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:mod:`sysconfig` --- Provide access to Python's configuration information ========================================================================= .. module:: sysconfig :synopsis: Python's configuration information .. moduleauthor:: Tarek Ziade <tarek@ziade.org> .. sectionauthor:: Tarek Ziade <tarek@ziade.org> .. index:: single: configuration information .. versionadded:: 2.7 **Source code:** :source:`Lib/sysconfig.py` -------------- The :mod:`sysconfig` module provides access to Python's configuration information like the list of installation paths and the configuration variables relevant for the current platform. Configuration variables ----------------------- A Python distribution contains a :file:`Makefile` and a :file:`pyconfig.h` header file that are necessary to build both the Python binary itself and third-party C extensions compiled using :mod:`distutils`. :mod:`sysconfig` puts all variables found in these files in a dictionary that can be accessed using :func:`get_config_vars` or :func:`get_config_var`. Notice that on Windows, it's a much smaller set. .. function:: get_config_vars(\*args) With no arguments, return a dictionary of all configuration variables relevant for the current platform. With arguments, return a list of values that result from looking up each argument in the configuration variable dictionary. For each argument, if the value is not found, return ``None``. .. function:: get_config_var(name) Return the value of a single variable *name*. Equivalent to ``get_config_vars().get(name)``. If *name* is not found, return ``None``. Example of usage:: >>> import sysconfig >>> sysconfig.get_config_var('Py_ENABLE_SHARED') 0 >>> sysconfig.get_config_var('LIBDIR') '/usr/local/lib' >>> sysconfig.get_config_vars('AR', 'CXX') ['ar', 'g++'] Installation paths ------------------ Python uses an installation scheme that differs depending on the platform and on the installation options. These schemes are stored in :mod:`sysconfig` under unique identifiers based on the value returned by :const:`os.name`. Every new component that is installed using :mod:`distutils` or a Distutils-based system will follow the same scheme to copy its file in the right places. Python currently supports seven schemes: - *posix_prefix*: scheme for Posix platforms like Linux or Mac OS X. This is the default scheme used when Python or a component is installed. - *posix_home*: scheme for Posix platforms used when a *home* option is used upon installation. This scheme is used when a component is installed through Distutils with a specific home prefix. - *posix_user*: scheme for Posix platforms used when a component is installed through Distutils and the *user* option is used. This scheme defines paths located under the user home directory. - *nt*: scheme for NT platforms like Windows. - *nt_user*: scheme for NT platforms, when the *user* option is used. - *os2*: scheme for OS/2 platforms. - *os2_home*: scheme for OS/2 platforms, when the *user* option is used. Each scheme is itself composed of a series of paths and each path has a unique identifier. Python currently uses eight paths: - *stdlib*: directory containing the standard Python library files that are not platform-specific. - *platstdlib*: directory containing the standard Python library files that are platform-specific. - *platlib*: directory for site-specific, platform-specific files. - *purelib*: directory for site-specific, non-platform-specific files. - *include*: directory for non-platform-specific header files. - *platinclude*: directory for platform-specific header files. - *scripts*: directory for script files. - *data*: directory for data files. :mod:`sysconfig` provides some functions to determine these paths. .. function:: get_scheme_names() Return a tuple containing all schemes currently supported in :mod:`sysconfig`. .. function:: get_path_names() Return a tuple containing all path names currently supported in :mod:`sysconfig`. .. function:: get_path(name, [scheme, [vars, [expand]]]) Return an installation path corresponding to the path *name*, from the install scheme named *scheme*. *name* has to be a value from the list returned by :func:`get_path_names`. :mod:`sysconfig` stores installation paths corresponding to each path name, for each platform, with variables to be expanded. For instance the *stdlib* path for the *nt* scheme is: ``{base}/Lib``. :func:`get_path` will use the variables returned by :func:`get_config_vars` to expand the path. All variables have default values for each platform so one may call this function and get the default value. If *scheme* is provided, it must be a value from the list returned by :func:`get_scheme_names`. Otherwise, the default scheme for the current platform is used. If *vars* is provided, it must be a dictionary of variables that will update the dictionary return by :func:`get_config_vars`. If *expand* is set to ``False``, the path will not be expanded using the variables. If *name* is not found, return ``None``. .. function:: get_paths([scheme, [vars, [expand]]]) Return a dictionary containing all installation paths corresponding to an installation scheme. See :func:`get_path` for more information. If *scheme* is not provided, will use the default scheme for the current platform. If *vars* is provided, it must be a dictionary of variables that will update the dictionary used to expand the paths. If *expand* is set to false, the paths will not be expanded. If *scheme* is not an existing scheme, :func:`get_paths` will raise a :exc:`KeyError`. Other functions --------------- .. function:: get_python_version() Return the ``MAJOR.MINOR`` Python version number as a string. Similar to ``sys.version[:3]``. .. function:: get_platform() Return a string that identifies the current platform. This is used mainly to distinguish platform-specific build directories and platform-specific built distributions. Typically includes the OS name and version and the architecture (as supplied by :func:`os.uname`), although the exact information included depends on the OS; e.g. for IRIX the architecture isn't particularly important (IRIX only runs on SGI hardware), but for Linux the kernel version isn't particularly important. Examples of returned values: - linux-i586 - linux-alpha (?) - solaris-2.6-sun4u - irix-5.3 - irix64-6.2 Windows will return one of: - win-amd64 (64bit Windows on AMD64, aka x86_64, Intel64, and EM64T) - win-ia64 (64bit Windows on Itanium) - win32 (all others - specifically, sys.platform is returned) Mac OS X can return: - macosx-10.6-ppc - macosx-10.4-ppc64 - macosx-10.3-i386 - macosx-10.4-fat For other non-POSIX platforms, currently just returns :data:`sys.platform`. .. function:: is_python_build() Return ``True`` if the current Python installation was built from source. .. function:: parse_config_h(fp[, vars]) Parse a :file:`config.h`\-style file. *fp* is a file-like object pointing to the :file:`config.h`\-like file. A dictionary containing name/value pairs is returned. If an optional dictionary is passed in as the second argument, it is used instead of a new dictionary, and updated with the values read in the file. .. function:: get_config_h_filename() Return the path of :file:`pyconfig.h`. .. function:: get_makefile_filename() Return the path of :file:`Makefile`.