[Python-Dev] Issue 13524: subprocess on Windows (original) (raw)

Tim Golden mail at timgolden.me.uk
Sun Dec 4 13:20:11 CET 2011

On 04/12/2011 11:42, Nick Coghlan wrote:

There's actually two questions to be answered: 1. What should we do in 3.2 and 2.7? 2. Should we do anything more in 3.3?

Agreed.

1. Unset 'SystemRoot' in a windows shell 2. Run the test suite and observe the scale of the breakage

Sorry; something I should have highlighted in the earlier post. Behaviour varies between Windows versions. On WinXP, if you unset SystemRoot in a cmd shell, you won't be able to run the test suite: Python won't even start up. On Win7 Python will start but, eg, the random module will fail.

This is actually a separate issue: how much of Python will work without a valid SystemRoot. The OP's issue was that if you use subprocess to start an arbitrary process (you get the same problem if you try "notepad.exe") and pass it an env block without a valid SystemRoot then that process will likely fail to start up. And it won't be obvious why.

The case where someone tries to run Python (in general) without a valid SystemRoot is a tiny cornercase and you'd be quite right to push that back and say "Don't do that". I don't believe we have to test for it or add code to work around it.

While I put the idea forward, I agree that an exception is more likely than not to break existing code. I just can't see any clear alternative, apart from option 1: we do nothing.

TJG

More information about the Python-Dev mailing list