[ python-Bugs-1057048 ] subprocess works poorly on Windows with Python 2.3

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Bugs item #1057048, was opened at 2004-10-29 21:24
Message generated for change (Comment added) made by chas17360
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Category: Python Library
Group: Python 2.4
Status: Closed
Resolution: Works For Me
Priority: 5
Private: No
Submitted By: Russell Owen (reowen)
Assigned to: Nobody/Anonymous (nobody)
Summary: subprocess works poorly on Windows with Python 2.3

Initial Comment:
My understanding was that subprocess.py was supposed to be 
backwards compatible with at least Python 2.3 if not 2.2. Wanting 
subprocess and backwards compatibility, I grabbed the subprocess.py 
from 2.4b1, changed the import if so that win32api was used (since I 
had no _subprocess library!) and found several problems, of which 
this is one (one per bug report):

If the executable has a space in its path name (as is standard on 
Windows) and command-line arguments, things fail miserably:

from subprocess import *
Popen('"C:\\Program Files\\ds9\\xpaget" ds9 mode')

produces an error that C:\Program cannot be run. Clearly the double 
quoting isn't making it through Popen. Note that this runs just fine if 
there are no command line arguments, i.e. this works:

Popen('"C:\\Program Files\\ds9\\xpaget"')

Note that this same bug also exists in os.popen3, so you may have 
inherited it.

This bug does NOT occur on a unix build on MacOS X.

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Comment By: chas17360 (chas17360)
Date: 2006-12-13 13:02

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I may have found a related problem:

The following appears in function list2cmdline():

            elif c == '"':
                # Double backspaces.
                result.append('\\' * len(bs_buf)*2)
                bs_buf = []
                result.append('\\"')

i.e. the character(s) being checked is a double quote, but the comment
states 'Double backspaces'.  The code as it is (using Python25) causes a
problem when trying to perform a Windows XP copy on a file with whitespace
in it's name.  The problem does not occur if the double quote in the code
above is replaced by 2 back ticks.

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Comment By: Russell Owen (reowen)
Date: 2004-11-17 22:03

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I tried to follow up on this and today I cannot get it to fail on my
system. I 
suggest suspending or closing the bug report. If I figure out what was
going 
on and it still seems to be a bug, I'll reopen or file a new report. Sorry
for the 
trouble (and thanks for fixing the problem with opening console windows on

Windows).

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Comment By: Peter Åstrand (astrand)
Date: 2004-11-07 16:18

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I don't have a "c:\program files" directory on my system,
since it's a Swedish version of Windows. I've tested with
"c:\program\internet explorer\iexplore.exe" instead, but
cannot reproduce the problem: Not with subprocess with 2.4
or 2.3, and not with os.popen3 either. For example, I've tried:

w, r, x = os.popen3('"c:\\program\\internet
explorer\iexplore.exe" www.abc.se')

Please test and see if you can reproduce the problem with
Internet Explorer. 

As far as I know, it should be safe to install 2.4b1 without
trashing the 2.3 installation. 

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Comment By: Russell Owen (reowen)
Date: 2004-11-03 19:11

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I am using Windows 2000 Professional. I am not using command.com, at 
least not that I know of. I'm running my program from PythonWin or IDLE 
(most often the former).

Can I safely install 2.4b1 and not trash my 2.3 install? If so, I'll give
it a go. 
(I know this works on Mac and unix, but have no idea how it works on 
Windows).

Another possibility is to test the results at your end by editing 
subprocess.py to toggle that flag that makes win32api be used instead of 
_subprocess. Then launching any app using an explicit path should show the

problem (or not), since they are all in C:\\Program Files\...

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Comment By: Peter Åstrand (astrand)
Date: 2004-10-31 07:05

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Are you running on Windows 9X, or using command.com? 

If you are using shell=False (as in your example),
subprocess doesn't change the argument string in any way: It
is passed directly to CreateProcess. 

Can you confirm that the problem only exists with Python
2.3, and not with 2.4? In that case, it might be a bug in
win32api:s CreateProcess. 

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