While loop to test if a file exists in bash

Solution 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.

Solution 2:

If you are on linux and have inotify-tools installed, you can do this:

file=/tmp/list.txt
while [ ! -f "$file" ]
do
    inotifywait -qqt 2 -e create -e moved_to "$(dirname $file)"
done

This reduces the delay introduced by sleep while still polling every "x" seconds. You can add more events if you anticipate that they are needed.

Solution 3:

I had the same problem, put the ! outside the brackets;

while ! [ -f /tmp/list.txt ];
do
    echo "#"
    sleep 1
done

Also, if you add an echo inside the loop it will tell you if you are getting into the loop or not.