# `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 | Dossier d'installation
--- | ---
stdlib | `userbase/lib/pythonX.Y`
platstdlib | `userbase/lib/pythonX.Y`
platlib | `userbase/lib/pythonX.Y/site-packages`
purelib | `userbase/lib/pythonX.Y/site-packages`
include | `userbase/include/pythonX.Y`
scripts | `userbase/bin`
données | `userbase`

### `nt_user`

Path | Dossier d'installation
--- | ---
stdlib | `userbase\PythonXY`
platstdlib | `userbase\PythonXY`
platlib | `userbase\PythonXY\site-packages`
purelib | `userbase\PythonXY\site-packages`
include | `userbase\PythonXY\Include`
scripts | `userbase\PythonXY\Scripts`
données | `userbase`

### `osx_framework_user`

Path | Dossier d'installation
--- | ---
stdlib | `userbase/lib/python`
platstdlib | `userbase/lib/python`
platlib | `userbase/lib/python/site-packages`
purelib | `userbase/lib/python/site-packages`
include | `userbase/include/pythonX.Y`
scripts | `userbase/bin`
données | `userbase`

## Home scheme

L’idée derrière le « schéma home » est que vous compilez et maintenez un espace personnel de modules Python. Le nom de ce schéma vient de l’idée du dossier « home » sur Unix, vu qu’il n’est pas rare pour un utilisateur UNIX d'agencer son dossier home avec la même disposition que `/usr/` ou `/usr/local/`. Ce schéma peut être utilisé par n’importe qui, quel que soit le système d’exploitation.

### `posix_home`

Path | Dossier d'installation
--- | ---
stdlib | `home/lib/python`
platstdlib | `home/lib/python`
platlib | `home/lib/python`
purelib | `home/lib/python`
include | `home/include/python`
platinclude | `home/include/python`
scripts | `home/bin`
données | `home`

## Prefix scheme

Le schéma de préfixe est utile quand vous voulez une installation de Python pour faire la compilation/l’installation (c.-à-d. exécuter le script setup), mais utiliser les modules tiers d’une installation Python différente (ou quelque chose qui ressemble à une installation Python différente). Si cela vous semble inhabituel, ça l’est — c’est pourquoi les schémas user et home viennent avant. Cependant, il y a au moins deux cas connus où le schéma prefix est utile.

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 | Dossier d'installation
--- | ---
stdlib | `prefix/lib/pythonX.Y`
platstdlib | `prefix/lib/pythonX.Y`
platlib | `prefix/lib/pythonX.Y/site-packages`
purelib | `prefix/lib/pythonX.Y/site-packages`
include | `prefix/include/pythonX.Y`
platinclude | `prefix/include/pythonX.Y`
scripts | `prefix/bin`
données | `prefix`

### `nt`

Path | Dossier d'installation
--- | ---
stdlib | `prefix\Lib`
platstdlib | `prefix\Lib`
platlib | `prefix\Lib\site-packages`
purelib | `prefix\Lib\site-packages`
include | `prefix\Include`
platinclude | `prefix\Include`
scripts | `prefix\Scripts`
données | `prefix`

## 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 to `sysconfig` functions that take a scheme argument, such as `get_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()` and `get_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 by `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 `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 a `KeyError`.

## 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. running `make 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()`.