Attached is a patch that add "pipe" command to the "subprocess" module.

pipe(["ls"], ["grep", "test_"]) will return the output of 
"ls | grep test_".

Not sure about the name, maybe "chain" will be better?

Hello,

I was searching for a bug in subprocess
module when I saw your patch.

I was implementing the exact same functionality
and mixed some of your ideas in what I use now,
which is attached...

Feel free to use it

Here's a clean version with doc & test

enjoy !

- Added "shut pylint up" comment for ** keyword expansion
- Added Copyright & license header

Vincent,
GPL licenced code is incompatible with the inclusion into python.
And if I am correct, you should sign a contributor agreement. Then the
licence text is not necessary.

On Mon, Sep 1, 2008 at 5:13 PM, Amaury Forgeot d'Arc
<report@bugs.python.org> wrote:
> Amaury Forgeot d'Arc <amauryfa@gmail.com> added the comment:
>
> Vincent,
> GPL licenced code is incompatible with the inclusion into python.
> And if I am correct, you should sign a contributor agreement. Then the
> licence text is not necessary.

This is not a patch against python, this is a standalone script, just
implementing the same functionality as the original bug report in a
slightly different way...

But thanks for the input anyways.

If this functionality is really interesting people and agreed to be integrated
into upstream subprocess module, I can rework it the right way, or work
from the original patch from the bug report.

I've written a package which can do this with arbitrary redirection in all subcommands (and some more).

You can, for example, do this:

    >>> Pipe(Sh('echo -n foo >&2', {2: 1}), Sh('cat; echo ERROR >&2', {2: os.devnull})).capture(1).read()
    'foo'

The package is at: http://github.com/aht/pc.py

pipe.patch looks interesting to me.  I would replace **kwargs with a keyword-only argument named stderr, since that’s the only key used.  This requires more tests and docs.

I think this would be more useful if you could pass an optional input string (as in communicate()) and if it returned a (stdout, stderr) tuple. Or perhaps even a (return code, stdout, stderr) tuple; alternately, non-zero return codes could raise an exception.