How to terminate a python subprocess launched with shell=True

Question

I'm launching a subprocess with the following command:

p = subprocess.Popen(cmd, stdout=subprocess.PIPE, shell=True)

However, when I try to kill using:

p.terminate()

or

p.kill()

The command keeps running in the background, so I was wondering how can I actually terminate the process.

Note that when I run the command with:

p = subprocess.Popen(cmd.split(), stdout=subprocess.PIPE)

It does terminate successfully when issuing the p.terminate().

What does your cmd look like? It might contain a command which triggers several processes to be started. So it’s not clear which process you talk about. — Robert Siemer, Nov 27, 2014 at 15:47
related: Python: how to kill child process(es) when parent dies? — jfs, Jan 23, 2015 at 15:08

score 501 · Accepted Answer · 2011-01-25T09:07:49

Use a process group so as to enable sending a signal to all the process in the groups. For that, you should attach a session id to the parent process of the spawned/child processes, which is a shell in your case. This will make it the group leader of the processes. So now, when a signal is sent to the process group leader, it's transmitted to all of the child processes of this group.

Here's the code:

import os
import signal
import subprocess

# The os.setsid() is passed in the argument preexec_fn so
# it's run after the fork() and before  exec() to run the shell.
pro = subprocess.Popen(cmd, stdout=subprocess.PIPE, 
                       shell=True, preexec_fn=os.setsid) 

os.killpg(os.getpgid(pro.pid), signal.SIGTERM)  # Send the signal to all the process groups

靠悲無言

2024年11月7日星期四

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