[Python-Dev] Issue 13524: subprocess on Windows

Tim Golden mail at timgolden.me.uk
Mon Dec 5 10:01:17 CET 2011

On 05/12/2011 08:10, "Martin v. Löwis" wrote:
> I agree with Nick that we shouldn't do anything except perhaps
> for documentation changes. There are many other environment variables
> whose absence could also cause failures to run the executable,
> such as PATH, LD_LIBRARY_PATH, etc. Even not passing DISPLAY may
> cause the subprocess to fail starting.
> IOW, users should "normally" pass all environment variables, and
> only augment it with any specific additions and deletions that
> they know are needed for the subprocess. If a user deliberately
> passes a small set of environment variables (e.g. none), we must
> assume that it was deliberate, and that any resulting failures
> are desired. People do such stuff for security reasons, and
> side-stepping their enforcement is not appropriate for Python
> to do.

Having slept on this I must confess that this is pretty much the
conclusion I'd come to: we can't do anything in code which is
guaranteed to be correct in every case. The best we can do is
document. And, as Martin Packman pointed out (and I had missed),
this particular condition is already documented, at least enough
to point a user to.

We could probably do with a HOWTO (or blog post or whatever) on using
subprocess on Windows, not least because a fair amount of the docs
are Unix-centric and actually very slightly confusing for naive
Windows-based developers.

I think my proposal now is: do nothing. I'm aware that Nick Coghlan
has been making fairly extensive changes to the subprocess docs
recently and I don't I can propose anything on this matter which
amounts to more than shuffling the pieces around.


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