pex is a library for generating .pex (Python EXecutable) files which are executable Python environments in the spirit of virtualenvs. pex is an expansion upon the ideas outlined in PEP 441 and makes the deployment of Python applications as simple as cp. pex files may even include multiple platform-specific Python distributions, meaning that a single pex file can be portable across Linux and OS X.

pex files can be built using the pex tool. Build systems such as Pants and Buck also support building .pex files directly.

Still unsure about what pex does or how it works? Watch this quick lightning talk: WTF is PEX?.

pex is licensed under the Apache2 license.

To install pex, simply

$ pip install pex

You can also build pex in a git clone using tox:

$ tox -e package
$ cp dist/pex ~/bin

This builds a pex binary in dist/pex that can be copied onto your $PATH. The advantage to this approach is that it keeps your Python environment as empty as possible and is more in-line with what pex does philosophically.

Launch an interpreter with requests and flask in the environment:

$ pex -r requests -r flask

Run webserver.py in an environment containing flask and the setup.py package in the current working directory:

$ pex -r flask -s . -- webserver.py

Launch Sphinx in an ephemeral pex environment using the Sphinx entry point sphinx:main:

$ pex -r sphinx -e sphinx:main -- --help

Build a standalone pex binary into pex.pex:

$ pex -r pex -e pex.bin.pex:main -o pex.pex

Build a standalone pex binary but invoked using a specific Python version:

$ pex -r pex -e pex.bin.pex:main --python=pypy -o pypy-pex.pex

Most pex options compose well with one another, so the above commands can be mixed and matched.

More documentation about pex, building .pex files, and how .pex files work is available at http://pex.rtfd.org.

pex uses tox for test and development automation. To run the test suite, just invoke tox:

$ tox

To generate a coverage report (with more substantial integration tests):

$ tox -e coverage

To check style and sort ordering:

$ tox -e style,isort-check

To generate and open local sphinx documentation:

$ tox -e docs

To run the 'pex' tool from source (for 3.4, use 'py34-run'):

$ tox -e py27-run -- <cmdline>

To contribute, follow these instructions: http://pantsbuild.github.io/howto_contribute.html