ANN: Version 0.1.5 of sarge (a subprocess wrapper library) has been released.

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Vinay Sajip

Jun 18, 2018, 7:17:18 AM6/18/18
to Python Users, Python Announce, Sarge
Version 0.1.5 of Sarge, a cross-platform library which wraps the subprocess
module in the standard library, has been released.

What changed?

- Fixed #37: Instead of an OSError with a "no such file or directory" message,
  a ValueError is raised with a more informative "Command not found" message.

- Fixed #38: Replaced ``async`` keyword argument with ``async_``, as ``async``
  has become a keyword in Python 3.7.

- Fixed #39: Updated tutorial example on progress monitoring.

What does Sarge do?

Sarge tries to make interfacing with external programs from your
Python applications easier than just using subprocess alone.

Sarge offers the following features:

* A simple way to run command lines which allows a rich subset of Bash-
style shell command syntax, but parsed and run by sarge so that you
can run on Windows without cygwin (subject to having those commands

>>> from sarge import capture_stdout
>>> p = capture_stdout('echo foo | cat; echo bar')
>>> for line in p.stdout: print(repr(line))

* The ability to format shell commands with placeholders, such that
variables are quoted to prevent shell injection attacks.

* The ability to capture output streams without requiring you to
program your own threads. You just use a Capture object and then you
can read from it as and when you want.

* The ability to look for patterns in captured output and to interact
accordingly with the child process.

Advantages over subprocess

Sarge offers the following benefits compared to using subprocess:

* The API is very simple.

* It's easier to use command pipelines - using subprocess out of the
box often leads to deadlocks because pipe buffers get filled up.

* It would be nice to use Bash-style pipe syntax on Windows, but
Windows shells don't support some of the syntax which is useful, like
&&, ||, |& and so on. Sarge gives you that functionality on Windows,
without cygwin.

* Sometimes, subprocess.Popen.communicate() is not flexible enough for
one's needs - for example, when one needs to process output a line at
a time without buffering the entire output in memory.

* It's desirable to avoid shell injection problems by having the
ability to quote command arguments safely.

* subprocess allows you to let stderr be the same as stdout, but not
the other way around - and sometimes, you need to do that.

Python version and platform compatibility

Sarge is intended to be used on any Python version >= 2.6 and is
tested on Python versions 2.6, 2.7, 3.3, 3.4, 3.5, 3.6 and 3.7 on Linux,
Windows, and Mac OS X (not all versions are tested on all platforms,
but sarge is expected to work correctly on all these versions on all
these platforms).

Finding out more

You can read the documentation at

There's a lot more information, with examples, than I can put into
this post.

You can install Sarge using "pip install sarge" to try it out. The
project is hosted on BitBucket at

And you can leave feedback on the issue tracker there.

I hope you find Sarge useful!


Vinay Sajip

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