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Run child process with stdout and result on Win32?

Duncan Booth me at privacy.net
Mon Jun 7 11:01:14 EDT 2004 
Dave Sellars <dave at didnt.freeserve.co.uk> wrote in 
news:40c47dda$0$17461$afc38c87 at news.easynet.co.uk:

> Is there really no way to run a sub-process, gather its stdout/stderr, 
> and collect the return-code, on Win32???
> But that's what the docs say...
> 
> > These methods do not make it possible to retrieve the return code
> > from the child processes. The only way to control the input and
> > output streams and also retrieve the return codes is to use the
> > Popen3 and Popen4 classes from the popen2 module; these are only
> > available on Unix.
> 
> Surely not!?!?
> 
>    Dave.
> 
> 

Bizarrely, the return code is returned as the result of the *last* call to 
the close method on any of the file handles returned. i.e. You must close 
all of stdin, stdout and stderr handles returned (usually after 
reading/writing), and the last one you close will return a numeric exit 
code if the command returned a non-zero exit code. If the command returned 
a 0 exit code then the final close returns None.

>>> from popen2 import popen2
>>> fout, fin = popen2("dir c:\\temp")
>>> print fout.close(), fin.close()
None None
>>> fout, fin = popen2("dir c:\\xxx")
>>> print fout.close(), fin.close()
None 1
>>> fout, fin = popen2("dir c:\\xxx")
>>> print fin.close(), fout.close()
None 1
>>> 

So far as I can see, the documentation omits to mention this little fact (I 
read the source).
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