linuxbashshell

call a function (cleanup handler) at the termination of shell script

Is it possible to call a function at the time of termination of a shell script. I have some daemon processes running in the background whose process id is stored inside an array. At the time of termination (for whatsoever reason) I want a cleanup function/handler to get called which kills all the daemon processes.

# want the below function to be called when the shell script terminates for whatsoever reason
purge () {
  for pid in ${pids[@]}; do
    kill -9 $pid
  done
}

./daemon1 > a.txt 2>&1 & pids+=($!)
./daemon2 > b.txt 2>&1 & pids+=($!)
./daemon3 > c.txt 2>&1 & pids+=($!)

for pid in ${pids[@]}; do
  echo "process: $pid"
done
Solution

  • You just need to do:

    #!/bin/bash

purge () { ... }

trap purge EXIT

    From man bash about trap builtin:

    If a sigspec is EXIT (0) the command arg is executed on exit from the shell

    Check:

    LESS='+/^ +trap.*sigspec' man bash

    With this proper solution, regardless the exit, the function will be executed.