1 :mod:`site` --- Site-specific configuration hook
2 ================================================
5 :synopsis: Module responsible for site-specific configuration.
7 **Source code:** :source:`Lib/site.py`
11 .. highlightlang:: none
13 **This module is automatically imported during initialization.** The automatic
14 import can be suppressed using the interpreter's :option:`-S` option.
16 .. index:: triple: module; search; path
18 Importing this module will append site-specific paths to the module search path
19 and add a few builtins.
22 pair: site-python; directory
23 pair: site-packages; directory
25 It starts by constructing up to four directories from a head and a tail part.
26 For the head part, it uses ``sys.prefix`` and ``sys.exec_prefix``; empty heads
27 are skipped. For the tail part, it uses the empty string and then
28 :file:`lib/site-packages` (on Windows) or
29 :file:`lib/python|version|/site-packages` and then :file:`lib/site-python` (on
30 Unix and Macintosh). For each of the distinct head-tail combinations, it sees
31 if it refers to an existing directory, and if so, adds it to ``sys.path`` and
32 also inspects the newly added path for configuration files.
34 A path configuration file is a file whose name has the form :file:`{name}.pth`
35 and exists in one of the four directories mentioned above; its contents are
36 additional items (one per line) to be added to ``sys.path``. Non-existing items
37 are never added to ``sys.path``, and no check is made that the item refers to a
38 directory rather than a file. No item is added to ``sys.path`` more than
39 once. Blank lines and lines beginning with ``#`` are skipped. Lines starting
40 with ``import`` (followed by space or tab) are executed.
42 .. versionchanged:: 2.6
43 A space or tab is now required after the import keyword.
47 triple: path; configuration; file
49 For example, suppose ``sys.prefix`` and ``sys.exec_prefix`` are set to
50 :file:`/usr/local`. The Python X.Y library is then installed in
51 :file:`/usr/local/lib/python{X.Y}`. Suppose this has
52 a subdirectory :file:`/usr/local/lib/python{X.Y}/site-packages` with three
53 subsubdirectories, :file:`foo`, :file:`bar` and :file:`spam`, and two path
54 configuration files, :file:`foo.pth` and :file:`bar.pth`. Assume
55 :file:`foo.pth` contains the following::
57 # foo package configuration
63 and :file:`bar.pth` contains::
65 # bar package configuration
69 Then the following version-specific directories are added to
70 ``sys.path``, in this order::
72 /usr/local/lib/pythonX.Y/site-packages/bar
73 /usr/local/lib/pythonX.Y/site-packages/foo
75 Note that :file:`bletch` is omitted because it doesn't exist; the :file:`bar`
76 directory precedes the :file:`foo` directory because :file:`bar.pth` comes
77 alphabetically before :file:`foo.pth`; and :file:`spam` is omitted because it is
78 not mentioned in either path configuration file.
80 .. index:: module: sitecustomize
82 After these path manipulations, an attempt is made to import a module named
83 :mod:`sitecustomize`, which can perform arbitrary site-specific customizations.
84 It is typically created by a system administrator in the site-packages
85 directory. If this import fails with an :exc:`ImportError` exception, it is
88 .. index:: module: usercustomize
90 After this, an attempt is made to import a module named :mod:`usercustomize`,
91 which can perform arbitrary user-specific customizations, if
92 :data:`ENABLE_USER_SITE` is true. This file is intended to be created in the
93 user site-packages directory (see below), which is part of ``sys.path`` unless
94 disabled by :option:`-s`. An :exc:`ImportError` will be silently ignored.
96 Note that for some non-Unix systems, ``sys.prefix`` and ``sys.exec_prefix`` are
97 empty, and the path manipulations are skipped; however the import of
98 :mod:`sitecustomize` and :mod:`usercustomize` is still attempted.
103 A list of prefixes for site-packages directories.
105 .. versionadded:: 2.6
108 .. data:: ENABLE_USER_SITE
110 Flag showing the status of the user site-packages directory. ``True`` means
111 that it is enabled and was added to ``sys.path``. ``False`` means that it
112 was disabled by user request (with :option:`-s` or
113 :envvar:`PYTHONNOUSERSITE`). ``None`` means it was disabled for security
114 reasons (mismatch between user or group id and effective id) or by an
117 .. versionadded:: 2.6
122 Path to the user site-packages for the running Python. Can be ``None`` if
123 :func:`getusersitepackages` hasn't been called yet. Default value is
124 :file:`~/.local/lib/python{X.Y}/site-packages` for UNIX and non-framework Mac
125 OS X builds, :file:`~/Library/Python/{X.Y}/lib/python/site-packages` for Mac
126 framework builds, and :file:`{%APPDATA%}\\Python\\Python{XY}\\site-packages`
127 on Windows. This directory is a site directory, which means that
128 :file:`.pth` files in it will be processed.
130 .. versionadded:: 2.6
135 Path to the base directory for the user site-packages. Can be ``None`` if
136 :func:`getuserbase` hasn't been called yet. Default value is
137 :file:`~/.local` for UNIX and Mac OS X non-framework builds,
138 :file:`~/Library/Python/{X.Y}` for Mac framework builds, and
139 :file:`{%APPDATA%}\\Python` for Windows. This value is used by Distutils to
140 compute the installation directories for scripts, data files, Python modules,
141 etc. for the :ref:`user installation scheme <inst-alt-install-user>`. See
142 also :envvar:`PYTHONUSERBASE`.
144 .. versionadded:: 2.6
147 .. function:: addsitedir(sitedir, known_paths=None)
149 Add a directory to sys.path and process its :file:`.pth` files. Typically
150 used in :mod:`sitecustomize` or :mod:`usercustomize` (see above).
153 .. function:: getsitepackages()
155 Return a list containing all global site-packages directories (and possibly
158 .. versionadded:: 2.7
161 .. function:: getuserbase()
163 Return the path of the user base directory, :data:`USER_BASE`. If it is not
164 initialized yet, this function will also set it, respecting
165 :envvar:`PYTHONUSERBASE`.
167 .. versionadded:: 2.7
170 .. function:: getusersitepackages()
172 Return the path of the user-specific site-packages directory,
173 :data:`USER_SITE`. If it is not initialized yet, this function will also set
174 it, respecting :envvar:`PYTHONNOUSERSITE` and :data:`USER_BASE`.
176 .. versionadded:: 2.7
179 The :mod:`site` module also provides a way to get the user directories from the
184 $ python3 -m site --user-site
185 /home/user/.local/lib/python3.3/site-packages
189 If it is called without arguments, it will print the contents of
190 :data:`sys.path` on the standard output, followed by the value of
191 :data:`USER_BASE` and whether the directory exists, then the same thing for
192 :data:`USER_SITE`, and finally the value of :data:`ENABLE_USER_SITE`.
194 .. cmdoption:: --user-base
196 Print the path to the user base directory.
198 .. cmdoption:: --user-site
200 Print the path to the user site-packages directory.
202 If both options are given, user base and user site will be printed (always in
203 this order), separated by :data:`os.pathsep`.
205 If any option is given, the script will exit with one of these values: ``O`` if
206 the user site-packages directory is enabled, ``1`` if it was disabled by the
207 user, ``2`` if it is disabled for security reasons or by an administrator, and a
208 value greater than 2 if there is an error.
212 :pep:`370` -- Per user site-packages directory