1 :mod:`sysconfig` --- Provide access to Python's configuration information 2 ========================================================================= 3 4 .. module:: sysconfig 5 :synopsis: Python's configuration information 6 .. moduleauthor:: Tarek Ziade <tarek (a] ziade.org> 7 .. sectionauthor:: Tarek Ziade <tarek (a] ziade.org> 8 .. index:: 9 single: configuration information 10 11 .. versionadded:: 2.7 12 13 **Source code:** :source:`Lib/sysconfig.py` 14 15 -------------- 16 17 The :mod:`sysconfig` module provides access to Python's configuration 18 information like the list of installation paths and the configuration variables 19 relevant for the current platform. 20 21 Configuration variables 22 ----------------------- 23 24 A Python distribution contains a :file:`Makefile` and a :file:`pyconfig.h` 25 header file that are necessary to build both the Python binary itself and 26 third-party C extensions compiled using :mod:`distutils`. 27 28 :mod:`sysconfig` puts all variables found in these files in a dictionary that 29 can be accessed using :func:`get_config_vars` or :func:`get_config_var`. 30 31 Notice that on Windows, it's a much smaller set. 32 33 .. function:: get_config_vars(\*args) 34 35 With no arguments, return a dictionary of all configuration variables 36 relevant for the current platform. 37 38 With arguments, return a list of values that result from looking up each 39 argument in the configuration variable dictionary. 40 41 For each argument, if the value is not found, return ``None``. 42 43 44 .. function:: get_config_var(name) 45 46 Return the value of a single variable *name*. Equivalent to 47 ``get_config_vars().get(name)``. 48 49 If *name* is not found, return ``None``. 50 51 Example of usage:: 52 53 >>> import sysconfig 54 >>> sysconfig.get_config_var('Py_ENABLE_SHARED') 55 0 56 >>> sysconfig.get_config_var('LIBDIR') 57 '/usr/local/lib' 58 >>> sysconfig.get_config_vars('AR', 'CXX') 59 ['ar', 'g++'] 60 61 62 Installation paths 63 ------------------ 64 65 Python uses an installation scheme that differs depending on the platform and on 66 the installation options. These schemes are stored in :mod:`sysconfig` under 67 unique identifiers based on the value returned by :const:`os.name`. 68 69 Every new component that is installed using :mod:`distutils` or a 70 Distutils-based system will follow the same scheme to copy its file in the right 71 places. 72 73 Python currently supports seven schemes: 74 75 - *posix_prefix*: scheme for Posix platforms like Linux or Mac OS X. This is 76 the default scheme used when Python or a component is installed. 77 - *posix_home*: scheme for Posix platforms used when a *home* option is used 78 upon installation. This scheme is used when a component is installed through 79 Distutils with a specific home prefix. 80 - *posix_user*: scheme for Posix platforms used when a component is installed 81 through Distutils and the *user* option is used. This scheme defines paths 82 located under the user home directory. 83 - *nt*: scheme for NT platforms like Windows. 84 - *nt_user*: scheme for NT platforms, when the *user* option is used. 85 - *os2*: scheme for OS/2 platforms. 86 - *os2_home*: scheme for OS/2 patforms, when the *user* option is used. 87 88 Each scheme is itself composed of a series of paths and each path has a unique 89 identifier. Python currently uses eight paths: 90 91 - *stdlib*: directory containing the standard Python library files that are not 92 platform-specific. 93 - *platstdlib*: directory containing the standard Python library files that are 94 platform-specific. 95 - *platlib*: directory for site-specific, platform-specific files. 96 - *purelib*: directory for site-specific, non-platform-specific files. 97 - *include*: directory for non-platform-specific header files. 98 - *platinclude*: directory for platform-specific header files. 99 - *scripts*: directory for script files. 100 - *data*: directory for data files. 101 102 :mod:`sysconfig` provides some functions to determine these paths. 103 104 .. function:: get_scheme_names() 105 106 Return a tuple containing all schemes currently supported in 107 :mod:`sysconfig`. 108 109 110 .. function:: get_path_names() 111 112 Return a tuple containing all path names currently supported in 113 :mod:`sysconfig`. 114 115 116 .. function:: get_path(name, [scheme, [vars, [expand]]]) 117 118 Return an installation path corresponding to the path *name*, from the 119 install scheme named *scheme*. 120 121 *name* has to be a value from the list returned by :func:`get_path_names`. 122 123 :mod:`sysconfig` stores installation paths corresponding to each path name, 124 for each platform, with variables to be expanded. For instance the *stdlib* 125 path for the *nt* scheme is: ``{base}/Lib``. 126 127 :func:`get_path` will use the variables returned by :func:`get_config_vars` 128 to expand the path. All variables have default values for each platform so 129 one may call this function and get the default value. 130 131 If *scheme* is provided, it must be a value from the list returned by 132 :func:`get_scheme_names`. Otherwise, the default scheme for the current 133 platform is used. 134 135 If *vars* is provided, it must be a dictionary of variables that will update 136 the dictionary return by :func:`get_config_vars`. 137 138 If *expand* is set to ``False``, the path will not be expanded using the 139 variables. 140 141 If *name* is not found, return ``None``. 142 143 144 .. function:: get_paths([scheme, [vars, [expand]]]) 145 146 Return a dictionary containing all installation paths corresponding to an 147 installation scheme. See :func:`get_path` for more information. 148 149 If *scheme* is not provided, will use the default scheme for the current 150 platform. 151 152 If *vars* is provided, it must be a dictionary of variables that will 153 update the dictionary used to expand the paths. 154 155 If *expand* is set to false, the paths will not be expanded. 156 157 If *scheme* is not an existing scheme, :func:`get_paths` will raise a 158 :exc:`KeyError`. 159 160 161 Other functions 162 --------------- 163 164 .. function:: get_python_version() 165 166 Return the ``MAJOR.MINOR`` Python version number as a string. Similar to 167 ``sys.version[:3]``. 168 169 170 .. function:: get_platform() 171 172 Return a string that identifies the current platform. 173 174 This is used mainly to distinguish platform-specific build directories and 175 platform-specific built distributions. Typically includes the OS name and 176 version and the architecture (as supplied by :func:`os.uname`), although the 177 exact information included depends on the OS; e.g. for IRIX the architecture 178 isn't particularly important (IRIX only runs on SGI hardware), but for Linux 179 the kernel version isn't particularly important. 180 181 Examples of returned values: 182 183 - linux-i586 184 - linux-alpha (?) 185 - solaris-2.6-sun4u 186 - irix-5.3 187 - irix64-6.2 188 189 Windows will return one of: 190 191 - win-amd64 (64bit Windows on AMD64 (aka x86_64, Intel64, EM64T, etc) 192 - win-ia64 (64bit Windows on Itanium) 193 - win32 (all others - specifically, sys.platform is returned) 194 195 Mac OS X can return: 196 197 - macosx-10.6-ppc 198 - macosx-10.4-ppc64 199 - macosx-10.3-i386 200 - macosx-10.4-fat 201 202 For other non-POSIX platforms, currently just returns :data:`sys.platform`. 203 204 205 .. function:: is_python_build() 206 207 Return ``True`` if the current Python installation was built from source. 208 209 210 .. function:: parse_config_h(fp[, vars]) 211 212 Parse a :file:`config.h`\-style file. 213 214 *fp* is a file-like object pointing to the :file:`config.h`\-like file. 215 216 A dictionary containing name/value pairs is returned. If an optional 217 dictionary is passed in as the second argument, it is used instead of a new 218 dictionary, and updated with the values read in the file. 219 220 221 .. function:: get_config_h_filename() 222 223 Return the path of :file:`pyconfig.h`. 224 225 .. function:: get_makefile_filename() 226 227 Return the path of :file:`Makefile`. 228
