sysconfig
--- Provide access to Python's configuration information¶
Ajouté dans la version 3.2.
Source code: Lib/sysconfig
The 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 Makefile
and a pyconfig.h
header file that are necessary to build both the Python binary itself and
third-party C extensions compiled using setuptools
.
sysconfig
puts all variables found in these files in a dictionary that
can be accessed using get_config_vars()
or get_config_var()
.
Notice that on Windows, it's a much smaller set.
- sysconfig.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
.
- sysconfig.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 sysconfig
under
unique identifiers based on the value returned by os.name
.
The schemes are used by package installers to determine where to copy files to.
Python currently supports nine schemes:
posix_prefix: scheme for POSIX platforms like Linux or macOS. This is the default scheme used when Python or a component is installed.
posix_home: scheme for POSIX platforms, when the home option is used. This scheme defines paths located under a specific home prefix.
posix_user: scheme for POSIX platforms, when the user option is used. This scheme defines paths located under the user's home directory (
site.USER_BASE
).posix_venv: scheme for
Python virtual environments
on POSIX platforms; by default it is the same as posix_prefix.nt: scheme for Windows. This is the default scheme used when Python or a component is installed.
nt_user: scheme for Windows, when the user option is used.
nt_venv: scheme for
Python virtual environments
on Windows; by default it is the same as nt.venv: a scheme with values from either posix_venv or nt_venv depending on the platform Python runs on.
osx_framework_user: scheme for macOS, 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 ('pure' Python).
include: directory for non-platform-specific header files for the Python C-API.
platinclude: directory for platform-specific header files for the Python C-API.
scripts: directory for script files.
data: directory for data files.
User scheme¶
This scheme is designed to be the most convenient solution for users that don't have write permission to the global site-packages directory or don't want to install into it.
Files will be installed into subdirectories of site.USER_BASE
(written
as userbase
hereafter). This scheme installs pure Python modules and
extension modules in the same location (also known as site.USER_SITE
).
posix_user
¶
Path |
Installation directory |
---|---|
stdlib |
|
platstdlib |
|
platlib |
|
purelib |
|
include |
|
scripts |
|
data |
|
nt_user
¶
Path |
Installation directory |
---|---|
stdlib |
|
platstdlib |
|
platlib |
|
purelib |
|
include |
|
scripts |
|
data |
|
osx_framework_user
¶
Path |
Installation directory |
---|---|
stdlib |
|
platstdlib |
|
platlib |
|
purelib |
|
include |
|
scripts |
|
data |
|
Home scheme¶
The idea behind the "home scheme" is that you build and maintain a personal
stash of Python modules. This scheme's name is derived from the idea of a
"home" directory on Unix, since it's not unusual for a Unix user to make their
home directory have a layout similar to /usr/
or /usr/local/
.
This scheme can be used by anyone, regardless of the operating system they
are installing for.
posix_home
¶
Path |
Installation directory |
---|---|
stdlib |
|
platstdlib |
|
platlib |
|
purelib |
|
include |
|
platinclude |
|
scripts |
|
data |
|
Prefix scheme¶
The "prefix scheme" is useful when you wish to use one Python installation to perform the build/install (i.e., to run the setup script), but install modules into the third-party module directory of a different Python installation (or something that looks like a different Python installation). If this sounds a trifle unusual, it is---that's why the user and home schemes come before. However, there are at least two known cases where the prefix scheme will be useful.
First, consider that many Linux distributions put Python in /usr
, rather
than the more traditional /usr/local
. This is entirely appropriate,
since in those cases Python is part of "the system" rather than a local add-on.
However, if you are installing Python modules from source, you probably want
them to go in /usr/local/lib/python2.X
rather than
/usr/lib/python2.X
.
Another possibility is a network filesystem where the name used to write to a
remote directory is different from the name used to read it: for example, the
Python interpreter accessed as /usr/local/bin/python
might search for
modules in /usr/local/lib/python2.X
, but those modules would have to
be installed to, say, /mnt/@server/export/lib/python2.X
.
posix_prefix
¶
Path |
Installation directory |
---|---|
stdlib |
|
platstdlib |
|
platlib |
|
purelib |
|
include |
|
platinclude |
|
scripts |
|
data |
|
nt
¶
Path |
Installation directory |
---|---|
stdlib |
|
platstdlib |
|
platlib |
|
purelib |
|
include |
|
platinclude |
|
scripts |
|
data |
|
Installation path functions¶
sysconfig
provides some functions to determine these installation paths.
- sysconfig.get_scheme_names()¶
Return a tuple containing all schemes currently supported in
sysconfig
.
- sysconfig.get_default_scheme()¶
Return the default scheme name for the current platform.
Ajouté dans la version 3.10: This function was previously named
_get_default_scheme()
and considered an implementation detail.Modifié dans la version 3.11: When Python runs from a virtual environment, the venv scheme is returned.
- sysconfig.get_preferred_scheme(key)¶
Return a preferred scheme name for an installation layout specified by key.
key must be either
"prefix"
,"home"
, or"user"
.The return value is a scheme name listed in
get_scheme_names()
. It can be passed tosysconfig
functions that take a scheme argument, such asget_paths()
.Ajouté dans la version 3.10.
Modifié dans la version 3.11: When Python runs from a virtual environment and
key="prefix"
, the venv scheme is returned.
- sysconfig._get_preferred_schemes()¶
Return a dict containing preferred scheme names on the current platform. Python implementers and redistributors may add their preferred schemes to the
_INSTALL_SCHEMES
module-level global value, and modify this function to return those scheme names, to e.g. provide different schemes for system and language package managers to use, so packages installed by either do not mix with those by the other.End users should not use this function, but
get_default_scheme()
andget_preferred_scheme()
instead.Ajouté dans la version 3.10.
- sysconfig.get_path_names()¶
Return a tuple containing all path names currently supported in
sysconfig
.
- sysconfig.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
get_path_names()
.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
.get_path()
will use the variables returned byget_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
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 returned by
get_config_vars()
.If expand is set to
False
, the path will not be expanded using the variables.If name is not found, raise a
KeyError
.
- sysconfig.get_paths([scheme[, vars[, expand]]])¶
Return a dictionary containing all installation paths corresponding to an installation scheme. See
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,
get_paths()
will raise aKeyError
.
Autres fonctions¶
- sysconfig.get_python_version()¶
Return the
MAJOR.MINOR
Python version number as a string. Similar to'%d.%d' % sys.version_info[:2]
.
- sysconfig.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.Exemples de valeurs renvoyées :
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)
macOS 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
.
- sysconfig.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. runningmake install
or installing via a binary installer.
- sysconfig.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.
- sysconfig.get_config_h_filename()¶
Return the path of
pyconfig.h
.
- sysconfig.get_makefile_filename()¶
Return the path of
Makefile
.
Using sysconfig
as a script¶
You can use 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
get_platform()
, get_python_version()
, get_path()
and
get_config_vars()
.