:mod:`sysconfig` --- Provide access to Python's configuration information ========================================================================= .. module:: sysconfig :synopsis: Python's configuration information .. moduleauthor:: Tarek Ziade .. sectionauthor:: Tarek Ziade .. versionadded:: 2.7 .. index:: single: configuration information 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` file and a :file:`python.h` that are used to build the Python binary itself, but also any C extension created in a third party project and compiled using :mod:`distutils`. :mod:`sysconfig` put all variables found in these files in a dictionnary 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, returns 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 platform 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 platform 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 OS2 platforms. - *os2_home*: scheme for OS2 patforms, 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 files. - *platlib*: directory for the site-specific, platform-specific files. - *purelib*: directory for the site-specific, non platform-specific files. - *include*: directory containing the non-platform-specific header files. - *platinclude*: directory containing the platform-specific header files. - *scripts*: directory containing the script files. - *data*: directory containing the data files. :mod:`sysconfig` provides some functions to read 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 the 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_path_names`. Otherwise, the default scheme for the current platform is used. If *vars* is provided, it must be a dictionnary of variables that will update the dictionnary 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 dictionnary 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 dictionnary of variables that will update the dictionnary 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 'os.uname()'), although the exact information included depends on the OS; eg. 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, EM64T, etc) - 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 'sys.platform'. .. function:: is_python_build(): Returns True if the current Python installation was built from source. .. function:: parse_config_h(fp[, vars]): Parse a config.h-style file. *fp* is a file-like object pointing to the 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(): Returns the path of pyconfig.h