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<li><a class="reference internal" href="#">Operating System Utilities</a></li>
<li><a class="reference internal" href="#system-functions">System Functions</a></li>
<li><a class="reference internal" href="#process-control">Process Control</a></li>
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 <section id="operating-system-utilities">
<h1>Operating System Utilities<a class="headerlink" href="#operating-system-utilities" title="Permalink to this headline">¶</a></h1>
<dl class="c function">
<dt class="sig sig-object c" id="c.PyOS_FSPath">
<a class="reference internal" href="structures.html#c.PyObject" title="PyObject">PyObject</a> *PyOS_FSPath(<a class="reference internal" href="structures.html#c.PyObject" title="PyObject">PyObject</a> *path)<a class="headerlink" href="#c.PyOS_FSPath" title="Permalink to this definition">¶</a> </dt>
<dd>Return value: New reference. Part of the <a class="reference internal" href="stable.html#stable">Stable ABI</a> since version 3.6.Return the file system representation for path. If the object is a
<a class="reference internal" href="../library/stdtypes.html#str" title="str"><code class="xref py py-class docutils literal notranslate">str</code></a> or <a class="reference internal" href="../library/stdtypes.html#bytes" title="bytes"><code class="xref py py-class docutils literal notranslate">bytes</code></a> object, then its reference count is
incremented. If the object implements the <a class="reference internal" href="../library/os.html#os.PathLike" title="os.PathLike"><code class="xref py py-class docutils literal notranslate">os.PathLike</code></a> interface,
then <a class="reference internal" href="../library/os.html#os.PathLike.__fspath__" title="os.PathLike.__fspath__"><code class="xref py py-meth docutils literal notranslate">__fspath__()</code></a> is returned as long as it is a
<a class="reference internal" href="../library/stdtypes.html#str" title="str"><code class="xref py py-class docutils literal notranslate">str</code></a> or <a class="reference internal" href="../library/stdtypes.html#bytes" title="bytes"><code class="xref py py-class docutils literal notranslate">bytes</code></a> object. Otherwise <a class="reference internal" href="../library/exceptions.html#TypeError" title="TypeError"><code class="xref py py-exc docutils literal notranslate">TypeError</code></a> is raised
and <code class="docutils literal notranslate">NULL</code> is returned.
<div class="versionadded">
New in version 3.6.
</div>
</dd></dl>

<dl class="c function">
<dt class="sig sig-object c" id="c.Py_FdIsInteractive">
int Py_FdIsInteractive(FILE *fp, const char *filename)<a class="headerlink" href="#c.Py_FdIsInteractive" title="Permalink to this definition">¶</a> </dt>
<dd>Return true (nonzero) if the standard I/O file fp with name filename is
deemed interactive. This is the case for files for which <code class="docutils literal notranslate">isatty(fileno(fp))</code>
is true. If the global flag <a class="reference internal" href="init.html#c.Py_InteractiveFlag" title="Py_InteractiveFlag"><code class="xref c c-data docutils literal notranslate">Py_InteractiveFlag</code></a> is true, this function
also returns true if the filename pointer is <code class="docutils literal notranslate">NULL</code> or if the name is equal to
one of the strings <code class="docutils literal notranslate">'&lt;stdin&gt;'</code> or <code class="docutils literal notranslate">'???'</code>.
</dd></dl>

<dl class="c function">
<dt class="sig sig-object c" id="c.PyOS_BeforeFork">
void PyOS_BeforeFork()<a class="headerlink" href="#c.PyOS_BeforeFork" title="Permalink to this definition">¶</a> </dt>
<dd> Part of the <a class="reference internal" href="stable.html#stable">Stable ABI</a> on platforms with fork() since version 3.7.Function to prepare some internal state before a process fork. This
should be called before calling <code class="xref c c-func docutils literal notranslate">fork()</code> or any similar function
that clones the current process.
Only available on systems where <code class="xref c c-func docutils literal notranslate">fork()</code> is defined.
<div class="admonition warning">
Warning
The C <code class="xref c c-func docutils literal notranslate">fork()</code> call should only be made from the
<a class="reference internal" href="init.html#fork-and-threads">“main” thread</a> (of the
<a class="reference internal" href="init.html#sub-interpreter-support">“main” interpreter</a>). The same is
true for <code class="docutils literal notranslate">PyOS_BeforeFork()</code>.
</div>
<div class="versionadded">
New in version 3.7.
</div>
</dd></dl>

<dl class="c function">
<dt class="sig sig-object c" id="c.PyOS_AfterFork_Parent">
void PyOS_AfterFork_Parent()<a class="headerlink" href="#c.PyOS_AfterFork_Parent" title="Permalink to this definition">¶</a> </dt>
<dd> Part of the <a class="reference internal" href="stable.html#stable">Stable ABI</a> on platforms with fork() since version 3.7.Function to update some internal state after a process fork. This
should be called from the parent process after calling <code class="xref c c-func docutils literal notranslate">fork()</code>
or any similar function that clones the current process, regardless
of whether process cloning was successful.
Only available on systems where <code class="xref c c-func docutils literal notranslate">fork()</code> is defined.
<div class="admonition warning">
Warning
The C <code class="xref c c-func docutils literal notranslate">fork()</code> call should only be made from the
<a class="reference internal" href="init.html#fork-and-threads">“main” thread</a> (of the
<a class="reference internal" href="init.html#sub-interpreter-support">“main” interpreter</a>). The same is
true for <code class="docutils literal notranslate">PyOS_AfterFork_Parent()</code>.
</div>
<div class="versionadded">
New in version 3.7.
</div>
</dd></dl>

<dl class="c function">
<dt class="sig sig-object c" id="c.PyOS_AfterFork_Child">
void PyOS_AfterFork_Child()<a class="headerlink" href="#c.PyOS_AfterFork_Child" title="Permalink to this definition">¶</a> </dt>
<dd> Part of the <a class="reference internal" href="stable.html#stable">Stable ABI</a> on platforms with fork() since version 3.7.Function to update internal interpreter state after a process fork.
This must be called from the child process after calling <code class="xref c c-func docutils literal notranslate">fork()</code>,
or any similar function that clones the current process, if there is
any chance the process will call back into the Python interpreter.
Only available on systems where <code class="xref c c-func docutils literal notranslate">fork()</code> is defined.
<div class="admonition warning">
Warning
The C <code class="xref c c-func docutils literal notranslate">fork()</code> call should only be made from the
<a class="reference internal" href="init.html#fork-and-threads">“main” thread</a> (of the
<a class="reference internal" href="init.html#sub-interpreter-support">“main” interpreter</a>). The same is
true for <code class="docutils literal notranslate">PyOS_AfterFork_Child()</code>.
</div>
<div class="versionadded">
New in version 3.7.
</div>
<div class="admonition seealso">
See also
<a class="reference internal" href="../library/os.html#os.register_at_fork" title="os.register_at_fork"><code class="xref py py-func docutils literal notranslate">os.register_at_fork()</code></a> allows registering custom Python functions
to be called by <a class="reference internal" href="#c.PyOS_BeforeFork" title="PyOS_BeforeFork"><code class="xref c c-func docutils literal notranslate">PyOS_BeforeFork()</code></a>,
<a class="reference internal" href="#c.PyOS_AfterFork_Parent" title="PyOS_AfterFork_Parent"><code class="xref c c-func docutils literal notranslate">PyOS_AfterFork_Parent()</code></a> and <a class="reference internal" href="#c.PyOS_AfterFork_Child" title="PyOS_AfterFork_Child"><code class="xref c c-func docutils literal notranslate">PyOS_AfterFork_Child()</code></a>.
</div>
</dd></dl>

<dl class="c function">
<dt class="sig sig-object c" id="c.PyOS_AfterFork">
void PyOS_AfterFork()<a class="headerlink" href="#c.PyOS_AfterFork" title="Permalink to this definition">¶</a> </dt>
<dd> Part of the <a class="reference internal" href="stable.html#stable">Stable ABI</a> on platforms with fork().Function to update some internal state after a process fork; this should be
called in the new process if the Python interpreter will continue to be used.
If a new executable is loaded into the new process, this function does not need
to be called.
<div class="deprecated">
Deprecated since version 3.7: This function is superseded by <a class="reference internal" href="#c.PyOS_AfterFork_Child" title="PyOS_AfterFork_Child"><code class="xref c c-func docutils literal notranslate">PyOS_AfterFork_Child()</code></a>.
</div>
</dd></dl>

<dl class="c function">
<dt class="sig sig-object c" id="c.PyOS_CheckStack">
int PyOS_CheckStack()<a class="headerlink" href="#c.PyOS_CheckStack" title="Permalink to this definition">¶</a> </dt>
<dd> Part of the <a class="reference internal" href="stable.html#stable">Stable ABI</a> on platforms with USE_STACKCHECK since version 3.7.Return true when the interpreter runs out of stack space. This is a reliable
check, but is only available when <code class="xref py py-const docutils literal notranslate">USE_STACKCHECK</code> is defined (currently
on Windows using the Microsoft Visual C++ compiler). <code class="xref py py-const docutils literal notranslate">USE_STACKCHECK</code>
will be defined automatically; you should never change the definition in your
own code.
</dd></dl>

<dl class="c function">
<dt class="sig sig-object c" id="c.PyOS_getsig">
PyOS_sighandler_t PyOS_getsig(int i)<a class="headerlink" href="#c.PyOS_getsig" title="Permalink to this definition">¶</a> </dt>
<dd> Part of the <a class="reference internal" href="stable.html#stable">Stable ABI</a>.Return the current signal handler for signal i. This is a thin wrapper around
either <code class="xref c c-func docutils literal notranslate">sigaction()</code> or <code class="xref c c-func docutils literal notranslate">signal()</code>. Do not call those functions
directly! <code class="xref c c-type docutils literal notranslate">PyOS_sighandler_t</code> is a typedef alias for void (*)(int).
</dd></dl>

<dl class="c function">
<dt class="sig sig-object c" id="c.PyOS_setsig">
PyOS_sighandler_t PyOS_setsig(int i, PyOS_sighandler_t h)<a class="headerlink" href="#c.PyOS_setsig" title="Permalink to this definition">¶</a> </dt>
<dd> Part of the <a class="reference internal" href="stable.html#stable">Stable ABI</a>.Set the signal handler for signal i to be h; return the old signal handler.
This is a thin wrapper around either <code class="xref c c-func docutils literal notranslate">sigaction()</code> or <code class="xref c c-func docutils literal notranslate">signal()</code>. Do
not call those functions directly! <code class="xref c c-type docutils literal notranslate">PyOS_sighandler_t</code> is a typedef
alias for void (*)(int).
</dd></dl>

<dl class="c function">
<dt class="sig sig-object c" id="c.Py_DecodeLocale">
wchar_t *Py_DecodeLocale(const char *arg, size_t *size)<a class="headerlink" href="#c.Py_DecodeLocale" title="Permalink to this definition">¶</a> </dt>
<dd> Part of the <a class="reference internal" href="stable.html#stable">Stable ABI</a> since version 3.7.<div class="admonition warning">
Warning
This function should not be called directly: use the <a class="reference internal" href="init_config.html#c.PyConfig" title="PyConfig"><code class="xref c c-type docutils literal notranslate">PyConfig</code></a>
API with the <code class="xref c c-func docutils literal notranslate">PyConfig_SetBytesString()</code> function which ensures
that <a class="reference internal" href="init_config.html#c-preinit">Python is preinitialized</a>.
This function must not be called before <a class="reference internal" href="init_config.html#c-preinit">Python is preinitialized</a> and so that the LC_CTYPE locale is properly configured: see
the <a class="reference internal" href="init_config.html#c.Py_PreInitialize" title="Py_PreInitialize"><code class="xref c c-func docutils literal notranslate">Py_PreInitialize()</code></a> function.
</div>
Decode a byte string from the <a class="reference internal" href="../glossary.html#term-filesystem-encoding-and-error-handler">filesystem encoding and error handler</a>.
If the error handler is <a class="reference internal" href="../library/codecs.html#surrogateescape">surrogateescape error handler</a>, undecodable bytes are decoded as characters in range
U+DC80..U+DCFF; and if a byte sequence can be decoded as a surrogate
character, the bytes are escaped using the surrogateescape error handler
instead of decoding them.
Return a pointer to a newly allocated wide character string, use
<a class="reference internal" href="memory.html#c.PyMem_RawFree" title="PyMem_RawFree"><code class="xref c c-func docutils literal notranslate">PyMem_RawFree()</code></a> to free the memory. If size is not <code class="docutils literal notranslate">NULL</code>, write
the number of wide characters excluding the null character into <code class="docutils literal notranslate">*size</code>
Return <code class="docutils literal notranslate">NULL</code> on decoding error or memory allocation error. If size is
not <code class="docutils literal notranslate">NULL</code>, <code class="docutils literal notranslate">*size</code> is set to <code class="docutils literal notranslate">(size_t)-1</code> on memory error or set to
<code class="docutils literal notranslate">(size_t)-2</code> on decoding error.
The <a class="reference internal" href="../glossary.html#term-filesystem-encoding-and-error-handler">filesystem encoding and error handler</a> are selected by
<code class="xref c c-func docutils literal notranslate">PyConfig_Read()</code>: see <a class="reference internal" href="init_config.html#c.PyConfig.filesystem_encoding" title="PyConfig.filesystem_encoding"><code class="xref c c-member docutils literal notranslate">filesystem_encoding</code></a> and
<a class="reference internal" href="init_config.html#c.PyConfig.filesystem_errors" title="PyConfig.filesystem_errors"><code class="xref c c-member docutils literal notranslate">filesystem_errors</code></a> members of <a class="reference internal" href="init_config.html#c.PyConfig" title="PyConfig"><code class="xref c c-type docutils literal notranslate">PyConfig</code></a>.
Decoding errors should never happen, unless there is a bug in the C
library.
Use the <a class="reference internal" href="#c.Py_EncodeLocale" title="Py_EncodeLocale"><code class="xref c c-func docutils literal notranslate">Py_EncodeLocale()</code></a> function to encode the character string
back to a byte string.
<div class="admonition seealso">
See also
The <a class="reference internal" href="unicode.html#c.PyUnicode_DecodeFSDefaultAndSize" title="PyUnicode_DecodeFSDefaultAndSize"><code class="xref c c-func docutils literal notranslate">PyUnicode_DecodeFSDefaultAndSize()</code></a> and
<a class="reference internal" href="unicode.html#c.PyUnicode_DecodeLocaleAndSize" title="PyUnicode_DecodeLocaleAndSize"><code class="xref c c-func docutils literal notranslate">PyUnicode_DecodeLocaleAndSize()</code></a> functions.
</div>
<div class="versionadded">
New in version 3.5.
</div>
<div class="versionchanged">
Changed in version 3.7: The function now uses the UTF-8 encoding in the <a class="reference internal" href="../library/os.html#utf8-mode">Python UTF-8 Mode</a>.
</div>
<div class="versionchanged">
Changed in version 3.8: The function now uses the UTF-8 encoding on Windows if
<a class="reference internal" href="init.html#c.Py_LegacyWindowsFSEncodingFlag" title="Py_LegacyWindowsFSEncodingFlag"><code class="xref c c-data docutils literal notranslate">Py_LegacyWindowsFSEncodingFlag</code></a> is zero;
</div>
</dd></dl>

<dl class="c function">
<dt class="sig sig-object c" id="c.Py_EncodeLocale">
char *Py_EncodeLocale(const wchar_t *text, size_t *error_pos)<a class="headerlink" href="#c.Py_EncodeLocale" title="Permalink to this definition">¶</a> </dt>
<dd> Part of the <a class="reference internal" href="stable.html#stable">Stable ABI</a> since version 3.7.Encode a wide character string to the <a class="reference internal" href="../glossary.html#term-filesystem-encoding-and-error-handler">filesystem encoding and error
handler</a>. If the error handler is <a class="reference internal" href="../library/codecs.html#surrogateescape">surrogateescape error handler</a>, surrogate characters in the range U+DC80..U+DCFF are
converted to bytes 0x80..0xFF.
Return a pointer to a newly allocated byte string, use <a class="reference internal" href="memory.html#c.PyMem_Free" title="PyMem_Free"><code class="xref c c-func docutils literal notranslate">PyMem_Free()</code></a>
to free the memory. Return <code class="docutils literal notranslate">NULL</code> on encoding error or memory allocation
error.
If error_pos is not <code class="docutils literal notranslate">NULL</code>, <code class="docutils literal notranslate">*error_pos</code> is set to <code class="docutils literal notranslate">(size_t)-1</code> on
success, or set to the index of the invalid character on encoding error.
The <a class="reference internal" href="../glossary.html#term-filesystem-encoding-and-error-handler">filesystem encoding and error handler</a> are selected by
<code class="xref c c-func docutils literal notranslate">PyConfig_Read()</code>: see <a class="reference internal" href="init_config.html#c.PyConfig.filesystem_encoding" title="PyConfig.filesystem_encoding"><code class="xref c c-member docutils literal notranslate">filesystem_encoding</code></a> and
<a class="reference internal" href="init_config.html#c.PyConfig.filesystem_errors" title="PyConfig.filesystem_errors"><code class="xref c c-member docutils literal notranslate">filesystem_errors</code></a> members of <a class="reference internal" href="init_config.html#c.PyConfig" title="PyConfig"><code class="xref c c-type docutils literal notranslate">PyConfig</code></a>.
Use the <a class="reference internal" href="#c.Py_DecodeLocale" title="Py_DecodeLocale"><code class="xref c c-func docutils literal notranslate">Py_DecodeLocale()</code></a> function to decode the bytes string back
to a wide character string.
<div class="admonition warning">
Warning
This function must not be called before <a class="reference internal" href="init_config.html#c-preinit">Python is preinitialized</a> and so that the LC_CTYPE locale is properly configured: see
the <a class="reference internal" href="init_config.html#c.Py_PreInitialize" title="Py_PreInitialize"><code class="xref c c-func docutils literal notranslate">Py_PreInitialize()</code></a> function.
</div>
<div class="admonition seealso">
See also
The <a class="reference internal" href="unicode.html#c.PyUnicode_EncodeFSDefault" title="PyUnicode_EncodeFSDefault"><code class="xref c c-func docutils literal notranslate">PyUnicode_EncodeFSDefault()</code></a> and
<a class="reference internal" href="unicode.html#c.PyUnicode_EncodeLocale" title="PyUnicode_EncodeLocale"><code class="xref c c-func docutils literal notranslate">PyUnicode_EncodeLocale()</code></a> functions.
</div>
<div class="versionadded">
New in version 3.5.
</div>
<div class="versionchanged">
Changed in version 3.7: The function now uses the UTF-8 encoding in the <a class="reference internal" href="../library/os.html#utf8-mode">Python UTF-8 Mode</a>.
</div>
<div class="versionchanged">
Changed in version 3.8: The function now uses the UTF-8 encoding on Windows if
<a class="reference internal" href="init.html#c.Py_LegacyWindowsFSEncodingFlag" title="Py_LegacyWindowsFSEncodingFlag"><code class="xref c c-data docutils literal notranslate">Py_LegacyWindowsFSEncodingFlag</code></a> is zero.
</div>
</dd></dl>

</section>
<section id="system-functions">
<h1>System Functions<a class="headerlink" href="#system-functions" title="Permalink to this headline">¶</a></h1>
These are utility functions that make functionality from the <a class="reference internal" href="../library/sys.html#module-sys" title="sys: Access system-specific parameters and functions."><code class="xref py py-mod docutils literal notranslate">sys</code></a> module
accessible to C code. They all work with the current interpreter thread’s
<a class="reference internal" href="../library/sys.html#module-sys" title="sys: Access system-specific parameters and functions."><code class="xref py py-mod docutils literal notranslate">sys</code></a> module’s dict, which is contained in the internal thread state structure.
<dl class="c function">
<dt class="sig sig-object c" id="c.PySys_GetObject">
<a class="reference internal" href="structures.html#c.PyObject" title="PyObject">PyObject</a> *PySys_GetObject(const char *name)<a class="headerlink" href="#c.PySys_GetObject" title="Permalink to this definition">¶</a> </dt>
<dd>Return value: Borrowed reference. Part of the <a class="reference internal" href="stable.html#stable">Stable ABI</a>.Return the object name from the <a class="reference internal" href="../library/sys.html#module-sys" title="sys: Access system-specific parameters and functions."><code class="xref py py-mod docutils literal notranslate">sys</code></a> module or <code class="docutils literal notranslate">NULL</code> if it does
not exist, without setting an exception.
</dd></dl>

<dl class="c function">
<dt class="sig sig-object c" id="c.PySys_SetObject">
int PySys_SetObject(const char *name, <a class="reference internal" href="structures.html#c.PyObject" title="PyObject">PyObject</a> *v)<a class="headerlink" href="#c.PySys_SetObject" title="Permalink to this definition">¶</a> </dt>
<dd> Part of the <a class="reference internal" href="stable.html#stable">Stable ABI</a>.Set name in the <a class="reference internal" href="../library/sys.html#module-sys" title="sys: Access system-specific parameters and functions."><code class="xref py py-mod docutils literal notranslate">sys</code></a> module to v unless v is <code class="docutils literal notranslate">NULL</code>, in which
case name is deleted from the sys module. Returns <code class="docutils literal notranslate">0</code> on success, <code class="docutils literal notranslate">-1</code>
on error.
</dd></dl>

<dl class="c function">
<dt class="sig sig-object c" id="c.PySys_ResetWarnOptions">
void PySys_ResetWarnOptions()<a class="headerlink" href="#c.PySys_ResetWarnOptions" title="Permalink to this definition">¶</a> </dt>
<dd> Part of the <a class="reference internal" href="stable.html#stable">Stable ABI</a>.Reset <a class="reference internal" href="../library/sys.html#sys.warnoptions" title="sys.warnoptions"><code class="xref py py-data docutils literal notranslate">sys.warnoptions</code></a> to an empty list. This function may be
called prior to <a class="reference internal" href="init.html#c.Py_Initialize" title="Py_Initialize"><code class="xref c c-func docutils literal notranslate">Py_Initialize()</code></a>.
</dd></dl>

<dl class="c function">
<dt class="sig sig-object c" id="c.PySys_AddWarnOption">
void PySys_AddWarnOption(const wchar_t *s)<a class="headerlink" href="#c.PySys_AddWarnOption" title="Permalink to this definition">¶</a> </dt>
<dd> Part of the <a class="reference internal" href="stable.html#stable">Stable ABI</a>.Append s to <a class="reference internal" href="../library/sys.html#sys.warnoptions" title="sys.warnoptions"><code class="xref py py-data docutils literal notranslate">sys.warnoptions</code></a>. This function must be called prior
to <a class="reference internal" href="init.html#c.Py_Initialize" title="Py_Initialize"><code class="xref c c-func docutils literal notranslate">Py_Initialize()</code></a> in order to affect the warnings filter list.
</dd></dl>

<dl class="c function">
<dt class="sig sig-object c" id="c.PySys_AddWarnOptionUnicode">
void PySys_AddWarnOptionUnicode(<a class="reference internal" href="structures.html#c.PyObject" title="PyObject">PyObject</a> *unicode)<a class="headerlink" href="#c.PySys_AddWarnOptionUnicode" title="Permalink to this definition">¶</a> </dt>
<dd> Part of the <a class="reference internal" href="stable.html#stable">Stable ABI</a>.Append unicode to <a class="reference internal" href="../library/sys.html#sys.warnoptions" title="sys.warnoptions"><code class="xref py py-data docutils literal notranslate">sys.warnoptions</code></a>.
Note: this function is not currently usable from outside the CPython
implementation, as it must be called prior to the implicit import of
<a class="reference internal" href="../library/warnings.html#module-warnings" title="warnings: Issue warning messages and control their disposition."><code class="xref py py-mod docutils literal notranslate">warnings</code></a> in <a class="reference internal" href="init.html#c.Py_Initialize" title="Py_Initialize"><code class="xref c c-func docutils literal notranslate">Py_Initialize()</code></a> to be effective, but can’t be
called until enough of the runtime has been initialized to permit the
creation of Unicode objects.
</dd></dl>

<dl class="c function">
<dt class="sig sig-object c" id="c.PySys_SetPath">
void PySys_SetPath(const wchar_t *path)<a class="headerlink" href="#c.PySys_SetPath" title="Permalink to this definition">¶</a> </dt>
<dd> Part of the <a class="reference internal" href="stable.html#stable">Stable ABI</a>.Set <a class="reference internal" href="../library/sys.html#sys.path" title="sys.path"><code class="xref py py-data docutils literal notranslate">sys.path</code></a> to a list object of paths found in path which should
be a list of paths separated with the platform’s search path delimiter
(<code class="docutils literal notranslate">:</code> on Unix, <code class="docutils literal notranslate">;</code> on Windows).
</dd></dl>

<dl class="c function">
<dt class="sig sig-object c" id="c.PySys_WriteStdout">
void PySys_WriteStdout(const char *format, ...)<a class="headerlink" href="#c.PySys_WriteStdout" title="Permalink to this definition">¶</a> </dt>
<dd> Part of the <a class="reference internal" href="stable.html#stable">Stable ABI</a>.Write the output string described by format to <a class="reference internal" href="../library/sys.html#sys.stdout" title="sys.stdout"><code class="xref py py-data docutils literal notranslate">sys.stdout</code></a>. No
exceptions are raised, even if truncation occurs (see below).
format should limit the total size of the formatted output string to
1000 bytes or less – after 1000 bytes, the output string is truncated.
In particular, this means that no unrestricted “%s” formats should occur;
these should be limited using “%.&lt;N&gt;s” where &lt;N&gt; is a decimal number
calculated so that &lt;N&gt; plus the maximum size of other formatted text does not
exceed 1000 bytes. Also watch out for “%f”, which can print hundreds of
digits for very large numbers.
If a problem occurs, or <a class="reference internal" href="../library/sys.html#sys.stdout" title="sys.stdout"><code class="xref py py-data docutils literal notranslate">sys.stdout</code></a> is unset, the formatted message
is written to the real (C level) stdout.
</dd></dl>

<dl class="c function">
<dt class="sig sig-object c" id="c.PySys_WriteStderr">
void PySys_WriteStderr(const char *format, ...)<a class="headerlink" href="#c.PySys_WriteStderr" title="Permalink to this definition">¶</a> </dt>
<dd> Part of the <a class="reference internal" href="stable.html#stable">Stable ABI</a>.As <a class="reference internal" href="#c.PySys_WriteStdout" title="PySys_WriteStdout"><code class="xref c c-func docutils literal notranslate">PySys_WriteStdout()</code></a>, but write to <a class="reference internal" href="../library/sys.html#sys.stderr" title="sys.stderr"><code class="xref py py-data docutils literal notranslate">sys.stderr</code></a> or stderr
instead.
</dd></dl>

<dl class="c function">
<dt class="sig sig-object c" id="c.PySys_FormatStdout">
void PySys_FormatStdout(const char *format, ...)<a class="headerlink" href="#c.PySys_FormatStdout" title="Permalink to this definition">¶</a> </dt>
<dd> Part of the <a class="reference internal" href="stable.html#stable">Stable ABI</a>.Function similar to PySys_WriteStdout() but format the message using
<a class="reference internal" href="unicode.html#c.PyUnicode_FromFormatV" title="PyUnicode_FromFormatV"><code class="xref c c-func docutils literal notranslate">PyUnicode_FromFormatV()</code></a> and don’t truncate the message to an
arbitrary length.
<div class="versionadded">
New in version 3.2.
</div>
</dd></dl>

<dl class="c function">
<dt class="sig sig-object c" id="c.PySys_FormatStderr">
void PySys_FormatStderr(const char *format, ...)<a class="headerlink" href="#c.PySys_FormatStderr" title="Permalink to this definition">¶</a> </dt>
<dd> Part of the <a class="reference internal" href="stable.html#stable">Stable ABI</a>.As <a class="reference internal" href="#c.PySys_FormatStdout" title="PySys_FormatStdout"><code class="xref c c-func docutils literal notranslate">PySys_FormatStdout()</code></a>, but write to <a class="reference internal" href="../library/sys.html#sys.stderr" title="sys.stderr"><code class="xref py py-data docutils literal notranslate">sys.stderr</code></a> or stderr
instead.
<div class="versionadded">
New in version 3.2.
</div>
</dd></dl>

<dl class="c function">
<dt class="sig sig-object c" id="c.PySys_AddXOption">
void PySys_AddXOption(const wchar_t *s)<a class="headerlink" href="#c.PySys_AddXOption" title="Permalink to this definition">¶</a> </dt>
<dd> Part of the <a class="reference internal" href="stable.html#stable">Stable ABI</a> since version 3.7.Parse s as a set of <a class="reference internal" href="../using/cmdline.html#cmdoption-X"><code class="xref std std-option docutils literal notranslate">-X</code></a> options and add them to the current
options mapping as returned by <a class="reference internal" href="#c.PySys_GetXOptions" title="PySys_GetXOptions"><code class="xref c c-func docutils literal notranslate">PySys_GetXOptions()</code></a>. This function
may be called prior to <a class="reference internal" href="init.html#c.Py_Initialize" title="Py_Initialize"><code class="xref c c-func docutils literal notranslate">Py_Initialize()</code></a>.
<div class="versionadded">
New in version 3.2.
</div>
</dd></dl>

<dl class="c function">
<dt class="sig sig-object c" id="c.PySys_GetXOptions">
<a class="reference internal" href="structures.html#c.PyObject" title="PyObject">PyObject</a> *PySys_GetXOptions()<a class="headerlink" href="#c.PySys_GetXOptions" title="Permalink to this definition">¶</a> </dt>
<dd>Return value: Borrowed reference. Part of the <a class="reference internal" href="stable.html#stable">Stable ABI</a> since version 3.7.Return the current dictionary of <a class="reference internal" href="../using/cmdline.html#cmdoption-X"><code class="xref std std-option docutils literal notranslate">-X</code></a> options, similarly to
<a class="reference internal" href="../library/sys.html#sys._xoptions" title="sys._xoptions"><code class="xref py py-data docutils literal notranslate">sys._xoptions</code></a>. On error, <code class="docutils literal notranslate">NULL</code> is returned and an exception is
set.
<div class="versionadded">
New in version 3.2.
</div>
</dd></dl>

<dl class="c function">
<dt class="sig sig-object c" id="c.PySys_Audit">
int PySys_Audit(const char *event, const char *format, ...)<a class="headerlink" href="#c.PySys_Audit" title="Permalink to this definition">¶</a> </dt>
<dd>Raise an auditing event with any active hooks. Return zero for success
and non-zero with an exception set on failure.
If any hooks have been added, format and other arguments will be used
to construct a tuple to pass. Apart from <code class="docutils literal notranslate">N</code>, the same format characters
as used in <a class="reference internal" href="arg.html#c.Py_BuildValue" title="Py_BuildValue"><code class="xref c c-func docutils literal notranslate">Py_BuildValue()</code></a> are available. If the built value is not
a tuple, it will be added into a single-element tuple. (The <code class="docutils literal notranslate">N</code> format
option consumes a reference, but since there is no way to know whether
arguments to this function will be consumed, using it may cause reference
leaks.)
Note that <code class="docutils literal notranslate">#</code> format characters should always be treated as
<a class="reference internal" href="intro.html#c.Py_ssize_t" title="Py_ssize_t"><code class="xref c c-type docutils literal notranslate">Py_ssize_t</code></a>, regardless of whether <code class="docutils literal notranslate">PY_SSIZE_T_CLEAN</code> was defined.
<a class="reference internal" href="../library/sys.html#sys.audit" title="sys.audit"><code class="xref py py-func docutils literal notranslate">sys.audit()</code></a> performs the same function from Python code.
<div class="versionadded">
New in version 3.8.
</div>
<div class="versionchanged">
Changed in version 3.8.2: Require <a class="reference internal" href="intro.html#c.Py_ssize_t" title="Py_ssize_t"><code class="xref c c-type docutils literal notranslate">Py_ssize_t</code></a> for <code class="docutils literal notranslate">#</code> format characters. Previously, an
unavoidable deprecation warning was raised.
</div>
</dd></dl>

<dl class="c function">
<dt class="sig sig-object c" id="c.PySys_AddAuditHook">
int PySys_AddAuditHook(Py_AuditHookFunction hook, void *userData)<a class="headerlink" href="#c.PySys_AddAuditHook" title="Permalink to this definition">¶</a> </dt>
<dd>Append the callable hook to the list of active auditing hooks.
Return zero on success
and non-zero on failure. If the runtime has been initialized, also set an
error on failure. Hooks added through this API are called for all
interpreters created by the runtime.
The userData pointer is passed into the hook function. Since hook
functions may be called from different runtimes, this pointer should not
refer directly to Python state.
This function is safe to call before <a class="reference internal" href="init.html#c.Py_Initialize" title="Py_Initialize"><code class="xref c c-func docutils literal notranslate">Py_Initialize()</code></a>. When called
after runtime initialization, existing audit hooks are notified and may
silently abort the operation by raising an error subclassed from
<a class="reference internal" href="../library/exceptions.html#Exception" title="Exception"><code class="xref py py-class docutils literal notranslate">Exception</code></a> (other errors will not be silenced).
The hook function is of type int (*)(const char *event, <a class="reference internal" href="structures.html#c.PyObject" title="PyObject">PyObject</a> *args, void *userData), where args is guaranteed to be a
<a class="reference internal" href="tuple.html#c.PyTupleObject" title="PyTupleObject"><code class="xref c c-type docutils literal notranslate">PyTupleObject</code></a>. The hook function is always called with the GIL
held by the Python interpreter that raised the event.
See <a class="pep reference external" href="https://www.python.org/dev/peps/pep-0578">PEP 578</a> for a detailed description of auditing. Functions in the
runtime and standard library that raise events are listed in the
<a class="reference internal" href="../library/audit_events.html#audit-events">audit events table</a>.
Details are in each function’s documentation.
If the interpreter is initialized, this function raises a auditing event
<code class="docutils literal notranslate">sys.addaudithook</code> with no arguments. If any existing hooks raise an
exception derived from <a class="reference internal" href="../library/exceptions.html#Exception" title="Exception"><code class="xref py py-class docutils literal notranslate">Exception</code></a>, the new hook will not be
added and the exception is cleared. As a result, callers cannot assume
that their hook has been added unless they control all existing hooks.

<div class="versionadded">
New in version 3.8.
</div>
</dd></dl>

</section>
<section id="process-control">
<h1>Process Control<a class="headerlink" href="#process-control" title="Permalink to this headline">¶</a></h1>
<dl class="c function">
<dt class="sig sig-object c" id="c.Py_FatalError">
void Py_FatalError(const char *message)<a class="headerlink" href="#c.Py_FatalError" title="Permalink to this definition">¶</a> </dt>
<dd> Part of the <a class="reference internal" href="stable.html#stable">Stable ABI</a>.Print a fatal error message and kill the process. No cleanup is performed.
This function should only be invoked when a condition is detected that would
make it dangerous to continue using the Python interpreter; e.g., when the
object administration appears to be corrupted. On Unix, the standard C library
function <code class="xref c c-func docutils literal notranslate">abort()</code> is called which will attempt to produce a <code class="file docutils literal notranslate">core</code>
file.
The <code class="docutils literal notranslate">Py_FatalError()</code> function is replaced with a macro which logs
automatically the name of the current function, unless the
<code class="docutils literal notranslate">Py_LIMITED_API</code> macro is defined.
<div class="versionchanged">
Changed in version 3.9: Log the function name automatically.
</div>
</dd></dl>

<dl class="c function">
<dt class="sig sig-object c" id="c.Py_Exit">
void Py_Exit(int status)<a class="headerlink" href="#c.Py_Exit" title="Permalink to this definition">¶</a> </dt>
<dd> Part of the <a class="reference internal" href="stable.html#stable">Stable ABI</a>.Exit the current process. This calls <a class="reference internal" href="init.html#c.Py_FinalizeEx" title="Py_FinalizeEx"><code class="xref c c-func docutils literal notranslate">Py_FinalizeEx()</code></a> and then calls the
standard C library function <code class="docutils literal notranslate">exit(status)</code>. If <a class="reference internal" href="init.html#c.Py_FinalizeEx" title="Py_FinalizeEx"><code class="xref c c-func docutils literal notranslate">Py_FinalizeEx()</code></a>
indicates an error, the exit status is set to 120.
<div class="versionchanged">
Changed in version 3.6: Errors from finalization no longer ignored.
</div>
</dd></dl>

<dl class="c function">
<dt class="sig sig-object c" id="c.Py_AtExit">
int Py_AtExit(void (*func)())<a class="headerlink" href="#c.Py_AtExit" title="Permalink to this definition">¶</a> </dt>
<dd> Part of the <a class="reference internal" href="stable.html#stable">Stable ABI</a>.Register a cleanup function to be called by <a class="reference internal" href="init.html#c.Py_FinalizeEx" title="Py_FinalizeEx"><code class="xref c c-func docutils literal notranslate">Py_FinalizeEx()</code></a>. The cleanup
function will be called with no arguments and should return no value. At most
32 cleanup functions can be registered. When the registration is successful,
<a class="reference internal" href="#c.Py_AtExit" title="Py_AtExit"><code class="xref c c-func docutils literal notranslate">Py_AtExit()</code></a> returns <code class="docutils literal notranslate">0</code>; on failure, it returns <code class="docutils literal notranslate">-1</code>. The cleanup
function registered last is called first. Each cleanup function will be called
at most once. Since Python’s internal finalization will have completed before
the cleanup function, no Python APIs should be called by func.
</dd></dl>

</section>

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<li><a class="reference internal" href="#">Operating System Utilities</a></li>
<li><a class="reference internal" href="#system-functions">System Functions</a></li>
<li><a class="reference internal" href="#process-control">Process Control</a></li>
</ul>

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