitting232040
-Node: Regexp Field Splitting233158
-Node: Single Character Fields236835
-Node: Command Line Field Separator237895
-Node: Full Line Fields241113
-Ref: Full Line Fields-Footnote-1242635
-Ref: Full Line Fields-Footnote-2242681
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-Node: Constant Size244856
-Node: Fixed width data245588
-Node: Skipping intervening249055
-Node: Allowing trailing data249853
-Node: Fields with fixed data250890
-Node: Splitting By Content252408
-Ref: Splitting By Content-Footnote-1256244
-Node: More CSV256407
-Node: FS versus FPAT258022
-Node: Testing field creation259182
-Node: Multiple Line260807
-Node: Getline267084
-Node: Plain Getline269553
-Node: Getline/Variable272126
-Node: Getline/File273277
-Node: Getline/Variable/File274665
-Ref: Getline/Variable/File-Footnote-1276270
-Node: Getline/Pipe276358
-Node: Getline/Variable/Pipe279062
-Node: Getline/Coprocess280197
-Node: Getline/Variable/Coprocess281464
-Node: Getline Notes282206
-Node: Getline Summary285003
-Ref: table-getline-variants285427
-Node: Read Timeout286176
-Ref: Read Timeout-Footnote-1290092
-Node: Retrying Input290150
-Node: Command-line directories291349
-Node: Input Summary292255
-Node: Input Exercises295427
-Node: Printing295861
-Node: Print297695
-Node: Print Examples299152
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-Node: OFMT303949
-Node: Printf305305
-Node: Basic Printf306090
-Node: Control Letters307664
-Node: Format Modifiers312826
-Node: Printf Examples318841
-Node: Redirection321327
-Node: Special FD328168
-Ref: Special FD-Footnote-1331336
-Node: Special Files331410
-Node: Other Inherited Files332027
-Node: Special Network333028
-Node: Special Caveats333888
-Node: Close Files And Pipes334837
-Ref: table-close-pipe-return-values341744
-Ref: Close Files And Pipes-Footnote-1342558
-Ref: Close Files And Pipes-Footnote-2342706
-Node: Nonfatal342858
-Node: Output Summary345196
-Node: Output Exercises346418
-Node: Expressions347097
-Node: Values348285
-Node: Constants348963
-Node: Scalar Constants349654
-Ref: Scalar Constants-Footnote-1352164
-Node: Nondecimal-numbers352414
-Node: Regexp Constants355415
-Node: Using Constant Regexps355941
-Node: Standard Regexp Constants356563
-Node: Strong Regexp Constants359751
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-Node: Assignment Options366033
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-Node: Strings And Numbers369028
-Ref: Strings And Numbers-Footnote-1372091
-Node: Locale influences conversions372200
-Ref: table-locale-affects374958
-Node: All Operators375577
-Node: Arithmetic Ops376206
-Node: Concatenation378922
-Ref: Concatenation-Footnote-1381769
-Node: Assignment Ops381876
-Ref: table-assign-ops386867
-Node: Increment Ops388181
-Node: Truth Values and Conditions391641
-Node: Truth Values392715
-Node: Typing and Comparison393763
-Node: Variable Typing394583
-Ref: Variable Typing-Footnote-1401046
-Ref: Variable Typing-Footnote-2401118
-Node: Comparison Operators401195
-Ref: table-relational-ops401614
-Node: POSIX String Comparison405110
-Ref: POSIX String Comparison-Footnote-1406805
-Ref: POSIX String Comparison-Footnote-2406944
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-Ref: Boolean Ops-Footnote-1411510
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-Node: BEGIN/END435307
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-Node: ARGC and ARGV499092
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-Node: Array Intro507908
-Ref: figure-array-elements509883
-Ref: Array Intro-Footnote-1512588
-Node: Reference to Elements512716
-Node: Assigning Elements515180
-Node: Array Example515671
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-Ref: I/O Functions-Footnote-2596497
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-Ref: Time Functions-Footnote-2607356
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-Ref: Time Functions-Footnote-4607625
-Ref: Time Functions-Footnote-5607737
-Ref: Time Functions-Footnote-6607964
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-Ref: table-bitwise-ops608824
-Ref: Bitwise Functions-Footnote-1614888
-Ref: Bitwise Functions-Footnote-2615061
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-Node: I18N Functions618773
-Node: User-defined620424
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-Ref: Definition Syntax-Footnote-1626930
-Node: Function Example627001
-Ref: Function Example-Footnote-1629923
-Node: Function Calling629945
-Node: Calling A Function630533
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-Node: Pass By Value/Reference634485
-Node: Function Caveats637129
-Ref: Function Caveats-Footnote-1639176
-Node: Return Statement639296
-Node: Dynamic Typing642275
-Node: Indirect Calls643205
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-Node: Library Functions656837
-Ref: Library Functions-Footnote-1660321
-Ref: Library Functions-Footnote-2660464
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-Ref: Library Names-Footnote-2664525
-Node: General Functions664611
-Node: Strtonum Function665793
-Node: Assert Function668815
-Node: Round Function672141
-Node: Cliff Random Function673681
-Node: Ordinal Functions674697
-Ref: Ordinal Functions-Footnote-1677760
-Ref: Ordinal Functions-Footnote-2678012
-Node: Join Function678222
-Ref: Join Function-Footnote-1679992
-Node: Getlocaltime Function680192
-Node: Readfile Function683934
-Node: Shell Quoting685911
-Node: Isnumeric Function687339
-Node: Data File Management688727
-Node: Filetrans Function689359
-Node: Rewind Function693455
-Node: File Checking695364
-Ref: File Checking-Footnote-1696698
-Node: Empty Files696899
-Node: Ignoring Assigns698878
-Node: Getopt Function700428
-Ref: Getopt Function-Footnote-1715725
-Node: Passwd Functions715925
-Ref: Passwd Functions-Footnote-1724764
-Node: Group Functions724852
-Ref: Group Functions-Footnote-1732750
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-Node: Clones739334
-Node: Cut Program740558
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-Node: Split Program769634
-Ref: Split Program-Footnote-1779527
-Node: Tee Program779700
-Node: Uniq Program782490
-Node: Wc Program790078
-Node: Bytes vs. Characters790465
-Node: Using extensions792013
-Node: wc program792767
-Node: Miscellaneous Programs797632
-Node: Dupword Program798845
-Node: Alarm Program800875
-Node: Translate Program805730
-Ref: Translate Program-Footnote-1810295
-Node: Labels Program810565
-Ref: Labels Program-Footnote-1813916
-Node: Word Sorting814000
-Node: History Sorting818072
-Node: Extract Program820297
-Node: Simple Sed828310
-Node: Igawk Program831384
-Ref: Igawk Program-Footnote-1846013
-Ref: Igawk Program-Footnote-2846215
-Ref: Igawk Program-Footnote-3846337
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-Node: Signature Program849514
-Node: Programs Summary850761
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-Ref: Two-way I/O-Footnote-2885278
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-Node: List of Debugger Commands951659
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-Node: Inexactness of computations1007846
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-Node: Strange values1012934
-Ref: Strange values-Footnote-11015522
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-Ref: table-predefined-precision-strings1019933
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-Ref: Setting the rounding mode-Footnote-11026070
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-Node: Floating point summary1035738
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-Node: Extension Intro1039481
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-Ref: figure-register-new-function1043549
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-Node: Extension API Functions Introduction1048418
-Ref: table-api-std-headers1050254
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-Ref: General Data Types-Footnote-11063210
-Node: Memory Allocation Functions1063509
-Ref: Memory Allocation Functions-Footnote-11068010
-Node: Constructor Functions1068109
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-Node: Registration Functions1073295
-Node: Extension Functions1073995
-Node: Exit Callback Functions1079317
-Node: Extension Version String1080567
-Node: Input Parsers1081230
-Node: Output Wrappers1093951
-Node: Two-way processors1098463
-Node: Printing Messages1100728
-Ref: Printing Messages-Footnote-11101899
-Node: Updating ERRNO1102052
-Node: Requesting Values1102791
-Ref: table-value-types-returned1103528
-Node: Accessing Parameters1104637
-Node: Symbol Table Access1105874
-Node: Symbol table by name1106386
-Ref: Symbol table by name-Footnote-11109411
-Node: Symbol table by cookie1109539
-Ref: Symbol table by cookie-Footnote-11113724
-Node: Cached values1113788
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-Node: Extension API Variables1140716
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-Node: Building the Documentation1272094
-Node: Non-Unix Installation1273478
-Node: PC Installation1273942
-Node: PC Binary Installation1274787
-Node: PC Compiling1275660
-Node: PC Using1276766
-Node: Cygwin1280262
-Node: MSYS1281486
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-Node: OpenVMS GNV1292138
-Node: Bugs1292881
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-Node: Usenet1300814
-Node: Performance bugs1302003
-Node: Asking for help1304924
-Node: Maintainers1306891
-Node: Other Versions1307898
-Node: Installation summary1316481
-Node: Notes1317821
-Node: Compatibility Mode1318615
-Node: Additions1319397
-Node: Accessing The Source1320322
-Node: Adding Code1321817
-Node: New Ports1328632
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-Node: Glossary1359891
-Node: Copying1391778
-Node: GNU Free Documentation License1429321
-Node: Index1454441
+Node: Top1229
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+Node: OpenVMS Compilation1330322
+Ref: OpenVMS Compilation-Footnote-11331805
+Node: OpenVMS Dynamic Extensions1331867
+Node: OpenVMS Installation Details1333503
+Node: OpenVMS Running1335938
+Node: OpenVMS GNV1340075
+Node: Bugs1340830
+Node: Bug definition1341754
+Node: Bug address1345405
+Node: Usenet1348996
+Node: Performance bugs1350227
+Node: Asking for help1353245
+Node: Maintainers1355236
+Node: Other Versions1356263
+Node: Installation summary1365195
+Node: Notes1366579
+Node: Compatibility Mode1367389
+Node: Additions1368211
+Node: Accessing The Source1369156
+Node: Adding Code1370691
+Node: New Ports1377827
+Node: Derived Files1382337
+Ref: Derived Files-Footnote-11388184
+Ref: Derived Files-Footnote-21388219
+Ref: Derived Files-Footnote-31388836
+Node: Future Extensions1388950
+Node: Implementation Limitations1389622
+Node: Extension Design1390864
+Node: Old Extension Problems1392028
+Ref: Old Extension Problems-Footnote-11393604
+Node: Extension New Mechanism Goals1393665
+Ref: Extension New Mechanism Goals-Footnote-11397161
+Node: Extension Other Design Decisions1397362
+Node: Extension Future Growth1399561
+Node: Notes summary1400185
+Node: Basic Concepts1401398
+Node: Basic High Level1402083
+Ref: figure-general-flow1402365
+Ref: figure-process-flow1403067
+Ref: Basic High Level-Footnote-11406463
+Node: Basic Data Typing1406652
+Node: Glossary1410070
+Node: Copying1443192
+Node: GNU Free Documentation License1480953
+Node: Index1506276
End Tag Table
diff --git a/doc/gawk.texi b/doc/gawk.texi
index 4b5a8545..3ef80aa1 100644
--- a/doc/gawk.texi
+++ b/doc/gawk.texi
@@ -85,6 +85,16 @@
@set COMMONEXT (c.e.)
@set PAGE page
@end iftex
+@iflatex
+@set DOCUMENT book
+@set CHAPTER chapter
+@set APPENDIX appendix
+@set SECTION section
+@set SUBSECTION subsection
+@set DARKCORNER (d.c.)
+@set COMMONEXT (c.e.)
+@set PAGE page
+@end iflatex
@ifinfo
@set DOCUMENT Info file
@set CHAPTER major node
@@ -156,6 +166,10 @@
@set LEQ @math{@leq}
@set PI @math{@pi}
@end iftex
+@iflatex
+@set LEQ <=
+@set PI @i{pi}
+@end iflatex
@ifdocbook
@set LEQ @inlineraw{docbook, ≤}
@set PI @inlineraw{docbook, &pgr;}
@@ -247,6 +261,10 @@ Some comments on the layout for TeX.
@syncodeindex fn cp
@syncodeindex vr cp
@end iftex
+@iflatex
+@syncodeindex fn cp
+@syncodeindex vr cp
+@end iflatex
@ifxml
@syncodeindex fn cp
@syncodeindex vr cp
@@ -264,6 +282,9 @@ Some comments on the layout for TeX.
@iftex
@finalout
@end iftex
+@iflatex
+@finalout
+@end iflatex
@c Enabled '-quotes in PDF files so that cut/paste works in
@c more places.
@@ -14961,12 +14982,17 @@ you ``hooks'' into @command{gawk}'s command-line file
processing loop.
As with the @code{BEGIN} and @code{END} rules
@ifnottex
@ifnotdocbook
+@ifnotlatex
(@pxref{BEGIN/END}),
+@end ifnotlatex
@end ifnotdocbook
@end ifnottex
@iftex
(see the previous @value{SECTION}),
@end iftex
+@iflatex
+(see the previous @value{SECTION}),
+@end iflatex
@ifdocbook
(see the previous @value{SECTION}),
@end ifdocbook
@@ -27604,6 +27630,9 @@ the duplicated words occur at the end of one line and
the
@iftex
the
@end iftex
+@iflatex
+the
+@end iflatex
beginning of
another, making them very difficult to spot.
@c as here!
diff --git a/doc/gawktexi.in b/doc/gawktexi.in
index 6d28e031..c3e57598 100644
--- a/doc/gawktexi.in
+++ b/doc/gawktexi.in
@@ -80,6 +80,16 @@
@set COMMONEXT (c.e.)
@set PAGE page
@end iftex
+@iflatex
+@set DOCUMENT book
+@set CHAPTER chapter
+@set APPENDIX appendix
+@set SECTION section
+@set SUBSECTION subsection
+@set DARKCORNER (d.c.)
+@set COMMONEXT (c.e.)
+@set PAGE page
+@end iflatex
@ifinfo
@set DOCUMENT Info file
@set CHAPTER major node
@@ -151,6 +161,10 @@
@set LEQ @math{@leq}
@set PI @math{@pi}
@end iftex
+@iflatex
+@set LEQ <=
+@set PI @i{pi}
+@end iflatex
@ifdocbook
@set LEQ @inlineraw{docbook, ≤}
@set PI @inlineraw{docbook, &pgr;}
@@ -242,6 +256,10 @@ Some comments on the layout for TeX.
@syncodeindex fn cp
@syncodeindex vr cp
@end iftex
+@iflatex
+@syncodeindex fn cp
+@syncodeindex vr cp
+@end iflatex
@ifxml
@syncodeindex fn cp
@syncodeindex vr cp
@@ -259,6 +277,9 @@ Some comments on the layout for TeX.
@iftex
@finalout
@end iftex
+@iflatex
+@finalout
+@end iflatex
@c Enabled '-quotes in PDF files so that cut/paste works in
@c more places.
@@ -14148,12 +14169,17 @@ you ``hooks'' into @command{gawk}'s command-line file
processing loop.
As with the @code{BEGIN} and @code{END} rules
@ifnottex
@ifnotdocbook
+@ifnotlatex
(@pxref{BEGIN/END}),
+@end ifnotlatex
@end ifnotdocbook
@end ifnottex
@iftex
(see the previous @value{SECTION}),
@end iftex
+@iflatex
+(see the previous @value{SECTION}),
+@end iflatex
@ifdocbook
(see the previous @value{SECTION}),
@end ifdocbook
@@ -26486,6 +26512,9 @@ the duplicated words occur at the end of one line and
the
@iftex
the
@end iftex
+@iflatex
+the
+@end iflatex
beginning of
another, making them very difficult to spot.
@c as here!
diff --git a/doc/texinfo.tex b/doc/texinfo.tex
index cfc77a84..b1bf41ff 100644
--- a/doc/texinfo.tex
+++ b/doc/texinfo.tex
@@ -1,9 +1,9 @@
% texinfo.tex -- TeX macros to handle Texinfo files.
-%
+%
% Load plain if necessary, i.e., if running under initex.
\expandafter\ifx\csname fmtname\endcsname\relax\input plain\fi
%
-\def\texinfoversion{2022-11-12.22}
+\def\texinfoversion{2022-11-07.17}
%
% Copyright 1985, 1986, 1988, 1990-2022 Free Software Foundation, Inc.
%
@@ -218,7 +218,7 @@
% @errormsg{MSG}. Do the index-like expansions on MSG, but if things
% aren't perfect, it's not the end of the world, being an error message,
% after all.
-%
+%
\def\errormsg{\begingroup \indexnofonts \doerrormsg}
\def\doerrormsg#1{\errmessage{#1}}
@@ -432,7 +432,7 @@
}%
}
-% First remove any @comment, then any @c comment. Pass the result on to
+% First remove any @comment, then any @c comment. Pass the result on to
% \argcheckspaces.
\def\argremovecomment#1\comment#2\ArgTerm{\argremovec #1\c\ArgTerm}
\def\argremovec#1\c#2\ArgTerm{\argcheckspaces#1\^^M\ArgTerm}
@@ -1051,8 +1051,8 @@ where each line of input produces a line of output.}
end
end
}
- % The -2 in the arguments here gives all the input to TeX catcode 12
- % (other) or 10 (space), preventing undefined control sequence errors. See
+ % The -2 in the arguments here gives all the input to TeX catcode 12
+ % (other) or 10 (space), preventing undefined control sequence errors. See
% https://lists.gnu.org/archive/html/bug-texinfo/2019-08/msg00031.html
%
\endgroup
@@ -1146,7 +1146,7 @@ where each line of input produces a line of output.}
% for display in the outlines, and in other places. Thus, we have to
% double any backslashes. Otherwise, a name like "\node" will be
% interpreted as a newline (\n), followed by o, d, e. Not good.
-%
+%
% See http://www.ntg.nl/pipermail/ntg-pdftex/2004-July/000654.html and
% related messages. The final outcome is that it is up to the TeX user
% to double the backslashes and otherwise make the string valid, so
@@ -1434,7 +1434,7 @@ output) for that.)}
% We use the node names as the destinations.
%
% Currently we prefix the section name with the section number
- % for chapter and appendix headings only in order to avoid too much
+ % for chapter and appendix headings only in order to avoid too much
% horizontal space being required in the PDF viewer.
\def\numchapentry##1##2##3##4{%
\dopdfoutline{##2 ##1}{count-\expnumber{chap##2}}{##3}{##4}}%
@@ -1457,7 +1457,7 @@ output) for that.)}
% their "best" equivalent, based on the @documentencoding. Too
% much work for too little return. Just use the ASCII equivalents
% we use for the index sort strings.
- %
+ %
\indexnofonts
\setupdatafile
% We can have normal brace characters in the PDF outlines, unlike
@@ -1682,7 +1682,7 @@ output) for that.)}
% We use node names as destinations.
%
% Currently we prefix the section name with the section number
- % for chapter and appendix headings only in order to avoid too much
+ % for chapter and appendix headings only in order to avoid too much
% horizontal space being required in the PDF viewer.
\def\partentry##1##2##3##4{}% ignore parts in the outlines
\def\numchapentry##1##2##3##4{%
@@ -2707,7 +2707,7 @@ end
}
% Commands to set the quote options.
-%
+%
\parseargdef\codequoteundirected{%
\def\temp{#1}%
\ifx\temp\onword
@@ -2748,7 +2748,7 @@ end
% If we are in a monospaced environment, however, 1) always use \ttsl,
% and 2) do not add an italic correction.
\def\dosmartslant#1#2{%
- \ifusingtt
+ \ifusingtt
{{\ttsl #2}\let\next=\relax}%
{\def\next{{#1#2}\smartitaliccorrection}}%
\next
@@ -2936,14 +2936,14 @@ end
\gdef\codedash{\futurelet\next\codedashfinish}
\gdef\codedashfinish{%
\normaldash % always output the dash character itself.
- %
+ %
% Now, output a discretionary to allow a line break, unless
% (a) the next character is a -, or
% (b) the preceding character is a -.
% E.g., given --posix, we do not want to allow a break after either -.
% Given --foo-bar, we do want to allow a break between the - and the b.
\ifx\next\codedash \else
- \ifx\codedashprev\codedash
+ \ifx\codedashprev\codedash
\else \discretionary{}{}{}\fi
\fi
% we need the space after the = for the case when \next itself is a
@@ -3033,7 +3033,7 @@ end
% For pdfTeX and LuaTeX
\ifurefurlonlylink
% PDF plus option to not display url, show just arg
- \unhbox0
+ \unhbox0
\else
% PDF, normally display both arg and url for consistency,
% visibility, if the pdf is eventually used to print, etc.
@@ -3046,7 +3046,7 @@ end
% For XeTeX
\ifurefurlonlylink
% PDF plus option to not display url, show just arg
- \unhbox0
+ \unhbox0
\else
% PDF, normally display both arg and url for consistency,
% visibility, if the pdf is eventually used to print, etc.
@@ -3104,10 +3104,10 @@ end
}
}
-% By default we'll break after the special characters, but some people like to
-% break before the special chars, so allow that. Also allow no breaking at
+% By default we'll break after the special characters, but some people like to
+% break before the special chars, so allow that. Also allow no breaking at
% all, for manual control.
-%
+%
\parseargdef\urefbreakstyle{%
\def\txiarg{#1}%
\ifx\txiarg\wordnone
@@ -3126,10 +3126,10 @@ end
\def\wordnone{none}
% Allow a ragged right output to aid breaking long URL's. There can
-% be a break at the \allowbreak with no extra glue (if the existing stretch in
+% be a break at the \allowbreak with no extra glue (if the existing stretch in
% the line is sufficient), a break at the \penalty with extra glue added
% at the end of the line, or no break at all here.
-% Changing the value of the penalty and/or the amount of stretch affects how
+% Changing the value of the penalty and/or the amount of stretch affects how
% preferable one choice is over the other.
\def\urefallowbreak{%
\penalty0\relax
@@ -3344,7 +3344,7 @@ $$%
% @inlinefmt{FMTNAME,PROCESSED-TEXT} and @inlineraw{FMTNAME,RAW-TEXT}.
% Ignore unless FMTNAME == tex; then it is like @iftex and @tex,
% except specified as a normal braced arg, so no newlines to worry about.
-%
+%
\def\outfmtnametex{tex}
%
\long\def\inlinefmt#1{\doinlinefmt #1,\finish}
@@ -3352,7 +3352,7 @@ $$%
\def\inlinefmtname{#1}%
\ifx\inlinefmtname\outfmtnametex \ignorespaces #2\fi
}
-%
+%
% @inlinefmtifelse{FMTNAME,THEN-TEXT,ELSE-TEXT} expands THEN-TEXT if
% FMTNAME is tex, else ELSE-TEXT.
\long\def\inlinefmtifelse#1{\doinlinefmtifelse #1,,,\finish}
@@ -3368,7 +3368,7 @@ $$%
% *right* brace they would have to use a command anyway, so they may as
% well use a command to get a left brace too. We could re-use the
% delimiter character idea from \verb, but it seems like overkill.
-%
+%
\long\def\inlineraw{\tex \doinlineraw}
\long\def\doinlineraw#1{\doinlinerawtwo #1,\finish}
\def\doinlinerawtwo#1,#2,\finish{%
@@ -3654,7 +3654,7 @@ $$%
% for non-CM glyphs. That is ec* for regular text and tc* for the text
% companion symbols (LaTeX TS1 encoding). Both are part of the ec
% package and follow the same conventions.
-%
+%
\def\ecfont{\etcfont{e}}
\def\tcfont{\etcfont{t}}
%
@@ -3691,10 +3691,7 @@ $$%
% @textdegree - the normal degrees sign.
%
-\def\textdegree{%
- \ifmmode ^\circ
- \else {\tcfont \char 176}%
- \fi}
+\def\textdegree{$^\circ$}
% Laurent Siebenmann reports \Orb undefined with:
% Textures 1.7.7 (preloaded format=plain 93.10.14) (68K) 16 APR 2004 02:38
@@ -3736,7 +3733,7 @@ $$%
after the title page.}}%
\def\setshortcontentsaftertitlepage{%
\errmessage{@setshortcontentsaftertitlepage has been removed as a Texinfo
- command; move your @shortcontents and @contents commands if you
+ command; move your @shortcontents and @contents commands if you
want the contents after the title page.}}%
\parseargdef\shorttitlepage{%
@@ -3791,7 +3788,7 @@ $$%
% don't worry much about spacing, ragged right. This should be used
% inside a \vbox, and fonts need to be set appropriately first. \par should
% be specified before the end of the \vbox, since a vbox is a group.
-%
+%
\def\raggedtitlesettings{%
\rm
\hyphenpenalty=10000
@@ -4627,7 +4624,7 @@ $$%
% Like \expandablevalue, but completely expandable (the \message in the
% definition above operates at the execution level of TeX). Used when
% writing to auxiliary files, due to the expansion that \write does.
-% If flag is undefined, pass through an unexpanded @value command: maybe it
+% If flag is undefined, pass through an unexpanded @value command: maybe it
% will be set by the time it is read back in.
%
% NB flag names containing - or _ may not work here.
@@ -4651,7 +4648,7 @@ $$%
% @ifset VAR ... @end ifset reads the `...' iff VAR has been defined
% with @set.
-%
+%
% To get the special treatment we need for `@end ifset,' we call
% \makecond and then redefine.
%
@@ -4684,7 +4681,7 @@ $$%
% without the @) is in fact defined. We can only feasibly check at the
% TeX level, so something like `mathcode' is going to considered
% defined even though it is not a Texinfo command.
-%
+%
\makecond{ifcommanddefined}
\def\ifcommanddefined{\parsearg{\doifcmddefined{\let\next=\ifcmddefinedfail}}}
%
@@ -4792,8 +4789,8 @@ $$%
\def\docodeindex#1{\edef\indexname{#1}\parsearg\docodeindexxxx}
\def\docodeindexxxx #1{\docind{\indexname}{#1}}
-
-% Used for the aux, toc and index files to prevent expansion of Texinfo
+
+% Used for the aux, toc and index files to prevent expansion of Texinfo
% commands.
%
\def\atdummies{%
@@ -5139,11 +5136,11 @@ $$%
\let\value\indexnofontsvalue
}
-% Give the control sequence a definition that removes the {} that follows
+% Give the control sequence a definition that removes the {} that follows
% its use, e.g. @AA{} -> AA
\def\indexnofontsdef#1#2{\def#1##1{#2}}%
-
+
% #1 is the index name, #2 is the entry text.
@@ -5184,7 +5181,7 @@ $$%
\ifx\suffix\indexisfl\def\suffix{f1}\fi
% Open the file
\immediate\openout\csname#1indfile\endcsname \jobname.\suffix
- % Using \immediate above here prevents an object entering into the current
+ % Using \immediate above here prevents an object entering into the current
% box, which could confound checks such as those in \safewhatsit for
% preceding skips.
\typeout{Writing index file \jobname.\suffix}%
@@ -5236,7 +5233,7 @@ $$%
\ifx\segment\isfinish
\else
%
- % Fully expand the segment, throwing away any @sortas directives, and
+ % Fully expand the segment, throwing away any @sortas directives, and
% trim spaces.
\edef\trimmed{\segment}%
\edef\trimmed{\expandafter\eatspaces\expandafter{\trimmed}}%
@@ -5300,12 +5297,12 @@ $$%
% the current value of \escapechar.
\def\escapeisbackslash{\escapechar=`\\}
-% Use \ in index files by default. texi2dvi didn't support @ as the escape
-% character (as it checked for "\entry" in the files, and not "@entry"). When
-% the new version of texi2dvi has had a chance to become more prevalent, then
-% the escape character can change back to @ again. This should be an easy
-% change to make now because both @ and \ are only used as escape characters in
-% index files, never standing for themselves.
+% Use \ in index files by default. texi2dvi didn't support @ as the escape
+% character (as it checked for "\entry" in the files, and not "@entry"). When
+% the new version of texi2dvi has had a chance to become more prevalent, then
+% the escape character can change back to @ again. This should be an easy
+% change to make now because both @ and \ are only used as escape characters
in
+% index files, never standing for themselves.
%
\set txiindexescapeisbackslash
@@ -5328,7 +5325,7 @@ $$%
\def\}{\rbracechar{}}%
\uccode`\~=`\\ \uppercase{\def~{\backslashchar{}}}%
%
- % Split the entry into primary entry and any subentries, and get the index
+ % Split the entry into primary entry and any subentries, and get the index
% sort key.
\splitindexentry\indextext
%
@@ -5509,18 +5506,18 @@ $$%
\uccode`\~=`\\ \uppercase{\if\noexpand~}\noexpand#1
\ifflagclear{txiskipindexfileswithbackslash}{%
\errmessage{%
-ERROR: A sorted index file in an obsolete format was skipped.
+ERROR: A sorted index file in an obsolete format was skipped.
To fix this problem, please upgrade your version of 'texi2dvi'
or 'texi2pdf' to that at <https://ftp.gnu.org/gnu/texinfo>.
-If you are using an old version of 'texindex' (part of the Texinfo
+If you are using an old version of 'texindex' (part of the Texinfo
distribution), you may also need to upgrade to a newer version (at least 6.0).
You may be able to typeset the index if you run
'texindex \jobname.\indexname' yourself.
-You could also try setting the 'txiindexescapeisbackslash' flag by
+You could also try setting the 'txiindexescapeisbackslash' flag by
running a command like
-'texi2dvi -t "@set txiindexescapeisbackslash" \jobname.texi'. If you do
+'texi2dvi -t "@set txiindexescapeisbackslash" \jobname.texi'. If you do
this, Texinfo will try to use index files in the old format.
-If you continue to have problems, deleting the index files and starting again
+If you continue to have problems, deleting the index files and starting again
might help (with 'rm \jobname.?? \jobname.??s')%
}%
}{%
@@ -5593,7 +5590,7 @@ might help (with 'rm \jobname.?? \jobname.??s')%
% bottom of a column to reduce an increase in inter-line spacing.
\nobreak
\vskip 0pt plus 5\baselineskip
- \penalty -300
+ \penalty -300
\vskip 0pt plus -5\baselineskip
%
% Typeset the initial. Making this add up to a whole number of
@@ -5709,7 +5706,7 @@ might help (with 'rm \jobname.?? \jobname.??s')%
\advance\dimen@ii by 1\dimen@i
\ifdim\wd\boxA > \dimen@ii % If the entry doesn't fit in one line
\ifdim\dimen@ > 0.8\dimen@ii % due to long index text
- % Try to split the text roughly evenly. \dimen@ will be the length of
+ % Try to split the text roughly evenly. \dimen@ will be the length of
% the first line.
\dimen@ = 0.7\dimen@
\dimen@ii = \hsize
@@ -5917,7 +5914,7 @@ might help (with 'rm \jobname.?? \jobname.??s')%
\newbox\balancedcolumns
\setbox\balancedcolumns=\vbox{shouldnt see this}%
%
-% Only called for the last of the double column material. \doublecolumnout
+% Only called for the last of the double column material. \doublecolumnout
% does the others.
\def\balancecolumns{%
\setbox0 = \vbox{\unvbox\PAGE}% like \box255 but more efficient, see p.120.
@@ -5945,7 +5942,7 @@ might help (with 'rm \jobname.?? \jobname.??s')%
}%
% Now the left column is in box 1, and the right column in box 3.
%
- % Check whether the left column has come out higher than the page itself.
+ % Check whether the left column has come out higher than the page itself.
% (Note that we have doubled \vsize for the double columns, so
% the actual height of the page is 0.5\vsize).
\ifdim2\ht1>\vsize
@@ -6242,7 +6239,7 @@ might help (with 'rm \jobname.?? \jobname.??s')%
\let\top\unnumbered
% Sections.
-%
+%
\outer\parseargdef\numberedsec{\numhead1{#1}} % normally calls seczzz
\def\seczzz#1{%
\global\subsecno=0 \global\subsubsecno=0 \global\advance\secno by 1
@@ -6265,7 +6262,7 @@ might help (with 'rm \jobname.?? \jobname.??s')%
}
% Subsections.
-%
+%
% normally calls numberedsubseczzz:
\outer\parseargdef\numberedsubsec{\numhead2{#1}}
\def\numberedsubseczzz#1{%
@@ -6290,7 +6287,7 @@ might help (with 'rm \jobname.?? \jobname.??s')%
}
% Subsubsections.
-%
+%
% normally numberedsubsubseczzz:
\outer\parseargdef\numberedsubsubsec{\numhead3{#1}}
\def\numberedsubsubseczzz#1{%
@@ -7352,7 +7349,7 @@ might help (with 'rm \jobname.?? \jobname.??s')%
% @indentedblock is like @quotation, but indents only on the left and
% has no optional argument.
-%
+%
\makedispenvdef{indentedblock}{\indentedblockstart}
%
\def\indentedblockstart{%
@@ -7646,7 +7643,7 @@ might help (with 'rm \jobname.?? \jobname.??s')%
% @deftypefnnewline on|off says whether the return type of typed functions
% are printed on their own line. This affects @deftypefn, @deftypefun,
% @deftypeop, and @deftypemethod.
-%
+%
\parseargdef\deftypefnnewline{%
\def\temp{#1}%
\ifx\temp\onword
@@ -7814,7 +7811,7 @@ might help (with 'rm \jobname.?? \jobname.??s')%
\tclose{\temp}% typeset the return type
\ifrettypeownline
% put return type on its own line; prohibit line break following:
- \hfil\vadjust{\nobreak}\break
+ \hfil\vadjust{\nobreak}\break
\else
\space % type on same line, so just followed by a space
\fi
@@ -7961,7 +7958,7 @@ might help (with 'rm \jobname.?? \jobname.??s')%
\scantokens{#1@comment}%
%
% The \comment is to remove the \newlinechar added by \scantokens, and
- % can be noticed by \parsearg. Note \c isn't used because this means cedilla
+ % can be noticed by \parsearg. Note \c isn't used because this means
cedilla
% in math mode.
}
@@ -8156,7 +8153,7 @@ might help (with 'rm \jobname.?? \jobname.??s')%
% list to some hook where the argument is to be expanded. If there are
% less than 10 arguments that hook is to be replaced by ##N where N
% is the position in that list, that is to say the macro arguments are to be
-% defined `a la TeX in the macro body.
+% defined `a la TeX in the macro body.
%
% That gets used by \mbodybackslash (above).
%
@@ -8190,8 +8187,8 @@ might help (with 'rm \jobname.?? \jobname.??s')%
%
% Read recursive and nonrecursive macro bodies. (They're different since
% rec and nonrec macros end differently.)
-%
-% We are in \macrobodyctxt, and the \xdef causes backslashshes in the macro
+%
+% We are in \macrobodyctxt, and the \xdef causes backslashshes in the macro
% body to be transformed.
% Set \macrobody to the body of the macro, and call \defmacro.
%
@@ -8225,7 +8222,7 @@ might help (with 'rm \jobname.?? \jobname.??s')%
% twice the \macarg.BLAH macros does not cost too much processing power.
\def\parsemmanyargdef@@#1,{%
\if#1;\let\next=\relax
- \else
+ \else
\let\next=\parsemmanyargdef@@
\edef\tempb{\eatspaces{#1}}%
\expandafter\def\expandafter\tempa
@@ -8310,7 +8307,7 @@ might help (with 'rm \jobname.?? \jobname.??s')%
% Replace arguments by their values in the macro body, and place the result
% in macro \@tempa.
-%
+%
\def\macvalstoargs@{%
% To do this we use the property that token registers that are \the'ed
% within an \edef expand only once. So we are going to place all argument
@@ -8334,9 +8331,9 @@ might help (with 'rm \jobname.?? \jobname.??s')%
\expandafter\def\expandafter\@tempa\expandafter{\@tempc}%
}
-% Define the named-macro outside of this group and then close this group.
-%
-\def\macargexpandinbody@{%
+% Define the named-macro outside of this group and then close this group.
+%
+\def\macargexpandinbody@{%
\expandafter
\endgroup
\macargdeflist@
@@ -8374,7 +8371,7 @@ might help (with 'rm \jobname.?? \jobname.??s')%
}
% Trailing missing arguments are set to empty.
-%
+%
\def\setemptyargvalues@{%
\ifx\paramlist\nilm@
\let\next\macargexpandinbody@
@@ -8431,32 +8428,32 @@ might help (with 'rm \jobname.?? \jobname.??s')%
\ifcase\paramno
% 0
\expandafter\xdef\csname\the\macname\endcsname{%
- \begingroup
+ \bgroup
\noexpand\spaceisspace
\noexpand\endlineisspace
\noexpand\expandafter % skip any whitespace after the macro name.
\expandafter\noexpand\csname\the\macname @@@\endcsname}%
\expandafter\xdef\csname\the\macname @@@\endcsname{%
- \endgroup
+ \egroup
\noexpand\scanmacro{\macrobody}}%
\or % 1
\expandafter\xdef\csname\the\macname\endcsname{%
- \begingroup
+ \bgroup
\noexpand\braceorline
\expandafter\noexpand\csname\the\macname @@@\endcsname}%
\expandafter\xdef\csname\the\macname @@@\endcsname##1{%
- \endgroup
+ \egroup
\noexpand\scanmacro{\macrobody}%
}%
\else % at most 9
\ifnum\paramno<10\relax
% @MACNAME sets the context for reading the macro argument
- % @MACNAME@@ gets the argument, processes backslashes and appends a
+ % @MACNAME@@ gets the argument, processes backslashes and appends a
% comma.
% @MACNAME@@@ removes braces surrounding the argument list.
% @MACNAME@@@@ scans the macro body with arguments substituted.
\expandafter\xdef\csname\the\macname\endcsname{%
- \begingroup
+ \bgroup
\noexpand\expandafter % This \expandafter skip any spaces after the
\noexpand\macroargctxt % macro before we change the catcode of space.
\noexpand\expandafter
@@ -8470,7 +8467,7 @@ might help (with 'rm \jobname.?? \jobname.??s')%
\expandafter\xdef
\expandafter\expandafter
\csname\the\macname @@@@\endcsname\paramlist{%
- \endgroup\noexpand\scanmacro{\macrobody}}%
+ \egroup\noexpand\scanmacro{\macrobody}}%
\else % 10 or more:
\expandafter\xdef\csname\the\macname\endcsname{%
\noexpand\getargvals@{\the\macname}{\argl}%
@@ -8495,11 +8492,11 @@ might help (with 'rm \jobname.?? \jobname.??s')%
% Call #1 with a list of tokens #2, with any doubled backslashes in #2
% compressed to one.
%
-% This implementation works by expansion, and not execution (so we cannot use
-% \def or similar). This reduces the risk of this failing in contexts where
-% complete expansion is done with no execution (for example, in writing out to
+% This implementation works by expansion, and not execution (so we cannot use
+% \def or similar). This reduces the risk of this failing in contexts where
+% complete expansion is done with no execution (for example, in writing out to
% an auxiliary file for an index entry).
-%
+%
% State is kept in the input stream: the argument passed to
% @look_ahead, @gobble_and_check_finish and @add_segment is
%
@@ -8521,11 +8518,11 @@ might help (with 'rm \jobname.?? \jobname.??s')%
% #3 - NEXT_TOKEN
% #4 used to look ahead
%
-% If the next token is not a backslash, process the rest of the argument;
+% If the next token is not a backslash, process the rest of the argument;
% otherwise, remove the next token.
@gdef@look_ahead#1!#2#3#4{%
@ifx#4\%
- @expandafter@gobble_and_check_finish
+ @expandafter@gobble_and_check_finish
@else
@expandafter@add_segment
@fi#1!{#2}#4#4%
@@ -8549,9 +8546,9 @@ might help (with 'rm \jobname.?? \jobname.??s')%
% #3 - NEXT_TOKEN
% #4 is input stream until next backslash
%
-% Input stream is either at the start of the argument, or just after a
-% backslash sequence, either a lone backslash, or a doubled backslash.
-% NEXT_TOKEN contains the first token in the input stream: if it is \finish,
+% Input stream is either at the start of the argument, or just after a
+% backslash sequence, either a lone backslash, or a doubled backslash.
+% NEXT_TOKEN contains the first token in the input stream: if it is \finish,
% finish; otherwise, append to ARG_RESULT the segment of the argument up until
% the next backslash. PENDING_BACKSLASH contains a backslash to represent
% a backslash just before the start of the input stream that has not been
@@ -8563,13 +8560,13 @@ might help (with 'rm \jobname.?? \jobname.??s')%
% append the pending backslash to the result, followed by the next segment
@expandafter@is_fi@look_ahead#1#2#4!{\}@fi
% this @fi is discarded by @look_ahead.
- % we can't get rid of it with \expandafter because we don't know how
+ % we can't get rid of it with \expandafter because we don't know how
% long #4 is.
}
% #1 - THE_MACRO
% #2 - ARG_RESULT
-% #3 discards the res of the conditional in @add_segment, and @is_fi ends the
+% #3 discards the res of the conditional in @add_segment, and @is_fi ends the
% conditional.
@gdef@call_the_macro#1#2!#3@fi{@is_fi #1{#2}}
@@ -8581,7 +8578,7 @@ might help (with 'rm \jobname.?? \jobname.??s')%
% for reading the argument (slightly different in the two cases). Then,
% to read the argument, in the whole-line case, it then calls the regular
% \parsearg MAC; in the lbrace case, it calls \passargtomacro MAC.
-%
+%
\def\braceorline#1{\let\macnamexxx=#1\futurelet\nchar\braceorlinexxx}
\def\braceorlinexxx{%
\ifx\nchar\bgroup
@@ -8635,7 +8632,7 @@ might help (with 'rm \jobname.?? \jobname.??s')%
% Used so that the @top node doesn't have to be wrapped in an @ifnottex
% conditional.
-% \doignore goes to more effort to skip nested conditionals but we don't need
+% \doignore goes to more effort to skip nested conditionals but we don't need
% that here.
\def\omittopnode{%
\ifx\lastnode\wordTop
@@ -8712,7 +8709,7 @@ might help (with 'rm \jobname.?? \jobname.??s')%
% automatically in xrefs, if the third arg is not explicitly specified.
% This was provided as a "secret" @set xref-automatic-section-title
% variable, now it's official.
-%
+%
\parseargdef\xrefautomaticsectiontitle{%
\def\temp{#1}%
\ifx\temp\onword
@@ -8728,7 +8725,7 @@ might help (with 'rm \jobname.?? \jobname.??s')%
\fi\fi
}
-%
+%
% @xref, @pxref, and @ref generate cross-references. For \xrefX, #1 is
% the node name, #2 the name of the Info cross-reference, #3 the printed
% node name, #4 the name of the Info file, #5 the name of the printed
@@ -8881,24 +8878,24 @@ might help (with 'rm \jobname.?? \jobname.??s')%
\fi
\else
% node/anchor (non-float) references.
- %
+ %
% If we use \unhbox to print the node names, TeX does not insert
% empty discretionaries after hyphens, which means that it will not
% find a line break at a hyphen in a node names. Since some manuals
% are best written with fairly long node names, containing hyphens,
% this is a loss. Therefore, we give the text of the node name
% again, so it is as if TeX is seeing it for the first time.
- %
+ %
\ifdim \wd\printedmanualbox > 0pt
% Cross-manual reference with a printed manual name.
- %
+ %
\crossmanualxref{\cite{\printedmanual\unskip}}%
%
\else\ifdim \wd\infofilenamebox > 0pt
% Cross-manual reference with only an info filename (arg 4), no
% printed manual name (arg 5). This is essentially the same as
% the case above; we output the filename, since we have nothing else.
- %
+ %
\crossmanualxref{\code{\infofilename\unskip}}%
%
\else
@@ -8937,20 +8934,20 @@ might help (with 'rm \jobname.?? \jobname.??s')%
\space\putwordpage\tie\refx{#1-pg}}
% Output a cross-manual xref to #1. Used just above (twice).
-%
+%
% Only include the text "Section ``foo'' in" if the foo is neither
% missing or Top. Thus, @xref{,,,foo,The Foo Manual} outputs simply
% "see The Foo Manual", the idea being to refer to the whole manual.
-%
+%
% But, this being TeX, we can't easily compare our node name against the
% string "Top" while ignoring the possible spaces before and after in
% the input. By adding the arbitrary 7sp below, we make it much less
% likely that a real node name would have the same width as "Top" (e.g.,
% in a monospaced font). Hopefully it will never happen in practice.
-%
+%
% For the same basic reason, we retypeset the "Top" at every
% reference, since the current font is indeterminate.
-%
+%
\def\crossmanualxref#1{%
\setbox\toprefbox = \hbox{Top\kern7sp}%
\setbox2 = \hbox{\ignorespaces \printedrefname \unskip \kern7sp}%
@@ -9027,9 +9024,9 @@ might help (with 'rm \jobname.?? \jobname.??s')%
\fi
}
-% This is the macro invoked by entries in the aux file. Define a control
-% sequence for a cross-reference target (we prepend XR to the control sequence
-% name to avoid collisions). The value is the page number. If this is a float
+% This is the macro invoked by entries in the aux file. Define a control
+% sequence for a cross-reference target (we prepend XR to the control sequence
+% name to avoid collisions). The value is the page number. If this is a
float
% type, we have more work to do.
%
\def\xrdef#1#2{%
@@ -9045,10 +9042,10 @@ might help (with 'rm \jobname.?? \jobname.??s')%
\bgroup
\expandafter\gdef\csname XR\safexrefname\endcsname{#2}%
\egroup
- % We put the \gdef inside a group to avoid the definitions building up on
- % TeX's save stack, which can cause it to run out of space for aux files with
+ % We put the \gdef inside a group to avoid the definitions building up on
+ % TeX's save stack, which can cause it to run out of space for aux files
with
% thousands of lines. \gdef doesn't use the save stack, but \csname does
- % when it defines an unknown control sequence as \relax.
+ % when it defines an unknown control sequence as \relax.
%
% Was that xref control sequence that we just defined for a float?
\expandafter\iffloat\csname XR\safexrefname\endcsname
@@ -10066,7 +10063,7 @@ directory should work if nowhere else does.}
\gdefchar^^ae{\v Z}
\gdefchar^^af{\dotaccent Z}
%
- \gdefchar^^b0{\textdegree}
+ \gdefchar^^b0{\textdegree{}}
\gdefchar^^b1{\ogonek{a}}
\gdefchar^^b2{\ogonek{ }}
\gdefchar^^b3{\l}
@@ -10246,7 +10243,7 @@ directory should work if nowhere else does.}
\uppercase{.}
\endgroup
\else
- \errhelp = \EMsimple
+ \errhelp = \EMsimple
\errmessage{Unicode character U+#1 not supported, sorry}%
\fi
\else
@@ -10279,7 +10276,7 @@ directory should work if nowhere else does.}
\countUTFz = "#1\relax
\begingroup
\parseXMLCharref
-
+
% Give \u8:... its definition. The sequence of seven \expandafter's
% expands after the \gdef three times, e.g.
%
@@ -10291,7 +10288,7 @@ directory should work if nowhere else does.}
\expandafter\expandafter
\expandafter\expandafter
\expandafter\gdef \UTFviiiTmp{#2}%
- %
+ %
\expandafter\ifx\csname uni:#1\endcsname \relax \else
\message{Internal error, already defined: #1}%
\fi
@@ -10330,7 +10327,7 @@ directory should work if nowhere else does.}
\divide\countUTFz by 64
\countUTFy = \countUTFz % Save to be the future value of \countUTFz.
\multiply\countUTFz by 64
-
+
% \countUTFz is now \countUTFx with the last 5 bits cleared. Subtract
% in order to get the last five bits.
\advance\countUTFx by -\countUTFz
@@ -10365,7 +10362,7 @@ directory should work if nowhere else does.}
% U+0080..U+00FF =
https://en.wikipedia.org/wiki/Latin-1_Supplement_(Unicode_block)
% U+0100..U+017F = https://en.wikipedia.org/wiki/Latin_Extended-A
% U+0180..U+024F = https://en.wikipedia.org/wiki/Latin_Extended-B
-%
+%
% Many of our renditions are less than wonderful, and all the missing
% characters are available somewhere. Loading the necessary fonts
% awaits user request. We can't truly support Unicode without
@@ -10489,7 +10486,7 @@ directory should work if nowhere else does.}
\DeclareUnicodeCharacter{00AE}{\registeredsymbol{}}%
\DeclareUnicodeCharacter{00AF}{\={ }}%
%
- \DeclareUnicodeCharacter{00B0}{\textdegree}
+ \DeclareUnicodeCharacter{00B0}{\ringaccent{ }}%
\DeclareUnicodeCharacter{00B1}{\ensuremath\pm}%
\DeclareUnicodeCharacter{00B2}{$^2$}%
\DeclareUnicodeCharacter{00B3}{$^3$}%
@@ -10993,7 +10990,7 @@ directory should work if nowhere else does.}
%
\DeclareUnicodeCharacter{20AC}{\euro{}}%
%
- \DeclareUnicodeCharacter{2192}{\arrow}%
+ \DeclareUnicodeCharacter{2192}{\expansion{}}%
\DeclareUnicodeCharacter{21D2}{\result{}}%
%
% Mathematical symbols
@@ -11607,7 +11604,7 @@ directory should work if nowhere else does.}
\def\texinfochars{%
\let< = \activeless
\let> = \activegtr
- \let~ = \activetilde
+ \let~ = \activetilde
\let^ = \activehat
\setregularquotes
\let\b = \strong
-----------------------------------------------------------------------
hooks/post-receive
--
gawk
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- [SCM] gawk branch, feature/latex-support, created. gawk-4.1.0-4975-g0f23965e,
Arnold Robbins <=