Let bash script run all the time but be abortable

Question

I have a bash script like this:

#!/bin/bash
startsomeservice &
echo $! > service.pid

while true; do
    # dosomething in repeat all the time here
    foo bar
    sleep 5
done

# cleanup stuff on abort here
rm tmpfiles
kill $(cat service.pid)

the problem of this script is, that i cant abort it. If i press ctrl+c i just go into the next loop... Is it possible to run a script like this but to have it abortable?

Answer 1

Since you are executing the script with Bash, you can do the following:

#!/bin/bash

startsomeservice &
echo $! > service.pid

finish()
{
    rm tmpfiles
    kill $(cat service.pid)
    exit
}
trap finish SIGINT

while :; do
    foo bar
    sleep 5
done

Please note that this behaviour is Bash specific, if you run it with Dash, for instance, you will see two differences:

1. You cannot capture SIGINT
2. The interrupt signal will break the shell loop.

Note also that you will break a shell loop with a single C-c when you execute the loop directly from an interactive prompt, even if you're running Bash. See this detailed discussion about SIGINT handling from shells.