How to check if there exists a process with a given pid in Python?

Question

Is there a way to check to see if a pid corresponds to a valid process? I'm getting a pid from a different source other than from os.getpid() and I need to check to see if a process with that pid doesn't exist on the machine.

I need it to be available in Unix and Windows. I'm also checking to see if the PID is NOT in use.

Answer 1

Sending signal 0 to a pid will raise an OSError exception if the pid is not running, and do nothing otherwise.

import os

def check_pid(pid):        
    """ Check For the existence of a unix pid. """
    try:
        os.kill(pid, 0)
    except OSError:
        return False
    else:
        return True