How to kill a process started using os.system() in python3

benalex · 02-27-2018, 07:27 AM

Hi All,

I'm using python3 and has written code which uses
os.system() to launch a command line utility on Linux Ubuntu 14.0 PC.

Actually if I run this utility on Ubuntu command line and I want to stop running, it says press Ctrl + C. By pressing Ctrl+C the utility stops and command prompt will be available.
Now, after launching this utility from python code and I want to stop it after running for 5 minutes, how do I kill this process ?

Please help me.

Ztcoracat · 02-28-2018, 12:22 AM

Hi & Welcome to LQ.-

If you just want to kill the python interpeter try here:

https://stackoverflow.com/questions/...m-the-terminal

HTH

NevemTeve · 02-28-2018, 01:41 AM

@OP: You cannot, os.system won't return to you until the external program has terminated.
Maybe you could use subprocess.popen to get more control over the child-process.

teckk · 02-28-2018, 11:24 AM

Run process for 10 seconds and quit.

Code:

import time, multiprocessing

def test():
    for i in range(1, 1000000):
        print (i) #Simulated process
        time.sleep(.2)
        
a = multiprocessing.Process(target=test, name="Test")
a.start()
time.sleep(10)
a.terminate()
a.join()

benalex · 03-01-2018, 10:32 AM

Quote:

Originally Posted by teckk

Run process for 10 seconds and quit.

Code:

import time, multiprocessing

def test():
    for i in range(1, 1000000):
        print (i) #Simulated process
        time.sleep(.2)
        
a = multiprocessing.Process(target=test, name="Test")
a.start()
time.sleep(10)
a.terminate()
a.join()

Hi,

Actually I want to invoke a linux command line utility and to kill that I have to send a Ctrl + C command. How can I accomplish this in python using multiprocess or using subprocess ?

-ben

NevemTeve · 03-01-2018, 12:38 PM

Well, I mentioned 'popen'. Have you tried to use it in your program?

teckk · 03-01-2018, 12:47 PM

That was an example @benalex. Make a little effort.

Code:

#subprocess.Popen for 5 seconds, then quit

import time, subprocess

a = subprocess.Popen("exec " + '$TERM', stdout=subprocess.PIPE, shell=True)

time.sleep(5)
subprocess.Popen.kill(a)

Edit:
Actually that could be shortened.
Another example.

Code:

#subprocess.Popen multiple processes for x seconds, then quit

import time, subprocess

a = subprocess.Popen('xterm -bg red', shell=True)
b = subprocess.Popen('xterm -bg blue', shell=True)
c = subprocess.Popen('xterm -bg green', shell=True)

time.sleep(5)
subprocess.Popen.kill(a)
time.sleep(2)
subprocess.Popen.kill(b)
time.sleep(2)
subprocess.Popen.kill(c)

benalex · 03-02-2018, 11:15 AM

Quote:

Originally Posted by teckk

That was an example @benalex. Make a little effort.

Code:

#subprocess.Popen for 5 seconds, then quit

import time, subprocess

a = subprocess.Popen("exec " + '$TERM', stdout=subprocess.PIPE, shell=True)

time.sleep(5)
subprocess.Popen.kill(a)

Edit:
Actually that could be shortened.
Another example.

Code:

#subprocess.Popen multiple processes for x seconds, then quit

import time, subprocess

a = subprocess.Popen('xterm -bg red', shell=True)
b = subprocess.Popen('xterm -bg blue', shell=True)
c = subprocess.Popen('xterm -bg green', shell=True)

time.sleep(5)
subprocess.Popen.kill(a)
time.sleep(2)
subprocess.Popen.kill(b)
time.sleep(2)
subprocess.Popen.kill(c)

Hi,

I tried all but after that when I checked "ps -aef" I could see the task is
alive in background. So I added sudo killall <myprocess> in my python code.
This killed the utility which I invoked using subprocess.Popen()

I tried opening emacs using p1 = subprocess.Popen('emacs &', shell=True)
After that if i kill using subprocess.Popen.kill(p1), it doesn't kill the
process.

How to kill this process ?

-ben

teckk · 03-02-2018, 12:41 PM

Open up top or htop and look at what you are doing.

Code:

p1 = subprocess.Popen('emacs &', shell=True)

You spawned another shell.

Code:

import os, signal, subprocess, time

a = subprocess.Popen('xterm &', shell=True, preexec_fn=os.setsid)

time.sleep(5)
                       
os.killpg(os.getpgid(a.pid), signal.SIGTERM)

teckk · 03-02-2018, 01:06 PM

While in python shell

Code:

>>>import os
>>>import signal
>>>import subprocess
>>>help(os)
>>>help(signal)
>>>help(subprocess)

Use the / to search. n and shift+n for next-last.

Sefyir · 03-02-2018, 08:40 PM

Quote:

os.system() to launch a command line utility on Linux Ubuntu 14.0 PC.

Actually if I run this utility on Ubuntu command line and I want to stop running, it says press Ctrl + C

What is this utility?

This may be useful, the question states the linux version works fine
https://stackoverflow.com/questions/...cts-on-windows

NevemTeve · 03-06-2018, 01:48 AM

ping(8)

pan64 · 03-06-2018, 02:56 AM

you must not use & with popen, just

Code:

p1 = subprocess.Popen('emacs', shell=False)
subprocess.Popen.kill(p1)

& will produce an additional process (shell=True too), therefore you will not (be able to) find the process itself easily (and therefore you will kill probably its parent)