site — Site-specific configuration hook

Código-fonte: Lib/site.py

Este módulo é importado automaticamente durante a inicialização. A importação automática pode ser suprimida usando a opção -S do interpretador.

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.

Alterado na versão 3.3: A importação do módulo usado para acionar a manipulação de caminhos, mesmo ao usar -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 threading 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.

Alterado na versão 3.5: Suporte para o diretório “site-python” foi removido.

Alterado na versão 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/.

Alterado na versão 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.

Um arquivo de configuração de caminho é aquele cujo nome tem o formato name.pth e que existe em um dos quatro diretórios mencionados acima; seu conteúdo são itens adicionais (um por linha) a serem adicionados ao sys.path. Itens inexistentes nunca são adicionados ao sys.path e não é verificado se o item se refere a um diretório, e não a um arquivo. Nenhum item é adicionado ao sys.path mais de uma vez. Linhas em branco e linhas iniciadas com # são ignoradas. Linhas iniciadas com import (seguidas de espaço ou tabulação) são executadas.

Nota

Uma linha executável em um arquivo .pth é executada a cada inicialização do Python, independentemente de um módulo em particular ser realmente usado. Seu impacto deve, portanto, ser reduzido ao mínimo. O objetivo principal das linhas executáveis ​é tornar o(s) módulo(s) correspondente(s) importável (carregar ganchos de importação de terceiros, ajustar PATH etc). Qualquer outra inicialização deve ser feita na importação real de um módulo, se e quando isso acontecer. Limitar um fragmento de código a uma única linha é uma medida deliberada para desencorajar colocar qualquer coisa mais complexa aqui.

Alterado na versão 3.13: The .pth files are now decoded by UTF-8 at first and then by the locale encoding if it fails.

Por exemplo, suponha que sys.prefix e sys.exec_prefix sejam definidos com /usr/local. A biblioteca Python X.Y é instalado em /usr/local/lib/pythonX.Y. Suponha que isso tenha um subdiretório /usr/local/lib/pythonX.Y/site-packages com três subsubdiretórios, foo, bar e spam, e dois caminhos arquivos de configuração, foo.pth e bar.pth. Presuma que foo.pth contém o seguinte:

# foo package configuration

foo
bar
bletch

e que bar.pth contém:

# bar package configuration

bar

Em seguida, os seguintes diretórios específicos da versão são adicionados a sys.path, nesta ordem:

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

Observe que bletch é omitido porque não existe; o diretório bar precede o diretório foo porque bar.pth vem em ordem alfabética antes de foo.pth; e spam é omitido porque não é mencionado em nenhum dos arquivos de configuração de caminho.

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 to '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 to '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.

Configuração 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 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.

Alterado na versão 3.4: Activation of rlcompleter and history was made automatic.

Conteúdo do módulo

site.PREFIXES

A list of prefixes for site-packages directories.

site.ENABLE_USER_SITE

Flag showing the status of the user site-packages directory. True means that it is enabled and was added to sys.path. False means that it was disabled by user request (with -s or PYTHONNOUSERSITE). None means it was disabled for security reasons (mismatch between user or group id and effective id) or by an administrator.

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()

Adds all the standard site-specific directories to the module search path. This function is called automatically when this module is imported, unless the Python interpreter was started with the -S flag.

Alterado na versão 3.3: This function used to be called unconditionally.

site.addsitedir(sitedir, known_paths=None)

Add a directory to sys.path and process its .pth files. Typically used in sitecustomize or usercustomize (see above).

site.getsitepackages()

Return a list containing all global site-packages directories.

Adicionado na versão 3.2.

site.getuserbase()

Return the path of the user base directory, USER_BASE. If it is not initialized yet, this function will also set it, respecting PYTHONUSERBASE.

Adicionado na versão 3.2.

site.getusersitepackages()

Return the path of the user-specific site-packages directory, USER_SITE. If it is not initialized yet, this function will also set it, respecting USER_BASE. To determine if the user-specific site-packages was added to sys.path ENABLE_USER_SITE should be used.

Adicionado na versão 3.2.

Interface de linha de comando

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

If it is called without arguments, it will print the contents of sys.path on the standard output, followed by the value of USER_BASE and whether the directory exists, then the same thing for USER_SITE, and finally the value of ENABLE_USER_SITE.

--user-base

Print the path to the user base directory.

--user-site

Print the path to the user site-packages directory.

If both options are given, user base and user site will be printed (always in this order), separated by os.pathsep.

If any option is given, the script will exit with one of these values: 0 if the user site-packages directory is enabled, 1 if it was disabled by the user, 2 if it is disabled for security reasons or by an administrator, and a value greater than 2 if there is an error.

Ver também