I found a problem in subprocess.Popen's _execute_child() method for POSIX, where the child process will close the fds for sys.stdout and/or sys.stderr if I use those as stdout and/or stderr when creating a subprocess.Popen object.
Here's what I saw by default when using the 2.4.4 version of Python...
% ./python
Python 2.4.4 (#1, Nov 28 2006, 14:08:29)
[GCC 3.4.6 20060404 (Red Hat 3.4.6-3)] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>>
>>> import sys, subprocess
>>> uname = subprocess.Popen('uname -a', shell=True, stdout=sys.stdout)
>>> uname: write error: Bad file descriptor
>>>
Then, I updated subprocess.py and made the following changes...
% diff subprocess.py subprocess.py.orig
924c924
< # fd more than once and don't close sys.stdout or sys.stderr.
---
> # fd more than once.
927c927
< if c2pwrite and c2pwrite not in (p2cread, sys.stdout.fileno(), sys.stderr.fileno()):
---
> if c2pwrite and c2pwrite not in (p2cread,):
929c929
< if errwrite and errwrite not in (p2cread, c2pwrite, sys.stdout.fileno(), sys.stderr.fileno()):
---
> if errwrite and errwrite not in (p2cread, c2pwrite):
After that, I saw the following...
% ./python
Python 2.4.4 (#1, Nov 28 2006, 14:08:29)
[GCC 3.4.6 20060404 (Red Hat 3.4.6-3)] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>>
>>> import sys, subprocess
>>> uname = subprocess.Popen('uname -a', shell=True, stdout=sys.stdout)
>>> Linux schnauzer 2.6.9-42.0.2.ELsmp #1 SMP Thu Aug 17 18:00:32 EDT 2006 i686 i686 i386 GNU/Linux
>>>
I'm attaching the modified version of subprocess.py. Please consider adding this fix to future versions of Python. Thanks!
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