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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">
<span id="os"></span><h1>Operating System Utilities<a class="headerlink" href="#operating-system-utilities" title="Link to this heading">¶</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"><span class="n"><span class="pre">PyObject</span></span></a><span class="w"> </span><span class="p"><span class="pre">*</span></span><span class="sig-name descname"><span class="n"><span class="pre">PyOS_FSPath</span></span></span><span class="sig-paren">(</span><a class="reference internal" href="structures.html#c.PyObject" title="PyObject"><span class="n"><span class="pre">PyObject</span></span></a><span class="w"> </span><span class="p"><span class="pre">*</span></span><span class="n"><span class="pre">path</span></span><span class="sig-paren">)</span><a class="headerlink" href="#c.PyOS_FSPath" title="Link to this definition">¶</a><br /></dt>
<dd><em class="refcount">Return value: New reference.</em><em class="stableabi"> Part of the <a class="reference internal" href="stable.html#stable"><span class="std std-ref">Stable ABI</span></a> since version 3.6.</em><p>Return the file system representation for <em>path</em>. 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"><span class="pre">str</span></code></a> or <a class="reference internal" href="../library/stdtypes.html#bytes" title="bytes"><code class="xref py py-class docutils literal notranslate"><span class="pre">bytes</span></code></a> object, then a new
<a class="reference internal" href="../glossary.html#term-strong-reference"><span class="xref std std-term">strong reference</span></a> is returned.
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"><span class="pre">os.PathLike</span></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"><span class="pre">__fspath__()</span></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"><span class="pre">str</span></code></a> or <a class="reference internal" href="../library/stdtypes.html#bytes" title="bytes"><code class="xref py py-class docutils literal notranslate"><span class="pre">bytes</span></code></a> object. Otherwise <a class="reference internal" href="../library/exceptions.html#TypeError" title="TypeError"><code class="xref py py-exc docutils literal notranslate"><span class="pre">TypeError</span></code></a> is raised
and <code class="docutils literal notranslate"><span class="pre">NULL</span></code> is returned.</p>
<div class="versionadded">
<p><span class="versionmodified added">New in version 3.6.</span></p>
</div>
</dd></dl>

<dl class="c function">
<dt class="sig sig-object c" id="c.Py_FdIsInteractive">
<span class="kt"><span class="pre">int</span></span><span class="w"> </span><span class="sig-name descname"><span class="n"><span class="pre">Py_FdIsInteractive</span></span></span><span class="sig-paren">(</span><span class="n"><span class="pre">FILE</span></span><span class="w"> </span><span class="p"><span class="pre">*</span></span><span class="n"><span class="pre">fp</span></span>, <span class="k"><span class="pre">const</span></span><span class="w"> </span><span class="kt"><span class="pre">char</span></span><span class="w"> </span><span class="p"><span class="pre">*</span></span><span class="n"><span class="pre">filename</span></span><span class="sig-paren">)</span><a class="headerlink" href="#c.Py_FdIsInteractive" title="Link to this definition">¶</a><br /></dt>
<dd><p>Return true (nonzero) if the standard I/O file <em>fp</em> with name <em>filename</em> is
deemed interactive.  This is the case for files for which <code class="docutils literal notranslate"><span class="pre">isatty(fileno(fp))</span></code>
is true.  If the <a class="reference internal" href="init_config.html#c.PyConfig.interactive" title="PyConfig.interactive"><code class="xref c c-member docutils literal notranslate"><span class="pre">PyConfig.interactive</span></code></a> is non-zero, this function
also returns true if the <em>filename</em> pointer is <code class="docutils literal notranslate"><span class="pre">NULL</span></code> or if the name is equal to
one of the strings <code class="docutils literal notranslate"><span class="pre">'&lt;stdin&gt;'</span></code> or <code class="docutils literal notranslate"><span class="pre">'???'</span></code>.</p>
<p>This function must not be called before Python is initialized.</p>
</dd></dl>

<dl class="c function">
<dt class="sig sig-object c" id="c.PyOS_BeforeFork">
<span class="kt"><span class="pre">void</span></span><span class="w"> </span><span class="sig-name descname"><span class="n"><span class="pre">PyOS_BeforeFork</span></span></span><span class="sig-paren">(</span><span class="sig-paren">)</span><a class="headerlink" href="#c.PyOS_BeforeFork" title="Link to this definition">¶</a><br /></dt>
<dd><em class="stableabi"> Part of the <a class="reference internal" href="stable.html#stable"><span class="std std-ref">Stable ABI</span></a> on platforms with fork() since version 3.7.</em><p>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"><span class="pre">fork()</span></code> or any similar function
that clones the current process.
Only available on systems where <code class="xref c c-func docutils literal notranslate"><span class="pre">fork()</span></code> is defined.</p>
<div class="admonition warning">
<p class="admonition-title">Warning</p>
<p>The C <code class="xref c c-func docutils literal notranslate"><span class="pre">fork()</span></code> call should only be made from the
<a class="reference internal" href="init.html#fork-and-threads"><span class="std std-ref">“main” thread</span></a> (of the
<a class="reference internal" href="init.html#sub-interpreter-support"><span class="std std-ref">“main” interpreter</span></a>).  The same is
true for <code class="docutils literal notranslate"><span class="pre">PyOS_BeforeFork()</span></code>.</p>
</div>
<div class="versionadded">
<p><span class="versionmodified added">New in version 3.7.</span></p>
</div>
</dd></dl>

<dl class="c function">
<dt class="sig sig-object c" id="c.PyOS_AfterFork_Parent">
<span class="kt"><span class="pre">void</span></span><span class="w"> </span><span class="sig-name descname"><span class="n"><span class="pre">PyOS_AfterFork_Parent</span></span></span><span class="sig-paren">(</span><span class="sig-paren">)</span><a class="headerlink" href="#c.PyOS_AfterFork_Parent" title="Link to this definition">¶</a><br /></dt>
<dd><em class="stableabi"> Part of the <a class="reference internal" href="stable.html#stable"><span class="std std-ref">Stable ABI</span></a> on platforms with fork() since version 3.7.</em><p>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"><span class="pre">fork()</span></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"><span class="pre">fork()</span></code> is defined.</p>
<div class="admonition warning">
<p class="admonition-title">Warning</p>
<p>The C <code class="xref c c-func docutils literal notranslate"><span class="pre">fork()</span></code> call should only be made from the
<a class="reference internal" href="init.html#fork-and-threads"><span class="std std-ref">“main” thread</span></a> (of the
<a class="reference internal" href="init.html#sub-interpreter-support"><span class="std std-ref">“main” interpreter</span></a>).  The same is
true for <code class="docutils literal notranslate"><span class="pre">PyOS_AfterFork_Parent()</span></code>.</p>
</div>
<div class="versionadded">
<p><span class="versionmodified added">New in version 3.7.</span></p>
</div>
</dd></dl>

<dl class="c function">
<dt class="sig sig-object c" id="c.PyOS_AfterFork_Child">
<span class="kt"><span class="pre">void</span></span><span class="w"> </span><span class="sig-name descname"><span class="n"><span class="pre">PyOS_AfterFork_Child</span></span></span><span class="sig-paren">(</span><span class="sig-paren">)</span><a class="headerlink" href="#c.PyOS_AfterFork_Child" title="Link to this definition">¶</a><br /></dt>
<dd><em class="stableabi"> Part of the <a class="reference internal" href="stable.html#stable"><span class="std std-ref">Stable ABI</span></a> on platforms with fork() since version 3.7.</em><p>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"><span class="pre">fork()</span></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"><span class="pre">fork()</span></code> is defined.</p>
<div class="admonition warning">
<p class="admonition-title">Warning</p>
<p>The C <code class="xref c c-func docutils literal notranslate"><span class="pre">fork()</span></code> call should only be made from the
<a class="reference internal" href="init.html#fork-and-threads"><span class="std std-ref">“main” thread</span></a> (of the
<a class="reference internal" href="init.html#sub-interpreter-support"><span class="std std-ref">“main” interpreter</span></a>).  The same is
true for <code class="docutils literal notranslate"><span class="pre">PyOS_AfterFork_Child()</span></code>.</p>
</div>
<div class="versionadded">
<p><span class="versionmodified added">New in version 3.7.</span></p>
</div>
<div class="admonition seealso">
<p class="admonition-title">See also</p>
<p><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"><span class="pre">os.register_at_fork()</span></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"><span class="pre">PyOS_BeforeFork()</span></code></a>,
<a class="reference internal" href="#c.PyOS_AfterFork_Parent" title="PyOS_AfterFork_Parent"><code class="xref c c-func docutils literal notranslate"><span class="pre">PyOS_AfterFork_Parent()</span></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"><span class="pre">PyOS_AfterFork_Child()</span></code></a>.</p>
</div>
</dd></dl>

<dl class="c function">
<dt class="sig sig-object c" id="c.PyOS_AfterFork">
<span class="kt"><span class="pre">void</span></span><span class="w"> </span><span class="sig-name descname"><span class="n"><span class="pre">PyOS_AfterFork</span></span></span><span class="sig-paren">(</span><span class="sig-paren">)</span><a class="headerlink" href="#c.PyOS_AfterFork" title="Link to this definition">¶</a><br /></dt>
<dd><em class="stableabi"> Part of the <a class="reference internal" href="stable.html#stable"><span class="std std-ref">Stable ABI</span></a> on platforms with fork().</em><p>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.</p>
<div class="deprecated">
<p><span class="versionmodified deprecated">Deprecated since version 3.7: </span>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"><span class="pre">PyOS_AfterFork_Child()</span></code></a>.</p>
</div>
</dd></dl>

<dl class="c function">
<dt class="sig sig-object c" id="c.PyOS_CheckStack">
<span class="kt"><span class="pre">int</span></span><span class="w"> </span><span class="sig-name descname"><span class="n"><span class="pre">PyOS_CheckStack</span></span></span><span class="sig-paren">(</span><span class="sig-paren">)</span><a class="headerlink" href="#c.PyOS_CheckStack" title="Link to this definition">¶</a><br /></dt>
<dd><em class="stableabi"> Part of the <a class="reference internal" href="stable.html#stable"><span class="std std-ref">Stable ABI</span></a> on platforms with USE_STACKCHECK since version 3.7.</em><p id="index-0">Return true when the interpreter runs out of stack space.  This is a reliable
check, but is only available when <code class="xref c c-macro docutils literal notranslate"><span class="pre">USE_STACKCHECK</span></code> is defined (currently
on certain versions of Windows using the Microsoft Visual C++ compiler).
<code class="xref c c-macro docutils literal notranslate"><span class="pre">USE_STACKCHECK</span></code> will be defined automatically; you should never
change the definition in your own code.</p>
</dd></dl>

<dl class="c type">
<dt class="sig sig-object c" id="c.PyOS_sighandler_t">
<span class="k"><span class="pre">typedef</span></span><span class="w"> </span><span class="kt"><span class="pre">void</span></span><span class="w"> </span><span class="p"><span class="pre">(</span></span><span class="p"><span class="pre">*</span></span><span class="sig-name descname"><span class="n"><span class="pre">PyOS_sighandler_t</span></span></span><span class="p"><span class="pre">)</span></span><span class="p"><span class="pre">(</span></span><span class="kt"><span class="pre">int</span></span><span class="p"><span class="pre">)</span></span><a class="headerlink" href="#c.PyOS_sighandler_t" title="Link to this definition">¶</a><br /></dt>
<dd><em class="stableabi"> Part of the <a class="reference internal" href="stable.html#stable"><span class="std std-ref">Stable ABI</span></a>.</em></dd></dl>

<dl class="c function">
<dt class="sig sig-object c" id="c.PyOS_getsig">
<a class="reference internal" href="#c.PyOS_sighandler_t" title="PyOS_sighandler_t"><span class="n"><span class="pre">PyOS_sighandler_t</span></span></a><span class="w"> </span><span class="sig-name descname"><span class="n"><span class="pre">PyOS_getsig</span></span></span><span class="sig-paren">(</span><span class="kt"><span class="pre">int</span></span><span class="w"> </span><span class="n"><span class="pre">i</span></span><span class="sig-paren">)</span><a class="headerlink" href="#c.PyOS_getsig" title="Link to this definition">¶</a><br /></dt>
<dd><em class="stableabi"> Part of the <a class="reference internal" href="stable.html#stable"><span class="std std-ref">Stable ABI</span></a>.</em><p>Return the current signal handler for signal <em>i</em>.  This is a thin wrapper around
either <code class="xref c c-func docutils literal notranslate"><span class="pre">sigaction()</span></code> or <code class="xref c c-func docutils literal notranslate"><span class="pre">signal()</span></code>.  Do not call those functions
directly!</p>
</dd></dl>

<dl class="c function">
<dt class="sig sig-object c" id="c.PyOS_setsig">
<a class="reference internal" href="#c.PyOS_sighandler_t" title="PyOS_sighandler_t"><span class="n"><span class="pre">PyOS_sighandler_t</span></span></a><span class="w"> </span><span class="sig-name descname"><span class="n"><span class="pre">PyOS_setsig</span></span></span><span class="sig-paren">(</span><span class="kt"><span class="pre">int</span></span><span class="w"> </span><span class="n"><span class="pre">i</span></span>, <a class="reference internal" href="#c.PyOS_sighandler_t" title="PyOS_sighandler_t"><span class="n"><span class="pre">PyOS_sighandler_t</span></span></a><span class="w"> </span><span class="n"><span class="pre">h</span></span><span class="sig-paren">)</span><a class="headerlink" href="#c.PyOS_setsig" title="Link to this definition">¶</a><br /></dt>
<dd><em class="stableabi"> Part of the <a class="reference internal" href="stable.html#stable"><span class="std std-ref">Stable ABI</span></a>.</em><p>Set the signal handler for signal <em>i</em> to be <em>h</em>; return the old signal handler.
This is a thin wrapper around either <code class="xref c c-func docutils literal notranslate"><span class="pre">sigaction()</span></code> or <code class="xref c c-func docutils literal notranslate"><span class="pre">signal()</span></code>.  Do
not call those functions directly!</p>
</dd></dl>

<dl class="c function">
<dt class="sig sig-object c" id="c.Py_DecodeLocale">
<span class="n"><span class="pre">wchar_t</span></span><span class="w"> </span><span class="p"><span class="pre">*</span></span><span class="sig-name descname"><span class="n"><span class="pre">Py_DecodeLocale</span></span></span><span class="sig-paren">(</span><span class="k"><span class="pre">const</span></span><span class="w"> </span><span class="kt"><span class="pre">char</span></span><span class="w"> </span><span class="p"><span class="pre">*</span></span><span class="n"><span class="pre">arg</span></span>, <span class="n"><span class="pre">size_t</span></span><span class="w"> </span><span class="p"><span class="pre">*</span></span><span class="n"><span class="pre">size</span></span><span class="sig-paren">)</span><a class="headerlink" href="#c.Py_DecodeLocale" title="Link to this definition">¶</a><br /></dt>
<dd><em class="stableabi"> Part of the <a class="reference internal" href="stable.html#stable"><span class="std std-ref">Stable ABI</span></a> since version 3.7.</em><div class="admonition warning">
<p class="admonition-title">Warning</p>
<p>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"><span class="pre">PyConfig</span></code></a>
API with the <a class="reference internal" href="init_config.html#c.PyConfig_SetBytesString" title="PyConfig_SetBytesString"><code class="xref c c-func docutils literal notranslate"><span class="pre">PyConfig_SetBytesString()</span></code></a> function which ensures
that <a class="reference internal" href="init_config.html#c-preinit"><span class="std std-ref">Python is preinitialized</span></a>.</p>
<p>This function must not be called before <a class="reference internal" href="init_config.html#c-preinit"><span class="std std-ref">Python is preinitialized</span></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"><span class="pre">Py_PreInitialize()</span></code></a> function.</p>
</div>
<p>Decode a byte string from the <a class="reference internal" href="../glossary.html#term-filesystem-encoding-and-error-handler"><span class="xref std std-term">filesystem encoding and error handler</span></a>.
If the error handler is <a class="reference internal" href="../library/codecs.html#surrogateescape"><span class="std std-ref">surrogateescape error handler</span></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.</p>
<p>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"><span class="pre">PyMem_RawFree()</span></code></a> to free the memory. If size is not <code class="docutils literal notranslate"><span class="pre">NULL</span></code>, write
the number of wide characters excluding the null character into <code class="docutils literal notranslate"><span class="pre">*size</span></code></p>
<p>Return <code class="docutils literal notranslate"><span class="pre">NULL</span></code> on decoding error or memory allocation error. If <em>size</em> is
not <code class="docutils literal notranslate"><span class="pre">NULL</span></code>, <code class="docutils literal notranslate"><span class="pre">*size</span></code> is set to <code class="docutils literal notranslate"><span class="pre">(size_t)-1</span></code> on memory error or set to
<code class="docutils literal notranslate"><span class="pre">(size_t)-2</span></code> on decoding error.</p>
<p>The <a class="reference internal" href="../glossary.html#term-filesystem-encoding-and-error-handler"><span class="xref std std-term">filesystem encoding and error handler</span></a> are selected by
<a class="reference internal" href="init_config.html#c.PyConfig_Read" title="PyConfig_Read"><code class="xref c c-func docutils literal notranslate"><span class="pre">PyConfig_Read()</span></code></a>: 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"><span class="pre">filesystem_encoding</span></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"><span class="pre">filesystem_errors</span></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"><span class="pre">PyConfig</span></code></a>.</p>
<p>Decoding errors should never happen, unless there is a bug in the C
library.</p>
<p>Use the <a class="reference internal" href="#c.Py_EncodeLocale" title="Py_EncodeLocale"><code class="xref c c-func docutils literal notranslate"><span class="pre">Py_EncodeLocale()</span></code></a> function to encode the character string
back to a byte string.</p>
<div class="admonition seealso">
<p class="admonition-title">See also</p>
<p>The <a class="reference internal" href="unicode.html#c.PyUnicode_DecodeFSDefaultAndSize" title="PyUnicode_DecodeFSDefaultAndSize"><code class="xref c c-func docutils literal notranslate"><span class="pre">PyUnicode_DecodeFSDefaultAndSize()</span></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"><span class="pre">PyUnicode_DecodeLocaleAndSize()</span></code></a> functions.</p>
</div>
<div class="versionadded">
<p><span class="versionmodified added">New in version 3.5.</span></p>
</div>
<div class="versionchanged">
<p><span class="versionmodified changed">Changed in version 3.7: </span>The function now uses the UTF-8 encoding in the <a class="reference internal" href="../library/os.html#utf8-mode"><span class="std std-ref">Python UTF-8 Mode</span></a>.</p>
</div>
<div class="versionchanged">
<p><span class="versionmodified changed">Changed in version 3.8: </span>The function now uses the UTF-8 encoding on Windows if
<a class="reference internal" href="init_config.html#c.PyPreConfig.legacy_windows_fs_encoding" title="PyPreConfig.legacy_windows_fs_encoding"><code class="xref c c-member docutils literal notranslate"><span class="pre">PyPreConfig.legacy_windows_fs_encoding</span></code></a> is zero;</p>
</div>
</dd></dl>

<dl class="c function">
<dt class="sig sig-object c" id="c.Py_EncodeLocale">
<span class="kt"><span class="pre">char</span></span><span class="w"> </span><span class="p"><span class="pre">*</span></span><span class="sig-name descname"><span class="n"><span class="pre">Py_EncodeLocale</span></span></span><span class="sig-paren">(</span><span class="k"><span class="pre">const</span></span><span class="w"> </span><span class="n"><span class="pre">wchar_t</span></span><span class="w"> </span><span class="p"><span class="pre">*</span></span><span class="n"><span class="pre">text</span></span>, <span class="n"><span class="pre">size_t</span></span><span class="w"> </span><span class="p"><span class="pre">*</span></span><span class="n"><span class="pre">error_pos</span></span><span class="sig-paren">)</span><a class="headerlink" href="#c.Py_EncodeLocale" title="Link to this definition">¶</a><br /></dt>
<dd><em class="stableabi"> Part of the <a class="reference internal" href="stable.html#stable"><span class="std std-ref">Stable ABI</span></a> since version 3.7.</em><p>Encode a wide character string to the <a class="reference internal" href="../glossary.html#term-filesystem-encoding-and-error-handler"><span class="xref std std-term">filesystem encoding and error
handler</span></a>. If the error handler is <a class="reference internal" href="../library/codecs.html#surrogateescape"><span class="std std-ref">surrogateescape error handler</span></a>, surrogate characters in the range U+DC80..U+DCFF are
converted to bytes 0x80..0xFF.</p>
<p>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"><span class="pre">PyMem_Free()</span></code></a>
to free the memory. Return <code class="docutils literal notranslate"><span class="pre">NULL</span></code> on encoding error or memory allocation
error.</p>
<p>If error_pos is not <code class="docutils literal notranslate"><span class="pre">NULL</span></code>, <code class="docutils literal notranslate"><span class="pre">*error_pos</span></code> is set to <code class="docutils literal notranslate"><span class="pre">(size_t)-1</span></code> on
success,  or set to the index of the invalid character on encoding error.</p>
<p>The <a class="reference internal" href="../glossary.html#term-filesystem-encoding-and-error-handler"><span class="xref std std-term">filesystem encoding and error handler</span></a> are selected by
<a class="reference internal" href="init_config.html#c.PyConfig_Read" title="PyConfig_Read"><code class="xref c c-func docutils literal notranslate"><span class="pre">PyConfig_Read()</span></code></a>: 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"><span class="pre">filesystem_encoding</span></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"><span class="pre">filesystem_errors</span></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"><span class="pre">PyConfig</span></code></a>.</p>
<p>Use the <a class="reference internal" href="#c.Py_DecodeLocale" title="Py_DecodeLocale"><code class="xref c c-func docutils literal notranslate"><span class="pre">Py_DecodeLocale()</span></code></a> function to decode the bytes string back
to a wide character string.</p>
<div class="admonition warning">
<p class="admonition-title">Warning</p>
<p>This function must not be called before <a class="reference internal" href="init_config.html#c-preinit"><span class="std std-ref">Python is preinitialized</span></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"><span class="pre">Py_PreInitialize()</span></code></a> function.</p>
</div>
<div class="admonition seealso">
<p class="admonition-title">See also</p>
<p>The <a class="reference internal" href="unicode.html#c.PyUnicode_EncodeFSDefault" title="PyUnicode_EncodeFSDefault"><code class="xref c c-func docutils literal notranslate"><span class="pre">PyUnicode_EncodeFSDefault()</span></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"><span class="pre">PyUnicode_EncodeLocale()</span></code></a> functions.</p>
</div>
<div class="versionadded">
<p><span class="versionmodified added">New in version 3.5.</span></p>
</div>
<div class="versionchanged">
<p><span class="versionmodified changed">Changed in version 3.7: </span>The function now uses the UTF-8 encoding in the <a class="reference internal" href="../library/os.html#utf8-mode"><span class="std std-ref">Python UTF-8 Mode</span></a>.</p>
</div>
<div class="versionchanged">
<p><span class="versionmodified changed">Changed in version 3.8: </span>The function now uses the UTF-8 encoding on Windows if
<a class="reference internal" href="init_config.html#c.PyPreConfig.legacy_windows_fs_encoding" title="PyPreConfig.legacy_windows_fs_encoding"><code class="xref c c-member docutils literal notranslate"><span class="pre">PyPreConfig.legacy_windows_fs_encoding</span></code></a> is zero.</p>
</div>
</dd></dl>

</section>
<section id="system-functions">
<span id="systemfunctions"></span><h1>System Functions<a class="headerlink" href="#system-functions" title="Link to this heading">¶</a></h1>
<p>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"><span class="pre">sys</span></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"><span class="pre">sys</span></code></a> module’s dict, which is contained in the internal thread state structure.</p>
<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"><span class="n"><span class="pre">PyObject</span></span></a><span class="w"> </span><span class="p"><span class="pre">*</span></span><span class="sig-name descname"><span class="n"><span class="pre">PySys_GetObject</span></span></span><span class="sig-paren">(</span><span class="k"><span class="pre">const</span></span><span class="w"> </span><span class="kt"><span class="pre">char</span></span><span class="w"> </span><span class="p"><span class="pre">*</span></span><span class="n"><span class="pre">name</span></span><span class="sig-paren">)</span><a class="headerlink" href="#c.PySys_GetObject" title="Link to this definition">¶</a><br /></dt>
<dd><em class="refcount">Return value: Borrowed reference.</em><em class="stableabi"> Part of the <a class="reference internal" href="stable.html#stable"><span class="std std-ref">Stable ABI</span></a>.</em><p>Return the object <em>name</em> 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"><span class="pre">sys</span></code></a> module or <code class="docutils literal notranslate"><span class="pre">NULL</span></code> if it does
not exist, without setting an exception.</p>
</dd></dl>

<dl class="c function">
<dt class="sig sig-object c" id="c.PySys_SetObject">
<span class="kt"><span class="pre">int</span></span><span class="w"> </span><span class="sig-name descname"><span class="n"><span class="pre">PySys_SetObject</span></span></span><span class="sig-paren">(</span><span class="k"><span class="pre">const</span></span><span class="w"> </span><span class="kt"><span class="pre">char</span></span><span class="w"> </span><span class="p"><span class="pre">*</span></span><span class="n"><span class="pre">name</span></span>, <a class="reference internal" href="structures.html#c.PyObject" title="PyObject"><span class="n"><span class="pre">PyObject</span></span></a><span class="w"> </span><span class="p"><span class="pre">*</span></span><span class="n"><span class="pre">v</span></span><span class="sig-paren">)</span><a class="headerlink" href="#c.PySys_SetObject" title="Link to this definition">¶</a><br /></dt>
<dd><em class="stableabi"> Part of the <a class="reference internal" href="stable.html#stable"><span class="std std-ref">Stable ABI</span></a>.</em><p>Set <em>name</em> 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"><span class="pre">sys</span></code></a> module to <em>v</em> unless <em>v</em> is <code class="docutils literal notranslate"><span class="pre">NULL</span></code>, in which
case <em>name</em> is deleted from the sys module. Returns <code class="docutils literal notranslate"><span class="pre">0</span></code> on success, <code class="docutils literal notranslate"><span class="pre">-1</span></code>
on error.</p>
</dd></dl>

<dl class="c function">
<dt class="sig sig-object c" id="c.PySys_ResetWarnOptions">
<span class="kt"><span class="pre">void</span></span><span class="w"> </span><span class="sig-name descname"><span class="n"><span class="pre">PySys_ResetWarnOptions</span></span></span><span class="sig-paren">(</span><span class="sig-paren">)</span><a class="headerlink" href="#c.PySys_ResetWarnOptions" title="Link to this definition">¶</a><br /></dt>
<dd><em class="stableabi"> Part of the <a class="reference internal" href="stable.html#stable"><span class="std std-ref">Stable ABI</span></a>.</em><p>Reset <a class="reference internal" href="../library/sys.html#sys.warnoptions" title="sys.warnoptions"><code class="xref py py-data docutils literal notranslate"><span class="pre">sys.warnoptions</span></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"><span class="pre">Py_Initialize()</span></code></a>.</p>
</dd></dl>

<dl class="c function">
<dt class="sig sig-object c" id="c.PySys_AddWarnOption">
<span class="kt"><span class="pre">void</span></span><span class="w"> </span><span class="sig-name descname"><span class="n"><span class="pre">PySys_AddWarnOption</span></span></span><span class="sig-paren">(</span><span class="k"><span class="pre">const</span></span><span class="w"> </span><span class="n"><span class="pre">wchar_t</span></span><span class="w"> </span><span class="p"><span class="pre">*</span></span><span class="n"><span class="pre">s</span></span><span class="sig-paren">)</span><a class="headerlink" href="#c.PySys_AddWarnOption" title="Link to this definition">¶</a><br /></dt>
<dd><em class="stableabi"> Part of the <a class="reference internal" href="stable.html#stable"><span class="std std-ref">Stable ABI</span></a>.</em><p>This API is kept for backward compatibility: setting
<a class="reference internal" href="init_config.html#c.PyConfig.warnoptions" title="PyConfig.warnoptions"><code class="xref c c-member docutils literal notranslate"><span class="pre">PyConfig.warnoptions</span></code></a> should be used instead, see <a class="reference internal" href="init_config.html#init-config"><span class="std std-ref">Python
Initialization Configuration</span></a>.</p>
<p>Append <em>s</em> to <a class="reference internal" href="../library/sys.html#sys.warnoptions" title="sys.warnoptions"><code class="xref py py-data docutils literal notranslate"><span class="pre">sys.warnoptions</span></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"><span class="pre">Py_Initialize()</span></code></a> in order to affect the warnings filter list.</p>
<div class="deprecated">
<p><span class="versionmodified deprecated">Deprecated since version 3.11.</span></p>
</div>
</dd></dl>

<dl class="c function">
<dt class="sig sig-object c" id="c.PySys_AddWarnOptionUnicode">
<span class="kt"><span class="pre">void</span></span><span class="w"> </span><span class="sig-name descname"><span class="n"><span class="pre">PySys_AddWarnOptionUnicode</span></span></span><span class="sig-paren">(</span><a class="reference internal" href="structures.html#c.PyObject" title="PyObject"><span class="n"><span class="pre">PyObject</span></span></a><span class="w"> </span><span class="p"><span class="pre">*</span></span><span class="n"><span class="pre">unicode</span></span><span class="sig-paren">)</span><a class="headerlink" href="#c.PySys_AddWarnOptionUnicode" title="Link to this definition">¶</a><br /></dt>
<dd><em class="stableabi"> Part of the <a class="reference internal" href="stable.html#stable"><span class="std std-ref">Stable ABI</span></a>.</em><p>This API is kept for backward compatibility: setting
<a class="reference internal" href="init_config.html#c.PyConfig.warnoptions" title="PyConfig.warnoptions"><code class="xref c c-member docutils literal notranslate"><span class="pre">PyConfig.warnoptions</span></code></a> should be used instead, see <a class="reference internal" href="init_config.html#init-config"><span class="std std-ref">Python
Initialization Configuration</span></a>.</p>
<p>Append <em>unicode</em> to <a class="reference internal" href="../library/sys.html#sys.warnoptions" title="sys.warnoptions"><code class="xref py py-data docutils literal notranslate"><span class="pre">sys.warnoptions</span></code></a>.</p>
<p>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"><span class="pre">warnings</span></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"><span class="pre">Py_Initialize()</span></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.</p>
<div class="deprecated">
<p><span class="versionmodified deprecated">Deprecated since version 3.11.</span></p>
</div>
</dd></dl>

<dl class="c function">
<dt class="sig sig-object c" id="c.PySys_SetPath">
<span class="kt"><span class="pre">void</span></span><span class="w"> </span><span class="sig-name descname"><span class="n"><span class="pre">PySys_SetPath</span></span></span><span class="sig-paren">(</span><span class="k"><span class="pre">const</span></span><span class="w"> </span><span class="n"><span class="pre">wchar_t</span></span><span class="w"> </span><span class="p"><span class="pre">*</span></span><span class="n"><span class="pre">path</span></span><span class="sig-paren">)</span><a class="headerlink" href="#c.PySys_SetPath" title="Link to this definition">¶</a><br /></dt>
<dd><em class="stableabi"> Part of the <a class="reference internal" href="stable.html#stable"><span class="std std-ref">Stable ABI</span></a>.</em><p>This API is kept for backward compatibility: setting
<a class="reference internal" href="init_config.html#c.PyConfig.module_search_paths" title="PyConfig.module_search_paths"><code class="xref c c-member docutils literal notranslate"><span class="pre">PyConfig.module_search_paths</span></code></a> and
<a class="reference internal" href="init_config.html#c.PyConfig.module_search_paths_set" title="PyConfig.module_search_paths_set"><code class="xref c c-member docutils literal notranslate"><span class="pre">PyConfig.module_search_paths_set</span></code></a> should be used instead, see
<a class="reference internal" href="init_config.html#init-config"><span class="std std-ref">Python Initialization Configuration</span></a>.</p>
<p>Set <a class="reference internal" href="../library/sys.html#sys.path" title="sys.path"><code class="xref py py-data docutils literal notranslate"><span class="pre">sys.path</span></code></a> to a list object of paths found in <em>path</em> which should
be a list of paths separated with the platform’s search path delimiter
(<code class="docutils literal notranslate"><span class="pre">:</span></code> on Unix, <code class="docutils literal notranslate"><span class="pre">;</span></code> on Windows).</p>
<div class="deprecated">
<p><span class="versionmodified deprecated">Deprecated since version 3.11.</span></p>
</div>
</dd></dl>

<dl class="c function">
<dt class="sig sig-object c" id="c.PySys_WriteStdout">
<span class="kt"><span class="pre">void</span></span><span class="w"> </span><span class="sig-name descname"><span class="n"><span class="pre">PySys_WriteStdout</span></span></span><span class="sig-paren">(</span><span class="k"><span class="pre">const</span></span><span class="w"> </span><span class="kt"><span class="pre">char</span></span><span class="w"> </span><span class="p"><span class="pre">*</span></span><span class="n"><span class="pre">format</span></span>, <span class="p"><span class="pre">...</span></span><span class="sig-paren">)</span><a class="headerlink" href="#c.PySys_WriteStdout" title="Link to this definition">¶</a><br /></dt>
<dd><em class="stableabi"> Part of the <a class="reference internal" href="stable.html#stable"><span class="std std-ref">Stable ABI</span></a>.</em><p>Write the output string described by <em>format</em> to <a class="reference internal" href="../library/sys.html#sys.stdout" title="sys.stdout"><code class="xref py py-data docutils literal notranslate"><span class="pre">sys.stdout</span></code></a>.  No
exceptions are raised, even if truncation occurs (see below).</p>
<p><em>format</em> 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.</p>
<p>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"><span class="pre">sys.stdout</span></code></a> is unset, the formatted message
is written to the real (C level) <em>stdout</em>.</p>
</dd></dl>

<dl class="c function">
<dt class="sig sig-object c" id="c.PySys_WriteStderr">
<span class="kt"><span class="pre">void</span></span><span class="w"> </span><span class="sig-name descname"><span class="n"><span class="pre">PySys_WriteStderr</span></span></span><span class="sig-paren">(</span><span class="k"><span class="pre">const</span></span><span class="w"> </span><span class="kt"><span class="pre">char</span></span><span class="w"> </span><span class="p"><span class="pre">*</span></span><span class="n"><span class="pre">format</span></span>, <span class="p"><span class="pre">...</span></span><span class="sig-paren">)</span><a class="headerlink" href="#c.PySys_WriteStderr" title="Link to this definition">¶</a><br /></dt>
<dd><em class="stableabi"> Part of the <a class="reference internal" href="stable.html#stable"><span class="std std-ref">Stable ABI</span></a>.</em><p>As <a class="reference internal" href="#c.PySys_WriteStdout" title="PySys_WriteStdout"><code class="xref c c-func docutils literal notranslate"><span class="pre">PySys_WriteStdout()</span></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"><span class="pre">sys.stderr</span></code></a> or <em>stderr</em>
instead.</p>
</dd></dl>

<dl class="c function">
<dt class="sig sig-object c" id="c.PySys_FormatStdout">
<span class="kt"><span class="pre">void</span></span><span class="w"> </span><span class="sig-name descname"><span class="n"><span class="pre">PySys_FormatStdout</span></span></span><span class="sig-paren">(</span><span class="k"><span class="pre">const</span></span><span class="w"> </span><span class="kt"><span class="pre">char</span></span><span class="w"> </span><span class="p"><span class="pre">*</span></span><span class="n"><span class="pre">format</span></span>, <span class="p"><span class="pre">...</span></span><span class="sig-paren">)</span><a class="headerlink" href="#c.PySys_FormatStdout" title="Link to this definition">¶</a><br /></dt>
<dd><em class="stableabi"> Part of the <a class="reference internal" href="stable.html#stable"><span class="std std-ref">Stable ABI</span></a>.</em><p>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"><span class="pre">PyUnicode_FromFormatV()</span></code></a> and don’t truncate the message to an
arbitrary length.</p>
<div class="versionadded">
<p><span class="versionmodified added">New in version 3.2.</span></p>
</div>
</dd></dl>

<dl class="c function">
<dt class="sig sig-object c" id="c.PySys_FormatStderr">
<span class="kt"><span class="pre">void</span></span><span class="w"> </span><span class="sig-name descname"><span class="n"><span class="pre">PySys_FormatStderr</span></span></span><span class="sig-paren">(</span><span class="k"><span class="pre">const</span></span><span class="w"> </span><span class="kt"><span class="pre">char</span></span><span class="w"> </span><span class="p"><span class="pre">*</span></span><span class="n"><span class="pre">format</span></span>, <span class="p"><span class="pre">...</span></span><span class="sig-paren">)</span><a class="headerlink" href="#c.PySys_FormatStderr" title="Link to this definition">¶</a><br /></dt>
<dd><em class="stableabi"> Part of the <a class="reference internal" href="stable.html#stable"><span class="std std-ref">Stable ABI</span></a>.</em><p>As <a class="reference internal" href="#c.PySys_FormatStdout" title="PySys_FormatStdout"><code class="xref c c-func docutils literal notranslate"><span class="pre">PySys_FormatStdout()</span></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"><span class="pre">sys.stderr</span></code></a> or <em>stderr</em>
instead.</p>
<div class="versionadded">
<p><span class="versionmodified added">New in version 3.2.</span></p>
</div>
</dd></dl>

<dl class="c function">
<dt class="sig sig-object c" id="c.PySys_AddXOption">
<span class="kt"><span class="pre">void</span></span><span class="w"> </span><span class="sig-name descname"><span class="n"><span class="pre">PySys_AddXOption</span></span></span><span class="sig-paren">(</span><span class="k"><span class="pre">const</span></span><span class="w"> </span><span class="n"><span class="pre">wchar_t</span></span><span class="w"> </span><span class="p"><span class="pre">*</span></span><span class="n"><span class="pre">s</span></span><span class="sig-paren">)</span><a class="headerlink" href="#c.PySys_AddXOption" title="Link to this definition">¶</a><br /></dt>
<dd><em class="stableabi"> Part of the <a class="reference internal" href="stable.html#stable"><span class="std std-ref">Stable ABI</span></a> since version 3.7.</em><p>This API is kept for backward compatibility: setting
<a class="reference internal" href="init_config.html#c.PyConfig.xoptions" title="PyConfig.xoptions"><code class="xref c c-member docutils literal notranslate"><span class="pre">PyConfig.xoptions</span></code></a> should be used instead, see <a class="reference internal" href="init_config.html#init-config"><span class="std std-ref">Python
Initialization Configuration</span></a>.</p>
<p>Parse <em>s</em> as a set of <a class="reference internal" href="../using/cmdline.html#cmdoption-X"><code class="xref std std-option docutils literal notranslate"><span class="pre">-X</span></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"><span class="pre">PySys_GetXOptions()</span></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"><span class="pre">Py_Initialize()</span></code></a>.</p>
<div class="versionadded">
<p><span class="versionmodified added">New in version 3.2.</span></p>
</div>
<div class="deprecated">
<p><span class="versionmodified deprecated">Deprecated since version 3.11.</span></p>
</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"><span class="n"><span class="pre">PyObject</span></span></a><span class="w"> </span><span class="p"><span class="pre">*</span></span><span class="sig-name descname"><span class="n"><span class="pre">PySys_GetXOptions</span></span></span><span class="sig-paren">(</span><span class="sig-paren">)</span><a class="headerlink" href="#c.PySys_GetXOptions" title="Link to this definition">¶</a><br /></dt>
<dd><em class="refcount">Return value: Borrowed reference.</em><em class="stableabi"> Part of the <a class="reference internal" href="stable.html#stable"><span class="std std-ref">Stable ABI</span></a> since version 3.7.</em><p>Return the current dictionary of <a class="reference internal" href="../using/cmdline.html#cmdoption-X"><code class="xref std std-option docutils literal notranslate"><span class="pre">-X</span></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"><span class="pre">sys._xoptions</span></code></a>.  On error, <code class="docutils literal notranslate"><span class="pre">NULL</span></code> is returned and an exception is
set.</p>
<div class="versionadded">
<p><span class="versionmodified added">New in version 3.2.</span></p>
</div>
</dd></dl>

<dl class="c function">
<dt class="sig sig-object c" id="c.PySys_Audit">
<span class="kt"><span class="pre">int</span></span><span class="w"> </span><span class="sig-name descname"><span class="n"><span class="pre">PySys_Audit</span></span></span><span class="sig-paren">(</span><span class="k"><span class="pre">const</span></span><span class="w"> </span><span class="kt"><span class="pre">char</span></span><span class="w"> </span><span class="p"><span class="pre">*</span></span><span class="n"><span class="pre">event</span></span>, <span class="k"><span class="pre">const</span></span><span class="w"> </span><span class="kt"><span class="pre">char</span></span><span class="w"> </span><span class="p"><span class="pre">*</span></span><span class="n"><span class="pre">format</span></span>, <span class="p"><span class="pre">...</span></span><span class="sig-paren">)</span><a class="headerlink" href="#c.PySys_Audit" title="Link to this definition">¶</a><br /></dt>
<dd><p>Raise an auditing event with any active hooks. Return zero for success
and non-zero with an exception set on failure.</p>
<p>If any hooks have been added, <em>format</em> and other arguments will be used
to construct a tuple to pass. Apart from <code class="docutils literal notranslate"><span class="pre">N</span></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"><span class="pre">Py_BuildValue()</span></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"><span class="pre">N</span></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.)</p>
<p>Note that <code class="docutils literal notranslate"><span class="pre">#</span></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"><span class="pre">Py_ssize_t</span></code></a>, regardless of whether <code class="docutils literal notranslate"><span class="pre">PY_SSIZE_T_CLEAN</span></code> was defined.</p>
<p><a class="reference internal" href="../library/sys.html#sys.audit" title="sys.audit"><code class="xref py py-func docutils literal notranslate"><span class="pre">sys.audit()</span></code></a> performs the same function from Python code.</p>
<div class="versionadded">
<p><span class="versionmodified added">New in version 3.8.</span></p>
</div>
<div class="versionchanged">
<p><span class="versionmodified changed">Changed in version 3.8.2: </span>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"><span class="pre">Py_ssize_t</span></code></a> for <code class="docutils literal notranslate"><span class="pre">#</span></code> format characters. Previously, an
unavoidable deprecation warning was raised.</p>
</div>
</dd></dl>

<dl class="c function">
<dt class="sig sig-object c" id="c.PySys_AddAuditHook">
<span class="kt"><span class="pre">int</span></span><span class="w"> </span><span class="sig-name descname"><span class="n"><span class="pre">PySys_AddAuditHook</span></span></span><span class="sig-paren">(</span><a class="reference internal" href="#c.Py_AuditHookFunction" title="Py_AuditHookFunction"><span class="n"><span class="pre">Py_AuditHookFunction</span></span></a><span class="w"> </span><span class="n"><span class="pre">hook</span></span>, <span class="kt"><span class="pre">void</span></span><span class="w"> </span><span class="p"><span class="pre">*</span></span><span class="n"><span class="pre">userData</span></span><span class="sig-paren">)</span><a class="headerlink" href="#c.PySys_AddAuditHook" title="Link to this definition">¶</a><br /></dt>
<dd><p>Append the callable <em>hook</em> 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.</p>
<p>The <em>userData</em> 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.</p>
<p>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"><span class="pre">Py_Initialize()</span></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"><span class="pre">Exception</span></code></a> (other errors will not be silenced).</p>
<p>The hook function is always called with the GIL held by the Python
interpreter that raised the event.</p>
<p>See <span class="target" id="index-1"></span><a class="pep reference external" href="https://peps.python.org/pep-0578/"><strong>PEP 578</strong></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"><span class="std std-ref">audit events table</span></a>.
Details are in each function’s documentation.</p>
<p class="audit-hook"><p>If the interpreter is initialized, this function raises an auditing event
<code class="docutils literal notranslate"><span class="pre">sys.addaudithook</span></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"><span class="pre">Exception</span></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.</p>
</p>
<dl class="c type">
<dt class="sig sig-object c" id="c.Py_AuditHookFunction">
<span class="k"><span class="pre">typedef</span></span><span class="w"> </span><span class="kt"><span class="pre">int</span></span><span class="w"> </span><span class="p"><span class="pre">(</span></span><span class="p"><span class="pre">*</span></span><span class="sig-name descname"><span class="n"><span class="pre">Py_AuditHookFunction</span></span></span><span class="p"><span class="pre">)</span></span><span class="p"><span class="pre">(</span></span><span class="k"><span class="pre">const</span></span><span class="w"> </span><span class="kt"><span class="pre">char</span></span><span class="w"> </span><span class="p"><span class="pre">*</span></span><span class="n"><span class="pre">event</span></span><span class="p"><span class="pre">,</span></span><span class="w"> </span><a class="reference internal" href="structures.html#c.PyObject" title="PyObject"><span class="n"><span class="pre">PyObject</span></span></a><span class="w"> </span><span class="p"><span class="pre">*</span></span><span class="n"><span class="pre">args</span></span><span class="p"><span class="pre">,</span></span><span class="w"> </span><span class="kt"><span class="pre">void</span></span><span class="w"> </span><span class="p"><span class="pre">*</span></span><span class="n"><span class="pre">userData</span></span><span class="p"><span class="pre">)</span></span><a class="headerlink" href="#c.Py_AuditHookFunction" title="Link to this definition">¶</a><br /></dt>
<dd><p>The type of the hook function.
<em>event</em> is the C string event argument passed to <a class="reference internal" href="#c.PySys_Audit" title="PySys_Audit"><code class="xref c c-func docutils literal notranslate"><span class="pre">PySys_Audit()</span></code></a>.
<em>args</em> 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"><span class="pre">PyTupleObject</span></code></a>.
<em>userData</em> is the argument passed to PySys_AddAuditHook().</p>
</dd></dl>

<div class="versionadded">
<p><span class="versionmodified added">New in version 3.8.</span></p>
</div>
</dd></dl>

</section>
<section id="process-control">
<span id="processcontrol"></span><h1>Process Control<a class="headerlink" href="#process-control" title="Link to this heading">¶</a></h1>
<dl class="c function">
<dt class="sig sig-object c" id="c.Py_FatalError">
<span class="kt"><span class="pre">void</span></span><span class="w"> </span><span class="sig-name descname"><span class="n"><span class="pre">Py_FatalError</span></span></span><span class="sig-paren">(</span><span class="k"><span class="pre">const</span></span><span class="w"> </span><span class="kt"><span class="pre">char</span></span><span class="w"> </span><span class="p"><span class="pre">*</span></span><span class="n"><span class="pre">message</span></span><span class="sig-paren">)</span><a class="headerlink" href="#c.Py_FatalError" title="Link to this definition">¶</a><br /></dt>
<dd><em class="stableabi"> Part of the <a class="reference internal" href="stable.html#stable"><span class="std std-ref">Stable ABI</span></a>.</em><p id="index-2">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"><span class="pre">abort()</span></code> is called which will attempt to produce a <code class="file docutils literal notranslate"><span class="pre">core</span></code>
file.</p>
<p>The <code class="docutils literal notranslate"><span class="pre">Py_FatalError()</span></code> function is replaced with a macro which logs
automatically the name of the current function, unless the
<code class="docutils literal notranslate"><span class="pre">Py_LIMITED_API</span></code> macro is defined.</p>
<div class="versionchanged">
<p><span class="versionmodified changed">Changed in version 3.9: </span>Log the function name automatically.</p>
</div>
</dd></dl>

<dl class="c function">
<dt class="sig sig-object c" id="c.Py_Exit">
<span class="kt"><span class="pre">void</span></span><span class="w"> </span><span class="sig-name descname"><span class="n"><span class="pre">Py_Exit</span></span></span><span class="sig-paren">(</span><span class="kt"><span class="pre">int</span></span><span class="w"> </span><span class="n"><span class="pre">status</span></span><span class="sig-paren">)</span><a class="headerlink" href="#c.Py_Exit" title="Link to this definition">¶</a><br /></dt>
<dd><em class="stableabi"> Part of the <a class="reference internal" href="stable.html#stable"><span class="std std-ref">Stable ABI</span></a>.</em><p id="index-3">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"><span class="pre">Py_FinalizeEx()</span></code></a> and then calls the
standard C library function <code class="docutils literal notranslate"><span class="pre">exit(status)</span></code>.  If <a class="reference internal" href="init.html#c.Py_FinalizeEx" title="Py_FinalizeEx"><code class="xref c c-func docutils literal notranslate"><span class="pre">Py_FinalizeEx()</span></code></a>
indicates an error, the exit status is set to 120.</p>
<div class="versionchanged">
<p><span class="versionmodified changed">Changed in version 3.6: </span>Errors from finalization no longer ignored.</p>
</div>
</dd></dl>

<dl class="c function">
<dt class="sig sig-object c" id="c.Py_AtExit">
<span class="kt"><span class="pre">int</span></span><span class="w"> </span><span class="sig-name descname"><span class="n"><span class="pre">Py_AtExit</span></span></span><span class="sig-paren">(</span><span class="kt"><span class="pre">void</span></span><span class="w"> </span><span class="p"><span class="pre">(</span></span><span class="p"><span class="pre">*</span></span><span class="n"><span class="pre">func</span></span><span class="p"><span class="pre">)</span></span><span class="p"><span class="pre">(</span></span><span class="p"><span class="pre">)</span></span><span class="sig-paren">)</span><a class="headerlink" href="#c.Py_AtExit" title="Link to this definition">¶</a><br /></dt>
<dd><em class="stableabi"> Part of the <a class="reference internal" href="stable.html#stable"><span class="std std-ref">Stable ABI</span></a>.</em><p id="index-4">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"><span class="pre">Py_FinalizeEx()</span></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"><span class="pre">Py_AtExit()</span></code></a> returns <code class="docutils literal notranslate"><span class="pre">0</span></code>; on failure, it returns <code class="docutils literal notranslate"><span class="pre">-1</span></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 <em>func</em>.</p>
</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>
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