popen pipes fail when cwd is a UNC path

Tim Black

In my recent experience, popen os pipes always fail when cwd is a UNC
path. Can anyone shed any light on this? Although I've seen lots of
UNC path-related problems in this newsgroup, I've not been able to
find anything specifically about os pipes and UNC paths.

Here's a session dump that demonstrates what I'm talking about:

Python 2.3.4 (#53, May 25 2004, 21:17:02) [MSC v.1200 32 bit (Intel)]
on win32
Type "help", "copyright" , "credits" or "license" for more information.

os.getcwd() 'c:\\Python23' f=os.popen("dir "); r=f.read(); print f.close() None os.getcwd() 'c:\\Python23' os.chdir("c:\\" )
os.getcwd() 'c:\\' f=os.popen("dir "); r=f.read(); print f.close() None os.chdir("\\\\T imb\\Python23")
os.getcwd() '\\\\Timb\\Pyth on23' f=os.popen("dir "); r=f.read(); print f.close()

1

As you can see, this last pipe fails. This only happens when cwd is a
UNC path. Please let me know if you have seen this, solved this, know
a nice workaround, etc. as I find this quite annoying.

Thanks,
Tim

Jul 18 '05 #1

Subscribe Reply

3423

Mark Hadfield

Tim Black wrote:

In my recent experience, popen os pipes always fail when cwd is a UNC
path. Can anyone shed any light on this? Although I've seen lots of
UNC path-related problems in this newsgroup, I've not been able to
find anything specifically about os pipes and UNC paths.

It's a problem with the Windows command interpreter (cmd.exe on the NT
family) which gets invoked by popen. To demonstrate this. try cd'ing to
a UNC path. You will get a message like

'\\foo\bar' is an invalid current directory path. UNC paths are not
supported.
--
Mark Hadfield "Ka puwaha te tai nei, Hoea tatou"
m.********@niwa .co.nz
National Institute for Water and Atmospheric Research (NIWA)

Jul 18 '05 #2

Steve Christensen

In article <ch**********@n ewsreader.mailg ate.org>, Mark Hadfield wrote:

Tim Black wrote:
In my recent experience, popen os pipes always fail when cwd is a UNC
path. Can anyone shed any light on this? Although I've seen lots of
UNC path-related problems in this newsgroup, I've not been able to
find anything specifically about os pipes and UNC paths.

It's a problem with the Windows command interpreter (cmd.exe on the NT
family) which gets invoked by popen. To demonstrate this. try cd'ing to
a UNC path. You will get a message like

'\\foo\bar' is an invalid current directory path. UNC paths are not
supported.

It won't be directly applicable to the original problem... But, you can
use 'pushd' on a UNC path. It will temporarily map the UNC path to a
drive letter. When you do a 'popd' it will unmap the drive letter.

-Steve

Jul 18 '05 #3

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