What is the easiest way to see if a process with a given pid exists in Python?

posix, python

Solution

Instead of os.waitpid, you can also use os.kill with signal 0:

>>> os.kill(8861, 0)
>>> os.kill(12765, 0)
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
OSError: [Errno 3] No such process
>>>

Edit: more expansively:

import errno
import os

def pid_exists(pid):
    try:
        os.kill(pid, 0)
    except OSError, e:
        return e.errno == errno.EPERM
    else:
        return True

This works fine on my Linux box. I haven't verified that "signal 0" is actually Posix, but it's always worked on every Unix variant I've tried.

Problem

In a POSIX system, I want to see if a given process (PID 4356, for example) is running. It would be even better if I could get metadata about that process.

Original source

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