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.. highlight:: c
.. _init-config:
***********************************
Python Initialization Configuration
***********************************
.. versionadded:: 3.8
Python can be initialized with :c:func:`Py_InitializeFromConfig` and the
:c:type:`PyConfig` structure. It can be preinitialized with
:c:func:`Py_PreInitialize` and the :c:type:`PyPreConfig` structure.
There are two kinds of configuration:
* The :ref:`Python Configuration <init-python-config>` can be used to build a
customized Python which behaves as the regular Python. For example,
environment variables and command line arguments are used to configure
Python.
* The :ref:`Isolated Configuration <init-isolated-conf>` can be used to embed
Python into an application. It isolates Python from the system. For example,
environment variables are ignored, the LC_CTYPE locale is left unchanged and
no signal handler is registered.
The :c:func:`Py_RunMain` function can be used to write a customized Python
program.
See also :ref:`Initialization, Finalization, and Threads <initialization>`.
.. seealso::
:pep:`587` "Python Initialization Configuration".
Example
=======
Example of customized Python always running in isolated mode::
int main(int argc, char **argv)
{
PyStatus status;
PyConfig config;
PyConfig_InitPythonConfig(&config);
config.isolated = 1;
/* Decode command line arguments.
Implicitly preinitialize Python (in isolated mode). */
status = PyConfig_SetBytesArgv(&config, argc, argv);
if (PyStatus_Exception(status)) {
goto exception;
}
status = Py_InitializeFromConfig(&config);
if (PyStatus_Exception(status)) {
goto exception;
}
PyConfig_Clear(&config);
return Py_RunMain();
exception:
PyConfig_Clear(&config);
if (PyStatus_IsExit(status)) {
return status.exitcode;
}
/* Display the error message and exit the process with
non-zero exit code */
Py_ExitStatusException(status);
}
PyWideStringList
================
.. c:type:: PyWideStringList
List of ``wchar_t*`` strings.
If *length* is non-zero, *items* must be non-``NULL`` and all strings must be
non-``NULL``.
.. c:namespace:: NULL
Methods:
.. c:function:: PyStatus PyWideStringList_Append(PyWideStringList *list, const wchar_t *item)
Append *item* to *list*.
Python must be preinitialized to call this function.
.. c:function:: PyStatus PyWideStringList_Insert(PyWideStringList *list, Py_ssize_t index, const wchar_t *item)
Insert *item* into *list* at *index*.
If *index* is greater than or equal to *list* length, append *item* to
*list*.
*index* must be greater than or equal to ``0``.
Python must be preinitialized to call this function.
.. c:namespace:: PyWideStringList
Structure fields:
.. c:member:: Py_ssize_t length
List length.
.. c:member:: wchar_t** items
List items.
PyStatus
========
.. c:type:: PyStatus
Structure to store an initialization function status: success, error
or exit.
For an error, it can store the C function name which created the error.
Structure fields:
.. c:member:: int exitcode
Exit code. Argument passed to ``exit()``.
.. c:member:: const char *err_msg
Error message.
.. c:member:: const char *func
Name of the function which created an error, can be ``NULL``.
.. c:namespace:: NULL
Functions to create a status:
.. c:function:: PyStatus PyStatus_Ok(void)
Success.
.. c:function:: PyStatus PyStatus_Error(const char *err_msg)
Initialization error with a message.
*err_msg* must not be ``NULL``.
.. c:function:: PyStatus PyStatus_NoMemory(void)
Memory allocation failure (out of memory).
.. c:function:: PyStatus PyStatus_Exit(int exitcode)
Exit Python with the specified exit code.
Functions to handle a status:
.. c:function:: int PyStatus_Exception(PyStatus status)
Is the status an error or an exit? If true, the exception must be
handled; by calling :c:func:`Py_ExitStatusException` for example.
.. c:function:: int PyStatus_IsError(PyStatus status)
Is the result an error?
.. c:function:: int PyStatus_IsExit(PyStatus status)
Is the result an exit?
.. c:function:: void Py_ExitStatusException(PyStatus status)
Call ``exit(exitcode)`` if *status* is an exit. Print the error
message and exit with a non-zero exit code if *status* is an error. Must
only be called if ``PyStatus_Exception(status)`` is non-zero.
.. note::
Internally, Python uses macros which set ``PyStatus.func``,
whereas functions to create a status set ``func`` to ``NULL``.
Example::
PyStatus alloc(void **ptr, size_t size)
{
*ptr = PyMem_RawMalloc(size);
if (*ptr == NULL) {
return PyStatus_NoMemory();
}
return PyStatus_Ok();
}
int main(int argc, char **argv)
{
void *ptr;
PyStatus status = alloc(&ptr, 16);
if (PyStatus_Exception(status)) {
Py_ExitStatusException(status);
}
PyMem_Free(ptr);
return 0;
}
PyPreConfig
===========
.. c:type:: PyPreConfig
Structure used to preinitialize Python.
.. c:namespace:: NULL
Function to initialize a preconfiguration:
.. c:function:: void PyPreConfig_InitPythonConfig(PyPreConfig *preconfig)
Initialize the preconfiguration with :ref:`Python Configuration
<init-python-config>`.
.. c:function:: void PyPreConfig_InitIsolatedConfig(PyPreConfig *preconfig)
Initialize the preconfiguration with :ref:`Isolated Configuration
<init-isolated-conf>`.
.. c:namespace:: PyPreConfig
Structure fields:
.. c:member:: int allocator
Name of the Python memory allocators:
* ``PYMEM_ALLOCATOR_NOT_SET`` (``0``): don't change memory allocators
(use defaults).
* ``PYMEM_ALLOCATOR_DEFAULT`` (``1``): :ref:`default memory allocators
<default-memory-allocators>`.
* ``PYMEM_ALLOCATOR_DEBUG`` (``2``): :ref:`default memory allocators
<default-memory-allocators>` with :ref:`debug hooks
<pymem-debug-hooks>`.
* ``PYMEM_ALLOCATOR_MALLOC`` (``3``): use ``malloc()`` of the C library.
* ``PYMEM_ALLOCATOR_MALLOC_DEBUG`` (``4``): force usage of
``malloc()`` with :ref:`debug hooks <pymem-debug-hooks>`.
* ``PYMEM_ALLOCATOR_PYMALLOC`` (``5``): :ref:`Python pymalloc memory
allocator <pymalloc>`.
* ``PYMEM_ALLOCATOR_PYMALLOC_DEBUG`` (``6``): :ref:`Python pymalloc
memory allocator <pymalloc>` with :ref:`debug hooks
<pymem-debug-hooks>`.
* ``PYMEM_ALLOCATOR_MIMALLOC`` (``6``): use ``mimalloc``, a fast
malloc replacement.
* ``PYMEM_ALLOCATOR_MIMALLOC_DEBUG`` (``7``): use ``mimalloc``, a fast
malloc replacement with :ref:`debug hooks <pymem-debug-hooks>`.
``PYMEM_ALLOCATOR_PYMALLOC`` and ``PYMEM_ALLOCATOR_PYMALLOC_DEBUG`` are
not supported if Python is :option:`configured using --without-pymalloc
<--without-pymalloc>`.
``PYMEM_ALLOCATOR_MIMALLOC`` and ``PYMEM_ALLOCATOR_MIMALLOC_DEBUG`` are
not supported if Python is :option:`configured using --without-mimalloc
<--without-mimalloc>` or if the underlying atomic support isn't
available.
See :ref:`Memory Management <memory>`.
Default: ``PYMEM_ALLOCATOR_NOT_SET``.
.. c:member:: int configure_locale
Set the LC_CTYPE locale to the user preferred locale.
If equals to ``0``, set :c:member:`~PyPreConfig.coerce_c_locale` and
:c:member:`~PyPreConfig.coerce_c_locale_warn` members to ``0``.
See the :term:`locale encoding`.
Default: ``1`` in Python config, ``0`` in isolated config.
.. c:member:: int coerce_c_locale
If equals to ``2``, coerce the C locale.
If equals to ``1``, read the LC_CTYPE locale to decide if it should be
coerced.
See the :term:`locale encoding`.
Default: ``-1`` in Python config, ``0`` in isolated config.
.. c:member:: int coerce_c_locale_warn
If non-zero, emit a warning if the C locale is coerced.
Default: ``-1`` in Python config, ``0`` in isolated config.
.. c:member:: int dev_mode
:ref:`Python Development Mode <devmode>`: see
:c:member:`PyConfig.dev_mode`.
Default: ``-1`` in Python mode, ``0`` in isolated mode.
.. c:member:: int isolated
Isolated mode: see :c:member:`PyConfig.isolated`.
Default: ``0`` in Python mode, ``1`` in isolated mode.
.. c:member:: int legacy_windows_fs_encoding
If non-zero:
* Set :c:member:`PyPreConfig.utf8_mode` to ``0``,
* Set :c:member:`PyConfig.filesystem_encoding` to ``"mbcs"``,
* Set :c:member:`PyConfig.filesystem_errors` to ``"replace"``.
Initialized from the :envvar:`PYTHONLEGACYWINDOWSFSENCODING` environment
variable value.
Only available on Windows. ``#ifdef MS_WINDOWS`` macro can be used for
Windows specific code.
Default: ``0``.
.. c:member:: int parse_argv
If non-zero, :c:func:`Py_PreInitializeFromArgs` and
:c:func:`Py_PreInitializeFromBytesArgs` parse their ``argv`` argument the
same way the regular Python parses command line arguments: see
:ref:`Command Line Arguments <using-on-cmdline>`.
Default: ``1`` in Python config, ``0`` in isolated config.
.. c:member:: int use_environment
Use :ref:`environment variables <using-on-envvars>`? See
:c:member:`PyConfig.use_environment`.
Default: ``1`` in Python config and ``0`` in isolated config.
.. c:member:: int utf8_mode
If non-zero, enable the :ref:`Python UTF-8 Mode <utf8-mode>`.
Set to ``0`` or ``1`` by the :option:`-X utf8 <-X>` command line option
and the :envvar:`PYTHONUTF8` environment variable.
Also set to ``1`` if the ``LC_CTYPE`` locale is ``C`` or ``POSIX``.
Default: ``-1`` in Python config and ``0`` in isolated config.
.. _c-preinit:
Preinitialize Python with PyPreConfig
=====================================
The preinitialization of Python:
* Set the Python memory allocators (:c:member:`PyPreConfig.allocator`)
* Configure the LC_CTYPE locale (:term:`locale encoding`)
* Set the :ref:`Python UTF-8 Mode <utf8-mode>`
(:c:member:`PyPreConfig.utf8_mode`)
The current preconfiguration (``PyPreConfig`` type) is stored in
``_PyRuntime.preconfig``.
Functions to preinitialize Python:
.. c:function:: PyStatus Py_PreInitialize(const PyPreConfig *preconfig)
Preinitialize Python from *preconfig* preconfiguration.
*preconfig* must not be ``NULL``.
.. c:function:: PyStatus Py_PreInitializeFromBytesArgs(const PyPreConfig *preconfig, int argc, char * const *argv)
Preinitialize Python from *preconfig* preconfiguration.
Parse *argv* command line arguments (bytes strings) if
:c:member:`~PyPreConfig.parse_argv` of *preconfig* is non-zero.
*preconfig* must not be ``NULL``.
.. c:function:: PyStatus Py_PreInitializeFromArgs(const PyPreConfig *preconfig, int argc, wchar_t * const * argv)
Preinitialize Python from *preconfig* preconfiguration.
Parse *argv* command line arguments (wide strings) if
:c:member:`~PyPreConfig.parse_argv` of *preconfig* is non-zero.
*preconfig* must not be ``NULL``.
The caller is responsible to handle exceptions (error or exit) using
:c:func:`PyStatus_Exception` and :c:func:`Py_ExitStatusException`.
For :ref:`Python Configuration <init-python-config>`
(:c:func:`PyPreConfig_InitPythonConfig`), if Python is initialized with
command line arguments, the command line arguments must also be passed to
preinitialize Python, since they have an effect on the pre-configuration
like encodings. For example, the :option:`-X utf8 <-X>` command line option
enables the :ref:`Python UTF-8 Mode <utf8-mode>`.
``PyMem_SetAllocator()`` can be called after :c:func:`Py_PreInitialize` and
before :c:func:`Py_InitializeFromConfig` to install a custom memory allocator.
It can be called before :c:func:`Py_PreInitialize` if
:c:member:`PyPreConfig.allocator` is set to ``PYMEM_ALLOCATOR_NOT_SET``.
Python memory allocation functions like :c:func:`PyMem_RawMalloc` must not be
used before the Python preinitialization, whereas calling directly ``malloc()``
and ``free()`` is always safe. :c:func:`Py_DecodeLocale` must not be called
before the Python preinitialization.
Example using the preinitialization to enable
the :ref:`Python UTF-8 Mode <utf8-mode>`::
PyStatus status;
PyPreConfig preconfig;
PyPreConfig_InitPythonConfig(&preconfig);
preconfig.utf8_mode = 1;
status = Py_PreInitialize(&preconfig);
if (PyStatus_Exception(status)) {
Py_ExitStatusException(status);
}
/* at this point, Python speaks UTF-8 */
Py_Initialize();
/* ... use Python API here ... */
Py_Finalize();
PyConfig
========
.. c:type:: PyConfig
Structure containing most parameters to configure Python.
When done, the :c:func:`PyConfig_Clear` function must be used to release the
configuration memory.
.. c:namespace:: NULL
Structure methods:
.. c:function:: void PyConfig_InitPythonConfig(PyConfig *config)
Initialize configuration with the :ref:`Python Configuration
<init-python-config>`.
.. c:function:: void PyConfig_InitIsolatedConfig(PyConfig *config)
Initialize configuration with the :ref:`Isolated Configuration
<init-isolated-conf>`.
.. c:function:: PyStatus PyConfig_SetString(PyConfig *config, wchar_t * const *config_str, const wchar_t *str)
Copy the wide character string *str* into ``*config_str``.
:ref:`Preinitialize Python <c-preinit>` if needed.
.. c:function:: PyStatus PyConfig_SetBytesString(PyConfig *config, wchar_t * const *config_str, const char *str)
Decode *str* using :c:func:`Py_DecodeLocale` and set the result into
``*config_str``.
:ref:`Preinitialize Python <c-preinit>` if needed.
.. c:function:: PyStatus PyConfig_SetArgv(PyConfig *config, int argc, wchar_t * const *argv)
Set command line arguments (:c:member:`~PyConfig.argv` member of
*config*) from the *argv* list of wide character strings.
:ref:`Preinitialize Python <c-preinit>` if needed.
.. c:function:: PyStatus PyConfig_SetBytesArgv(PyConfig *config, int argc, char * const *argv)
Set command line arguments (:c:member:`~PyConfig.argv` member of
*config*) from the *argv* list of bytes strings. Decode bytes using
:c:func:`Py_DecodeLocale`.
:ref:`Preinitialize Python <c-preinit>` if needed.
.. c:function:: PyStatus PyConfig_SetWideStringList(PyConfig *config, PyWideStringList *list, Py_ssize_t length, wchar_t **items)
Set the list of wide strings *list* to *length* and *items*.
:ref:`Preinitialize Python <c-preinit>` if needed.
.. c:function:: PyStatus PyConfig_Read(PyConfig *config)
Read all Python configuration.
Fields which are already initialized are left unchanged.
Fields for :ref:`path configuration <init-path-config>` are no longer
calculated or modified when calling this function, as of Python 3.11.
The :c:func:`PyConfig_Read` function only parses
:c:member:`PyConfig.argv` arguments once: :c:member:`PyConfig.parse_argv`
is set to ``2`` after arguments are parsed. Since Python arguments are
stripped from :c:member:`PyConfig.argv`, parsing arguments twice would
parse the application options as Python options.
:ref:`Preinitialize Python <c-preinit>` if needed.
.. versionchanged:: 3.10
The :c:member:`PyConfig.argv` arguments are now only parsed once,
:c:member:`PyConfig.parse_argv` is set to ``2`` after arguments are
parsed, and arguments are only parsed if
:c:member:`PyConfig.parse_argv` equals ``1``.
.. versionchanged:: 3.11
:c:func:`PyConfig_Read` no longer calculates all paths, and so fields
listed under :ref:`Python Path Configuration <init-path-config>` may
no longer be updated until :c:func:`Py_InitializeFromConfig` is
called.
.. c:function:: void PyConfig_Clear(PyConfig *config)
Release configuration memory.
Most ``PyConfig`` methods :ref:`preinitialize Python <c-preinit>` if needed.
In that case, the Python preinitialization configuration
(:c:type:`PyPreConfig`) is based on the :c:type:`PyConfig`. If configuration
fields which are in common with :c:type:`PyPreConfig` are tuned, they must
be set before calling a :c:type:`PyConfig` method:
* :c:member:`PyConfig.dev_mode`
* :c:member:`PyConfig.isolated`
* :c:member:`PyConfig.parse_argv`
* :c:member:`PyConfig.use_environment`
Moreover, if :c:func:`PyConfig_SetArgv` or :c:func:`PyConfig_SetBytesArgv`
is used, this method must be called before other methods, since the
preinitialization configuration depends on command line arguments (if
:c:member:`~PyConfig.parse_argv` is non-zero).
The caller of these methods is responsible to handle exceptions (error or
exit) using ``PyStatus_Exception()`` and ``Py_ExitStatusException()``.
.. c:namespace:: PyConfig
Structure fields:
.. c:member:: PyWideStringList argv
.. index::
single: main()
single: argv (in module sys)
Set :data:`sys.argv` command line arguments based on
:c:member:`~PyConfig.argv`. These parameters are similar to those passed
to the program's :c:func:`main` function with the difference that the
first entry should refer to the script file to be executed rather than
the executable hosting the Python interpreter. If there isn't a script
that will be run, the first entry in :c:member:`~PyConfig.argv` can be an
empty string.
Set :c:member:`~PyConfig.parse_argv` to ``1`` to parse
:c:member:`~PyConfig.argv` the same way the regular Python parses Python
command line arguments and then to strip Python arguments from
:c:member:`~PyConfig.argv`.
If :c:member:`~PyConfig.argv` is empty, an empty string is added to
ensure that :data:`sys.argv` always exists and is never empty.
Default: ``NULL``.
See also the :c:member:`~PyConfig.orig_argv` member.
.. c:member:: int safe_path
If equals to zero, ``Py_RunMain()`` prepends a potentially unsafe path to
:data:`sys.path` at startup:
* If :c:member:`argv[0] <PyConfig.argv>` is equal to ``L"-m"``
(``python -m module``), prepend the current working directory.
* If running a script (``python script.py``), prepend the script's
directory. If it's a symbolic link, resolve symbolic links.
* Otherwise (``python -c code`` and ``python``), prepend an empty string,
which means the current working directory.
Set to ``1`` by the :option:`-P` command line option and the
:envvar:`PYTHONSAFEPATH` environment variable.
Default: ``0`` in Python config, ``1`` in isolated config.
.. versionadded:: 3.11
.. c:member:: wchar_t* base_exec_prefix
:data:`sys.base_exec_prefix`.
Default: ``NULL``.
Part of the :ref:`Python Path Configuration <init-path-config>` output.
See also :c:member:`PyConfig.exec_prefix`.
.. c:member:: wchar_t* base_executable
Python base executable: ``sys._base_executable``.
Set by the ``__PYVENV_LAUNCHER__`` environment variable.
Set from :c:member:`PyConfig.executable` if ``NULL``.
Default: ``NULL``.
Part of the :ref:`Python Path Configuration <init-path-config>` output.
See also :c:member:`PyConfig.executable`.
.. c:member:: wchar_t* base_prefix
:data:`sys.base_prefix`.
Default: ``NULL``.
Part of the :ref:`Python Path Configuration <init-path-config>` output.
See also :c:member:`PyConfig.prefix`.
.. c:member:: int buffered_stdio
If equals to ``0`` and :c:member:`~PyConfig.configure_c_stdio` is non-zero,
disable buffering on the C streams stdout and stderr.
Set to ``0`` by the :option:`-u` command line option and the
:envvar:`PYTHONUNBUFFERED` environment variable.
stdin is always opened in buffered mode.
Default: ``1``.
.. c:member:: int bytes_warning
If equals to ``1``, issue a warning when comparing :class:`bytes` or
:class:`bytearray` with :class:`str`, or comparing :class:`bytes` with
:class:`int`.
If equal or greater to ``2``, raise a :exc:`BytesWarning` exception in these
cases.
Incremented by the :option:`-b` command line option.
Default: ``0``.
.. c:member:: int warn_default_encoding
If non-zero, emit a :exc:`EncodingWarning` warning when :class:`io.TextIOWrapper`
uses its default encoding. See :ref:`io-encoding-warning` for details.
Default: ``0``.
.. versionadded:: 3.10
.. c:member:: int code_debug_ranges
If equals to ``0``, disables the inclusion of the end line and column
mappings in code objects. Also disables traceback printing carets to
specific error locations.
Set to ``0`` by the :envvar:`PYTHONNODEBUGRANGES` environment variable
and by the :option:`-X no_debug_ranges <-X>` command line option.
Default: ``1``.
.. versionadded:: 3.11
.. c:member:: wchar_t* check_hash_pycs_mode
Control the validation behavior of hash-based ``.pyc`` files:
value of the :option:`--check-hash-based-pycs` command line option.
Valid values:
- ``L"always"``: Hash the source file for invalidation regardless of
value of the 'check_source' flag.
- ``L"never"``: Assume that hash-based pycs always are valid.
- ``L"default"``: The 'check_source' flag in hash-based pycs
determines invalidation.
Default: ``L"default"``.
See also :pep:`552` "Deterministic pycs".
.. c:member:: int configure_c_stdio
If non-zero, configure C standard streams:
* On Windows, set the binary mode (``O_BINARY``) on stdin, stdout and
stderr.
* If :c:member:`~PyConfig.buffered_stdio` equals zero, disable buffering
of stdin, stdout and stderr streams.
* If :c:member:`~PyConfig.interactive` is non-zero, enable stream
buffering on stdin and stdout (only stdout on Windows).
Default: ``1`` in Python config, ``0`` in isolated config.
.. c:member:: int dev_mode
If non-zero, enable the :ref:`Python Development Mode <devmode>`.
Set to ``1`` by the :option:`-X dev <-X>` option and the
:envvar:`PYTHONDEVMODE` environment variable.
Default: ``-1`` in Python mode, ``0`` in isolated mode.
.. c:member:: int dump_refs
Dump Python references?
If non-zero, dump all objects which are still alive at exit.
Set to ``1`` by the :envvar:`PYTHONDUMPREFS` environment variable.
Needs a special build of Python with the ``Py_TRACE_REFS`` macro defined:
see the :option:`configure --with-trace-refs option <--with-trace-refs>`.
Default: ``0``.
.. c:member:: wchar_t* exec_prefix
The site-specific directory prefix where the platform-dependent Python
files are installed: :data:`sys.exec_prefix`.
Default: ``NULL``.
Part of the :ref:`Python Path Configuration <init-path-config>` output.
See also :c:member:`PyConfig.base_exec_prefix`.
.. c:member:: wchar_t* executable
The absolute path of the executable binary for the Python interpreter:
:data:`sys.executable`.
Default: ``NULL``.
Part of the :ref:`Python Path Configuration <init-path-config>` output.
See also :c:member:`PyConfig.base_executable`.
.. c:member:: int faulthandler
Enable faulthandler?
If non-zero, call :func:`faulthandler.enable` at startup.
Set to ``1`` by :option:`-X faulthandler <-X>` and the
:envvar:`PYTHONFAULTHANDLER` environment variable.
Default: ``-1`` in Python mode, ``0`` in isolated mode.
.. c:member:: wchar_t* filesystem_encoding
:term:`Filesystem encoding <filesystem encoding and error handler>`:
:func:`sys.getfilesystemencoding`.
On macOS, Android and VxWorks: use ``"utf-8"`` by default.
On Windows: use ``"utf-8"`` by default, or ``"mbcs"`` if
:c:member:`~PyPreConfig.legacy_windows_fs_encoding` of
:c:type:`PyPreConfig` is non-zero.
Default encoding on other platforms:
* ``"utf-8"`` if :c:member:`PyPreConfig.utf8_mode` is non-zero.
* ``"ascii"`` if Python detects that ``nl_langinfo(CODESET)`` announces
the ASCII encoding, whereas the ``mbstowcs()`` function
decodes from a different encoding (usually Latin1).
* ``"utf-8"`` if ``nl_langinfo(CODESET)`` returns an empty string.
* Otherwise, use the :term:`locale encoding`:
``nl_langinfo(CODESET)`` result.
At Python startup, the encoding name is normalized to the Python codec
name. For example, ``"ANSI_X3.4-1968"`` is replaced with ``"ascii"``.
See also the :c:member:`~PyConfig.filesystem_errors` member.
.. c:member:: wchar_t* filesystem_errors
:term:`Filesystem error handler <filesystem encoding and error handler>`:
:func:`sys.getfilesystemencodeerrors`.
On Windows: use ``"surrogatepass"`` by default, or ``"replace"`` if
:c:member:`~PyPreConfig.legacy_windows_fs_encoding` of
:c:type:`PyPreConfig` is non-zero.
On other platforms: use ``"surrogateescape"`` by default.
Supported error handlers:
* ``"strict"``
* ``"surrogateescape"``
* ``"surrogatepass"`` (only supported with the UTF-8 encoding)
See also the :c:member:`~PyConfig.filesystem_encoding` member.
.. c:member:: unsigned long hash_seed
.. c:member:: int use_hash_seed
Randomized hash function seed.
If :c:member:`~PyConfig.use_hash_seed` is zero, a seed is chosen randomly
at Python startup, and :c:member:`~PyConfig.hash_seed` is ignored.
Set by the :envvar:`PYTHONHASHSEED` environment variable.
Default *use_hash_seed* value: ``-1`` in Python mode, ``0`` in isolated
mode.
.. c:member:: wchar_t* home
Set the default Python "home" directory, that is, the location of the
standard Python libraries (see :envvar:`PYTHONHOME`).
Set by the :envvar:`PYTHONHOME` environment variable.
Default: ``NULL``.
Part of the :ref:`Python Path Configuration <init-path-config>` input.
.. c:member:: int import_time
If non-zero, profile import time.
Set the ``1`` by the :option:`-X importtime <-X>` option and the
:envvar:`PYTHONPROFILEIMPORTTIME` environment variable.
Default: ``0``.
.. c:member:: int inspect
Enter interactive mode after executing a script or a command.
If greater than ``0``, enable inspect: when a script is passed as first
argument or the -c option is used, enter interactive mode after executing
the script or the command, even when :data:`sys.stdin` does not appear to
be a terminal.
Incremented by the :option:`-i` command line option. Set to ``1`` if the
:envvar:`PYTHONINSPECT` environment variable is non-empty.
Default: ``0``.
.. c:member:: int install_signal_handlers
Install Python signal handlers?
Default: ``1`` in Python mode, ``0`` in isolated mode.
.. c:member:: int interactive
If greater than ``0``, enable the interactive mode (REPL).
Incremented by the :option:`-i` command line option.
Default: ``0``.
.. c:member:: int int_max_str_digits
Configures the :ref:`integer string conversion length limitation
<int_max_str_digits>`. An initial value of ``-1`` means the value will
be taken from the command line or environment or otherwise default to
4300 (:data:`sys.int_info.default_max_str_digits`). A value of ``0``
disables the limitation. Values greater than zero but less than 640
(:data:`sys.int_info.str_digits_check_threshold`) are unsupported and
will produce an error.
Configured by the :option:`-X int_max_str_digits <-X>` command line
flag or the :envvar:`PYTHONINTMAXSTRDIGITS` environment variable.
Default: ``-1`` in Python mode. 4300
(:data:`sys.int_info.default_max_str_digits`) in isolated mode.
.. versionadded:: 3.12
.. c:member:: int cpu_count
If the value of :c:member:`~PyConfig.cpu_count` is not ``-1`` then it will
override the return values of :func:`os.cpu_count`,
:func:`os.process_cpu_count`, and :func:`multiprocessing.cpu_count`.
Configured by the :samp:`-X cpu_count={n|default}` command line
flag or the :envvar:`PYTHON_CPU_COUNT` environment variable.
Default: ``-1``.
.. versionadded:: 3.13
.. c:member:: int isolated
If greater than ``0``, enable isolated mode:
* Set :c:member:`~PyConfig.safe_path` to ``1``:
don't prepend a potentially unsafe path to :data:`sys.path` at Python
startup, such as the current directory, the script's directory or an
empty string.
* Set :c:member:`~PyConfig.use_environment` to ``0``: ignore ``PYTHON``
environment variables.
* Set :c:member:`~PyConfig.user_site_directory` to ``0``: don't add the user
site directory to :data:`sys.path`.
* Python REPL doesn't import :mod:`readline` nor enable default readline
configuration on interactive prompts.
Set to ``1`` by the :option:`-I` command line option.
Default: ``0`` in Python mode, ``1`` in isolated mode.
See also the :ref:`Isolated Configuration <init-isolated-conf>` and
:c:member:`PyPreConfig.isolated`.
.. c:member:: int legacy_windows_stdio
If non-zero, use :class:`io.FileIO` instead of
:class:`!io._WindowsConsoleIO` for :data:`sys.stdin`, :data:`sys.stdout`
and :data:`sys.stderr`.
Set to ``1`` if the :envvar:`PYTHONLEGACYWINDOWSSTDIO` environment
variable is set to a non-empty string.
Only available on Windows. ``#ifdef MS_WINDOWS`` macro can be used for
Windows specific code.
Default: ``0``.
See also the :pep:`528` (Change Windows console encoding to UTF-8).
.. c:member:: int malloc_stats
If non-zero, dump statistics on :ref:`Python pymalloc memory allocator
<pymalloc>` at exit.
Set to ``1`` by the :envvar:`PYTHONMALLOCSTATS` environment variable.
The option is ignored if Python is :option:`configured using
the --without-pymalloc option <--without-pymalloc>`.
Default: ``0``.
.. c:member:: wchar_t* platlibdir
Platform library directory name: :data:`sys.platlibdir`.
Set by the :envvar:`PYTHONPLATLIBDIR` environment variable.
Default: value of the ``PLATLIBDIR`` macro which is set by the
:option:`configure --with-platlibdir option <--with-platlibdir>`
(default: ``"lib"``, or ``"DLLs"`` on Windows).
Part of the :ref:`Python Path Configuration <init-path-config>` input.
.. versionadded:: 3.9
.. versionchanged:: 3.11
This macro is now used on Windows to locate the standard
library extension modules, typically under ``DLLs``. However,
for compatibility, note that this value is ignored for any
non-standard layouts, including in-tree builds and virtual
environments.
.. c:member:: wchar_t* pythonpath_env
Module search paths (:data:`sys.path`) as a string separated by ``DELIM``
(:data:`os.pathsep`).
Set by the :envvar:`PYTHONPATH` environment variable.
Default: ``NULL``.
Part of the :ref:`Python Path Configuration <init-path-config>` input.
.. c:member:: PyWideStringList module_search_paths
.. c:member:: int module_search_paths_set
Module search paths: :data:`sys.path`.
If :c:member:`~PyConfig.module_search_paths_set` is equal to ``0``,
:c:func:`Py_InitializeFromConfig` will replace
:c:member:`~PyConfig.module_search_paths` and sets
:c:member:`~PyConfig.module_search_paths_set` to ``1``.
Default: empty list (``module_search_paths``) and ``0``
(``module_search_paths_set``).
Part of the :ref:`Python Path Configuration <init-path-config>` output.