
``site`` --- Site-specific configuration hook
*********************************************

**Source code:** Lib/site.py

======================================================================

**This module is automatically imported during initialization.** The
automatic import can be suppressed using the interpreter's *-S*
option.

Importing this module will append site-specific paths to the module
search path and add a few builtins.

It starts by constructing up to four directories from a head and a
tail part. For the head part, it uses ``sys.prefix`` and
``sys.exec_prefix``; empty heads are skipped.  For the tail part, it
uses the empty string and then ``lib/site-packages`` (on Windows) or
``lib/python|version|/site-packages`` and then ``lib/site-python`` (on
Unix and Macintosh).  For each of the distinct head-tail combinations,
it sees if it refers to an existing directory, and if so, adds it to
``sys.path`` and also inspects the newly added path for configuration
files.

A path configuration file is a file whose name has the form
``*name*.pth`` and exists in one of the four directories mentioned
above; its contents are additional items (one per line) to be added to
``sys.path``.  Non-existing items are never added to ``sys.path``, and
no check is made that the item refers to a directory rather than a
file.  No item is added to ``sys.path`` more than once.  Blank lines
and lines beginning with ``#`` are skipped.  Lines starting with
``import`` (followed by space or tab) are executed.

For example, suppose ``sys.prefix`` and ``sys.exec_prefix`` are set to
``/usr/local``.  The Python X.Y library is then installed in
``/usr/local/lib/python*X.Y*``.  Suppose this has a subdirectory
``/usr/local/lib/python*X.Y*/site-packages`` with three
subsubdirectories, ``foo``, ``bar`` and ``spam``, and two path
configuration files, ``foo.pth`` and ``bar.pth``.  Assume ``foo.pth``
contains the following:

   # foo package configuration

   foo
   bar
   bletch

and ``bar.pth`` contains:

   # bar package configuration

   bar

Then the following version-specific directories are added to
``sys.path``, in this order:

   /usr/local/lib/pythonX.Y/site-packages/bar
   /usr/local/lib/pythonX.Y/site-packages/foo

Note that ``bletch`` is omitted because it doesn't exist; the ``bar``
directory precedes the ``foo`` directory because ``bar.pth`` comes
alphabetically before ``foo.pth``; and ``spam`` is omitted because it
is not mentioned in either path configuration file.

After these path manipulations, an attempt is made to import a module
named ``sitecustomize``, which can perform arbitrary site-specific
customizations. It is typically created by a system administrator in
the site-packages directory.  If this import fails with an
``ImportError`` exception, it is silently ignored.

After this, an attempt is made to import a module named
``usercustomize``, which can perform arbitrary user-specific
customizations, if ``ENABLE_USER_SITE`` is true.  This file is
intended to be created in the user site-packages directory (see
below), which is part of ``sys.path`` unless disabled by *-s*.  An
``ImportError`` will be silently ignored.

Note that for some non-Unix systems, ``sys.prefix`` and
``sys.exec_prefix`` are empty, and the path manipulations are skipped;
however the import of ``sitecustomize`` and ``usercustomize`` is still
attempted.

site.PREFIXES

   A list of prefixes for site-packages directories.

site.ENABLE_USER_SITE

   Flag showing the status of the user site-packages directory.
   ``True`` means that it is enabled and was added to ``sys.path``.
   ``False`` means that it was disabled by user request (with *-s* or
   ``PYTHONNOUSERSITE``).  ``None`` means it was disabled for security
   reasons (mismatch between user or group id and effective id) or by
   an administrator.

site.USER_SITE

   Path to the user site-packages for the running Python.  Can be
   ``None`` if ``getusersitepackages()`` hasn't been called yet.
   Default value is ``~/.local/lib/python*X.Y*/site-packages`` for
   UNIX and non-framework Mac OS X builds,
   ``~/Library/Python/*X.Y*/lib/python/site-packages`` for Mac
   framework builds, and
   ``*%APPDATA%*\Python\Python*XY*\site-packages`` on Windows.  This
   directory is a site directory, which means that ``.pth`` files in
   it will be processed.

site.USER_BASE

   Path to the base directory for the user site-packages.  Can be
   ``None`` if ``getuserbase()`` hasn't been called yet.  Default
   value is ``~/.local`` for UNIX and Mac OS X non-framework builds,
   ``~/Library/Python/*X.Y*`` for Mac framework builds, and
   ``*%APPDATA%*\Python`` for Windows.  This value is used by
   Distutils to compute the installation directories for scripts, data
   files, Python modules, etc. for the *user installation scheme*.
   See also ``PYTHONUSERBASE``.

site.addsitedir(sitedir, known_paths=None)

   Add a directory to sys.path and process its ``.pth`` files.
   Typically used in ``sitecustomize`` or ``usercustomize`` (see
   above).

site.getsitepackages()

   Return a list containing all global site-packages directories (and
   possibly site-python).

   New in version 3.2.

site.getuserbase()

   Return the path of the user base directory, ``USER_BASE``.  If it
   is not initialized yet, this function will also set it, respecting
   ``PYTHONUSERBASE``.

   New in version 3.2.

site.getusersitepackages()

   Return the path of the user-specific site-packages directory,
   ``USER_SITE``.  If it is not initialized yet, this function will
   also set it, respecting ``PYTHONNOUSERSITE`` and ``USER_BASE``.

   New in version 3.2.

The ``site`` module also provides a way to get the user directories
from the command line:

   $ python3 -m site --user-site
   /home/user/.local/lib/python3.3/site-packages

If it is called without arguments, it will print the contents of
``sys.path`` on the standard output, followed by the value of
``USER_BASE`` and whether the directory exists, then the same thing
for ``USER_SITE``, and finally the value of ``ENABLE_USER_SITE``.

--user-base

   Print the path to the user base directory.

--user-site

   Print the path to the user site-packages directory.

If both options are given, user base and user site will be printed
(always in this order), separated by ``os.pathsep``.

If any option is given, the script will exit with one of these values:
``O`` if the user site-packages directory is enabled, ``1`` if it was
disabled by the user, ``2`` if it is disabled for security reasons or
by an administrator, and a value greater than 2 if there is an error.

See also:

   **PEP 370** -- Per user site-packages directory
