1 :mod:`sysconfig` --- Provide access to Python's configuration information 2 ========================================================================= 3 4 .. module:: sysconfig 5 :synopsis: Python's configuration information 6 7 .. moduleauthor:: Tarek Ziad <tarek (a] ziade.org> 8 .. sectionauthor:: Tarek Ziad <tarek (a] ziade.org> 9 10 .. versionadded:: 3.2 11 12 **Source code:** :source:`Lib/sysconfig.py` 13 14 .. index:: 15 single: configuration information 16 17 -------------- 18 19 The :mod:`sysconfig` module provides access to Python's configuration 20 information like the list of installation paths and the configuration variables 21 relevant for the current platform. 22 23 Configuration variables 24 ----------------------- 25 26 A Python distribution contains a :file:`Makefile` and a :file:`pyconfig.h` 27 header file that are necessary to build both the Python binary itself and 28 third-party C extensions compiled using :mod:`distutils`. 29 30 :mod:`sysconfig` puts all variables found in these files in a dictionary that 31 can be accessed using :func:`get_config_vars` or :func:`get_config_var`. 32 33 Notice that on Windows, it's a much smaller set. 34 35 .. function:: get_config_vars(\*args) 36 37 With no arguments, return a dictionary of all configuration variables 38 relevant for the current platform. 39 40 With arguments, return a list of values that result from looking up each 41 argument in the configuration variable dictionary. 42 43 For each argument, if the value is not found, return ``None``. 44 45 46 .. function:: get_config_var(name) 47 48 Return the value of a single variable *name*. Equivalent to 49 ``get_config_vars().get(name)``. 50 51 If *name* is not found, return ``None``. 52 53 Example of usage:: 54 55 >>> import sysconfig 56 >>> sysconfig.get_config_var('Py_ENABLE_SHARED') 57 0 58 >>> sysconfig.get_config_var('LIBDIR') 59 '/usr/local/lib' 60 >>> sysconfig.get_config_vars('AR', 'CXX') 61 ['ar', 'g++'] 62 63 64 Installation paths 65 ------------------ 66 67 Python uses an installation scheme that differs depending on the platform and on 68 the installation options. These schemes are stored in :mod:`sysconfig` under 69 unique identifiers based on the value returned by :const:`os.name`. 70 71 Every new component that is installed using :mod:`distutils` or a 72 Distutils-based system will follow the same scheme to copy its file in the right 73 places. 74 75 Python currently supports seven schemes: 76 77 - *posix_prefix*: scheme for Posix platforms like Linux or Mac OS X. This is 78 the default scheme used when Python or a component is installed. 79 - *posix_home*: scheme for Posix platforms used when a *home* option is used 80 upon installation. This scheme is used when a component is installed through 81 Distutils with a specific home prefix. 82 - *posix_user*: scheme for Posix platforms used when a component is installed 83 through Distutils and the *user* option is used. This scheme defines paths 84 located under the user home directory. 85 - *nt*: scheme for NT platforms like Windows. 86 - *nt_user*: scheme for NT platforms, 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 ``'%d.%d' % sys.version_info[:2]``. 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 'os.uname()'), although the 177 exact information included depends on the OS; e.g., on Linux, the kernel 178 version isn't particularly important. 179 180 Examples of returned values: 181 182 - linux-i586 183 - linux-alpha (?) 184 - solaris-2.6-sun4u 185 186 Windows will return one of: 187 188 - win-amd64 (64bit Windows on AMD64, aka x86_64, Intel64, and EM64T) 189 - win32 (all others - specifically, sys.platform is returned) 190 191 Mac OS X can return: 192 193 - macosx-10.6-ppc 194 - macosx-10.4-ppc64 195 - macosx-10.3-i386 196 - macosx-10.4-fat 197 198 For other non-POSIX platforms, currently just returns :data:`sys.platform`. 199 200 201 .. function:: is_python_build() 202 203 Return ``True`` if the running Python interpreter was built from source and 204 is being run from its built location, and not from a location resulting from 205 e.g. running ``make install`` or installing via a binary installer. 206 207 208 .. function:: parse_config_h(fp[, vars]) 209 210 Parse a :file:`config.h`\-style file. 211 212 *fp* is a file-like object pointing to the :file:`config.h`\-like file. 213 214 A dictionary containing name/value pairs is returned. If an optional 215 dictionary is passed in as the second argument, it is used instead of a new 216 dictionary, and updated with the values read in the file. 217 218 219 .. function:: get_config_h_filename() 220 221 Return the path of :file:`pyconfig.h`. 222 223 .. function:: get_makefile_filename() 224 225 Return the path of :file:`Makefile`. 226 227 Using :mod:`sysconfig` as a script 228 ---------------------------------- 229 230 You can use :mod:`sysconfig` as a script with Python's *-m* option: 231 232 .. code-block:: shell-session 233 234 $ python -m sysconfig 235 Platform: "macosx-10.4-i386" 236 Python version: "3.2" 237 Current installation scheme: "posix_prefix" 238 239 Paths: 240 data = "/usr/local" 241 include = "/Users/tarek/Dev/svn.python.org/py3k/Include" 242 platinclude = "." 243 platlib = "/usr/local/lib/python3.2/site-packages" 244 platstdlib = "/usr/local/lib/python3.2" 245 purelib = "/usr/local/lib/python3.2/site-packages" 246 scripts = "/usr/local/bin" 247 stdlib = "/usr/local/lib/python3.2" 248 249 Variables: 250 AC_APPLE_UNIVERSAL_BUILD = "0" 251 AIX_GENUINE_CPLUSPLUS = "0" 252 AR = "ar" 253 ARFLAGS = "rc" 254 ... 255 256 This call will print in the standard output the information returned by 257 :func:`get_platform`, :func:`get_python_version`, :func:`get_path` and 258 :func:`get_config_vars`. 259
