Bash : Poll for a file creation and terminate if exits

Question

I'm trying to write a script that traps a exit signal and terminate. Instead of using the usual bash trap method, I would like to monitor a file creation every 10 seconds and cleanup some stuff before termination.

Here is what I have tried:

poll_time=10 // poll every 10 seconds
((term_time=$SECONDS+240)) // monitor until 4 min from current script time exec

while (( $SECONDS < $term_time)) do
    if [[ -r $some_path/file.txt ]]; then
        cleanup_function
        exit
fi
sleep ${poll_time}
done

//if file doesnt exit continue with below code
//blah blah blah ....

Is there a better way to do this? will above lines of code work?

Answer 1

inotifywait from inotify-tools is what you need (to look at at least). Line like this will do the same trick your script is intended to do:

inotifywait -e create --timeout 240 "${some_path}/file.txt" && { cleanup_function; exit ; }

with the difference inotifywait works in event-based manner, so no polling or sleeping required.