Exit a Python process not kill it (via ssh)

Question

I am starting my script locally via:

sudo python run.py remote

This script happens to also open a subprocess (if that matters)

webcam = subprocess.Popen('avconv -f video4linux2 -s 320x240 -r 20 -i /dev/video0 -an -metadata title="OfficeBot" -f flv rtmp://6f7528a4.fme.bambuser.com/b-fme/xxx', shell = True)

I want to know how to terminate this script when I SSH in.

I understand I can do:

sudo pkill -f "python run.py remote"

or use:

ps -f -C python

to find the process ID and kill it that way.

However none of these gracefully kill the process, I want to able to trigger the equilivent of CTRL/CMD C to register an exit command (I do lots of things on shutdown that aren't triggered when the process is simply killed).

Thank you!

Community · Accepted Answer · 2017-05-23 10:25:51Z

3

You should use "signals" for it:

http://docs.python.org/2/library/signal.html

Example:

import signal, os

def handler(signum, frame):
    print 'Signal handler called with signal', signum

signal.signal(signal.SIGINT, handler)
#do your stuff

then in terminal:

kill -INT $PID

or ctrl+c if your script is active in current shell

http://en.wikipedia.org/wiki/Unix_signal

also this might be useful:

How do you create a daemon in Python?

edited May 23, 2017 at 10:25

CommunityBot

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answered May 19, 2013 at 22:24

fsw

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1 Comment

Titan Over a year ago

This works great for the main process, however my subprocess continues to output: def killme(signum, frame): webcam.kill() sys.exit()

Thomas Fenzl · Accepted Answer · 2013-05-19 22:29:19Z

2

You can use signals for communicating with your process. If you want to emulate CTRL-C the signal is SIGINT (which you can raise by kill -INT and process id. You can also modify the behavior for SIGTERM which would make your program shut down cleanly under a broader range of circumstances.

answered May 19, 2013 at 22:29

Thomas Fenzl

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