==========
dib-python
==========

Adds a symlink to ``/usr/local/bin/dib-python`` which points at either a
``python2`` or ``python3`` executable as appropriate.

In-chroot scripts should use this as their interpreter
(``#!/usr/local/bin/dib-python``) to make scripts that are compatible
with both ``python2`` and ``python3``.  We can not assume
``/usr/bin/python`` exists, as some platforms have started shipping with
only Python 3.

``DIB_PYTHON`` will be exported as the python interpreter.  You should
use this instead of ``python script.py`` (e.g. ``${DIB_PYTHON}
script.py``).  Note you can also call ``/usr/local/bin/dib-python
script.py`` but in some circumstances, such as creating a ``virtualenv``,
it can create somewhat confusing references to ``dib-python`` that
remain in the built image.

This does not install a python if one does not exist, and instead fails.

This also exports a variable ``DIB_PYTHON_VERSION`` which will either be
'2' or '3' depending on the python version which dib-python points to.


.. note::

  The ``dib-python`` interpreter will be removed in ``cleanup.d``.  It
  is only intended for build scripts.