Bash pipe and SIGTERM

Question

I have a Bash script "script" which roughly looks like:

#!/bin/bash

cmd1 | cmd2 | cmd3

When I do a kill script (or more precisely when I do a 'stop script' in supervisord), not all cmd* are killed. How can I make sure they are terminated along with the script that spawned them?

Answer 1

Supervisord has stopasgroup and killasgroup options (false by default) which determine whether to propagate SIGTERM/SIGKILL signals to child processes.

[program:script]
command=script
stopasgroup=true
killasgroup=true

(These config variables are both documented at http://supervisord.org/configuration.html.)

Answer 2

Not sure about how using supervisord, but with pkill you can use the -P option to kill from a parent process down to all the children. Here's the process trees (starting from my running ssh daemon).

$ pstree -a -p 1792
sshd,1792
  ├─sshd,27150
  │   └─sshd,27153
  │       └─zsh,27154
  │           └─test.sh,27325 ./test.sh
  │               └─cat,27326
  └─sshd,27182
      └─sshd,27184
          └─zsh,27185
              └─pstree,27357 -a -p 1792

In one session I have a script test.sh with pid 27325, and in the other I'm running the command pstree -a -p 1792 (because sshd had pid 1792)

And after I run pkill -TERM -P 27325:

$ pstree -a -p 1792   
sshd,1792
  ├─sshd,27150
  │   └─sshd,27153
  │       └─zsh,27154
  └─sshd,27182
      └─sshd,27184
           └─zsh,27185
              └─pstree,27387 -a -p 1792

This answer was essentially rephrased from the this other answer on stackoverflow: https://stackoverflow.com/a/392155/263969