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4e40cec924
I decided to leave the (slightly expanded) Other Improvements entry as well, since someone looking for command line behavior changes isn't going to look in the 'sys' module section.
251 lines
9.2 KiB
ReStructuredText
251 lines
9.2 KiB
ReStructuredText
:mod:`site` --- Site-specific configuration hook
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================================================
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.. module:: site
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:synopsis: Module responsible for site-specific configuration.
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**Source code:** :source:`Lib/site.py`
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--------------
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.. highlightlang:: none
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**This module is automatically imported during initialization.** The automatic
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import can be suppressed using the interpreter's :option:`-S` option.
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.. index:: triple: module; search; path
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Importing this module will append site-specific paths to the module search path
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and add a few builtins, unless :option:`-S` was used. In that case, this module
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can be safely imported with no automatic modifications to the module search path
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or additions to the builtins. To explicitly trigger the usual site-specific
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additions, call the :func:`site.main` function.
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.. versionchanged:: 3.3
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Importing the module used to trigger paths manipulation even when using
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:option:`-S`.
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.. index::
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pair: site-python; directory
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pair: site-packages; directory
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It starts by constructing up to four directories from a head and a tail part.
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For the head part, it uses ``sys.prefix`` and ``sys.exec_prefix``; empty heads
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are skipped. For the tail part, it uses the empty string and then
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:file:`lib/site-packages` (on Windows) or
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:file:`lib/python{X.Y}/site-packages` and then :file:`lib/site-python` (on
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Unix and Macintosh). For each of the distinct head-tail combinations, it sees
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if it refers to an existing directory, and if so, adds it to ``sys.path`` and
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also inspects the newly added path for configuration files.
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.. deprecated:: 3.4
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Support for the "site-python" directory will be removed in 3.5.
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If a file named "pyvenv.cfg" exists one directory above sys.executable,
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sys.prefix and sys.exec_prefix are set to that directory and
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it is also checked for site-packages and site-python (sys.base_prefix and
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sys.base_exec_prefix will always be the "real" prefixes of the Python
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installation). If "pyvenv.cfg" (a bootstrap configuration file) contains
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the key "include-system-site-packages" set to anything other than "false"
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(case-insensitive), the system-level prefixes will still also be
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searched for site-packages; otherwise they won't.
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A path configuration file is a file whose name has the form :file:`{name}.pth`
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and exists in one of the four directories mentioned above; its contents are
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additional items (one per line) to be added to ``sys.path``. Non-existing items
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are never added to ``sys.path``, and no check is made that the item refers to a
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directory rather than a file. No item is added to ``sys.path`` more than
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once. Blank lines and lines beginning with ``#`` are skipped. Lines starting
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with ``import`` (followed by space or tab) are executed.
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.. index::
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single: package
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triple: path; configuration; file
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For example, suppose ``sys.prefix`` and ``sys.exec_prefix`` are set to
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:file:`/usr/local`. The Python X.Y library is then installed in
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:file:`/usr/local/lib/python{X.Y}`. Suppose this has
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a subdirectory :file:`/usr/local/lib/python{X.Y}/site-packages` with three
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subsubdirectories, :file:`foo`, :file:`bar` and :file:`spam`, and two path
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configuration files, :file:`foo.pth` and :file:`bar.pth`. Assume
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:file:`foo.pth` contains the following::
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# foo package configuration
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foo
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bar
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bletch
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and :file:`bar.pth` contains::
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# bar package configuration
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bar
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Then the following version-specific directories are added to
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``sys.path``, in this order::
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/usr/local/lib/pythonX.Y/site-packages/bar
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/usr/local/lib/pythonX.Y/site-packages/foo
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Note that :file:`bletch` is omitted because it doesn't exist; the :file:`bar`
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directory precedes the :file:`foo` directory because :file:`bar.pth` comes
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alphabetically before :file:`foo.pth`; and :file:`spam` is omitted because it is
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not mentioned in either path configuration file.
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.. index:: module: sitecustomize
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After these path manipulations, an attempt is made to import a module named
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:mod:`sitecustomize`, which can perform arbitrary site-specific customizations.
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It is typically created by a system administrator in the site-packages
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directory. If this import fails with an :exc:`ImportError` exception, it is
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silently ignored.
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.. index:: module: usercustomize
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After this, an attempt is made to import a module named :mod:`usercustomize`,
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which can perform arbitrary user-specific customizations, if
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:data:`ENABLE_USER_SITE` is true. This file is intended to be created in the
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user site-packages directory (see below), which is part of ``sys.path`` unless
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disabled by :option:`-s`. An :exc:`ImportError` will be silently ignored.
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Note that for some non-Unix systems, ``sys.prefix`` and ``sys.exec_prefix`` are
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empty, and the path manipulations are skipped; however the import of
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:mod:`sitecustomize` and :mod:`usercustomize` is still attempted.
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.. _rlcompleter-config:
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Readline configuration
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----------------------
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On systems that support :mod:`readline`, this module will also import and
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configure the :mod:`rlcompleter` module, if Python is started in
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:ref:`interactive mode <tut-interactive>` and without the :option:`-S` option.
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The default behavior is enable tab-completion and to use
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:file:`~/.python_history` as the history save file. To disable it, delete (or
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override) the :data:`sys.__interactivehook__` attribute in your
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:mod:`sitecustomize` or :mod:`usercustomize` module or your
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:envvar:`PYTHONSTARTUP` file.
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.. versionchanged:: 3.4
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Activation of rlcompleter and history was made automatic.
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Module contents
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---------------
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.. data:: PREFIXES
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A list of prefixes for site-packages directories.
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.. data:: ENABLE_USER_SITE
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Flag showing the status of the user site-packages directory. ``True`` means
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that it is enabled and was added to ``sys.path``. ``False`` means that it
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was disabled by user request (with :option:`-s` or
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:envvar:`PYTHONNOUSERSITE`). ``None`` means it was disabled for security
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reasons (mismatch between user or group id and effective id) or by an
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administrator.
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.. data:: USER_SITE
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Path to the user site-packages for the running Python. Can be ``None`` if
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:func:`getusersitepackages` hasn't been called yet. Default value is
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:file:`~/.local/lib/python{X.Y}/site-packages` for UNIX and non-framework Mac
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OS X builds, :file:`~/Library/Python/{X.Y}/lib/python/site-packages` for Mac
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framework builds, and :file:`{%APPDATA%}\\Python\\Python{XY}\\site-packages`
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on Windows. This directory is a site directory, which means that
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:file:`.pth` files in it will be processed.
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.. data:: USER_BASE
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Path to the base directory for the user site-packages. Can be ``None`` if
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:func:`getuserbase` hasn't been called yet. Default value is
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:file:`~/.local` for UNIX and Mac OS X non-framework builds,
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:file:`~/Library/Python/{X.Y}` for Mac framework builds, and
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:file:`{%APPDATA%}\\Python` for Windows. This value is used by Distutils to
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compute the installation directories for scripts, data files, Python modules,
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etc. for the :ref:`user installation scheme <inst-alt-install-user>`.
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See also :envvar:`PYTHONUSERBASE`.
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.. function:: main()
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Adds all the standard site-specific directories to the module search
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path. This function is called automatically when this module is imported,
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unless the Python interpreter was started with the :option:`-S` flag.
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.. versionchanged:: 3.3
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This function used to be called unconditionnally.
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.. function:: addsitedir(sitedir, known_paths=None)
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Add a directory to sys.path and process its :file:`.pth` files. Typically
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used in :mod:`sitecustomize` or :mod:`usercustomize` (see above).
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.. function:: getsitepackages()
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Return a list containing all global site-packages directories (and possibly
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site-python).
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.. versionadded:: 3.2
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.. function:: getuserbase()
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Return the path of the user base directory, :data:`USER_BASE`. If it is not
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initialized yet, this function will also set it, respecting
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:envvar:`PYTHONUSERBASE`.
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.. versionadded:: 3.2
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.. function:: getusersitepackages()
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Return the path of the user-specific site-packages directory,
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:data:`USER_SITE`. If it is not initialized yet, this function will also set
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it, respecting :envvar:`PYTHONNOUSERSITE` and :data:`USER_BASE`.
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.. versionadded:: 3.2
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The :mod:`site` module also provides a way to get the user directories from the
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command line:
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.. code-block:: sh
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$ python3 -m site --user-site
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/home/user/.local/lib/python3.3/site-packages
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.. program:: site
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If it is called without arguments, it will print the contents of
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:data:`sys.path` on the standard output, followed by the value of
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:data:`USER_BASE` and whether the directory exists, then the same thing for
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:data:`USER_SITE`, and finally the value of :data:`ENABLE_USER_SITE`.
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.. cmdoption:: --user-base
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Print the path to the user base directory.
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.. cmdoption:: --user-site
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Print the path to the user site-packages directory.
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If both options are given, user base and user site will be printed (always in
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this order), separated by :data:`os.pathsep`.
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If any option is given, the script will exit with one of these values: ``O`` if
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the user site-packages directory is enabled, ``1`` if it was disabled by the
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user, ``2`` if it is disabled for security reasons or by an administrator, and a
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value greater than 2 if there is an error.
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.. seealso::
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:pep:`370` -- Per user site-packages directory
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