Kill a running subprocess call

Question

I'm launching a program with subprocess on Python.

In some cases the program may freeze. This is out of my control. The only thing I can do from the command line it is launched from is CtrlEsc which kills the program quickly.

Is there any way to emulate this with subprocess? I am using subprocess.Popen(cmd, shell=True) to launch the program.

Answer 1

Well, there are a couple of methods on the object returned by subprocess.Popen() which may be of use: Popen.terminate() and Popen.kill(), which send a SIGTERM and SIGKILL respectively.

For example...

import subprocess
import time

process = subprocess.Popen(cmd, shell=True)
time.sleep(5)
process.terminate()

...would terminate the process after five seconds.

Or you can use os.kill() to send other signals, like SIGINT to simulate CTRL-C, with...

import subprocess
import time
import os
import signal

process = subprocess.Popen(cmd, shell=True)
time.sleep(5)
os.kill(process.pid, signal.SIGINT)

Answer 2

Your question is not too clear, but If I assume that you are about to launch a process wich goes to zombie and you want to be able to control that in some state of your script. If this in the case, I propose you the following:

p = subprocess.Popen([cmd_list], shell=False)

This in not really recommanded to pass through the shell. I would suggest you ti use shell=False, this way you risk less an overflow.

# Get the process id & try to terminate it gracefuly
pid = p.pid
p.terminate()

# Check if the process has really terminated & force kill if not.
try:
    os.kill(pid, 0)
    p.kill()
    print "Forced kill"
except OSError, e:
    print "Terminated gracefully"

Answer 3

You can use two signals to kill a running subprocess call i.e., signal.SIGTERM and signal.SIGKILL; for example

import subprocess
import os
import signal
import time
..
process = subprocess.Popen(..)
..
# killing all processes in the group
os.killpg(process.pid, signal.SIGTERM)
time.sleep(2)
if process.poll() is None:  # Force kill if process is still alive
    time.sleep(3)
    os.killpg(process.pid, signal.SIGKILL)

Answer 4

p = subprocess.Popen("echo 'foo' && sleep 60 && echo 'bar'", shell=True)
p.kill()

Check out the docs on the subprocess module for more info: http://docs.python.org/2/library/subprocess.html