Bash SIGUSR1 loop script

Question

I started learning bash 3-4 days ago and I have a task to do that I'm having hard time completing. I need to make a script, running a loop which after being signaled SIGUSR1, it should print the process id and exit. I'd be very thankful if i receive some help.

Answer 1

You'd do it this way:

#!/usr/bin/env bash

# Our USR1 signal handler
usr1_trap(){
    printf 'Here is the PID: %d\nExiting right-now!\n' $$
    exit
}

# Register USR1 signal handler
trap usr1_trap USR1

printf 'Run this to stop me:\nkill -USR1 %d\n' $$

# Wait in background, not consuming CPU
while :; do
   sleep 9223372036854775807 & # int max (2^63 - 1)
   wait $!
done