.. module:: sysconfig :synopsis: Python's configuration information
.. moduleauthor:: Tarek Ziadé <tarek@ziade.org>
.. sectionauthor:: Tarek Ziadé <tarek@ziade.org>
.. versionadded:: 3.2
Source code: :source:`Lib/sysconfig.py`
.. 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.
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++']
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:
Each scheme is itself composed of a series of paths and each path has a unique identifier. Python currently uses eight paths:
: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`.
.. function:: get_python_version() Return the ``MAJOR.MINOR`` Python version number as a string. Similar to ``'%d.%d' % sys.version_info[:2]``.
.. 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; e.g., on Linux, the kernel version isn't particularly important. Examples of returned values: - linux-i586 - linux-alpha (?) - solaris-2.6-sun4u Windows will return one of: - win-amd64 (64bit Windows on AMD64, aka x86_64, Intel64, and EM64T) - 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 running Python interpreter was built from source and is being run from its built location, and not from a location resulting from e.g. running ``make install`` or installing via a binary installer.
.. 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`.
You can use :mod:`sysconfig` as a script with Python's -m option:
$ python -m sysconfig
Platform: "macosx-10.4-i386"
Python version: "3.2"
Current installation scheme: "posix_prefix"
Paths:
data = "/usr/local"
include = "/Users/tarek/Dev/svn.python.org/py3k/Include"
platinclude = "."
platlib = "/usr/local/lib/python3.2/site-packages"
platstdlib = "/usr/local/lib/python3.2"
purelib = "/usr/local/lib/python3.2/site-packages"
scripts = "/usr/local/bin"
stdlib = "/usr/local/lib/python3.2"
Variables:
AC_APPLE_UNIVERSAL_BUILD = "0"
AIX_GENUINE_CPLUSPLUS = "0"
AR = "ar"
ARFLAGS = "rc"
...
This call will print in the standard output the information returned by :func:`get_platform`, :func:`get_python_version`, :func:`get_path` and :func:`get_config_vars`.
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