docs:bash:bash_loop [hartungdesign.net wiki]

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====== bash loop ======

===== while read =====
  * :-) This code WILL work on filenames with spaces
  * taken from http://www.macgeekery.com/tips/cli/handling_filenames_with_spaces_in_bash
  * quote //"For splits items on a space, regardless of if they’re quoted (if they’re stored in a variable). However, the read command does not."//<code>
ls -1L *.tiff | while read file;do
du -h -d 0 "${file}"
done
</code>
  * another example:<code>
ls -1L *.tiff | while read file;do
tiff2pdf -p letter -o "${file}".pdf "${file}"
done
</code>
  * use a file containing a list of filenames for a copy operation:<code>
cat fileswithnotesbug.txt | while read file;do
cp "${file}" /cygdrive/n/Receive/CIA/nsf/ClmTest/;
done
</code>


===== for =====
  * :!: This code will NOT work on filenames with spaces unless the IFS variable is set in bash (see man bash for more details)
  * note that the symbols used are backticks, not single quotes (backtick is the key left of 1)
<code>
for file in `ls -1L`;do
du -h -d 0 $file
done
</code>

Another example showing how to set up new folders with git repo's:
<code>
$ mkdir ~/git
$ cd ~/git
$ for i in a b c d
do
        mkdir $i
        cd $i
        git init
        echo "module $i" > $i.txt
        git add $i.txt
        git commit -m "Initial commit, submodule $i"
        cd ..
done
</code>

original url: http://www.kernel.org/pub/software/scm/git/docs/user-manual.html#submodules

===== other notes =====
  * http://www.linuxquestions.org/questions/showthread.php?t=453181
<code>
Props to this post, this is a very elegant solution to weird characters in filenames:
http://www.macgeekery.com/tips/cli/h...spaces_in_bash
Code:

find . -type f -print | while read i; do touch "${i}"; done


    That will fail if any filenames have leading or trailing spaces or end in a backslash. (Not to mention filenames containing newlines.)

Quote:
'for' splits on spaces. Period. Regardless of quoting.


    It does not split on spaces if there is no space in the value of $IFS.

Quote:
'read' does not.


    It does if more than one variable is given as an argument (and IFS contains a space).
</code>