using subprocess for non-terminating command

[zacherates]

> How should I handle these kind of commands (ping 127.0.0.1) with
> subprocess module. I am using subprocess, instead of os.system because
> at anypoint in time, I need access to stdout and stderr of execution.

Ping, for one, allows you to set an upper bound on how long it runs
(the -c option).  This is probably the cleanest approach if it's
available.

You can also send the subprocess signals if you need it to exit
(although, this is a unix thing so I'm not sure how portable it is).
You could emulate having a timeout on child.stdout.read by registering
a callback with Timer to kill the child.

Cheers,
   Aaron