site — Site-specific configuration hook

Вихідний код: Lib/site.py

Цей модуль автоматично імпортується під час ініціалізації. Автоматичний імпорт можна придушити за допомогою опції інтерпретатора -S.

Importing this module normally appends site-specific paths to the module search path and adds callables, including help() to the built-in namespace. However, Python startup option -S blocks this, and this module can be safely imported with no automatic modifications to the module search path or additions to the builtins. To explicitly trigger the usual site-specific additions, call the main() function.

Змінено в версії 3.3: Імпорт модуля, який використовується для ініціювання маніпуляцій шляхом, навіть якщо використовується -S.

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/pythonX.Y[t]/site-packages (on Unix and macOS). (The optional suffix «t» indicates the free-threaded build, and is appended if "t" is present in the sys.abiflags constant.) 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.

Змінено в версії 3.5: Підтримку каталогу «site-python» видалено.

Змінено в версії 3.13: On Unix, Free threading Python installations are identified by the «t» suffix in the version-specific directory name, such as lib/python3.13t/.

Змінено в версії 3.14: site is no longer responsible for updating sys.prefix and sys.exec_prefix on Virtual Environments. This is now done during the path initialization. As a result, under Virtual Environments, sys.prefix and sys.exec_prefix no longer depend on the site initialization, and are therefore unaffected by -S.

When running under a virtual environment, the pyvenv.cfg file in sys.prefix is checked for site-specific configurations. If the include-system-site-packages key exists and is set to true (case-insensitive), the system-level prefixes will be searched for site-packages, otherwise they won’t. If the system-level prefixes are not searched then the user site prefixes are also implicitly not searched for site-packages.

The site module recognizes two startup configuration files of the form name.pth for path configurations, and name.start for pre-first-line code execution. Both files can exist in one of the four directories mentioned above. Within each directory, these files are sorted alphabetically by filename, then parsed in sorted order.

Path extensions (.pth files)

name.pth contains additional items (one per line) to be appended to sys.path. Items that name non-existing directories 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.

For backward compatibility, lines starting with import (followed by space or tab) are executed with exec().

Змінено в версії 3.13: The .pth files are now decoded by UTF-8 at first and then by the locale encoding if it fails.

Змінено в версії 3.15: .pth file lines starting with import are deprecated. During the deprecation period, such lines are still executed (except in the case below), but a diagnostic message is emitted only when the -v flag is given.

import lines in name.pth are silently ignored when a matching name.start file exists.

Errors on individual lines no longer abort processing of the rest of the file. Each error is reported and the remaining lines continue to be processed.

Deprecated since version 3.15, will be removed in version 3.20: Decoding name.pth files in any encoding other than utf-8-sig is deprecated in Python 3.15, and support for decoding from the locale encoding will be removed in Python 3.20.

import lines in name.pth files are deprecated and will be silently ignored in Python 3.18 and 3.19. In Python 3.20 a warning will be produced for import lines in name.pth files.

Startup entry points (.start files)

Added in version 3.15.

A startup entry point file is a file whose name has the form name.start and exists in one of the site-packages directories described above. Each file specifies entry points to be called during interpreter startup, using the pkg.mod:callable syntax understood by pkgutil.resolve_name().

Each non-blank line that does not begin with # must contain an entry point reference in the form pkg.mod:callable. The colon and callable portion are mandatory. Each callable is invoked with no arguments, and any return value is discarded.

.start files are processed after all .pth path extensions have been applied to sys.path, ensuring that paths are available before any startup code runs.

Unlike sys.path extensions from .pth files, duplicate entry points are not de-duplicated — if an entry point appears more than once, it will be called more than once.

If an exception occurs during resolution or invocation of an entry point, a traceback is printed to sys.stderr and processing continues with the remaining entry points.

.start files must be encoded in UTF-8.

PEP 829 defined the original specification for these features.

Примітка

If a name.start file exists alongside a name.pth file with the same base name, any import lines in the .pth file are ignored in favor of the entry points in the .start file.

Примітка

Executable lines (import lines in name.pth files and name.start file entry points) are always run at Python startup (unless -S is given to disable the site.py module entirely), regardless of whether a particular module is actually going to be used.

Примітка

name.start files invoke pkgutil.resolve_name() with strict=True, which requires the full pkg.mod:callable form.

Startup file examples

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/pythonX.Y. Suppose this has a subdirectory /usr/local/lib/pythonX.Y/site-packages with three sub-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

і bar.pth містить:

# bar package configuration

bar

Потім до sys.path додаються наступні каталоги для певної версії в такому порядку:

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

Зауважте, що bletch пропущено, оскільки його не існує; каталог bar передує каталогу foo, оскільки bar.pth стоїть перед foo.pth в алфавітному порядку; і spam пропущено, оскільки він не згадується в обох файлах конфігурації шляху.

Let’s say that there is also a foo.start file containing the following:

# foo package startup code

foo.submod:initialize

Now, after sys.path has been extended as above, and before Python turns control over to user code, the foo.submod module is imported and the initialize() function from that module is called.

Migrating from import lines in .pth files to .start files

If your package currently ships a name.pth file, you can keep all sys.path extension lines unchanged. Only import lines need to be migrated.

To migrate, create a callable (taking zero arguments) within an importable module in your package. Reference it as a pkg.mod:callable entry point in a matching name.start file. Move everything on your import line after the first semi-colon into the callable() function.

If your package must straddle older Pythons that do not support PEP 829 and newer Pythons that do, change the import lines in your name.pth to use the following form:

import pkg.mod; pkg.mod.callable()

Older Pythons will execute these import lines, while newer Pythons will ignore them in favor of the name.start file. After the straddling period, remove all import lines from your .pth files.

sitecustomize

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 or its subclass exception, and the exception’s name attribute equals 'sitecustomize', it is silently ignored. If Python is started without output streams available, as with pythonw.exe on Windows (which is used by default to start IDLE), attempted output from sitecustomize is ignored. Any other exception causes a silent and perhaps mysterious failure of the process.

usercustomize

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. If this import fails with an ImportError or its subclass exception, and the exception’s name attribute equals 'usercustomize', it is 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.

Конфігурація Readline

On systems that support readline, this module will also import and configure the rlcompleter module, if Python is started in interactive mode and without the -S option. The default behavior is to enable tab completion and to use ~/.python_history as the history save file. To disable it, delete (or override) the sys.__interactivehook__ attribute in your sitecustomize or usercustomize module or your PYTHONSTARTUP file.

Змінено в версії 3.4: Активацію rlcompleter та історії було зроблено автоматично.

Зміст модуля

site.PREFIXES

Список префіксів для каталогів пакетів сайту.

site.ENABLE_USER_SITE

Прапор, який показує статус каталогу пакетів сайтів користувача. True означає, що його ввімкнено та було додано до sys.path. False означає, що його було вимкнено за запитом користувача (з -s або PYTHONNOUSERSITE). None означає, що його було вимкнено з міркувань безпеки (невідповідність між ідентифікатором користувача чи групи та ефективним ідентифікатором) або адміністратором.

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/pythonX.Y[t]/site-packages for UNIX and non-framework macOS builds, ~/Library/Python/X.Y/lib/python/site-packages for macOS framework builds, and %APPDATA%\Python\PythonXY\site-packages on Windows. The optional «t» indicates the free-threaded build. 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 macOS non-framework builds, ~/Library/Python/X.Y for macOS framework builds, and %APPDATA%\Python for Windows. This value is used to compute the installation directories for scripts, data files, Python modules, etc. for the user installation scheme. See also PYTHONUSERBASE.

site.main()

Додає всі стандартні каталоги сайту до шляху пошуку модуля. Ця функція викликається автоматично під час імпорту цього модуля, якщо інтерпретатор Python не було запущено з прапорцем -S.

Змінено в версії 3.3: Ця функція раніше називалася безумовно.

site.addsitedir(sitedir, known_paths=None, *, defer_processing_start_files=False)

Add a directory to sys.path and parse the .pth and .start files found in that directory. Typically used in sitecustomize or usercustomize (see above).

The known_paths argument is an optional set of case-normalized paths used to prevent duplicate sys.path entries. When None (the default), the set is built from the current sys.path.

While .pth and .start files are always parsed, set defer_processing_start_files to True to prevent processing the startup data found in those files, so that you can process them explicitly (this is typically used by the main() function).

Змінено в версії 3.15: Also processes .start files. See Startup entry points (.start files). All .pth and .start files are now read and accumulated before any path extensions, import line execution, or entry point invocations take place.

site.getsitepackages()

Повертає список, що містить усі глобальні каталоги пакетів сайту.

Added in version 3.2.

site.getuserbase()

Повертає шлях до каталогу бази користувача, USER_BASE. Якщо він ще не ініціалізований, ця функція також встановить його, поважаючи PYTHONUSERBASE.

Added in version 3.2.

site.getusersitepackages()

Повертає шлях до каталогу пакетів сайтів користувача, USER_SITE. Якщо він ще не ініціалізований, ця функція також встановить його, поважаючи USER_BASE. Щоб визначити, чи було додано специфічні для користувача пакети сайтів до sys.path, слід використовувати ENABLE_USER_SITE.

Added in version 3.2.

Command-line interface

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

$ python -m site --user-site
/home/user/.local/lib/python3.11/site-packages

Якщо його викликати без аргументів, він надрукує вміст sys.path на стандартному виводі, а потім значення USER_BASE і те, чи існує каталог, потім те саме для USER_SITE і, нарешті, значення ENABLE_USER_SITE.

--user-base

Надрукуйте шлях до каталогу бази користувача.

--user-site

Надрукуйте шлях до каталогу site-packages користувача.

Якщо задано обидва параметри, буде надруковано базу користувачів і сайт користувачів (завжди в такому порядку), розділених os.pathsep.

Якщо вказано будь-який параметр, сценарій завершить роботу з одним із таких значень: 0, якщо каталог пакетів сайту користувача ввімкнено, 1, якщо він був вимкнений користувачем, 2, якщо його вимкнено з міркувань безпеки або адміністратором, і значення більше 2, якщо є помилка.

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