[gnuastro-commits] master a0731ec2: Book: Deleted cd command in the script of Writing scripts tutorial

[Mohammad Akhlaghi]

branch: master
commit a0731ec2e70fe3376d8e072471d111fb01151785
Author: Faezeh Bidjarchian <fbidjarchian@gamil.com>
Commit: Mohammad Akhlaghi <mohammad@akhlaghi.org>

    Book: Deleted cd command in the script of Writing scripts tutorial
    
    Until now, we used the 'cd' command in our commands to go to the directory
    of the downloaded files and then return to the current directory. But there
    is no need for the 'cd' command in the script and we can make a directory
    and put our files in it from the running directory.
    
    With this commit, the 'wget' command has been modified to use '-O' for
    writing the downloaded file directly within the download directory (and not
    need the 'cd' command). Also, the 'downloaddir' variable has been renamed
    to 'dldir' to be shorter and help make the 'wget' comands fit in one line.
---
 doc/gnuastro.texi | 50 +++++++++++++++++++++++++++-----------------------
 1 file changed, 27 insertions(+), 23 deletions(-)

diff --git a/doc/gnuastro.texi b/doc/gnuastro.texi
index 7a8ea237..ce95b8c4 100644
--- a/doc/gnuastro.texi
+++ b/doc/gnuastro.texi
@@ -4646,7 +4646,7 @@ $ cat gnuastro-tutorial-1.sh
 #   hlsp_xdf_hst_wfc3ir-60mas_hudf_FILTER_v1_sci.fits
 # To make the script easier to read, a prefix and suffix variable are
 # used to sandwich the filter name into one short line.
-downloaddir=download
+dldir=download
 xdfsuffix=_v1_sci.fits
 xdfprefix=hlsp_xdf_hst_wfc3ir-60mas_hudf_
 xdfurl=http://archive.stsci.edu/pub/hlsp/xdf
@@ -4654,15 +4654,15 @@ xdfurl=http://archive.stsci.edu/pub/hlsp/xdf
 # The file name and full URLs of the input data.
 f105w_in=$xdfprefix"f105w"$xdfsuffix
 f160w_in=$xdfprefix"f160w"$xdfsuffix
-f105w_full=$xdfurl/$f105w_in
-f160w_full=$xdfurl/$f160w_in
+f105w_url=$xdfurl/$f105w_in
+f160w_url=$xdfurl/$f160w_in
 
 # Go into the download directory and download the images there,
 # then come back up to the top running directory.
-mkdir $downloaddir
-cd $downloaddir
-wget $f105w_full
-wget $f160w_full
+mkdir $dldir
+cd $dldir
+wget $f105w_url
+wget $f160w_url
 cd ..
 
 
@@ -4683,9 +4683,9 @@ deep_polygon="$vertice1:$vertice2:$vertice3:$vertice4"
 
 mkdir $flatdir
 astcrop --mode=wcs -h0 --output=$f105w_flat \
-        --polygon=$deep_polygon $downloaddir/$f105w_in
+        --polygon=$deep_polygon $dldir/$f105w_in
 astcrop --mode=wcs -h0 --output=$f160w_flat \
-        --polygon=$deep_polygon $downloaddir/$f160w_in
+        --polygon=$deep_polygon $dldirdir/$f160w_in
 @end example
 
 The first thing you may notice is that even if you already have the downloaded 
input images, this script will always try to re-download them.
@@ -4723,6 +4723,13 @@ On some systems (including GNU/Linux distributions), 
@code{mkdir} has options to
 @example
 if ! [ -d DIRNAME ]; then mkdir DIRNAME; fi
 @end example
+
+@item Avoid changing directories (with `@code{cd}') within the script
+You can directly read and write files within other directories.
+Therefore using @code{cd} to enter a directory (like what we did above, around 
the @code{wget} commands), running command there and coming out is extra, and 
not good practice.
+This is because the running directory is part of the environment of a command.
+You can simply give the directory name before the input and output file names 
to use them from anywhere on the file system.
+See the same @code{wget} commands below for an example
 @end table
 
 @cartouche
@@ -4770,7 +4777,7 @@ set -e
 #   hlsp_xdf_hst_wfc3ir-60mas_hudf_FILTER_v1_sci.fits
 # To make the script easier to read, a prefix and suffix variable are
 # used to sandwich the filter name into one short line.
-downloaddir=download
+dldir=download
 xdfsuffix=_v1_sci.fits
 xdfprefix=hlsp_xdf_hst_wfc3ir-60mas_hudf_
 xdfurl=http://archive.stsci.edu/pub/hlsp/xdf
@@ -4778,20 +4785,17 @@ xdfurl=http://archive.stsci.edu/pub/hlsp/xdf
 # The file name and full URLs of the input data.
 f105w_in=$xdfprefix"f105w"$xdfsuffix
 f160w_in=$xdfprefix"f160w"$xdfsuffix
-f105w_full=$xdfurl/$f105w_in
-f160w_full=$xdfurl/$f160w_in
+f105w_url=$xdfurl/$f105w_in
+f160w_url=$xdfurl/$f160w_in
 
-# Go into the download directory and download the images there,
-# then come back up to the top running directory.
-if ! [ -d $downloaddir ]; then mkdir $downloaddir; fi
-cd $downloaddir
-if ! [ -f $f105w_in ]; then wget $f105w_full; fi
-if ! [ -f $f160w_in ]; then wget $f160w_full; fi
-cd ..
+# Make sure the download directory exists, and download the images.
+if ! [ -d $dldir    ]; then mkdir $dldir; fi
+if ! [ -f $f105w_in ]; then wget $f105w_url -O $dldir/$f105w_in; fi
+if ! [ -f $f160w_in ]; then wget $f160w_url -O $dldir/$f160w_in; fi
 
 
-# Only work on the deep region
-# ----------------------------
+# Crop out the deep region
+# ------------------------
 #
 # To help in readability, each vertice of the deep/flat field is stored
 # as a separate variable. They are then merged into one variable to
@@ -4808,11 +4812,11 @@ deep_polygon="$vertice1:$vertice2:$vertice3:$vertice4"
 if ! [ -d $flatdir ]; then mkdir $flatdir; fi
 if ! [ -f $f105w_flat ]; then
     astcrop --mode=wcs -h0 --output=$f105w_flat \
-            --polygon=$deep_polygon $downloaddir/$f105w_in
+            --polygon=$deep_polygon $dldir/$f105w_in
 fi
 if ! [ -f $f160w_flat ]; then
     astcrop --mode=wcs -h0 --output=$f160w_flat \
-            --polygon=$deep_polygon $downloaddir/$f160w_in
+            --polygon=$deep_polygon $dldir/$f160w_in
 fi
 @end example