[bug-gawk] Suggestion on documentation about Dos quoting

[Vincent Belaïche]

Hello,

Not a bug, just a suggestion about info node "(gawk) DOS Quoting".

OK, this is out of scope of AWK, but let us be complete about the
explanation or do nothing. Hopefully, my proposal is not too verbous.

VBR,
        Vincent.




---
L'absence de virus dans ce courrier électronique a été vérifiée par le logiciel 
antivirus Avast.
https://www.avast.com/antivirus

diff --git a/doc/gawk.texi b/doc/gawk.texi
index e1b8fbb..551a3d5 100644
--- a/doc/gawk.texi
+++ b/doc/gawk.texi
@@ -49,6 +49,14 @@
 @set MINUS
 @end ifdocbook
 
address@hidden
address@hidden TIMES @times
address@hidden iftex
address@hidden
address@hidden TIMES *
address@hidden ifnottex
+        
+
 @set xref-automatic-section-title
 
 @c The following information should be updated here only!
@@ -3017,14 +3025,55 @@ it is worth addressing.
 @cindex Brink, Jeroen
 The ``shells'' 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 print all lines in a file surrounded by double quotes:
-
+escaped double-quote character in a command-line script.  The following
+example, courtesy of Jeroen Brink, shows how to escape the double quotes
+from this one liner script that prints all lines in a file surrounded by
+double quotes:
address@hidden
address@hidden print "\"" $0 "\"" @}
address@hidden example
address@hidden
+In an MSDOS command-line the one-liner script above may be passed as
+follows:
 @example
 gawk "@{ print \"\042\" $0 \"\042\" @}" @var{file}
 @end example
 
+In this example the @code{\042} is the octal code for a double-quote as
+interpretable by the @code{print} function.
+
+In MSDOS escaping double-quotes is a little tricky because you use
+backslashes to escape double-quotes, but backslashes themselves are not
+escaped in the usual way, indeed they are either duplicated or not
+depending on whether there is a subsequent double-quote.  The MSDOS rule
+is the following to double-quote a string:
+
address@hidden
address@hidden
+For each double quote in the orginal string, let @var{N} be the number
+of backslash(es) before each , @var{N} might be 0, replace these @var{N}
+backslash(es) by @address@hidden@var{N}+1} backslash(es)
address@hidden
+Let @var{N} be the number of backslash(es) tailing the original string,
address@hidden might be @math{0}, then replace these @var{N} backslash(es) by
address@hidden@address@hidden backslash(es)
address@hidden
+Surround the resulting string by double-quotes.
address@hidden enumerate
+
+So to double-quote the one-liner script @address@hidden print "\"" $0 "\"" @}}
+from the previous example you would do it this way in the MSDOS command
+line:
+
address@hidden
+gawk "@{ print \"\\\"\" $0 \"\\\"\" @}" @var{file}
address@hidden example
+
address@hidden
+However, the use of @code{\042} instead of @code{\\\"} is also possible
+and easier to read, because backslashes that are not followed by a
+double-quote don't need duplication.
+
 
 @node Sample Data Files
 @section @value{DDF}s for the Examples