1

I have the following simple bash script:

for VAR
do
   echo file found $VAR
done

what I want is for it to print all the files that contain the extension .png. I would expect the following command line to work, but it does not. Why?

ls *.png | myscript.sh

or

./myscript.sh < `ls *.png`
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3
  • Looping on the contents of a variable is not the same as piping the results of a command to another command. The results of ls will be available to myscript.sh as its standard input, not as a variable. Commented Mar 7, 2012 at 18:37
  • how would you modify my script to loop the standard input? Commented Mar 7, 2012 at 18:44
  • Second calling syntax is wrong: it redirects content of the first file found to your script. Commented Mar 7, 2012 at 18:48

2 Answers 2

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3

You need xargs:

ls *.png | xargs myscript.sh

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4 Comments

your command does not work for me. Am I missing something here?
try [..] |xargs ./myscript.sh, if the scritpt is not in your PATH.
This works because xargs passes its stdin to the given command as command line parameters.
The non-obvious part for me was parsing of arguments with "for".
3

To read standard input script should look like:

while read line; do
  echo file found $line
done
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1 Comment

Edited to remove the parentheses: original answer won't work because the parentheses will cause the read command to occur in a subshell, thus the variable will disappear when the subshell exits.

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