1 :mod:`site` --- Site-specific configuration hook 2 ================================================ 3 4 .. module:: site 5 :synopsis: Module responsible for site-specific configuration. 6 7 **Source code:** :source:`Lib/site.py` 8 9 -------------- 10 11 .. highlightlang:: none 12 13 **This module is automatically imported during initialization.** The automatic 14 import can be suppressed using the interpreter's :option:`-S` option. 15 16 .. index:: triple: module; search; path 17 18 Importing this module will append site-specific paths to the module search path 19 and add a few builtins, unless :option:`-S` was used. In that case, this module 20 can be safely imported with no automatic modifications to the module search path 21 or additions to the builtins. To explicitly trigger the usual site-specific 22 additions, call the :func:`site.main` function. 23 24 .. versionchanged:: 3.3 25 Importing the module used to trigger paths manipulation even when using 26 :option:`-S`. 27 28 .. index:: 29 pair: site-packages; directory 30 31 It starts by constructing up to four directories from a head and a tail part. 32 For the head part, it uses ``sys.prefix`` and ``sys.exec_prefix``; empty heads 33 are skipped. For the tail part, it uses the empty string and then 34 :file:`lib/site-packages` (on Windows) or 35 :file:`lib/python{X.Y}/site-packages` (on Unix and Macintosh). For each 36 of the distinct head-tail combinations, it sees if it refers to an existing 37 directory, and if so, adds it to ``sys.path`` and also inspects the newly 38 added path for configuration files. 39 40 .. versionchanged:: 3.5 41 Support for the "site-python" directory has been removed. 42 43 If a file named "pyvenv.cfg" exists one directory above sys.executable, 44 sys.prefix and sys.exec_prefix are set to that directory and 45 it is also checked for site-packages (sys.base_prefix and 46 sys.base_exec_prefix will always be the "real" prefixes of the Python 47 installation). If "pyvenv.cfg" (a bootstrap configuration file) contains 48 the key "include-system-site-packages" set to anything other than "false" 49 (case-insensitive), the system-level prefixes will still also be 50 searched for site-packages; otherwise they won't. 51 52 A path configuration file is a file whose name has the form :file:`{name}.pth` 53 and exists in one of the four directories mentioned above; its contents are 54 additional items (one per line) to be added to ``sys.path``. Non-existing items 55 are never added to ``sys.path``, and no check is made that the item refers to a 56 directory rather than a file. No item is added to ``sys.path`` more than 57 once. Blank lines and lines beginning with ``#`` are skipped. Lines starting 58 with ``import`` (followed by space or tab) are executed. 59 60 .. index:: 61 single: package 62 triple: path; configuration; file 63 64 For example, suppose ``sys.prefix`` and ``sys.exec_prefix`` are set to 65 :file:`/usr/local`. The Python X.Y library is then installed in 66 :file:`/usr/local/lib/python{X.Y}`. Suppose this has 67 a subdirectory :file:`/usr/local/lib/python{X.Y}/site-packages` with three 68 subsubdirectories, :file:`foo`, :file:`bar` and :file:`spam`, and two path 69 configuration files, :file:`foo.pth` and :file:`bar.pth`. Assume 70 :file:`foo.pth` contains the following:: 71 72 # foo package configuration 73 74 foo 75 bar 76 bletch 77 78 and :file:`bar.pth` contains:: 79 80 # bar package configuration 81 82 bar 83 84 Then the following version-specific directories are added to 85 ``sys.path``, in this order:: 86 87 /usr/local/lib/pythonX.Y/site-packages/bar 88 /usr/local/lib/pythonX.Y/site-packages/foo 89 90 Note that :file:`bletch` is omitted because it doesn't exist; the :file:`bar` 91 directory precedes the :file:`foo` directory because :file:`bar.pth` comes 92 alphabetically before :file:`foo.pth`; and :file:`spam` is omitted because it is 93 not mentioned in either path configuration file. 94 95 .. index:: module: sitecustomize 96 97 After these path manipulations, an attempt is made to import a module named 98 :mod:`sitecustomize`, which can perform arbitrary site-specific customizations. 99 It is typically created by a system administrator in the site-packages 100 directory. If this import fails with an :exc:`ImportError` exception, it is 101 silently ignored. If Python is started without output streams available, as 102 with :file:`pythonw.exe` on Windows (which is used by default to start IDLE), 103 attempted output from :mod:`sitecustomize` is ignored. Any exception other 104 than :exc:`ImportError` causes a silent and perhaps mysterious failure of the 105 process. 106 107 .. index:: module: usercustomize 108 109 After this, an attempt is made to import a module named :mod:`usercustomize`, 110 which can perform arbitrary user-specific customizations, if 111 :data:`ENABLE_USER_SITE` is true. This file is intended to be created in the 112 user site-packages directory (see below), which is part of ``sys.path`` unless 113 disabled by :option:`-s`. An :exc:`ImportError` will be silently ignored. 114 115 Note that for some non-Unix systems, ``sys.prefix`` and ``sys.exec_prefix`` are 116 empty, and the path manipulations are skipped; however the import of 117 :mod:`sitecustomize` and :mod:`usercustomize` is still attempted. 118 119 120 .. _rlcompleter-config: 121 122 Readline configuration 123 ---------------------- 124 125 On systems that support :mod:`readline`, this module will also import and 126 configure the :mod:`rlcompleter` module, if Python is started in 127 :ref:`interactive mode <tut-interactive>` and without the :option:`-S` option. 128 The default behavior is enable tab-completion and to use 129 :file:`~/.python_history` as the history save file. To disable it, delete (or 130 override) the :data:`sys.__interactivehook__` attribute in your 131 :mod:`sitecustomize` or :mod:`usercustomize` module or your 132 :envvar:`PYTHONSTARTUP` file. 133 134 .. versionchanged:: 3.4 135 Activation of rlcompleter and history was made automatic. 136 137 138 Module contents 139 --------------- 140 141 .. data:: PREFIXES 142 143 A list of prefixes for site-packages directories. 144 145 146 .. data:: ENABLE_USER_SITE 147 148 Flag showing the status of the user site-packages directory. ``True`` means 149 that it is enabled and was added to ``sys.path``. ``False`` means that it 150 was disabled by user request (with :option:`-s` or 151 :envvar:`PYTHONNOUSERSITE`). ``None`` means it was disabled for security 152 reasons (mismatch between user or group id and effective id) or by an 153 administrator. 154 155 156 .. data:: USER_SITE 157 158 Path to the user site-packages for the running Python. Can be ``None`` if 159 :func:`getusersitepackages` hasn't been called yet. Default value is 160 :file:`~/.local/lib/python{X.Y}/site-packages` for UNIX and non-framework Mac 161 OS X builds, :file:`~/Library/Python/{X.Y}/lib/python/site-packages` for Mac 162 framework builds, and :file:`{%APPDATA%}\\Python\\Python{XY}\\site-packages` 163 on Windows. This directory is a site directory, which means that 164 :file:`.pth` files in it will be processed. 165 166 167 .. data:: USER_BASE 168 169 Path to the base directory for the user site-packages. Can be ``None`` if 170 :func:`getuserbase` hasn't been called yet. Default value is 171 :file:`~/.local` for UNIX and Mac OS X non-framework builds, 172 :file:`~/Library/Python/{X.Y}` for Mac framework builds, and 173 :file:`{%APPDATA%}\\Python` for Windows. This value is used by Distutils to 174 compute the installation directories for scripts, data files, Python modules, 175 etc. for the :ref:`user installation scheme <inst-alt-install-user>`. 176 See also :envvar:`PYTHONUSERBASE`. 177 178 179 .. function:: main() 180 181 Adds all the standard site-specific directories to the module search 182 path. This function is called automatically when this module is imported, 183 unless the Python interpreter was started with the :option:`-S` flag. 184 185 .. versionchanged:: 3.3 186 This function used to be called unconditionally. 187 188 189 .. function:: addsitedir(sitedir, known_paths=None) 190 191 Add a directory to sys.path and process its :file:`.pth` files. Typically 192 used in :mod:`sitecustomize` or :mod:`usercustomize` (see above). 193 194 195 .. function:: getsitepackages() 196 197 Return a list containing all global site-packages directories. 198 199 .. versionadded:: 3.2 200 201 202 .. function:: getuserbase() 203 204 Return the path of the user base directory, :data:`USER_BASE`. If it is not 205 initialized yet, this function will also set it, respecting 206 :envvar:`PYTHONUSERBASE`. 207 208 .. versionadded:: 3.2 209 210 211 .. function:: getusersitepackages() 212 213 Return the path of the user-specific site-packages directory, 214 :data:`USER_SITE`. If it is not initialized yet, this function will also set 215 it, respecting :envvar:`PYTHONNOUSERSITE` and :data:`USER_BASE`. 216 217 .. versionadded:: 3.2 218 219 220 The :mod:`site` module also provides a way to get the user directories from the 221 command line: 222 223 .. code-block:: sh 224 225 $ python3 -m site --user-site 226 /home/user/.local/lib/python3.3/site-packages 227 228 .. program:: site 229 230 If it is called without arguments, it will print the contents of 231 :data:`sys.path` on the standard output, followed by the value of 232 :data:`USER_BASE` and whether the directory exists, then the same thing for 233 :data:`USER_SITE`, and finally the value of :data:`ENABLE_USER_SITE`. 234 235 .. cmdoption:: --user-base 236 237 Print the path to the user base directory. 238 239 .. cmdoption:: --user-site 240 241 Print the path to the user site-packages directory. 242 243 If both options are given, user base and user site will be printed (always in 244 this order), separated by :data:`os.pathsep`. 245 246 If any option is given, the script will exit with one of these values: ``O`` if 247 the user site-packages directory is enabled, ``1`` if it was disabled by the 248 user, ``2`` if it is disabled for security reasons or by an administrator, and a 249 value greater than 2 if there is an error. 250 251 .. seealso:: 252 253 :pep:`370` -- Per user site-packages directory 254
