subprocess -popen - reading stdout from child - hangs
gregpinero at gmail.com
gregpinero at gmail.com
Sun Sep 23 00:16:43 EDT 2007
On Sep 22, 11:28 pm, "gregpin... at gmail.com" <gregpin... at gmail.com>
wrote:
> Let's say I have this Python file called loop.py:
>
> import sys
> print 'hi'
> sys.stdout.flush()
> while 1:
> pass
>
> And I want to call it from another Python process and read the value
> 'hi'. How would I do it?
>
> So far I have tried this:
>
> >>> proc = subprocess.Popen('python /home/chiefinnovator/loop.py',shell=True,stdin=subprocess.PIPE,stdout=subprocess.PIPE)
> >>> proc.stdout.read()
>
> But it just hangs at read()
>
> proc.communicate() also just hangs. What am I doing wrong? Please
> advise.
Well, using this subclass of subprocess.Popen fixes the problem
(http://aspn.activestate.com/ASPN/Cookbook/Python/Recipe/440554)
I don't understand how it works though. Would anyone mind
explaining? I'm thinking there's something fundamental about Unix
processes I'm not understanding.
-Greg
More information about the Python-list
mailing list