Speno's Pythonic Avocado 4.2.2004


Popen5: useful!

I've been playing with Peter Astrand's Popen5 module lately. It's really nice and I hope that it will be accepted into Python's standard library eventually via PEP 324 .

I like this module because it allows nice and easy control over child processes. I get full control of the child's stdin, stdout, and stderr without having to do the dup dance (which I'd always have to lookup before this). And I can make an easy timeout without having to use SIGALRM.

I especially appreciate Popen5 in light of having spent way too much time tring to get a simple return value out of Twisted's utils.getProcessValue() last weekend. But that was mostly my fault. Smiley

Here's an example of using Popen5:

import popen5 import time import os import signal def main(): wait_time = 5 # seconds args = ['/sbin/ping', '-i', '10', 'localhost'] outf = open('ping.out', 'w+') errf = open('ping.err', 'w+') ping = popen5.Popen(args, stdout=outf, stderr=errf) print 'ping started with pid ', ping.pid time_done = time.time() + wait_time while ping.poll() == -1: if time.time() > time_done: print 'bored now!' os.kill(ping.pid, signal.SIGINT) time.sleep(1) os.waitpid(ping.pid, os.WNOHANG) break else: time.sleep(1) for f in [outf, errf]: f.seek(0) output = f.read() if output: print 'Contents of %s:' % f.name print output if __name__ == '__main__': main()

Take care.

P.S. Thanks to everyone who's left comments here. I'm learning a lot, and feel more like a member of the global Python community now. Since I won't make it to either PyCon or OSCON this year, I'm glad I have this.

This post references topics: python
posted at 23:41:36    #    comment []    trackback []
February 2004
2 3 4 5 6 7 8

One python programmer's search for understanding and avocados. This isn't personal, only pythonic.

XML-Image Letterimage

© 2004-2005, John P. Speno