Question

I’m working on a shell script that does certain changes on a txt file only if it does exist, however this test loop doesn’t work, I wonder why?
Thank you!

while [ ! -f /tmp/list.txt ] ;
do
      sleep 2
done

Answer 1

When you say “doesn’t work”, how do you know it doesn’t work?

You might try to figure out if the file actually exists by adding:

while [ ! -f /tmp/list.txt ]
do
  sleep 2 # or less like 0.2
done
ls -l /tmp/list.txt

You might also make sure that you’re using a Bash (or related) shell by typing ‘echo $SHELL’. I think that CSH and TCSH use a slightly different semantic for this loop.