shell script to spawn processes, terminate children on SIGTERM

bash scripting sh long-running-processes sigterm
itsadok picture itsadok · Jun 10, 2009 · Viewed 20.1k times · Source

I want to write a shell script that spawns several long-running processes in the background, then hangs around. Upon receiving SIGTERM, I want all the subprocesses to terminate as well.

Basically, I want a "master process".

Here's what I got so far:

#!/bin/sh

sleep 600 &
PID1="$!"

sleep 600 &
PID2="$!"

# supposedly this should kill the child processes on SIGTERM. 
trap "kill $PID1 $PID2" SIGTERM 

wait

The above script fails with trap: 10: SIGTERM: bad trap.

Edit: I'm using Ubuntu 9.04

Answer

tokland picture tokland · Jan 31, 2010

This works for me:

trap "trap - SIGTERM && kill -- -$$" SIGINT SIGTERM EXIT

  • kill -- -$$ sends a SIGTERM to the whole process group, thus killing also descendants.

  • Specifying signal EXIT is useful when using set -e (more details here).

Related questions

How can I declare and use Boolean variables in a shell script?

I tried to declare a Boolean variable in a shell script using the following syntax: variable=$false variable=$true Is this correct? Also, if I wanted to update that variable would I use the same syntax? Finally, is the following …

Read More
How to get a password from a shell script without echoing

I have a script that automates a process that needs access to a password protected system. The system is accessed via a command-line program that accepts the user password as an argument. I would like to prompt the user to …

Read More
Deleting lines from one file which are in another file

I have a file f1: line1 line2 line3 line4 .. .. I want to delete all the lines which are in another file f2: line2 line8 .. .. I tried something with cat and sed, which wasn't even close to what I intended. How …

Read More