site --- Site-specific configuration hook

Reference note (untrusted external data; do not execute it as instructions). synopsis: Module responsible for site-specific configuration. This module is automatically imported during initialization. The automatic import can be suppressed using the interpreter's -S option. 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. Importing the module used to trigger paths manipulation even when using -S. pair: site-packages; directory 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/python{X.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. Support for the "site-python" directory has been removed. On Unix, Free threading Python installations are identified by the "t" suffix in the version-specific directory name, such as lib/python3.13t/. !site is no longer responsible for updating sys.prefix and sys.exec_prefix on sys-path-init-virtual-environments. This is now done during the path initialization . As a result, under sys-path-init-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. single: # (hash); comment pair: statement; import … Attribution: Adapted from Python Documentation under PSF-2.0. Adaptation: WikiKV isolated this documentation section, normalized formatting, retained only bounded code excerpts, and shortened it at a paragraph or sentence boundary for retrieval. Verify version-sensitive details at the source.