Making sure a Python script with subprocesses dies on SIGINT

Question

I\'ve got a command that I\'m wrapping in script and spawning from a Python script using subprocess.Popen. I\'m trying to make sure it dies if the

Answer 1

The subprocess is by default part of the same process group, and only one can control and receive signals from the terminal, so there are a couple of different solutions.

Setting stdin as a PIPE (in contrast to inheriting from the parent process), this will prevent the child process from receiving signals associated to it.

subprocess.Popen(cmd, stdout=subprocess.PIPE, stderr=subprocess.PIPE, stdin=subprocess.PIPE)

Detaching from the parent process group, the child will no longer receive signals

def preexec_function():
    os.setpgrp()

subprocess.Popen(cmd, stdout=subprocess.PIPE, stderr=subprocess.PIPE, preexec_fn=preexec_function)

Explicitly ignoring signals in the child process

def preexec_function():
    signal.signal(signal.SIGINT, signal.SIG_IGN)

subprocess.Popen(cmd, stdout=subprocess.PIPE, stderr=subprocess.PIPE, preexec_fn=preexec_function)

This might however be overwritten by the child process.