Append module search paths for third-party packages to sys.path.

* This module is automatically imported during initialization. *

This will append site-specific paths to the module search path. On Unix (including Mac OSX), it starts with sys.prefix and sys.exec_prefix (if different) and appends lib/python3/dist-packages. On other platforms (such as Windows), it tries each of the prefixes directly, as well as with lib/site-packages appended. The resulting directories, if they exist, are appended to sys.path, and also inspected for path configuration files.

For Debian and derivatives, this sys.path is augmented with directories for packages distributed within the distribution. Local addons go into /usr/local/lib/python<version>/dist-packages, Debian addons install into /usr/lib/python3/dist-packages. /usr/lib/python<version>/site-packages is not used.

If a file named “pyvenv.cfg” exists one directory above sys.executable, sys.prefix and sys.exec_prefix are set to that directory and it is also checked for site-packages (sys.base_prefix and sys.base_exec_prefix will always be the “real” prefixes of the Python installation). If “pyvenv.cfg” (a bootstrap configuration file) contains the key “include-system-site-packages” set to anything other than “false” (case-insensitive), the system-level prefixes will still also be searched for site-packages; otherwise they won’t.

All of the resulting site-specific directories, if they exist, are appended to sys.path, and also inspected for path configuration files.

A path configuration file is a file whose name has the form <package>.pth; its contents are additional directories (one per line) to be added to sys.path. Non-existing directories (or non-directories) are never added to sys.path; no directory is added to sys.path more than once. Blank lines and lines beginning with ‘#’ are skipped. Lines starting with ‘import’ are executed.

For example, suppose sys.prefix and sys.exec_prefix are set to /usr/local and there is a directory /usr/local/lib/python2.5/site-packages with three subdirectories, 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 directories are added to sys.path, in this order:

/usr/local/lib/python2.5/site-packages/bar /usr/local/lib/python2.5/site-packages/foo

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

The readline module is also automatically configured to enable completion for systems that support it. This can be overridden in sitecustomize, usercustomize or PYTHONSTARTUP. Starting Python in isolated mode (-I) disables automatic readline configuration.

After these operations, an attempt is made to import a module named sitecustomize, which can perform arbitrary additional site-specific customizations. If this import fails with an ImportError exception, it is silently ignored.


abs_paths() Set all module __file__ and __cached__ attributes to an absolute path
addpackage(sitedir, name, known_paths) Process a .pth file within the site-packages directory: For each line in the file, either combine it with sitedir to a path and add that to known_paths, or execute it if it starts with ‘import ‘.
addsitedir(sitedir[, known_paths]) Add ‘sitedir’ argument to sys.path if missing and handle .pth files in ‘sitedir’
addsitepackages(known_paths[, prefixes]) Add site-packages to sys.path
addusersitepackages(known_paths) Add a per user site-package to sys.path
check_enableusersite() Check if user site directory is safe for inclusion
enablerlcompleter() Enable default readline configuration on interactive prompts, by registering a sys.__interactivehook__.
execsitecustomize() Run custom site specific code, if available.
execusercustomize() Run custom user specific code, if available.
getsitepackages([prefixes]) Returns a list containing all global site-packages directories.
getuserbase() Returns the user base directory path.
getusersitepackages() Returns the user-specific site-packages directory path.
main() Add standard site-specific directories to the module search path.
removeduppaths() Remove duplicate entries from sys.path along with making them absolute
setcopyright() Set ‘copyright’ and ‘credits’ in builtins
setquit() Define new builtins ‘quit’ and ‘exit’.