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<li><a class="reference internal" href="#">1. Command line and environment</a><ul>
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<li><a class="reference internal" href="#command-line">1.1. Command line</a><ul>
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<li><a class="reference internal" href="#interface-options">1.1.1. Interface options</a></li>
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<section id="command-line-and-environment">
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<span id="using-on-general"></span><h1><span class="section-number">1. </span>Command line and environment<a class="headerlink" href="#command-line-and-environment" title="Link to this heading">¶</a></h1>
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<p>The CPython interpreter scans the command line and the environment for various
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settings.</p>
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<div class="impl-detail compound">
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<p><strong>CPython implementation detail:</strong> Other implementations’ command line schemes may differ. See
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<a class="reference internal" href="../reference/introduction.html#implementations"><span class="std std-ref">Alternate Implementations</span></a> for further resources.</p>
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</div>
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<section id="command-line">
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<span id="using-on-cmdline"></span><h2><span class="section-number">1.1. </span>Command line<a class="headerlink" href="#command-line" title="Link to this heading">¶</a></h2>
|
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<p>When invoking Python, you may specify any of these options:</p>
|
||
<div class="highlight-sh notranslate"><div class="highlight"><pre><span></span>python<span class="w"> </span><span class="o">[</span>-bBdEhiIOPqRsSuvVWx?<span class="o">]</span><span class="w"> </span><span class="o">[</span>-c<span class="w"> </span><span class="nb">command</span><span class="w"> </span><span class="p">|</span><span class="w"> </span>-m<span class="w"> </span>module-name<span class="w"> </span><span class="p">|</span><span class="w"> </span>script<span class="w"> </span><span class="p">|</span><span class="w"> </span>-<span class="w"> </span><span class="o">]</span><span class="w"> </span><span class="o">[</span>args<span class="o">]</span>
|
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</pre></div>
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</div>
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<p>The most common use case is, of course, a simple invocation of a script:</p>
|
||
<div class="highlight-sh notranslate"><div class="highlight"><pre><span></span>python<span class="w"> </span>myscript.py
|
||
</pre></div>
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</div>
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<section id="interface-options">
|
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<span id="using-on-interface-options"></span><h3><span class="section-number">1.1.1. </span>Interface options<a class="headerlink" href="#interface-options" title="Link to this heading">¶</a></h3>
|
||
<p>The interpreter interface resembles that of the UNIX shell, but provides some
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||
additional methods of invocation:</p>
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||
<ul class="simple">
|
||
<li><p>When called with standard input connected to a tty device, it prompts for
|
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commands and executes them until an EOF (an end-of-file character, you can
|
||
produce that with <kbd class="kbd docutils literal notranslate">Ctrl</kbd>-<kbd class="kbd docutils literal notranslate">D</kbd> on UNIX or <kbd class="kbd docutils literal notranslate">Ctrl</kbd>-<kbd class="kbd docutils literal notranslate">Z,</kbd> <kbd class="kbd docutils literal notranslate">Enter</kbd> on Windows) is read.
|
||
For more on interactive mode, see <a class="reference internal" href="../tutorial/appendix.html#tut-interac"><span class="std std-ref">Interactive Mode</span></a>.</p></li>
|
||
<li><p>When called with a file name argument or with a file as standard input, it
|
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reads and executes a script from that file.</p></li>
|
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<li><p>When called with a directory name argument, it reads and executes an
|
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appropriately named script from that directory.</p></li>
|
||
<li><p>When called with <code class="docutils literal notranslate"><span class="pre">-c</span> <span class="pre">command</span></code>, it executes the Python statement(s) given as
|
||
<em>command</em>. Here <em>command</em> may contain multiple statements separated by
|
||
newlines. Leading whitespace is significant in Python statements!</p></li>
|
||
<li><p>When called with <code class="docutils literal notranslate"><span class="pre">-m</span> <span class="pre">module-name</span></code>, the given module is located on the
|
||
Python module path and executed as a script.</p></li>
|
||
</ul>
|
||
<p>In non-interactive mode, the entire input is parsed before it is executed.</p>
|
||
<p>An interface option terminates the list of options consumed by the interpreter,
|
||
all consecutive arguments will end up in <a class="reference internal" href="../library/sys.html#sys.argv" title="sys.argv"><code class="xref py py-data docutils literal notranslate"><span class="pre">sys.argv</span></code></a> – note that the first
|
||
element, subscript zero (<code class="docutils literal notranslate"><span class="pre">sys.argv[0]</span></code>), is a string reflecting the program’s
|
||
source.</p>
|
||
<dl class="std option">
|
||
<dt class="sig sig-object std" id="cmdoption-c">
|
||
<span class="sig-name descname"><span class="pre">-c</span></span><span class="sig-prename descclassname"> <span class="pre"><command></span></span><a class="headerlink" href="#cmdoption-c" title="Link to this definition">¶</a></dt>
|
||
<dd><p>Execute the Python code in <em>command</em>. <em>command</em> can be one or more
|
||
statements separated by newlines, with significant leading whitespace as in
|
||
normal module code.</p>
|
||
<p>If this option is given, the first element of <a class="reference internal" href="../library/sys.html#sys.argv" title="sys.argv"><code class="xref py py-data docutils literal notranslate"><span class="pre">sys.argv</span></code></a> will be
|
||
<code class="docutils literal notranslate"><span class="pre">"-c"</span></code> and the current directory will be added to the start of
|
||
<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> (allowing modules in that directory to be imported as top
|
||
level modules).</p>
|
||
<p class="audit-hook">Raises an <a class="reference internal" href="../library/sys.html#auditing"><span class="std std-ref">auditing event</span></a> <code class="docutils literal notranslate"><span class="pre">cpython.run_command</span></code> with argument <code class="docutils literal notranslate"><span class="pre">command</span></code>.</p>
|
||
</dd></dl>
|
||
|
||
<dl class="std option">
|
||
<dt class="sig sig-object std" id="cmdoption-m">
|
||
<span class="sig-name descname"><span class="pre">-m</span></span><span class="sig-prename descclassname"> <span class="pre"><module-name></span></span><a class="headerlink" href="#cmdoption-m" title="Link to this definition">¶</a></dt>
|
||
<dd><p>Search <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> for the named module and execute its contents as
|
||
the <a class="reference internal" href="../library/__main__.html#module-__main__" title="__main__: The environment where top-level code is run. Covers command-line interfaces, import-time behavior, and ``__name__ == '__main__'``."><code class="xref py py-mod docutils literal notranslate"><span class="pre">__main__</span></code></a> module.</p>
|
||
<p>Since the argument is a <em>module</em> name, you must not give a file extension
|
||
(<code class="docutils literal notranslate"><span class="pre">.py</span></code>). The module name should be a valid absolute Python module name, but
|
||
the implementation may not always enforce this (e.g. it may allow you to
|
||
use a name that includes a hyphen).</p>
|
||
<p>Package names (including namespace packages) are also permitted. When a
|
||
package name is supplied instead
|
||
of a normal module, the interpreter will execute <code class="docutils literal notranslate"><span class="pre"><pkg>.__main__</span></code> as
|
||
the main module. This behaviour is deliberately similar to the handling
|
||
of directories and zipfiles that are passed to the interpreter as the
|
||
script argument.</p>
|
||
<div class="admonition note">
|
||
<p class="admonition-title">Note</p>
|
||
<p>This option cannot be used with built-in modules and extension modules
|
||
written in C, since they do not have Python module files. However, it
|
||
can still be used for precompiled modules, even if the original source
|
||
file is not available.</p>
|
||
</div>
|
||
<p>If this option is given, the first element of <a class="reference internal" href="../library/sys.html#sys.argv" title="sys.argv"><code class="xref py py-data docutils literal notranslate"><span class="pre">sys.argv</span></code></a> will be the
|
||
full path to the module file (while the module file is being located, the
|
||
first element will be set to <code class="docutils literal notranslate"><span class="pre">"-m"</span></code>). As with the <a class="reference internal" href="#cmdoption-c"><code class="xref std std-option docutils literal notranslate"><span class="pre">-c</span></code></a> option,
|
||
the current directory will be added to the start of <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>.</p>
|
||
<p><a class="reference internal" href="#cmdoption-I"><code class="xref std std-option docutils literal notranslate"><span class="pre">-I</span></code></a> option can be used to run the script in isolated mode where
|
||
<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> contains neither the current directory nor the user’s
|
||
site-packages directory. All <code class="docutils literal notranslate"><span class="pre">PYTHON*</span></code> environment variables are
|
||
ignored, too.</p>
|
||
<p>Many standard library modules contain code that is invoked on their execution
|
||
as a script. An example is the <a class="reference internal" href="../library/timeit.html#module-timeit" title="timeit: Measure the execution time of small code snippets."><code class="xref py py-mod docutils literal notranslate"><span class="pre">timeit</span></code></a> module:</p>
|
||
<div class="highlight-sh notranslate"><div class="highlight"><pre><span></span>python<span class="w"> </span>-m<span class="w"> </span>timeit<span class="w"> </span>-s<span class="w"> </span><span class="s2">"setup here"</span><span class="w"> </span><span class="s2">"benchmarked code here"</span>
|
||
python<span class="w"> </span>-m<span class="w"> </span>timeit<span class="w"> </span>-h<span class="w"> </span><span class="c1"># for details</span>
|
||
</pre></div>
|
||
</div>
|
||
<p class="audit-hook">Raises an <a class="reference internal" href="../library/sys.html#auditing"><span class="std std-ref">auditing event</span></a> <code class="docutils literal notranslate"><span class="pre">cpython.run_module</span></code> with argument <code class="docutils literal notranslate"><span class="pre">module-name</span></code>.</p>
|
||
<div class="admonition seealso">
|
||
<p class="admonition-title">See also</p>
|
||
<dl class="simple">
|
||
<dt><a class="reference internal" href="../library/runpy.html#runpy.run_module" title="runpy.run_module"><code class="xref py py-func docutils literal notranslate"><span class="pre">runpy.run_module()</span></code></a></dt><dd><p>Equivalent functionality directly available to Python code</p>
|
||
</dd>
|
||
</dl>
|
||
<p><span class="target" id="index-0"></span><a class="pep reference external" href="https://peps.python.org/pep-0338/"><strong>PEP 338</strong></a> – Executing modules as scripts</p>
|
||
</div>
|
||
<div class="versionchanged">
|
||
<p><span class="versionmodified changed">Changed in version 3.1: </span>Supply the package name to run a <code class="docutils literal notranslate"><span class="pre">__main__</span></code> submodule.</p>
|
||
</div>
|
||
<div class="versionchanged">
|
||
<p><span class="versionmodified changed">Changed in version 3.4: </span>namespace packages are also supported</p>
|
||
</div>
|
||
</dd></dl>
|
||
|
||
<dl class="describe" id="cmdarg-dash">
|
||
<dt class="sig sig-object">
|
||
<span class="sig-name descname"><span class="pre">-</span></span></dt>
|
||
<dd><p>Read commands from standard input (<a class="reference internal" href="../library/sys.html#sys.stdin" title="sys.stdin"><code class="xref py py-data docutils literal notranslate"><span class="pre">sys.stdin</span></code></a>). If standard input is
|
||
a terminal, <a class="reference internal" href="#cmdoption-i"><code class="xref std std-option docutils literal notranslate"><span class="pre">-i</span></code></a> is implied.</p>
|
||
<p>If this option is given, the first element of <a class="reference internal" href="../library/sys.html#sys.argv" title="sys.argv"><code class="xref py py-data docutils literal notranslate"><span class="pre">sys.argv</span></code></a> will be
|
||
<code class="docutils literal notranslate"><span class="pre">"-"</span></code> and the current directory will be added to the start of
|
||
<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>.</p>
|
||
<p class="audit-hook" id="audit_event_cpython_run_stdin_1">Raises an <a class="reference internal" href="../library/sys.html#auditing"><span class="std std-ref">auditing event</span></a> <code class="docutils literal notranslate"><span class="pre">cpython.run_stdin</span></code> with no arguments.</p>
|
||
</dd></dl>
|
||
|
||
<dl class="describe" id="cmdarg-script">
|
||
<dt class="sig sig-object">
|
||
<span class="sig-name descname"><span class="pre"><script></span></span></dt>
|
||
<dd><p>Execute the Python code contained in <em>script</em>, which must be a filesystem
|
||
path (absolute or relative) referring to either a Python file, a directory
|
||
containing a <code class="docutils literal notranslate"><span class="pre">__main__.py</span></code> file, or a zipfile containing a
|
||
<code class="docutils literal notranslate"><span class="pre">__main__.py</span></code> file.</p>
|
||
<p>If this option is given, the first element of <a class="reference internal" href="../library/sys.html#sys.argv" title="sys.argv"><code class="xref py py-data docutils literal notranslate"><span class="pre">sys.argv</span></code></a> will be the
|
||
script name as given on the command line.</p>
|
||
<p>If the script name refers directly to a Python file, the directory
|
||
containing that file is added to the start of <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>, and the
|
||
file is executed as the <a class="reference internal" href="../library/__main__.html#module-__main__" title="__main__: The environment where top-level code is run. Covers command-line interfaces, import-time behavior, and ``__name__ == '__main__'``."><code class="xref py py-mod docutils literal notranslate"><span class="pre">__main__</span></code></a> module.</p>
|
||
<p>If the script name refers to a directory or zipfile, the script name is
|
||
added to the start of <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> and the <code class="docutils literal notranslate"><span class="pre">__main__.py</span></code> file in
|
||
that location is executed as the <a class="reference internal" href="../library/__main__.html#module-__main__" title="__main__: The environment where top-level code is run. Covers command-line interfaces, import-time behavior, and ``__name__ == '__main__'``."><code class="xref py py-mod docutils literal notranslate"><span class="pre">__main__</span></code></a> module.</p>
|
||
<p><a class="reference internal" href="#cmdoption-I"><code class="xref std std-option docutils literal notranslate"><span class="pre">-I</span></code></a> option can be used to run the script in isolated mode where
|
||
<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> contains neither the script’s directory nor the user’s
|
||
site-packages directory. All <code class="docutils literal notranslate"><span class="pre">PYTHON*</span></code> environment variables are
|
||
ignored, too.</p>
|
||
<p class="audit-hook" id="audit_event_cpython_run_file_0">Raises an <a class="reference internal" href="../library/sys.html#auditing"><span class="std std-ref">auditing event</span></a> <code class="docutils literal notranslate"><span class="pre">cpython.run_file</span></code> with argument <code class="docutils literal notranslate"><span class="pre">filename</span></code>.</p>
|
||
<div class="admonition seealso">
|
||
<p class="admonition-title">See also</p>
|
||
<dl class="simple">
|
||
<dt><a class="reference internal" href="../library/runpy.html#runpy.run_path" title="runpy.run_path"><code class="xref py py-func docutils literal notranslate"><span class="pre">runpy.run_path()</span></code></a></dt><dd><p>Equivalent functionality directly available to Python code</p>
|
||
</dd>
|
||
</dl>
|
||
</div>
|
||
</dd></dl>
|
||
|
||
<p>If no interface option is given, <a class="reference internal" href="#cmdoption-i"><code class="xref std std-option docutils literal notranslate"><span class="pre">-i</span></code></a> is implied, <code class="docutils literal notranslate"><span class="pre">sys.argv[0]</span></code> is
|
||
an empty string (<code class="docutils literal notranslate"><span class="pre">""</span></code>) and the current directory will be added to the
|
||
start of <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>. Also, tab-completion and history editing is
|
||
automatically enabled, if available on your platform (see
|
||
<a class="reference internal" href="../library/site.html#rlcompleter-config"><span class="std std-ref">Readline configuration</span></a>).</p>
|
||
<div class="admonition seealso">
|
||
<p class="admonition-title">See also</p>
|
||
<p><a class="reference internal" href="../tutorial/interpreter.html#tut-invoking"><span class="std std-ref">Invoking the Interpreter</span></a></p>
|
||
</div>
|
||
<div class="versionchanged">
|
||
<p><span class="versionmodified changed">Changed in version 3.4: </span>Automatic enabling of tab-completion and history editing.</p>
|
||
</div>
|
||
</section>
|
||
<section id="generic-options">
|
||
<span id="using-on-generic-options"></span><h3><span class="section-number">1.1.2. </span>Generic options<a class="headerlink" href="#generic-options" title="Link to this heading">¶</a></h3>
|
||
<dl class="std option">
|
||
<dt class="sig sig-object std" id="cmdoption-0">
|
||
<span class="sig-name descname"><span class="pre">-?</span></span><span class="sig-prename descclassname"></span><a class="headerlink" href="#cmdoption-0" title="Link to this definition">¶</a></dt>
|
||
<dt class="sig sig-object std" id="cmdoption-h">
|
||
<span class="sig-name descname"><span class="pre">-h</span></span><span class="sig-prename descclassname"></span><a class="headerlink" href="#cmdoption-h" title="Link to this definition">¶</a></dt>
|
||
<dt class="sig sig-object std" id="cmdoption-help">
|
||
<span class="sig-name descname"><span class="pre">--help</span></span><span class="sig-prename descclassname"></span><a class="headerlink" href="#cmdoption-help" title="Link to this definition">¶</a></dt>
|
||
<dd><p>Print a short description of all command line options and corresponding
|
||
environment variables and exit.</p>
|
||
</dd></dl>
|
||
|
||
<dl class="std option">
|
||
<dt class="sig sig-object std" id="cmdoption-help-env">
|
||
<span class="sig-name descname"><span class="pre">--help-env</span></span><span class="sig-prename descclassname"></span><a class="headerlink" href="#cmdoption-help-env" title="Link to this definition">¶</a></dt>
|
||
<dd><p>Print a short description of Python-specific environment variables
|
||
and exit.</p>
|
||
<div class="versionadded">
|
||
<p><span class="versionmodified added">Added in version 3.11.</span></p>
|
||
</div>
|
||
</dd></dl>
|
||
|
||
<dl class="std option">
|
||
<dt class="sig sig-object std" id="cmdoption-help-xoptions">
|
||
<span class="sig-name descname"><span class="pre">--help-xoptions</span></span><span class="sig-prename descclassname"></span><a class="headerlink" href="#cmdoption-help-xoptions" title="Link to this definition">¶</a></dt>
|
||
<dd><p>Print a description of implementation-specific <a class="reference internal" href="#cmdoption-X"><code class="xref std std-option docutils literal notranslate"><span class="pre">-X</span></code></a> options
|
||
and exit.</p>
|
||
<div class="versionadded">
|
||
<p><span class="versionmodified added">Added in version 3.11.</span></p>
|
||
</div>
|
||
</dd></dl>
|
||
|
||
<dl class="std option">
|
||
<dt class="sig sig-object std" id="cmdoption-help-all">
|
||
<span class="sig-name descname"><span class="pre">--help-all</span></span><span class="sig-prename descclassname"></span><a class="headerlink" href="#cmdoption-help-all" title="Link to this definition">¶</a></dt>
|
||
<dd><p>Print complete usage information and exit.</p>
|
||
<div class="versionadded">
|
||
<p><span class="versionmodified added">Added in version 3.11.</span></p>
|
||
</div>
|
||
</dd></dl>
|
||
|
||
<dl class="std option">
|
||
<dt class="sig sig-object std" id="cmdoption-V">
|
||
<span class="sig-name descname"><span class="pre">-V</span></span><span class="sig-prename descclassname"></span><a class="headerlink" href="#cmdoption-V" title="Link to this definition">¶</a></dt>
|
||
<dt class="sig sig-object std" id="cmdoption-version">
|
||
<span class="sig-name descname"><span class="pre">--version</span></span><span class="sig-prename descclassname"></span><a class="headerlink" href="#cmdoption-version" title="Link to this definition">¶</a></dt>
|
||
<dd><p>Print the Python version number and exit. Example output could be:</p>
|
||
<div class="highlight-none notranslate"><div class="highlight"><pre><span></span>Python 3.8.0b2+
|
||
</pre></div>
|
||
</div>
|
||
<p>When given twice, print more information about the build, like:</p>
|
||
<div class="highlight-none notranslate"><div class="highlight"><pre><span></span>Python 3.8.0b2+ (3.8:0c076caaa8, Apr 20 2019, 21:55:00)
|
||
[GCC 6.2.0 20161005]
|
||
</pre></div>
|
||
</div>
|
||
<div class="versionadded">
|
||
<p><span class="versionmodified added">Added in version 3.6: </span>The <code class="docutils literal notranslate"><span class="pre">-VV</span></code> option.</p>
|
||
</div>
|
||
</dd></dl>
|
||
|
||
</section>
|
||
<section id="miscellaneous-options">
|
||
<span id="using-on-misc-options"></span><h3><span class="section-number">1.1.3. </span>Miscellaneous options<a class="headerlink" href="#miscellaneous-options" title="Link to this heading">¶</a></h3>
|
||
<dl class="std option">
|
||
<dt class="sig sig-object std" id="cmdoption-b">
|
||
<span class="sig-name descname"><span class="pre">-b</span></span><span class="sig-prename descclassname"></span><a class="headerlink" href="#cmdoption-b" title="Link to this definition">¶</a></dt>
|
||
<dd><p>Issue a warning when converting <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> or <a class="reference internal" href="../library/stdtypes.html#bytearray" title="bytearray"><code class="xref py py-class docutils literal notranslate"><span class="pre">bytearray</span></code></a> to
|
||
<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> without specifying encoding or comparing <code class="xref py py-class docutils literal notranslate"><span class="pre">bytes</span></code> or
|
||
<code class="xref py py-class docutils literal notranslate"><span class="pre">bytearray</span></code> with <code class="xref py py-class docutils literal notranslate"><span class="pre">str</span></code> or <code class="xref py py-class docutils literal notranslate"><span class="pre">bytes</span></code> with <a class="reference internal" href="../library/functions.html#int" title="int"><code class="xref py py-class docutils literal notranslate"><span class="pre">int</span></code></a>.
|
||
Issue an error when the option is given twice (<code class="xref std std-option docutils literal notranslate"><span class="pre">-bb</span></code>).</p>
|
||
<div class="versionchanged">
|
||
<p><span class="versionmodified changed">Changed in version 3.5: </span>Affects also comparisons of <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> with <a class="reference internal" href="../library/functions.html#int" title="int"><code class="xref py py-class docutils literal notranslate"><span class="pre">int</span></code></a>.</p>
|
||
</div>
|
||
</dd></dl>
|
||
|
||
<dl class="std option">
|
||
<dt class="sig sig-object std" id="cmdoption-B">
|
||
<span class="sig-name descname"><span class="pre">-B</span></span><span class="sig-prename descclassname"></span><a class="headerlink" href="#cmdoption-B" title="Link to this definition">¶</a></dt>
|
||
<dd><p>If given, Python won’t try to write <code class="docutils literal notranslate"><span class="pre">.pyc</span></code> files on the
|
||
import of source modules. See also <span class="target" id="index-1"></span><a class="reference internal" href="#envvar-PYTHONDONTWRITEBYTECODE"><code class="xref std std-envvar docutils literal notranslate"><span class="pre">PYTHONDONTWRITEBYTECODE</span></code></a>.</p>
|
||
</dd></dl>
|
||
|
||
<dl class="std option">
|
||
<dt class="sig sig-object std" id="cmdoption-check-hash-based-pycs">
|
||
<span class="sig-name descname"><span class="pre">--check-hash-based-pycs</span></span><span class="sig-prename descclassname"> <span class="pre">default|always|never</span></span><a class="headerlink" href="#cmdoption-check-hash-based-pycs" title="Link to this definition">¶</a></dt>
|
||
<dd><p>Control the validation behavior of hash-based <code class="docutils literal notranslate"><span class="pre">.pyc</span></code> files. See
|
||
<a class="reference internal" href="../reference/import.html#pyc-invalidation"><span class="std std-ref">Cached bytecode invalidation</span></a>. When set to <code class="docutils literal notranslate"><span class="pre">default</span></code>, checked and unchecked
|
||
hash-based bytecode cache files are validated according to their default
|
||
semantics. When set to <code class="docutils literal notranslate"><span class="pre">always</span></code>, all hash-based <code class="docutils literal notranslate"><span class="pre">.pyc</span></code> files, whether
|
||
checked or unchecked, are validated against their corresponding source
|
||
file. When set to <code class="docutils literal notranslate"><span class="pre">never</span></code>, hash-based <code class="docutils literal notranslate"><span class="pre">.pyc</span></code> files are not validated
|
||
against their corresponding source files.</p>
|
||
<p>The semantics of timestamp-based <code class="docutils literal notranslate"><span class="pre">.pyc</span></code> files are unaffected by this
|
||
option.</p>
|
||
</dd></dl>
|
||
|
||
<dl class="std option">
|
||
<dt class="sig sig-object std" id="cmdoption-d">
|
||
<span class="sig-name descname"><span class="pre">-d</span></span><span class="sig-prename descclassname"></span><a class="headerlink" href="#cmdoption-d" title="Link to this definition">¶</a></dt>
|
||
<dd><p>Turn on parser debugging output (for expert only).
|
||
See also the <span class="target" id="index-2"></span><a class="reference internal" href="#envvar-PYTHONDEBUG"><code class="xref std std-envvar docutils literal notranslate"><span class="pre">PYTHONDEBUG</span></code></a> environment variable.</p>
|
||
<p>This option requires a <a class="reference internal" href="configure.html#debug-build"><span class="std std-ref">debug build of Python</span></a>, otherwise
|
||
it’s ignored.</p>
|
||
</dd></dl>
|
||
|
||
<dl class="std option">
|
||
<dt class="sig sig-object std" id="cmdoption-E">
|
||
<span class="sig-name descname"><span class="pre">-E</span></span><span class="sig-prename descclassname"></span><a class="headerlink" href="#cmdoption-E" title="Link to this definition">¶</a></dt>
|
||
<dd><p>Ignore all <code class="docutils literal notranslate"><span class="pre">PYTHON*</span></code> environment variables, e.g.
|
||
<span class="target" id="index-3"></span><a class="reference internal" href="#envvar-PYTHONPATH"><code class="xref std std-envvar docutils literal notranslate"><span class="pre">PYTHONPATH</span></code></a> and <span class="target" id="index-4"></span><a class="reference internal" href="#envvar-PYTHONHOME"><code class="xref std std-envvar docutils literal notranslate"><span class="pre">PYTHONHOME</span></code></a>, that might be set.</p>
|
||
<p>See also the <a class="reference internal" href="#cmdoption-P"><code class="xref std std-option docutils literal notranslate"><span class="pre">-P</span></code></a> and <a class="reference internal" href="#cmdoption-I"><code class="xref std std-option docutils literal notranslate"><span class="pre">-I</span></code></a> (isolated) options.</p>
|
||
</dd></dl>
|
||
|
||
<dl class="std option">
|
||
<dt class="sig sig-object std" id="cmdoption-i">
|
||
<span class="sig-name descname"><span class="pre">-i</span></span><span class="sig-prename descclassname"></span><a class="headerlink" href="#cmdoption-i" title="Link to this definition">¶</a></dt>
|
||
<dd><p>Enter interactive mode after execution.</p>
|
||
<p>Using the <a class="reference internal" href="#cmdoption-i"><code class="xref std std-option docutils literal notranslate"><span class="pre">-i</span></code></a> option will enter interactive mode in any of the following circumstances:</p>
|
||
<ul class="simple">
|
||
<li><p>When a script is passed as first argument</p></li>
|
||
<li><p>When the <a class="reference internal" href="#cmdoption-c"><code class="xref std std-option docutils literal notranslate"><span class="pre">-c</span></code></a> option is used</p></li>
|
||
<li><p>When the <a class="reference internal" href="#cmdoption-m"><code class="xref std std-option docutils literal notranslate"><span class="pre">-m</span></code></a> option is used</p></li>
|
||
</ul>
|
||
<p>Interactive mode will start even when <a class="reference internal" href="../library/sys.html#sys.stdin" title="sys.stdin"><code class="xref py py-data docutils literal notranslate"><span class="pre">sys.stdin</span></code></a> does not appear to be a terminal. The
|
||
<span class="target" id="index-5"></span><a class="reference internal" href="#envvar-PYTHONSTARTUP"><code class="xref std std-envvar docutils literal notranslate"><span class="pre">PYTHONSTARTUP</span></code></a> file is not read.</p>
|
||
<p>This can be useful to inspect global variables or a stack trace when a script
|
||
raises an exception. See also <span class="target" id="index-6"></span><a class="reference internal" href="#envvar-PYTHONINSPECT"><code class="xref std std-envvar docutils literal notranslate"><span class="pre">PYTHONINSPECT</span></code></a>.</p>
|
||
</dd></dl>
|
||
|
||
<dl class="std option">
|
||
<dt class="sig sig-object std" id="cmdoption-I">
|
||
<span class="sig-name descname"><span class="pre">-I</span></span><span class="sig-prename descclassname"></span><a class="headerlink" href="#cmdoption-I" title="Link to this definition">¶</a></dt>
|
||
<dd><p>Run Python in isolated mode. This also implies <a class="reference internal" href="#cmdoption-E"><code class="xref std std-option docutils literal notranslate"><span class="pre">-E</span></code></a>, <a class="reference internal" href="#cmdoption-P"><code class="xref std std-option docutils literal notranslate"><span class="pre">-P</span></code></a>
|
||
and <a class="reference internal" href="#cmdoption-s"><code class="xref std std-option docutils literal notranslate"><span class="pre">-s</span></code></a> options.</p>
|
||
<p>In isolated mode <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> contains neither the script’s directory nor
|
||
the user’s site-packages directory. All <code class="docutils literal notranslate"><span class="pre">PYTHON*</span></code> environment
|
||
variables are ignored, too. Further restrictions may be imposed to prevent
|
||
the user from injecting malicious code.</p>
|
||
<div class="versionadded">
|
||
<p><span class="versionmodified added">Added in version 3.4.</span></p>
|
||
</div>
|
||
</dd></dl>
|
||
|
||
<dl class="std option">
|
||
<dt class="sig sig-object std" id="cmdoption-O">
|
||
<span class="sig-name descname"><span class="pre">-O</span></span><span class="sig-prename descclassname"></span><a class="headerlink" href="#cmdoption-O" title="Link to this definition">¶</a></dt>
|
||
<dd><p>Remove assert statements and any code conditional on the value of
|
||
<a class="reference internal" href="../library/constants.html#debug__" title="__debug__"><code class="xref py py-const docutils literal notranslate"><span class="pre">__debug__</span></code></a>. Augment the filename for compiled
|
||
(<a class="reference internal" href="../glossary.html#term-bytecode"><span class="xref std std-term">bytecode</span></a>) files by adding <code class="docutils literal notranslate"><span class="pre">.opt-1</span></code> before the <code class="docutils literal notranslate"><span class="pre">.pyc</span></code>
|
||
extension (see <span class="target" id="index-7"></span><a class="pep reference external" href="https://peps.python.org/pep-0488/"><strong>PEP 488</strong></a>). See also <span class="target" id="index-8"></span><a class="reference internal" href="#envvar-PYTHONOPTIMIZE"><code class="xref std std-envvar docutils literal notranslate"><span class="pre">PYTHONOPTIMIZE</span></code></a>.</p>
|
||
<div class="versionchanged">
|
||
<p><span class="versionmodified changed">Changed in version 3.5: </span>Modify <code class="docutils literal notranslate"><span class="pre">.pyc</span></code> filenames according to <span class="target" id="index-9"></span><a class="pep reference external" href="https://peps.python.org/pep-0488/"><strong>PEP 488</strong></a>.</p>
|
||
</div>
|
||
</dd></dl>
|
||
|
||
<dl class="std option">
|
||
<dt class="sig sig-object std" id="cmdoption-OO">
|
||
<span class="sig-name descname"><span class="pre">-OO</span></span><span class="sig-prename descclassname"></span><a class="headerlink" href="#cmdoption-OO" title="Link to this definition">¶</a></dt>
|
||
<dd><p>Do <a class="reference internal" href="#cmdoption-O"><code class="xref std std-option docutils literal notranslate"><span class="pre">-O</span></code></a> and also discard docstrings. Augment the filename
|
||
for compiled (<a class="reference internal" href="../glossary.html#term-bytecode"><span class="xref std std-term">bytecode</span></a>) files by adding <code class="docutils literal notranslate"><span class="pre">.opt-2</span></code> before the
|
||
<code class="docutils literal notranslate"><span class="pre">.pyc</span></code> extension (see <span class="target" id="index-10"></span><a class="pep reference external" href="https://peps.python.org/pep-0488/"><strong>PEP 488</strong></a>).</p>
|
||
<div class="versionchanged">
|
||
<p><span class="versionmodified changed">Changed in version 3.5: </span>Modify <code class="docutils literal notranslate"><span class="pre">.pyc</span></code> filenames according to <span class="target" id="index-11"></span><a class="pep reference external" href="https://peps.python.org/pep-0488/"><strong>PEP 488</strong></a>.</p>
|
||
</div>
|
||
</dd></dl>
|
||
|
||
<dl class="std option">
|
||
<dt class="sig sig-object std" id="cmdoption-P">
|
||
<span class="sig-name descname"><span class="pre">-P</span></span><span class="sig-prename descclassname"></span><a class="headerlink" href="#cmdoption-P" title="Link to this definition">¶</a></dt>
|
||
<dd><p>Don’t prepend a potentially unsafe path to <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>:</p>
|
||
<ul class="simple">
|
||
<li><p><code class="docutils literal notranslate"><span class="pre">python</span> <span class="pre">-m</span> <span class="pre">module</span></code> command line: Don’t prepend the current working
|
||
directory.</p></li>
|
||
<li><p><code class="docutils literal notranslate"><span class="pre">python</span> <span class="pre">script.py</span></code> command line: Don’t prepend the script’s directory.
|
||
If it’s a symbolic link, resolve symbolic links.</p></li>
|
||
<li><p><code class="docutils literal notranslate"><span class="pre">python</span> <span class="pre">-c</span> <span class="pre">code</span></code> and <code class="docutils literal notranslate"><span class="pre">python</span></code> (REPL) command lines: Don’t prepend an
|
||
empty string, which means the current working directory.</p></li>
|
||
</ul>
|
||
<p>See also the <span class="target" id="index-12"></span><a class="reference internal" href="#envvar-PYTHONSAFEPATH"><code class="xref std std-envvar docutils literal notranslate"><span class="pre">PYTHONSAFEPATH</span></code></a> environment variable, and <a class="reference internal" href="#cmdoption-E"><code class="xref std std-option docutils literal notranslate"><span class="pre">-E</span></code></a>
|
||
and <a class="reference internal" href="#cmdoption-I"><code class="xref std std-option docutils literal notranslate"><span class="pre">-I</span></code></a> (isolated) options.</p>
|
||
<div class="versionadded">
|
||
<p><span class="versionmodified added">Added in version 3.11.</span></p>
|
||
</div>
|
||
</dd></dl>
|
||
|
||
<dl class="std option">
|
||
<dt class="sig sig-object std" id="cmdoption-q">
|
||
<span class="sig-name descname"><span class="pre">-q</span></span><span class="sig-prename descclassname"></span><a class="headerlink" href="#cmdoption-q" title="Link to this definition">¶</a></dt>
|
||
<dd><p>Don’t display the copyright and version messages even in interactive mode.</p>
|
||
<div class="versionadded">
|
||
<p><span class="versionmodified added">Added in version 3.2.</span></p>
|
||
</div>
|
||
</dd></dl>
|
||
|
||
<dl class="std option">
|
||
<dt class="sig sig-object std" id="cmdoption-R">
|
||
<span class="sig-name descname"><span class="pre">-R</span></span><span class="sig-prename descclassname"></span><a class="headerlink" href="#cmdoption-R" title="Link to this definition">¶</a></dt>
|
||
<dd><p>Turn on hash randomization. This option only has an effect if the
|
||
<span class="target" id="index-13"></span><a class="reference internal" href="#envvar-PYTHONHASHSEED"><code class="xref std std-envvar docutils literal notranslate"><span class="pre">PYTHONHASHSEED</span></code></a> environment variable is set to <code class="docutils literal notranslate"><span class="pre">0</span></code>, since hash
|
||
randomization is enabled by default.</p>
|
||
<p>On previous versions of Python, this option turns on hash randomization,
|
||
so that the <a class="reference internal" href="../reference/datamodel.html#object.__hash__" title="object.__hash__"><code class="xref py py-meth docutils literal notranslate"><span class="pre">__hash__()</span></code></a> values of str and bytes objects
|
||
are “salted” with an unpredictable random value. Although they remain
|
||
constant within an individual Python process, they are not predictable
|
||
between repeated invocations of Python.</p>
|
||
<p>Hash randomization is intended to provide protection against a
|
||
denial-of-service caused by carefully chosen inputs that exploit the worst
|
||
case performance of a dict construction, <em>O</em>(<em>n</em><sup>2</sup>) complexity. See
|
||
<a class="reference external" href="http://ocert.org/advisories/ocert-2011-003.html">http://ocert.org/advisories/ocert-2011-003.html</a> for details.</p>
|
||
<p><span class="target" id="index-14"></span><a class="reference internal" href="#envvar-PYTHONHASHSEED"><code class="xref std std-envvar docutils literal notranslate"><span class="pre">PYTHONHASHSEED</span></code></a> allows you to set a fixed value for the hash
|
||
seed secret.</p>
|
||
<div class="versionadded">
|
||
<p><span class="versionmodified added">Added in version 3.2.3.</span></p>
|
||
</div>
|
||
<div class="versionchanged">
|
||
<p><span class="versionmodified changed">Changed in version 3.7: </span>The option is no longer ignored.</p>
|
||
</div>
|
||
</dd></dl>
|
||
|
||
<dl class="std option">
|
||
<dt class="sig sig-object std" id="cmdoption-s">
|
||
<span class="sig-name descname"><span class="pre">-s</span></span><span class="sig-prename descclassname"></span><a class="headerlink" href="#cmdoption-s" title="Link to this definition">¶</a></dt>
|
||
<dd><p>Don’t add the <a class="reference internal" href="../library/site.html#site.USER_SITE" title="site.USER_SITE"><code class="xref py py-data docutils literal notranslate"><span class="pre">user</span> <span class="pre">site-packages</span> <span class="pre">directory</span></code></a> to
|
||
<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>.</p>
|
||
<p>See also <span class="target" id="index-15"></span><a class="reference internal" href="#envvar-PYTHONNOUSERSITE"><code class="xref std std-envvar docutils literal notranslate"><span class="pre">PYTHONNOUSERSITE</span></code></a>.</p>
|
||
<div class="admonition seealso">
|
||
<p class="admonition-title">See also</p>
|
||
<p><span class="target" id="index-16"></span><a class="pep reference external" href="https://peps.python.org/pep-0370/"><strong>PEP 370</strong></a> – Per user site-packages directory</p>
|
||
</div>
|
||
</dd></dl>
|
||
|
||
<dl class="std option">
|
||
<dt class="sig sig-object std" id="cmdoption-S">
|
||
<span class="sig-name descname"><span class="pre">-S</span></span><span class="sig-prename descclassname"></span><a class="headerlink" href="#cmdoption-S" title="Link to this definition">¶</a></dt>
|
||
<dd><p>Disable the import of the module <a class="reference internal" href="../library/site.html#module-site" title="site: Module responsible for site-specific configuration."><code class="xref py py-mod docutils literal notranslate"><span class="pre">site</span></code></a> and the site-dependent
|
||
manipulations of <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> that it entails. Also disable these
|
||
manipulations if <a class="reference internal" href="../library/site.html#module-site" title="site: Module responsible for site-specific configuration."><code class="xref py py-mod docutils literal notranslate"><span class="pre">site</span></code></a> is explicitly imported later (call
|
||
<a class="reference internal" href="../library/site.html#site.main" title="site.main"><code class="xref py py-func docutils literal notranslate"><span class="pre">site.main()</span></code></a> if you want them to be triggered).</p>
|
||
</dd></dl>
|
||
|
||
<dl class="std option">
|
||
<dt class="sig sig-object std" id="cmdoption-u">
|
||
<span class="sig-name descname"><span class="pre">-u</span></span><span class="sig-prename descclassname"></span><a class="headerlink" href="#cmdoption-u" title="Link to this definition">¶</a></dt>
|
||
<dd><p>Force the stdout and stderr streams to be unbuffered. This option has no
|
||
effect on the stdin stream.</p>
|
||
<p>See also <span class="target" id="index-17"></span><a class="reference internal" href="#envvar-PYTHONUNBUFFERED"><code class="xref std std-envvar docutils literal notranslate"><span class="pre">PYTHONUNBUFFERED</span></code></a>.</p>
|
||
<div class="versionchanged">
|
||
<p><span class="versionmodified changed">Changed in version 3.7: </span>The text layer of the stdout and stderr streams now is unbuffered.</p>
|
||
</div>
|
||
</dd></dl>
|
||
|
||
<dl class="std option">
|
||
<dt class="sig sig-object std" id="cmdoption-v">
|
||
<span class="sig-name descname"><span class="pre">-v</span></span><span class="sig-prename descclassname"></span><a class="headerlink" href="#cmdoption-v" title="Link to this definition">¶</a></dt>
|
||
<dd><p>Print a message each time a module is initialized, showing the place
|
||
(filename or built-in module) from which it is loaded. When given twice
|
||
(<code class="xref std std-option docutils literal notranslate"><span class="pre">-vv</span></code>), print a message for each file that is checked for when
|
||
searching for a module. Also provides information on module cleanup at exit.</p>
|
||
<div class="versionchanged">
|
||
<p><span class="versionmodified changed">Changed in version 3.10: </span>The <a class="reference internal" href="../library/site.html#module-site" title="site: Module responsible for site-specific configuration."><code class="xref py py-mod docutils literal notranslate"><span class="pre">site</span></code></a> module reports the site-specific paths
|
||
and <code class="file docutils literal notranslate"><span class="pre">.pth</span></code> files being processed.</p>
|
||
</div>
|
||
<p>See also <span class="target" id="index-18"></span><a class="reference internal" href="#envvar-PYTHONVERBOSE"><code class="xref std std-envvar docutils literal notranslate"><span class="pre">PYTHONVERBOSE</span></code></a>.</p>
|
||
</dd></dl>
|
||
|
||
<dl class="std option" id="using-on-warnings">
|
||
<dt class="sig sig-object std" id="cmdoption-W">
|
||
<span class="sig-name descname"><span class="pre">-W</span></span><span class="sig-prename descclassname"> <span class="pre">arg</span></span><a class="headerlink" href="#cmdoption-W" title="Link to this definition">¶</a></dt>
|
||
<dd><p>Warning control. Python’s warning machinery by default prints warning
|
||
messages 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>.</p>
|
||
<p>The simplest settings apply a particular action unconditionally to all
|
||
warnings emitted by a process (even those that are otherwise ignored by
|
||
default):</p>
|
||
<div class="highlight-sh notranslate"><div class="highlight"><pre><span></span>-Wdefault<span class="w"> </span><span class="c1"># Warn once per call location</span>
|
||
-Werror<span class="w"> </span><span class="c1"># Convert to exceptions</span>
|
||
-Walways<span class="w"> </span><span class="c1"># Warn every time</span>
|
||
-Wall<span class="w"> </span><span class="c1"># Same as -Walways</span>
|
||
-Wmodule<span class="w"> </span><span class="c1"># Warn once per calling module</span>
|
||
-Wonce<span class="w"> </span><span class="c1"># Warn once per Python process</span>
|
||
-Wignore<span class="w"> </span><span class="c1"># Never warn</span>
|
||
</pre></div>
|
||
</div>
|
||
<p>The action names can be abbreviated as desired and the interpreter will
|
||
resolve them to the appropriate action name. For example, <code class="docutils literal notranslate"><span class="pre">-Wi</span></code> is the
|
||
same as <code class="docutils literal notranslate"><span class="pre">-Wignore</span></code>.</p>
|
||
<p>The full form of argument is:</p>
|
||
<div class="highlight-sh notranslate"><div class="highlight"><pre><span></span>action:message:category:module:lineno
|
||
</pre></div>
|
||
</div>
|
||
<p>Empty fields match all values; trailing empty fields may be omitted. For
|
||
example <code class="docutils literal notranslate"><span class="pre">-W</span> <span class="pre">ignore::DeprecationWarning</span></code> ignores all DeprecationWarning
|
||
warnings.</p>
|
||
<p>The <em>action</em> field is as explained above but only applies to warnings that
|
||
match the remaining fields.</p>
|
||
<p>The <em>message</em> field must match the whole warning message; this match is
|
||
case-insensitive.</p>
|
||
<p>The <em>category</em> field matches the warning category
|
||
(ex: <code class="docutils literal notranslate"><span class="pre">DeprecationWarning</span></code>). This must be a class name; the match test
|
||
whether the actual warning category of the message is a subclass of the
|
||
specified warning category.</p>
|
||
<p>The <em>module</em> field matches the (fully qualified) module name; this match is
|
||
case-sensitive.</p>
|
||
<p>The <em>lineno</em> field matches the line number, where zero matches all line
|
||
numbers and is thus equivalent to an omitted line number.</p>
|
||
<p>Multiple <a class="reference internal" href="#cmdoption-W"><code class="xref std std-option docutils literal notranslate"><span class="pre">-W</span></code></a> options can be given; when a warning matches more than
|
||
one option, the action for the last matching option is performed. Invalid
|
||
<a class="reference internal" href="#cmdoption-W"><code class="xref std std-option docutils literal notranslate"><span class="pre">-W</span></code></a> options are ignored (though, a warning message is printed about
|
||
invalid options when the first warning is issued).</p>
|
||
<p>Warnings can also be controlled using the <span class="target" id="index-19"></span><a class="reference internal" href="#envvar-PYTHONWARNINGS"><code class="xref std std-envvar docutils literal notranslate"><span class="pre">PYTHONWARNINGS</span></code></a>
|
||
environment variable and from within a Python program using the
|
||
<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> module. For example, the <a class="reference internal" href="../library/warnings.html#warnings.filterwarnings" title="warnings.filterwarnings"><code class="xref py py-func docutils literal notranslate"><span class="pre">warnings.filterwarnings()</span></code></a>
|
||
function can be used to use a regular expression on the warning message.</p>
|
||
<p>See <a class="reference internal" href="../library/warnings.html#warning-filter"><span class="std std-ref">The Warnings Filter</span></a> and <a class="reference internal" href="../library/warnings.html#describing-warning-filters"><span class="std std-ref">Describing Warning Filters</span></a> for more
|
||
details.</p>
|
||
</dd></dl>
|
||
|
||
<dl class="std option">
|
||
<dt class="sig sig-object std" id="cmdoption-x">
|
||
<span class="sig-name descname"><span class="pre">-x</span></span><span class="sig-prename descclassname"></span><a class="headerlink" href="#cmdoption-x" title="Link to this definition">¶</a></dt>
|
||
<dd><p>Skip the first line of the source, allowing use of non-Unix forms of
|
||
<code class="docutils literal notranslate"><span class="pre">#!cmd</span></code>. This is intended for a DOS specific hack only.</p>
|
||
</dd></dl>
|
||
|
||
<dl class="std option">
|
||
<dt class="sig sig-object std" id="cmdoption-X">
|
||
<span class="sig-name descname"><span class="pre">-X</span></span><span class="sig-prename descclassname"></span><a class="headerlink" href="#cmdoption-X" title="Link to this definition">¶</a></dt>
|
||
<dd><p>Reserved for various implementation-specific options. CPython currently
|
||
defines the following possible values:</p>
|
||
<ul>
|
||
<li><p><code class="docutils literal notranslate"><span class="pre">-X</span> <span class="pre">faulthandler</span></code> to enable <a class="reference internal" href="../library/faulthandler.html#module-faulthandler" title="faulthandler: Dump the Python traceback."><code class="xref py py-mod docutils literal notranslate"><span class="pre">faulthandler</span></code></a>.
|
||
See also <span class="target" id="index-20"></span><a class="reference internal" href="#envvar-PYTHONFAULTHANDLER"><code class="xref std std-envvar docutils literal notranslate"><span class="pre">PYTHONFAULTHANDLER</span></code></a>.</p>
|
||
<div class="versionadded">
|
||
<p><span class="versionmodified added">Added in version 3.3.</span></p>
|
||
</div>
|
||
</li>
|
||
<li><p><code class="docutils literal notranslate"><span class="pre">-X</span> <span class="pre">showrefcount</span></code> to output the total reference count and number of used
|
||
memory blocks when the program finishes or after each statement in the
|
||
interactive interpreter. This only works on <a class="reference internal" href="configure.html#debug-build"><span class="std std-ref">debug builds</span></a>.</p>
|
||
<div class="versionadded">
|
||
<p><span class="versionmodified added">Added in version 3.4.</span></p>
|
||
</div>
|
||
</li>
|
||
<li><p><code class="docutils literal notranslate"><span class="pre">-X</span> <span class="pre">tracemalloc</span></code> to start tracing Python memory allocations using the
|
||
<a class="reference internal" href="../library/tracemalloc.html#module-tracemalloc" title="tracemalloc: Trace memory allocations."><code class="xref py py-mod docutils literal notranslate"><span class="pre">tracemalloc</span></code></a> module. By default, only the most recent frame is
|
||
stored in a traceback of a trace. Use <code class="docutils literal notranslate"><span class="pre">-X</span> <span class="pre">tracemalloc=NFRAME</span></code> to start
|
||
tracing with a traceback limit of <em>NFRAME</em> frames.
|
||
See <a class="reference internal" href="../library/tracemalloc.html#tracemalloc.start" title="tracemalloc.start"><code class="xref py py-func docutils literal notranslate"><span class="pre">tracemalloc.start()</span></code></a> and <span class="target" id="index-21"></span><a class="reference internal" href="#envvar-PYTHONTRACEMALLOC"><code class="xref std std-envvar docutils literal notranslate"><span class="pre">PYTHONTRACEMALLOC</span></code></a>
|
||
for more information.</p>
|
||
<div class="versionadded">
|
||
<p><span class="versionmodified added">Added in version 3.4.</span></p>
|
||
</div>
|
||
</li>
|
||
<li><p><code class="docutils literal notranslate"><span class="pre">-X</span> <span class="pre">int_max_str_digits</span></code> configures the <a class="reference internal" href="../library/stdtypes.html#int-max-str-digits"><span class="std std-ref">integer string conversion
|
||
length limitation</span></a>. See also
|
||
<span class="target" id="index-22"></span><a class="reference internal" href="#envvar-PYTHONINTMAXSTRDIGITS"><code class="xref std std-envvar docutils literal notranslate"><span class="pre">PYTHONINTMAXSTRDIGITS</span></code></a>.</p>
|
||
<div class="versionadded">
|
||
<p><span class="versionmodified added">Added in version 3.11.</span></p>
|
||
</div>
|
||
</li>
|
||
<li><p><code class="docutils literal notranslate"><span class="pre">-X</span> <span class="pre">importtime</span></code> to show how long each import takes. It shows module
|
||
name, cumulative time (including nested imports) and self time (excluding
|
||
nested imports). Note that its output may be broken in multi-threaded
|
||
application. Typical usage is <code class="docutils literal notranslate"><span class="pre">python3</span> <span class="pre">-X</span> <span class="pre">importtime</span> <span class="pre">-c</span> <span class="pre">'import</span>
|
||
<span class="pre">asyncio'</span></code>. See also <span class="target" id="index-23"></span><a class="reference internal" href="#envvar-PYTHONPROFILEIMPORTTIME"><code class="xref std std-envvar docutils literal notranslate"><span class="pre">PYTHONPROFILEIMPORTTIME</span></code></a>.</p>
|
||
<div class="versionadded">
|
||
<p><span class="versionmodified added">Added in version 3.7.</span></p>
|
||
</div>
|
||
</li>
|
||
<li><p><code class="docutils literal notranslate"><span class="pre">-X</span> <span class="pre">dev</span></code>: enable <a class="reference internal" href="../library/devmode.html#devmode"><span class="std std-ref">Python Development Mode</span></a>, introducing
|
||
additional runtime checks that are too expensive to be enabled by
|
||
default. See also <span class="target" id="index-24"></span><a class="reference internal" href="#envvar-PYTHONDEVMODE"><code class="xref std std-envvar docutils literal notranslate"><span class="pre">PYTHONDEVMODE</span></code></a>.</p>
|
||
<div class="versionadded">
|
||
<p><span class="versionmodified added">Added in version 3.7.</span></p>
|
||
</div>
|
||
</li>
|
||
<li><p><code class="docutils literal notranslate"><span class="pre">-X</span> <span class="pre">utf8</span></code> enables the <a class="reference internal" href="../library/os.html#utf8-mode"><span class="std std-ref">Python UTF-8 Mode</span></a>.
|
||
<code class="docutils literal notranslate"><span class="pre">-X</span> <span class="pre">utf8=0</span></code> explicitly disables <a class="reference internal" href="../library/os.html#utf8-mode"><span class="std std-ref">Python UTF-8 Mode</span></a>
|
||
(even when it would otherwise activate automatically).
|
||
See also <span class="target" id="index-25"></span><a class="reference internal" href="#envvar-PYTHONUTF8"><code class="xref std std-envvar docutils literal notranslate"><span class="pre">PYTHONUTF8</span></code></a>.</p>
|
||
<div class="versionadded">
|
||
<p><span class="versionmodified added">Added in version 3.7.</span></p>
|
||
</div>
|
||
</li>
|
||
<li><p><code class="docutils literal notranslate"><span class="pre">-X</span> <span class="pre">pycache_prefix=PATH</span></code> enables writing <code class="docutils literal notranslate"><span class="pre">.pyc</span></code> files to a parallel
|
||
tree rooted at the given directory instead of to the code tree. See also
|
||
<span class="target" id="index-26"></span><a class="reference internal" href="#envvar-PYTHONPYCACHEPREFIX"><code class="xref std std-envvar docutils literal notranslate"><span class="pre">PYTHONPYCACHEPREFIX</span></code></a>.</p>
|
||
<div class="versionadded">
|
||
<p><span class="versionmodified added">Added in version 3.8.</span></p>
|
||
</div>
|
||
</li>
|
||
<li><p><code class="docutils literal notranslate"><span class="pre">-X</span> <span class="pre">warn_default_encoding</span></code> issues a <a class="reference internal" href="../library/exceptions.html#EncodingWarning" title="EncodingWarning"><code class="xref py py-class docutils literal notranslate"><span class="pre">EncodingWarning</span></code></a> when the
|
||
locale-specific default encoding is used for opening files.
|
||
See also <span class="target" id="index-27"></span><a class="reference internal" href="#envvar-PYTHONWARNDEFAULTENCODING"><code class="xref std std-envvar docutils literal notranslate"><span class="pre">PYTHONWARNDEFAULTENCODING</span></code></a>.</p>
|
||
<div class="versionadded">
|
||
<p><span class="versionmodified added">Added in version 3.10.</span></p>
|
||
</div>
|
||
</li>
|
||
<li><p><code class="docutils literal notranslate"><span class="pre">-X</span> <span class="pre">no_debug_ranges</span></code> disables the inclusion of the tables mapping extra
|
||
location information (end line, start column offset and end column offset)
|
||
to every instruction in code objects. This is useful when smaller code
|
||
objects and pyc files are desired as well as suppressing the extra visual
|
||
location indicators when the interpreter displays tracebacks. See also
|
||
<span class="target" id="index-28"></span><a class="reference internal" href="#envvar-PYTHONNODEBUGRANGES"><code class="xref std std-envvar docutils literal notranslate"><span class="pre">PYTHONNODEBUGRANGES</span></code></a>.</p>
|
||
<div class="versionadded">
|
||
<p><span class="versionmodified added">Added in version 3.11.</span></p>
|
||
</div>
|
||
</li>
|
||
<li><p><code class="docutils literal notranslate"><span class="pre">-X</span> <span class="pre">frozen_modules</span></code> determines whether or not frozen modules are
|
||
ignored by the import machinery. A value of <code class="docutils literal notranslate"><span class="pre">on</span></code> means they get
|
||
imported and <code class="docutils literal notranslate"><span class="pre">off</span></code> means they are ignored. The default is <code class="docutils literal notranslate"><span class="pre">on</span></code>
|
||
if this is an installed Python (the normal case). If it’s under
|
||
development (running from the source tree) then the default is <code class="docutils literal notranslate"><span class="pre">off</span></code>.
|
||
Note that the <code class="xref py py-mod docutils literal notranslate"><span class="pre">importlib_bootstrap</span></code> and
|
||
<code class="xref py py-mod docutils literal notranslate"><span class="pre">importlib_bootstrap_external</span></code> frozen modules are always used, even
|
||
if this flag is set to <code class="docutils literal notranslate"><span class="pre">off</span></code>. See also <span class="target" id="index-29"></span><a class="reference internal" href="#envvar-PYTHON_FROZEN_MODULES"><code class="xref std std-envvar docutils literal notranslate"><span class="pre">PYTHON_FROZEN_MODULES</span></code></a>.</p>
|
||
<div class="versionadded">
|
||
<p><span class="versionmodified added">Added in version 3.11.</span></p>
|
||
</div>
|
||
</li>
|
||
<li><p><code class="docutils literal notranslate"><span class="pre">-X</span> <span class="pre">perf</span></code> enables support for the Linux <code class="docutils literal notranslate"><span class="pre">perf</span></code> profiler.
|
||
When this option is provided, the <code class="docutils literal notranslate"><span class="pre">perf</span></code> profiler will be able to
|
||
report Python calls. This option is only available on some platforms and
|
||
will do nothing if is not supported on the current system. The default value
|
||
is “off”. See also <span class="target" id="index-30"></span><a class="reference internal" href="#envvar-PYTHONPERFSUPPORT"><code class="xref std std-envvar docutils literal notranslate"><span class="pre">PYTHONPERFSUPPORT</span></code></a> and <a class="reference internal" href="../howto/perf_profiling.html#perf-profiling"><span class="std std-ref">Python support for the Linux perf profiler</span></a>.</p>
|
||
<div class="versionadded">
|
||
<p><span class="versionmodified added">Added in version 3.12.</span></p>
|
||
</div>
|
||
</li>
|
||
<li><p><code class="docutils literal notranslate"><span class="pre">-X</span> <span class="pre">perf_jit</span></code> enables support for the Linux <code class="docutils literal notranslate"><span class="pre">perf</span></code> profiler with DWARF
|
||
support. When this option is provided, the <code class="docutils literal notranslate"><span class="pre">perf</span></code> profiler will be able
|
||
to report Python calls using DWARF information. This option is only available on
|
||
some platforms and will do nothing if is not supported on the current
|
||
system. The default value is “off”. See also <span class="target" id="index-31"></span><a class="reference internal" href="#envvar-PYTHON_PERF_JIT_SUPPORT"><code class="xref std std-envvar docutils literal notranslate"><span class="pre">PYTHON_PERF_JIT_SUPPORT</span></code></a>
|
||
and <a class="reference internal" href="../howto/perf_profiling.html#perf-profiling"><span class="std std-ref">Python support for the Linux perf profiler</span></a>.</p>
|
||
<div class="versionadded">
|
||
<p><span class="versionmodified added">Added in version 3.13.</span></p>
|
||
</div>
|
||
</li>
|
||
<li><p><code class="samp docutils literal notranslate"><span class="pre">-X</span> <span class="pre">cpu_count=</span><em><span class="pre">n</span></em></code> overrides <a class="reference internal" href="../library/os.html#os.cpu_count" title="os.cpu_count"><code class="xref py py-func docutils literal notranslate"><span class="pre">os.cpu_count()</span></code></a>,
|
||
<a class="reference internal" href="../library/os.html#os.process_cpu_count" title="os.process_cpu_count"><code class="xref py py-func docutils literal notranslate"><span class="pre">os.process_cpu_count()</span></code></a>, and <a class="reference internal" href="../library/multiprocessing.html#multiprocessing.cpu_count" title="multiprocessing.cpu_count"><code class="xref py py-func docutils literal notranslate"><span class="pre">multiprocessing.cpu_count()</span></code></a>.
|
||
<em>n</em> must be greater than or equal to 1.
|
||
This option may be useful for users who need to limit CPU resources of a
|
||
container system. See also <span class="target" id="index-32"></span><a class="reference internal" href="#envvar-PYTHON_CPU_COUNT"><code class="xref std std-envvar docutils literal notranslate"><span class="pre">PYTHON_CPU_COUNT</span></code></a>.
|
||
If <em>n</em> is <code class="docutils literal notranslate"><span class="pre">default</span></code>, nothing is overridden.</p>
|
||
<div class="versionadded">
|
||
<p><span class="versionmodified added">Added in version 3.13.</span></p>
|
||
</div>
|
||
</li>
|
||
<li><p><code class="samp docutils literal notranslate"><span class="pre">-X</span> <span class="pre">presite=</span><em><span class="pre">package.module</span></em></code> specifies a module that should be
|
||
imported before the <a class="reference internal" href="../library/site.html#module-site" title="site: Module responsible for site-specific configuration."><code class="xref py py-mod docutils literal notranslate"><span class="pre">site</span></code></a> module is executed and before the
|
||
<a class="reference internal" href="../library/__main__.html#module-__main__" title="__main__: The environment where top-level code is run. Covers command-line interfaces, import-time behavior, and ``__name__ == '__main__'``."><code class="xref py py-mod docutils literal notranslate"><span class="pre">__main__</span></code></a> module exists. Therefore, the imported module isn’t
|
||
<a class="reference internal" href="../library/__main__.html#module-__main__" title="__main__: The environment where top-level code is run. Covers command-line interfaces, import-time behavior, and ``__name__ == '__main__'``."><code class="xref py py-mod docutils literal notranslate"><span class="pre">__main__</span></code></a>. This can be used to execute code early during Python
|
||
initialization. Python needs to be <a class="reference internal" href="configure.html#debug-build"><span class="std std-ref">built in debug mode</span></a>
|
||
for this option to exist. See also <span class="target" id="index-33"></span><a class="reference internal" href="#envvar-PYTHON_PRESITE"><code class="xref std std-envvar docutils literal notranslate"><span class="pre">PYTHON_PRESITE</span></code></a>.</p>
|
||
<div class="versionadded">
|
||
<p><span class="versionmodified added">Added in version 3.13.</span></p>
|
||
</div>
|
||
</li>
|
||
<li><p><code class="samp docutils literal notranslate"><span class="pre">-X</span> <span class="pre">gil=</span><em><span class="pre">0,1</span></em></code> forces the GIL to be disabled or enabled,
|
||
respectively. Setting to <code class="docutils literal notranslate"><span class="pre">0</span></code> is only available in builds configured with
|
||
<a class="reference internal" href="configure.html#cmdoption-disable-gil"><code class="xref std std-option docutils literal notranslate"><span class="pre">--disable-gil</span></code></a>. See also <span class="target" id="index-34"></span><a class="reference internal" href="#envvar-PYTHON_GIL"><code class="xref std std-envvar docutils literal notranslate"><span class="pre">PYTHON_GIL</span></code></a> and
|
||
<a class="reference internal" href="../whatsnew/3.13.html#whatsnew313-free-threaded-cpython"><span class="std std-ref">Free-threaded CPython</span></a>.</p>
|
||
<div class="versionadded">
|
||
<p><span class="versionmodified added">Added in version 3.13.</span></p>
|
||
</div>
|
||
</li>
|
||
</ul>
|
||
<p>It also allows passing arbitrary values and retrieving them through the
|
||
<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> dictionary.</p>
|
||
<div class="versionadded">
|
||
<p><span class="versionmodified added">Added in version 3.2.</span></p>
|
||
</div>
|
||
<div class="versionchanged">
|
||
<p><span class="versionmodified changed">Changed in version 3.9: </span>Removed the <code class="docutils literal notranslate"><span class="pre">-X</span> <span class="pre">showalloccount</span></code> option.</p>
|
||
</div>
|
||
<div class="versionchanged">
|
||
<p><span class="versionmodified changed">Changed in version 3.10: </span>Removed the <code class="docutils literal notranslate"><span class="pre">-X</span> <span class="pre">oldparser</span></code> option.</p>
|
||
</div>
|
||
</dd></dl>
|
||
|
||
</section>
|
||
<section id="controlling-color">
|
||
<span id="using-on-controlling-color"></span><h3><span class="section-number">1.1.4. </span>Controlling color<a class="headerlink" href="#controlling-color" title="Link to this heading">¶</a></h3>
|
||
<p>The Python interpreter is configured by default to use colors to highlight
|
||
output in certain situations such as when displaying tracebacks. This
|
||
behavior can be controlled by setting different environment variables.</p>
|
||
<p>Setting the environment variable <code class="docutils literal notranslate"><span class="pre">TERM</span></code> to <code class="docutils literal notranslate"><span class="pre">dumb</span></code> will disable color.</p>
|
||
<p>If the <a class="reference external" href="https://force-color.org/"><code class="docutils literal notranslate"><span class="pre">FORCE_COLOR</span></code></a> environment variable is set, then color will be
|
||
enabled regardless of the value of TERM. This is useful on CI systems which
|
||
aren’t terminals but can still display ANSI escape sequences.</p>
|
||
<p>If the <a class="reference external" href="https://no-color.org/"><code class="docutils literal notranslate"><span class="pre">NO_COLOR</span></code></a> environment variable is set, Python will disable all color
|
||
in the output. This takes precedence over <code class="docutils literal notranslate"><span class="pre">FORCE_COLOR</span></code>.</p>
|
||
<p>All these environment variables are used also by other tools to control color
|
||
output. To control the color output only in the Python interpreter, the
|
||
<span class="target" id="index-35"></span><a class="reference internal" href="#envvar-PYTHON_COLORS"><code class="xref std std-envvar docutils literal notranslate"><span class="pre">PYTHON_COLORS</span></code></a> environment variable can be used. This variable takes
|
||
precedence over <code class="docutils literal notranslate"><span class="pre">NO_COLOR</span></code>, which in turn takes precedence over
|
||
<code class="docutils literal notranslate"><span class="pre">FORCE_COLOR</span></code>.</p>
|
||
</section>
|
||
<section id="options-you-shouldn-t-use">
|
||
<h3><span class="section-number">1.1.5. </span>Options you shouldn’t use<a class="headerlink" href="#options-you-shouldn-t-use" title="Link to this heading">¶</a></h3>
|
||
<dl class="std option">
|
||
<dt class="sig sig-object std" id="cmdoption-J">
|
||
<span class="sig-name descname"><span class="pre">-J</span></span><span class="sig-prename descclassname"></span><a class="headerlink" href="#cmdoption-J" title="Link to this definition">¶</a></dt>
|
||
<dd><p>Reserved for use by <a class="reference external" href="https://www.jython.org/">Jython</a>.</p>
|
||
</dd></dl>
|
||
|
||
</section>
|
||
</section>
|
||
<section id="environment-variables">
|
||
<span id="using-on-envvars"></span><h2><span class="section-number">1.2. </span>Environment variables<a class="headerlink" href="#environment-variables" title="Link to this heading">¶</a></h2>
|
||
<p>These environment variables influence Python’s behavior, they are processed
|
||
before the command-line switches other than -E or -I. It is customary that
|
||
command-line switches override environmental variables where there is a
|
||
conflict.</p>
|
||
<dl class="std envvar">
|
||
<dt class="sig sig-object std" id="envvar-PYTHONHOME">
|
||
<span class="sig-name descname"><span class="pre">PYTHONHOME</span></span><a class="headerlink" href="#envvar-PYTHONHOME" title="Link to this definition">¶</a></dt>
|
||
<dd><p>Change the location of the standard Python libraries. By default, the
|
||
libraries are searched in <code class="file docutils literal notranslate"><em><span class="pre">prefix</span></em><span class="pre">/lib/python</span><em><span class="pre">version</span></em></code> and
|
||
<code class="file docutils literal notranslate"><em><span class="pre">exec_prefix</span></em><span class="pre">/lib/python</span><em><span class="pre">version</span></em></code>, where <code class="file docutils literal notranslate"><em><span class="pre">prefix</span></em></code> and
|
||
<code class="file docutils literal notranslate"><em><span class="pre">exec_prefix</span></em></code> are installation-dependent directories, both defaulting
|
||
to <code class="file docutils literal notranslate"><span class="pre">/usr/local</span></code>.</p>
|
||
<p>When <span class="target" id="index-36"></span><a class="reference internal" href="#envvar-PYTHONHOME"><code class="xref std std-envvar docutils literal notranslate"><span class="pre">PYTHONHOME</span></code></a> is set to a single directory, its value replaces
|
||
both <code class="file docutils literal notranslate"><em><span class="pre">prefix</span></em></code> and <code class="file docutils literal notranslate"><em><span class="pre">exec_prefix</span></em></code>. To specify different values
|
||
for these, set <span class="target" id="index-37"></span><a class="reference internal" href="#envvar-PYTHONHOME"><code class="xref std std-envvar docutils literal notranslate"><span class="pre">PYTHONHOME</span></code></a> to <code class="file docutils literal notranslate"><em><span class="pre">prefix</span></em><span class="pre">:</span><em><span class="pre">exec_prefix</span></em></code>.</p>
|
||
</dd></dl>
|
||
|
||
<dl class="std envvar">
|
||
<dt class="sig sig-object std" id="envvar-PYTHONPATH">
|
||
<span class="sig-name descname"><span class="pre">PYTHONPATH</span></span><a class="headerlink" href="#envvar-PYTHONPATH" title="Link to this definition">¶</a></dt>
|
||
<dd><p>Augment the default search path for module files. The format is the same as
|
||
the shell’s <span class="target" id="index-38"></span><code class="xref std std-envvar docutils literal notranslate"><span class="pre">PATH</span></code>: one or more directory pathnames separated by
|
||
<a class="reference internal" href="../library/os.html#os.pathsep" title="os.pathsep"><code class="xref py py-data docutils literal notranslate"><span class="pre">os.pathsep</span></code></a> (e.g. colons on Unix or semicolons on Windows).
|
||
Non-existent directories are silently ignored.</p>
|
||
<p>In addition to normal directories, individual <span class="target" id="index-39"></span><a class="reference internal" href="#envvar-PYTHONPATH"><code class="xref std std-envvar docutils literal notranslate"><span class="pre">PYTHONPATH</span></code></a> entries
|
||
may refer to zipfiles containing pure Python modules (in either source or
|
||
compiled form). Extension modules cannot be imported from zipfiles.</p>
|
||
<p>The default search path is installation dependent, but generally begins with
|
||
<code class="file docutils literal notranslate"><em><span class="pre">prefix</span></em><span class="pre">/lib/python</span><em><span class="pre">version</span></em></code> (see <span class="target" id="index-40"></span><a class="reference internal" href="#envvar-PYTHONHOME"><code class="xref std std-envvar docutils literal notranslate"><span class="pre">PYTHONHOME</span></code></a> above). It
|
||
is <em>always</em> appended to <span class="target" id="index-41"></span><a class="reference internal" href="#envvar-PYTHONPATH"><code class="xref std std-envvar docutils literal notranslate"><span class="pre">PYTHONPATH</span></code></a>.</p>
|
||
<p>An additional directory will be inserted in the search path in front of
|
||
<span class="target" id="index-42"></span><a class="reference internal" href="#envvar-PYTHONPATH"><code class="xref std std-envvar docutils literal notranslate"><span class="pre">PYTHONPATH</span></code></a> as described above under
|
||
<a class="reference internal" href="#using-on-interface-options"><span class="std std-ref">Interface options</span></a>. The search path can be manipulated from
|
||
within a Python program as the variable <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>.</p>
|
||
</dd></dl>
|
||
|
||
<dl class="std envvar">
|
||
<dt class="sig sig-object std" id="envvar-PYTHONSAFEPATH">
|
||
<span class="sig-name descname"><span class="pre">PYTHONSAFEPATH</span></span><a class="headerlink" href="#envvar-PYTHONSAFEPATH" title="Link to this definition">¶</a></dt>
|
||
<dd><p>If this is set to a non-empty string, don’t prepend a potentially unsafe
|
||
path to <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>: see the <a class="reference internal" href="#cmdoption-P"><code class="xref std std-option docutils literal notranslate"><span class="pre">-P</span></code></a> option for details.</p>
|
||
<div class="versionadded">
|
||
<p><span class="versionmodified added">Added in version 3.11.</span></p>
|
||
</div>
|
||
</dd></dl>
|
||
|
||
<dl class="std envvar">
|
||
<dt class="sig sig-object std" id="envvar-PYTHONPLATLIBDIR">
|
||
<span class="sig-name descname"><span class="pre">PYTHONPLATLIBDIR</span></span><a class="headerlink" href="#envvar-PYTHONPLATLIBDIR" title="Link to this definition">¶</a></dt>
|
||
<dd><p>If this is set to a non-empty string, it overrides the <a class="reference internal" href="../library/sys.html#sys.platlibdir" title="sys.platlibdir"><code class="xref py py-data docutils literal notranslate"><span class="pre">sys.platlibdir</span></code></a>
|
||
value.</p>
|
||
<div class="versionadded">
|
||
<p><span class="versionmodified added">Added in version 3.9.</span></p>
|
||
</div>
|
||
</dd></dl>
|
||
|
||
<dl class="std envvar">
|
||
<dt class="sig sig-object std" id="envvar-PYTHONSTARTUP">
|
||
<span class="sig-name descname"><span class="pre">PYTHONSTARTUP</span></span><a class="headerlink" href="#envvar-PYTHONSTARTUP" title="Link to this definition">¶</a></dt>
|
||
<dd><p>If this is the name of a readable file, the Python commands in that file are
|
||
executed before the first prompt is displayed in interactive mode. The file
|
||
is executed in the same namespace where interactive commands are executed so
|
||
that objects defined or imported in it can be used without qualification in
|
||
the interactive session. You can also change the prompts <a class="reference internal" href="../library/sys.html#sys.ps1" title="sys.ps1"><code class="xref py py-data docutils literal notranslate"><span class="pre">sys.ps1</span></code></a> and
|
||
<a class="reference internal" href="../library/sys.html#sys.ps2" title="sys.ps2"><code class="xref py py-data docutils literal notranslate"><span class="pre">sys.ps2</span></code></a> and the hook <a class="reference internal" href="../library/sys.html#sys.__interactivehook__" title="sys.__interactivehook__"><code class="xref py py-data docutils literal notranslate"><span class="pre">sys.__interactivehook__</span></code></a> in this file.</p>
|
||
<p class="audit-hook"><p>Raises an <a class="reference internal" href="../library/sys.html#auditing"><span class="std std-ref">auditing event</span></a> <code class="docutils literal notranslate"><span class="pre">cpython.run_startup</span></code> with
|
||
the filename as the argument when called on startup.</p>
|
||
</p>
|
||
</dd></dl>
|
||
|
||
<dl class="std envvar">
|
||
<dt class="sig sig-object std" id="envvar-PYTHONOPTIMIZE">
|
||
<span class="sig-name descname"><span class="pre">PYTHONOPTIMIZE</span></span><a class="headerlink" href="#envvar-PYTHONOPTIMIZE" title="Link to this definition">¶</a></dt>
|
||
<dd><p>If this is set to a non-empty string it is equivalent to specifying the
|
||
<a class="reference internal" href="#cmdoption-O"><code class="xref std std-option docutils literal notranslate"><span class="pre">-O</span></code></a> option. If set to an integer, it is equivalent to specifying
|
||
<a class="reference internal" href="#cmdoption-O"><code class="xref std std-option docutils literal notranslate"><span class="pre">-O</span></code></a> multiple times.</p>
|
||
</dd></dl>
|
||
|
||
<dl class="std envvar">
|
||
<dt class="sig sig-object std" id="envvar-PYTHONBREAKPOINT">
|
||
<span class="sig-name descname"><span class="pre">PYTHONBREAKPOINT</span></span><a class="headerlink" href="#envvar-PYTHONBREAKPOINT" title="Link to this definition">¶</a></dt>
|
||
<dd><p>If this is set, it names a callable using dotted-path notation. The module
|
||
containing the callable will be imported and then the callable will be run
|
||
by the default implementation of <a class="reference internal" href="../library/sys.html#sys.breakpointhook" title="sys.breakpointhook"><code class="xref py py-func docutils literal notranslate"><span class="pre">sys.breakpointhook()</span></code></a> which itself is
|
||
called by built-in <a class="reference internal" href="../library/functions.html#breakpoint" title="breakpoint"><code class="xref py py-func docutils literal notranslate"><span class="pre">breakpoint()</span></code></a>. If not set, or set to the empty
|
||
string, it is equivalent to the value “pdb.set_trace”. Setting this to the
|
||
string “0” causes the default implementation of <a class="reference internal" href="../library/sys.html#sys.breakpointhook" title="sys.breakpointhook"><code class="xref py py-func docutils literal notranslate"><span class="pre">sys.breakpointhook()</span></code></a>
|
||
to do nothing but return immediately.</p>
|
||
<div class="versionadded">
|
||
<p><span class="versionmodified added">Added in version 3.7.</span></p>
|
||
</div>
|
||
</dd></dl>
|
||
|
||
<dl class="std envvar">
|
||
<dt class="sig sig-object std" id="envvar-PYTHONDEBUG">
|
||
<span class="sig-name descname"><span class="pre">PYTHONDEBUG</span></span><a class="headerlink" href="#envvar-PYTHONDEBUG" title="Link to this definition">¶</a></dt>
|
||
<dd><p>If this is set to a non-empty string it is equivalent to specifying the
|
||
<a class="reference internal" href="#cmdoption-d"><code class="xref std std-option docutils literal notranslate"><span class="pre">-d</span></code></a> option. If set to an integer, it is equivalent to specifying
|
||
<a class="reference internal" href="#cmdoption-d"><code class="xref std std-option docutils literal notranslate"><span class="pre">-d</span></code></a> multiple times.</p>
|
||
<p>This environment variable requires a <a class="reference internal" href="configure.html#debug-build"><span class="std std-ref">debug build of Python</span></a>, otherwise it’s ignored.</p>
|
||
</dd></dl>
|
||
|
||
<dl class="std envvar">
|
||
<dt class="sig sig-object std" id="envvar-PYTHONINSPECT">
|
||
<span class="sig-name descname"><span class="pre">PYTHONINSPECT</span></span><a class="headerlink" href="#envvar-PYTHONINSPECT" title="Link to this definition">¶</a></dt>
|
||
<dd><p>If this is set to a non-empty string it is equivalent to specifying the
|
||
<a class="reference internal" href="#cmdoption-i"><code class="xref std std-option docutils literal notranslate"><span class="pre">-i</span></code></a> option.</p>
|
||
<p>This variable can also be modified by Python code using <a class="reference internal" href="../library/os.html#os.environ" title="os.environ"><code class="xref py py-data docutils literal notranslate"><span class="pre">os.environ</span></code></a>
|
||
to force inspect mode on program termination.</p>
|
||
<p class="audit-hook" id="audit_event_cpython_run_stdin_2">Raises an <a class="reference internal" href="../library/sys.html#auditing"><span class="std std-ref">auditing event</span></a> <code class="docutils literal notranslate"><span class="pre">cpython.run_stdin</span></code> with no arguments.</p>
|
||
<div class="versionchanged">
|
||
<p><span class="versionmodified changed">Changed in version 3.12.5: </span>(also 3.11.10, 3.10.15, 3.9.20, and 3.8.20)
|
||
Emits audit events.</p>
|
||
</div>
|
||
<div class="versionchanged">
|
||
<p><span class="versionmodified changed">Changed in version 3.13: </span>Uses PyREPL if possible, in which case <span class="target" id="index-43"></span><a class="reference internal" href="#envvar-PYTHONSTARTUP"><code class="xref std std-envvar docutils literal notranslate"><span class="pre">PYTHONSTARTUP</span></code></a> is
|
||
also executed. Emits audit events.</p>
|
||
</div>
|
||
</dd></dl>
|
||
|
||
<dl class="std envvar">
|
||
<dt class="sig sig-object std" id="envvar-PYTHONUNBUFFERED">
|
||
<span class="sig-name descname"><span class="pre">PYTHONUNBUFFERED</span></span><a class="headerlink" href="#envvar-PYTHONUNBUFFERED" title="Link to this definition">¶</a></dt>
|
||
<dd><p>If this is set to a non-empty string it is equivalent to specifying the
|
||
<a class="reference internal" href="#cmdoption-u"><code class="xref std std-option docutils literal notranslate"><span class="pre">-u</span></code></a> option.</p>
|
||
</dd></dl>
|
||
|
||
<dl class="std envvar">
|
||
<dt class="sig sig-object std" id="envvar-PYTHONVERBOSE">
|
||
<span class="sig-name descname"><span class="pre">PYTHONVERBOSE</span></span><a class="headerlink" href="#envvar-PYTHONVERBOSE" title="Link to this definition">¶</a></dt>
|
||
<dd><p>If this is set to a non-empty string it is equivalent to specifying the
|
||
<a class="reference internal" href="#cmdoption-v"><code class="xref std std-option docutils literal notranslate"><span class="pre">-v</span></code></a> option. If set to an integer, it is equivalent to specifying
|
||
<a class="reference internal" href="#cmdoption-v"><code class="xref std std-option docutils literal notranslate"><span class="pre">-v</span></code></a> multiple times.</p>
|
||
</dd></dl>
|
||
|
||
<dl class="std envvar">
|
||
<dt class="sig sig-object std" id="envvar-PYTHONCASEOK">
|
||
<span class="sig-name descname"><span class="pre">PYTHONCASEOK</span></span><a class="headerlink" href="#envvar-PYTHONCASEOK" title="Link to this definition">¶</a></dt>
|
||
<dd><p>If this is set, Python ignores case in <a class="reference internal" href="../reference/simple_stmts.html#import"><code class="xref std std-keyword docutils literal notranslate"><span class="pre">import</span></code></a> statements. This
|
||
only works on Windows and macOS.</p>
|
||
</dd></dl>
|
||
|
||
<dl class="std envvar">
|
||
<dt class="sig sig-object std" id="envvar-PYTHONDONTWRITEBYTECODE">
|
||
<span class="sig-name descname"><span class="pre">PYTHONDONTWRITEBYTECODE</span></span><a class="headerlink" href="#envvar-PYTHONDONTWRITEBYTECODE" title="Link to this definition">¶</a></dt>
|
||
<dd><p>If this is set to a non-empty string, Python won’t try to write <code class="docutils literal notranslate"><span class="pre">.pyc</span></code>
|
||
files on the import of source modules. This is equivalent to
|
||
specifying the <a class="reference internal" href="#cmdoption-B"><code class="xref std std-option docutils literal notranslate"><span class="pre">-B</span></code></a> option.</p>
|
||
</dd></dl>
|
||
|
||
<dl class="std envvar">
|
||
<dt class="sig sig-object std" id="envvar-PYTHONPYCACHEPREFIX">
|
||
<span class="sig-name descname"><span class="pre">PYTHONPYCACHEPREFIX</span></span><a class="headerlink" href="#envvar-PYTHONPYCACHEPREFIX" title="Link to this definition">¶</a></dt>
|
||
<dd><p>If this is set, Python will write <code class="docutils literal notranslate"><span class="pre">.pyc</span></code> files in a mirror directory tree
|
||
at this path, instead of in <code class="docutils literal notranslate"><span class="pre">__pycache__</span></code> directories within the source
|
||
tree. This is equivalent to specifying the <a class="reference internal" href="#cmdoption-X"><code class="xref std std-option docutils literal notranslate"><span class="pre">-X</span></code></a>
|
||
<code class="docutils literal notranslate"><span class="pre">pycache_prefix=PATH</span></code> option.</p>
|
||
<div class="versionadded">
|
||
<p><span class="versionmodified added">Added in version 3.8.</span></p>
|
||
</div>
|
||
</dd></dl>
|
||
|
||
<dl class="std envvar">
|
||
<dt class="sig sig-object std" id="envvar-PYTHONHASHSEED">
|
||
<span class="sig-name descname"><span class="pre">PYTHONHASHSEED</span></span><a class="headerlink" href="#envvar-PYTHONHASHSEED" title="Link to this definition">¶</a></dt>
|
||
<dd><p>If this variable is not set or set to <code class="docutils literal notranslate"><span class="pre">random</span></code>, a random value is used
|
||
to seed the hashes of str and bytes objects.</p>
|
||
<p>If <span class="target" id="index-44"></span><a class="reference internal" href="#envvar-PYTHONHASHSEED"><code class="xref std std-envvar docutils literal notranslate"><span class="pre">PYTHONHASHSEED</span></code></a> is set to an integer value, it is used as a fixed
|
||
seed for generating the hash() of the types covered by the hash
|
||
randomization.</p>
|
||
<p>Its purpose is to allow repeatable hashing, such as for selftests for the
|
||
interpreter itself, or to allow a cluster of python processes to share hash
|
||
values.</p>
|
||
<p>The integer must be a decimal number in the range [0,4294967295]. Specifying
|
||
the value 0 will disable hash randomization.</p>
|
||
<div class="versionadded">
|
||
<p><span class="versionmodified added">Added in version 3.2.3.</span></p>
|
||
</div>
|
||
</dd></dl>
|
||
|
||
<dl class="std envvar">
|
||
<dt class="sig sig-object std" id="envvar-PYTHONINTMAXSTRDIGITS">
|
||
<span class="sig-name descname"><span class="pre">PYTHONINTMAXSTRDIGITS</span></span><a class="headerlink" href="#envvar-PYTHONINTMAXSTRDIGITS" title="Link to this definition">¶</a></dt>
|
||
<dd><p>If this variable is set to an integer, it is used to configure the
|
||
interpreter’s global <a class="reference internal" href="../library/stdtypes.html#int-max-str-digits"><span class="std std-ref">integer string conversion length limitation</span></a>.</p>
|
||
<div class="versionadded">
|
||
<p><span class="versionmodified added">Added in version 3.11.</span></p>
|
||
</div>
|
||
</dd></dl>
|
||
|
||
<dl class="std envvar">
|
||
<dt class="sig sig-object std" id="envvar-PYTHONIOENCODING">
|
||
<span class="sig-name descname"><span class="pre">PYTHONIOENCODING</span></span><a class="headerlink" href="#envvar-PYTHONIOENCODING" title="Link to this definition">¶</a></dt>
|
||
<dd><p>If this is set before running the interpreter, it overrides the encoding used
|
||
for stdin/stdout/stderr, in the syntax <code class="docutils literal notranslate"><span class="pre">encodingname:errorhandler</span></code>. Both
|
||
the <code class="docutils literal notranslate"><span class="pre">encodingname</span></code> and the <code class="docutils literal notranslate"><span class="pre">:errorhandler</span></code> parts are optional and have
|
||
the same meaning as in <a class="reference internal" href="../library/stdtypes.html#str.encode" title="str.encode"><code class="xref py py-func docutils literal notranslate"><span class="pre">str.encode()</span></code></a>.</p>
|
||
<p>For stderr, the <code class="docutils literal notranslate"><span class="pre">:errorhandler</span></code> part is ignored; the handler will always be
|
||
<code class="docutils literal notranslate"><span class="pre">'backslashreplace'</span></code>.</p>
|
||
<div class="versionchanged">
|
||
<p><span class="versionmodified changed">Changed in version 3.4: </span>The <code class="docutils literal notranslate"><span class="pre">encodingname</span></code> part is now optional.</p>
|
||
</div>
|
||
<div class="versionchanged">
|
||
<p><span class="versionmodified changed">Changed in version 3.6: </span>On Windows, the encoding specified by this variable is ignored for interactive
|
||
console buffers unless <span class="target" id="index-45"></span><a class="reference internal" href="#envvar-PYTHONLEGACYWINDOWSSTDIO"><code class="xref std std-envvar docutils literal notranslate"><span class="pre">PYTHONLEGACYWINDOWSSTDIO</span></code></a> is also specified.
|
||
Files and pipes redirected through the standard streams are not affected.</p>
|
||
</div>
|
||
</dd></dl>
|
||
|
||
<dl class="std envvar">
|
||
<dt class="sig sig-object std" id="envvar-PYTHONNOUSERSITE">
|
||
<span class="sig-name descname"><span class="pre">PYTHONNOUSERSITE</span></span><a class="headerlink" href="#envvar-PYTHONNOUSERSITE" title="Link to this definition">¶</a></dt>
|
||
<dd><p>If this is set, Python won’t add the <a class="reference internal" href="../library/site.html#site.USER_SITE" title="site.USER_SITE"><code class="xref py py-data docutils literal notranslate"><span class="pre">user</span> <span class="pre">site-packages</span> <span class="pre">directory</span></code></a> to <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>.</p>
|
||
<div class="admonition seealso">
|
||
<p class="admonition-title">See also</p>
|
||
<p><span class="target" id="index-46"></span><a class="pep reference external" href="https://peps.python.org/pep-0370/"><strong>PEP 370</strong></a> – Per user site-packages directory</p>
|
||
</div>
|
||
</dd></dl>
|
||
|
||
<dl class="std envvar">
|
||
<dt class="sig sig-object std" id="envvar-PYTHONUSERBASE">
|
||
<span class="sig-name descname"><span class="pre">PYTHONUSERBASE</span></span><a class="headerlink" href="#envvar-PYTHONUSERBASE" title="Link to this definition">¶</a></dt>
|
||
<dd><p>Defines the <a class="reference internal" href="../library/site.html#site.USER_BASE" title="site.USER_BASE"><code class="xref py py-data docutils literal notranslate"><span class="pre">user</span> <span class="pre">base</span> <span class="pre">directory</span></code></a>, which is used to
|
||
compute the path of the <a class="reference internal" href="../library/site.html#site.USER_SITE" title="site.USER_SITE"><code class="xref py py-data docutils literal notranslate"><span class="pre">user</span> <span class="pre">site-packages</span> <span class="pre">directory</span></code></a>
|
||
and <a class="reference internal" href="../library/sysconfig.html#sysconfig-user-scheme"><span class="std std-ref">installation paths</span></a> for
|
||
<code class="docutils literal notranslate"><span class="pre">python</span> <span class="pre">-m</span> <span class="pre">pip</span> <span class="pre">install</span> <span class="pre">--user</span></code>.</p>
|
||
<div class="admonition seealso">
|
||
<p class="admonition-title">See also</p>
|
||
<p><span class="target" id="index-47"></span><a class="pep reference external" href="https://peps.python.org/pep-0370/"><strong>PEP 370</strong></a> – Per user site-packages directory</p>
|
||
</div>
|
||
</dd></dl>
|
||
|
||
<dl class="std envvar">
|
||
<dt class="sig sig-object std" id="envvar-PYTHONEXECUTABLE">
|
||
<span class="sig-name descname"><span class="pre">PYTHONEXECUTABLE</span></span><a class="headerlink" href="#envvar-PYTHONEXECUTABLE" title="Link to this definition">¶</a></dt>
|
||
<dd><p>If this environment variable is set, <code class="docutils literal notranslate"><span class="pre">sys.argv[0]</span></code> will be set to its
|
||
value instead of the value got through the C runtime. Only works on
|
||
macOS.</p>
|
||
</dd></dl>
|
||
|
||
<dl class="std envvar">
|
||
<dt class="sig sig-object std" id="envvar-PYTHONWARNINGS">
|
||
<span class="sig-name descname"><span class="pre">PYTHONWARNINGS</span></span><a class="headerlink" href="#envvar-PYTHONWARNINGS" title="Link to this definition">¶</a></dt>
|
||
<dd><p>This is equivalent to the <a class="reference internal" href="#cmdoption-W"><code class="xref std std-option docutils literal notranslate"><span class="pre">-W</span></code></a> option. If set to a comma
|
||
separated string, it is equivalent to specifying <a class="reference internal" href="#cmdoption-W"><code class="xref std std-option docutils literal notranslate"><span class="pre">-W</span></code></a> multiple
|
||
times, with filters later in the list taking precedence over those earlier
|
||
in the list.</p>
|
||
<p>The simplest settings apply a particular action unconditionally to all
|
||
warnings emitted by a process (even those that are otherwise ignored by
|
||
default):</p>
|
||
<div class="highlight-sh notranslate"><div class="highlight"><pre><span></span><span class="nv">PYTHONWARNINGS</span><span class="o">=</span>default<span class="w"> </span><span class="c1"># Warn once per call location</span>
|
||
<span class="nv">PYTHONWARNINGS</span><span class="o">=</span>error<span class="w"> </span><span class="c1"># Convert to exceptions</span>
|
||
<span class="nv">PYTHONWARNINGS</span><span class="o">=</span>always<span class="w"> </span><span class="c1"># Warn every time</span>
|
||
<span class="nv">PYTHONWARNINGS</span><span class="o">=</span>all<span class="w"> </span><span class="c1"># Same as PYTHONWARNINGS=always</span>
|
||
<span class="nv">PYTHONWARNINGS</span><span class="o">=</span>module<span class="w"> </span><span class="c1"># Warn once per calling module</span>
|
||
<span class="nv">PYTHONWARNINGS</span><span class="o">=</span>once<span class="w"> </span><span class="c1"># Warn once per Python process</span>
|
||
<span class="nv">PYTHONWARNINGS</span><span class="o">=</span>ignore<span class="w"> </span><span class="c1"># Never warn</span>
|
||
</pre></div>
|
||
</div>
|
||
<p>See <a class="reference internal" href="../library/warnings.html#warning-filter"><span class="std std-ref">The Warnings Filter</span></a> and <a class="reference internal" href="../library/warnings.html#describing-warning-filters"><span class="std std-ref">Describing Warning Filters</span></a> for more
|
||
details.</p>
|
||
</dd></dl>
|
||
|
||
<dl class="std envvar">
|
||
<dt class="sig sig-object std" id="envvar-PYTHONFAULTHANDLER">
|
||
<span class="sig-name descname"><span class="pre">PYTHONFAULTHANDLER</span></span><a class="headerlink" href="#envvar-PYTHONFAULTHANDLER" title="Link to this definition">¶</a></dt>
|
||
<dd><p>If this environment variable is set to a non-empty string,
|
||
<a class="reference internal" href="../library/faulthandler.html#faulthandler.enable" title="faulthandler.enable"><code class="xref py py-func docutils literal notranslate"><span class="pre">faulthandler.enable()</span></code></a> is called at startup: install a handler for
|
||
<a class="reference internal" href="../library/signal.html#signal.SIGSEGV" title="signal.SIGSEGV"><code class="xref py py-const docutils literal notranslate"><span class="pre">SIGSEGV</span></code></a>, <a class="reference internal" href="../library/signal.html#signal.SIGFPE" title="signal.SIGFPE"><code class="xref py py-const docutils literal notranslate"><span class="pre">SIGFPE</span></code></a>,
|
||
<a class="reference internal" href="../library/signal.html#signal.SIGABRT" title="signal.SIGABRT"><code class="xref py py-const docutils literal notranslate"><span class="pre">SIGABRT</span></code></a>, <a class="reference internal" href="../library/signal.html#signal.SIGBUS" title="signal.SIGBUS"><code class="xref py py-const docutils literal notranslate"><span class="pre">SIGBUS</span></code></a> and
|
||
<a class="reference internal" href="../library/signal.html#signal.SIGILL" title="signal.SIGILL"><code class="xref py py-const docutils literal notranslate"><span class="pre">SIGILL</span></code></a> signals to dump the Python traceback.
|
||
This is equivalent to <a class="reference internal" href="#cmdoption-X"><code class="xref std std-option docutils literal notranslate"><span class="pre">-X</span></code></a> <code class="docutils literal notranslate"><span class="pre">faulthandler</span></code> option.</p>
|
||
<div class="versionadded">
|
||
<p><span class="versionmodified added">Added in version 3.3.</span></p>
|
||
</div>
|
||
</dd></dl>
|
||
|
||
<dl class="std envvar">
|
||
<dt class="sig sig-object std" id="envvar-PYTHONTRACEMALLOC">
|
||
<span class="sig-name descname"><span class="pre">PYTHONTRACEMALLOC</span></span><a class="headerlink" href="#envvar-PYTHONTRACEMALLOC" title="Link to this definition">¶</a></dt>
|
||
<dd><p>If this environment variable is set to a non-empty string, start tracing
|
||
Python memory allocations using the <a class="reference internal" href="../library/tracemalloc.html#module-tracemalloc" title="tracemalloc: Trace memory allocations."><code class="xref py py-mod docutils literal notranslate"><span class="pre">tracemalloc</span></code></a> module. The value of
|
||
the variable is the maximum number of frames stored in a traceback of a
|
||
trace. For example, <code class="docutils literal notranslate"><span class="pre">PYTHONTRACEMALLOC=1</span></code> stores only the most recent
|
||
frame.
|
||
See the <a class="reference internal" href="../library/tracemalloc.html#tracemalloc.start" title="tracemalloc.start"><code class="xref py py-func docutils literal notranslate"><span class="pre">tracemalloc.start()</span></code></a> function for more information.
|
||
This is equivalent to setting the <a class="reference internal" href="#cmdoption-X"><code class="xref std std-option docutils literal notranslate"><span class="pre">-X</span></code></a> <code class="docutils literal notranslate"><span class="pre">tracemalloc</span></code> option.</p>
|
||
<div class="versionadded">
|
||
<p><span class="versionmodified added">Added in version 3.4.</span></p>
|
||
</div>
|
||
</dd></dl>
|
||
|
||
<dl class="std envvar">
|
||
<dt class="sig sig-object std" id="envvar-PYTHONPROFILEIMPORTTIME">
|
||
<span class="sig-name descname"><span class="pre">PYTHONPROFILEIMPORTTIME</span></span><a class="headerlink" href="#envvar-PYTHONPROFILEIMPORTTIME" title="Link to this definition">¶</a></dt>
|
||
<dd><p>If this environment variable is set to a non-empty string, Python will
|
||
show how long each import takes.
|
||
This is equivalent to setting the <a class="reference internal" href="#cmdoption-X"><code class="xref std std-option docutils literal notranslate"><span class="pre">-X</span></code></a> <code class="docutils literal notranslate"><span class="pre">importtime</span></code> option.</p>
|
||
<div class="versionadded">
|
||
<p><span class="versionmodified added">Added in version 3.7.</span></p>
|
||
</div>
|
||
</dd></dl>
|
||
|
||
<dl class="std envvar">
|
||
<dt class="sig sig-object std" id="envvar-PYTHONASYNCIODEBUG">
|
||
<span class="sig-name descname"><span class="pre">PYTHONASYNCIODEBUG</span></span><a class="headerlink" href="#envvar-PYTHONASYNCIODEBUG" title="Link to this definition">¶</a></dt>
|
||
<dd><p>If this environment variable is set to a non-empty string, enable the
|
||
<a class="reference internal" href="../library/asyncio-dev.html#asyncio-debug-mode"><span class="std std-ref">debug mode</span></a> of the <a class="reference internal" href="../library/asyncio.html#module-asyncio" title="asyncio: Asynchronous I/O."><code class="xref py py-mod docutils literal notranslate"><span class="pre">asyncio</span></code></a> module.</p>
|
||
<div class="versionadded">
|
||
<p><span class="versionmodified added">Added in version 3.4.</span></p>
|
||
</div>
|
||
</dd></dl>
|
||
|
||
<dl class="std envvar">
|
||
<dt class="sig sig-object std" id="envvar-PYTHONMALLOC">
|
||
<span class="sig-name descname"><span class="pre">PYTHONMALLOC</span></span><a class="headerlink" href="#envvar-PYTHONMALLOC" title="Link to this definition">¶</a></dt>
|
||
<dd><p>Set the Python memory allocators and/or install debug hooks.</p>
|
||
<p>Set the family of memory allocators used by Python:</p>
|
||
<ul class="simple">
|
||
<li><p><code class="docutils literal notranslate"><span class="pre">default</span></code>: use the <a class="reference internal" href="../c-api/memory.html#default-memory-allocators"><span class="std std-ref">default memory allocators</span></a>.</p></li>
|
||
<li><p><code class="docutils literal notranslate"><span class="pre">malloc</span></code>: use the <code class="xref c c-func docutils literal notranslate"><span class="pre">malloc()</span></code> function of the C library
|
||
for all domains (<a class="reference internal" href="../c-api/memory.html#c.PYMEM_DOMAIN_RAW" title="PYMEM_DOMAIN_RAW"><code class="xref c c-macro docutils literal notranslate"><span class="pre">PYMEM_DOMAIN_RAW</span></code></a>, <a class="reference internal" href="../c-api/memory.html#c.PYMEM_DOMAIN_MEM" title="PYMEM_DOMAIN_MEM"><code class="xref c c-macro docutils literal notranslate"><span class="pre">PYMEM_DOMAIN_MEM</span></code></a>,
|
||
<a class="reference internal" href="../c-api/memory.html#c.PYMEM_DOMAIN_OBJ" title="PYMEM_DOMAIN_OBJ"><code class="xref c c-macro docutils literal notranslate"><span class="pre">PYMEM_DOMAIN_OBJ</span></code></a>).</p></li>
|
||
<li><p><code class="docutils literal notranslate"><span class="pre">pymalloc</span></code>: use the <a class="reference internal" href="../c-api/memory.html#pymalloc"><span class="std std-ref">pymalloc allocator</span></a> for
|
||
<a class="reference internal" href="../c-api/memory.html#c.PYMEM_DOMAIN_MEM" title="PYMEM_DOMAIN_MEM"><code class="xref c c-macro docutils literal notranslate"><span class="pre">PYMEM_DOMAIN_MEM</span></code></a> and <a class="reference internal" href="../c-api/memory.html#c.PYMEM_DOMAIN_OBJ" title="PYMEM_DOMAIN_OBJ"><code class="xref c c-macro docutils literal notranslate"><span class="pre">PYMEM_DOMAIN_OBJ</span></code></a> domains and use
|
||
the <code class="xref c c-func docutils literal notranslate"><span class="pre">malloc()</span></code> function for the <a class="reference internal" href="../c-api/memory.html#c.PYMEM_DOMAIN_RAW" title="PYMEM_DOMAIN_RAW"><code class="xref c c-macro docutils literal notranslate"><span class="pre">PYMEM_DOMAIN_RAW</span></code></a> domain.</p></li>
|
||
<li><p><code class="docutils literal notranslate"><span class="pre">mimalloc</span></code>: use the <a class="reference internal" href="../c-api/memory.html#mimalloc"><span class="std std-ref">mimalloc allocator</span></a> for
|
||
<a class="reference internal" href="../c-api/memory.html#c.PYMEM_DOMAIN_MEM" title="PYMEM_DOMAIN_MEM"><code class="xref c c-macro docutils literal notranslate"><span class="pre">PYMEM_DOMAIN_MEM</span></code></a> and <a class="reference internal" href="../c-api/memory.html#c.PYMEM_DOMAIN_OBJ" title="PYMEM_DOMAIN_OBJ"><code class="xref c c-macro docutils literal notranslate"><span class="pre">PYMEM_DOMAIN_OBJ</span></code></a> domains and use
|
||
the <code class="xref c c-func docutils literal notranslate"><span class="pre">malloc()</span></code> function for the <a class="reference internal" href="../c-api/memory.html#c.PYMEM_DOMAIN_RAW" title="PYMEM_DOMAIN_RAW"><code class="xref c c-macro docutils literal notranslate"><span class="pre">PYMEM_DOMAIN_RAW</span></code></a> domain.</p></li>
|
||
</ul>
|
||
<p>Install <a class="reference internal" href="../c-api/memory.html#pymem-debug-hooks"><span class="std std-ref">debug hooks</span></a>:</p>
|
||
<ul class="simple">
|
||
<li><p><code class="docutils literal notranslate"><span class="pre">debug</span></code>: install debug hooks on top of the <a class="reference internal" href="../c-api/memory.html#default-memory-allocators"><span class="std std-ref">default memory
|
||
allocators</span></a>.</p></li>
|
||
<li><p><code class="docutils literal notranslate"><span class="pre">malloc_debug</span></code>: same as <code class="docutils literal notranslate"><span class="pre">malloc</span></code> but also install debug hooks.</p></li>
|
||
<li><p><code class="docutils literal notranslate"><span class="pre">pymalloc_debug</span></code>: same as <code class="docutils literal notranslate"><span class="pre">pymalloc</span></code> but also install debug hooks.</p></li>
|
||
<li><p><code class="docutils literal notranslate"><span class="pre">mimalloc_debug</span></code>: same as <code class="docutils literal notranslate"><span class="pre">mimalloc</span></code> but also install debug hooks.</p></li>
|
||
</ul>
|
||
<div class="versionadded">
|
||
<p><span class="versionmodified added">Added in version 3.6.</span></p>
|
||
</div>
|
||
<div class="versionchanged">
|
||
<p><span class="versionmodified changed">Changed in version 3.7: </span>Added the <code class="docutils literal notranslate"><span class="pre">"default"</span></code> allocator.</p>
|
||
</div>
|
||
</dd></dl>
|
||
|
||
<dl class="std envvar">
|
||
<dt class="sig sig-object std" id="envvar-PYTHONMALLOCSTATS">
|
||
<span class="sig-name descname"><span class="pre">PYTHONMALLOCSTATS</span></span><a class="headerlink" href="#envvar-PYTHONMALLOCSTATS" title="Link to this definition">¶</a></dt>
|
||
<dd><p>If set to a non-empty string, Python will print statistics of the
|
||
<a class="reference internal" href="../c-api/memory.html#pymalloc"><span class="std std-ref">pymalloc memory allocator</span></a> every time a new pymalloc object
|
||
arena is created, and on shutdown.</p>
|
||
<p>This variable is ignored if the <span class="target" id="index-48"></span><a class="reference internal" href="#envvar-PYTHONMALLOC"><code class="xref std std-envvar docutils literal notranslate"><span class="pre">PYTHONMALLOC</span></code></a> environment variable
|
||
is used to force the <code class="xref c c-func docutils literal notranslate"><span class="pre">malloc()</span></code> allocator of the C library, or if
|
||
Python is configured without <code class="docutils literal notranslate"><span class="pre">pymalloc</span></code> support.</p>
|
||
<div class="versionchanged">
|
||
<p><span class="versionmodified changed">Changed in version 3.6: </span>This variable can now also be used on Python compiled in release mode.
|
||
It now has no effect if set to an empty string.</p>
|
||
</div>
|
||
</dd></dl>
|
||
|
||
<dl class="std envvar">
|
||
<dt class="sig sig-object std" id="envvar-PYTHONLEGACYWINDOWSFSENCODING">
|
||
<span class="sig-name descname"><span class="pre">PYTHONLEGACYWINDOWSFSENCODING</span></span><a class="headerlink" href="#envvar-PYTHONLEGACYWINDOWSFSENCODING" title="Link to this definition">¶</a></dt>
|
||
<dd><p>If set to a non-empty string, the default <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> mode will revert to their pre-3.6 values of ‘mbcs’ and
|
||
‘replace’, respectively. Otherwise, the new defaults ‘utf-8’ and
|
||
‘surrogatepass’ are used.</p>
|
||
<p>This may also be enabled at runtime with
|
||
<a class="reference internal" href="../library/sys.html#sys._enablelegacywindowsfsencoding" title="sys._enablelegacywindowsfsencoding"><code class="xref py py-func docutils literal notranslate"><span class="pre">sys._enablelegacywindowsfsencoding()</span></code></a>.</p>
|
||
<div class="availability docutils container">
|
||
<p><a class="reference internal" href="../library/intro.html#availability"><span class="std std-ref">Availability</span></a>: Windows.</p>
|
||
</div>
|
||
<div class="versionadded">
|
||
<p><span class="versionmodified added">Added in version 3.6: </span>See <span class="target" id="index-49"></span><a class="pep reference external" href="https://peps.python.org/pep-0529/"><strong>PEP 529</strong></a> for more details.</p>
|
||
</div>
|
||
</dd></dl>
|
||
|
||
<dl class="std envvar">
|
||
<dt class="sig sig-object std" id="envvar-PYTHONLEGACYWINDOWSSTDIO">
|
||
<span class="sig-name descname"><span class="pre">PYTHONLEGACYWINDOWSSTDIO</span></span><a class="headerlink" href="#envvar-PYTHONLEGACYWINDOWSSTDIO" title="Link to this definition">¶</a></dt>
|
||
<dd><p>If set to a non-empty string, does not use the new console reader and
|
||
writer. This means that Unicode characters will be encoded according to
|
||
the active console code page, rather than using utf-8.</p>
|
||
<p>This variable is ignored if the standard streams are redirected (to files
|
||
or pipes) rather than referring to console buffers.</p>
|
||
<div class="availability docutils container">
|
||
<p><a class="reference internal" href="../library/intro.html#availability"><span class="std std-ref">Availability</span></a>: Windows.</p>
|
||
</div>
|
||
<div class="versionadded">
|
||
<p><span class="versionmodified added">Added in version 3.6.</span></p>
|
||
</div>
|
||
</dd></dl>
|
||
|
||
<dl class="std envvar">
|
||
<dt class="sig sig-object std" id="envvar-PYTHONCOERCECLOCALE">
|
||
<span class="sig-name descname"><span class="pre">PYTHONCOERCECLOCALE</span></span><a class="headerlink" href="#envvar-PYTHONCOERCECLOCALE" title="Link to this definition">¶</a></dt>
|
||
<dd><p>If set to the value <code class="docutils literal notranslate"><span class="pre">0</span></code>, causes the main Python command line application
|
||
to skip coercing the legacy ASCII-based C and POSIX locales to a more
|
||
capable UTF-8 based alternative.</p>
|
||
<p>If this variable is <em>not</em> set (or is set to a value other than <code class="docutils literal notranslate"><span class="pre">0</span></code>), the
|
||
<code class="docutils literal notranslate"><span class="pre">LC_ALL</span></code> locale override environment variable is also not set, and the
|
||
current locale reported for the <code class="docutils literal notranslate"><span class="pre">LC_CTYPE</span></code> category is either the default
|
||
<code class="docutils literal notranslate"><span class="pre">C</span></code> locale, or else the explicitly ASCII-based <code class="docutils literal notranslate"><span class="pre">POSIX</span></code> locale, then the
|
||
Python CLI will attempt to configure the following locales for the
|
||
<code class="docutils literal notranslate"><span class="pre">LC_CTYPE</span></code> category in the order listed before loading the interpreter
|
||
runtime:</p>
|
||
<ul class="simple">
|
||
<li><p><code class="docutils literal notranslate"><span class="pre">C.UTF-8</span></code></p></li>
|
||
<li><p><code class="docutils literal notranslate"><span class="pre">C.utf8</span></code></p></li>
|
||
<li><p><code class="docutils literal notranslate"><span class="pre">UTF-8</span></code></p></li>
|
||
</ul>
|
||
<p>If setting one of these locale categories succeeds, then the <code class="docutils literal notranslate"><span class="pre">LC_CTYPE</span></code>
|
||
environment variable will also be set accordingly in the current process
|
||
environment before the Python runtime is initialized. This ensures that in
|
||
addition to being seen by both the interpreter itself and other locale-aware
|
||
components running in the same process (such as the GNU <code class="docutils literal notranslate"><span class="pre">readline</span></code>
|
||
library), the updated setting is also seen in subprocesses (regardless of
|
||
whether or not those processes are running a Python interpreter), as well as
|
||
in operations that query the environment rather than the current C locale
|
||
(such as Python’s own <a class="reference internal" href="../library/locale.html#locale.getdefaultlocale" title="locale.getdefaultlocale"><code class="xref py py-func docutils literal notranslate"><span class="pre">locale.getdefaultlocale()</span></code></a>).</p>
|
||
<p>Configuring one of these locales (either explicitly or via the above
|
||
implicit locale coercion) automatically enables the <code class="docutils literal notranslate"><span class="pre">surrogateescape</span></code>
|
||
<a class="reference internal" href="../library/codecs.html#error-handlers"><span class="std std-ref">error handler</span></a> for <a class="reference internal" href="../library/sys.html#sys.stdin" title="sys.stdin"><code class="xref py py-data docutils literal notranslate"><span class="pre">sys.stdin</span></code></a> and
|
||
<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> (<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> continues to use <code class="docutils literal notranslate"><span class="pre">backslashreplace</span></code>
|
||
as it does in any other locale). This stream handling behavior can be
|
||
overridden using <span class="target" id="index-50"></span><a class="reference internal" href="#envvar-PYTHONIOENCODING"><code class="xref std std-envvar docutils literal notranslate"><span class="pre">PYTHONIOENCODING</span></code></a> as usual.</p>
|
||
<p>For debugging purposes, setting <code class="docutils literal notranslate"><span class="pre">PYTHONCOERCECLOCALE=warn</span></code> will cause
|
||
Python to emit warning messages on <code class="docutils literal notranslate"><span class="pre">stderr</span></code> if either the locale coercion
|
||
activates, or else if a locale that <em>would</em> have triggered coercion is
|
||
still active when the Python runtime is initialized.</p>
|
||
<p>Also note that even when locale coercion is disabled, or when it fails to
|
||
find a suitable target locale, <span class="target" id="index-51"></span><a class="reference internal" href="#envvar-PYTHONUTF8"><code class="xref std std-envvar docutils literal notranslate"><span class="pre">PYTHONUTF8</span></code></a> will still activate by
|
||
default in legacy ASCII-based locales. Both features must be disabled in
|
||
order to force the interpreter to use <code class="docutils literal notranslate"><span class="pre">ASCII</span></code> instead of <code class="docutils literal notranslate"><span class="pre">UTF-8</span></code> for
|
||
system interfaces.</p>
|
||
<div class="availability docutils container">
|
||
<p><a class="reference internal" href="../library/intro.html#availability"><span class="std std-ref">Availability</span></a>: Unix.</p>
|
||
</div>
|
||
<div class="versionadded">
|
||
<p><span class="versionmodified added">Added in version 3.7: </span>See <span class="target" id="index-52"></span><a class="pep reference external" href="https://peps.python.org/pep-0538/"><strong>PEP 538</strong></a> for more details.</p>
|
||
</div>
|
||
</dd></dl>
|
||
|
||
<dl class="std envvar">
|
||
<dt class="sig sig-object std" id="envvar-PYTHONDEVMODE">
|
||
<span class="sig-name descname"><span class="pre">PYTHONDEVMODE</span></span><a class="headerlink" href="#envvar-PYTHONDEVMODE" title="Link to this definition">¶</a></dt>
|
||
<dd><p>If this environment variable is set to a non-empty string, enable
|
||
<a class="reference internal" href="../library/devmode.html#devmode"><span class="std std-ref">Python Development Mode</span></a>, introducing additional runtime
|
||
checks that are too expensive to be enabled by default.
|
||
This is equivalent to setting the <a class="reference internal" href="#cmdoption-X"><code class="xref std std-option docutils literal notranslate"><span class="pre">-X</span></code></a> <code class="docutils literal notranslate"><span class="pre">dev</span></code> option.</p>
|
||
<div class="versionadded">
|
||
<p><span class="versionmodified added">Added in version 3.7.</span></p>
|
||
</div>
|
||
</dd></dl>
|
||
|
||
<dl class="std envvar">
|
||
<dt class="sig sig-object std" id="envvar-PYTHONUTF8">
|
||
<span class="sig-name descname"><span class="pre">PYTHONUTF8</span></span><a class="headerlink" href="#envvar-PYTHONUTF8" title="Link to this definition">¶</a></dt>
|
||
<dd><p>If set to <code class="docutils literal notranslate"><span class="pre">1</span></code>, enable the <a class="reference internal" href="../library/os.html#utf8-mode"><span class="std std-ref">Python UTF-8 Mode</span></a>.</p>
|
||
<p>If set to <code class="docutils literal notranslate"><span class="pre">0</span></code>, disable the <a class="reference internal" href="../library/os.html#utf8-mode"><span class="std std-ref">Python UTF-8 Mode</span></a>.</p>
|
||
<p>Setting any other non-empty string causes an error during interpreter
|
||
initialisation.</p>
|
||
<div class="versionadded">
|
||
<p><span class="versionmodified added">Added in version 3.7.</span></p>
|
||
</div>
|
||
</dd></dl>
|
||
|
||
<dl class="std envvar">
|
||
<dt class="sig sig-object std" id="envvar-PYTHONWARNDEFAULTENCODING">
|
||
<span class="sig-name descname"><span class="pre">PYTHONWARNDEFAULTENCODING</span></span><a class="headerlink" href="#envvar-PYTHONWARNDEFAULTENCODING" title="Link to this definition">¶</a></dt>
|
||
<dd><p>If this environment variable is set to a non-empty string, issue a
|
||
<a class="reference internal" href="../library/exceptions.html#EncodingWarning" title="EncodingWarning"><code class="xref py py-class docutils literal notranslate"><span class="pre">EncodingWarning</span></code></a> when the locale-specific default encoding is used.</p>
|
||
<p>See <a class="reference internal" href="../library/io.html#io-encoding-warning"><span class="std std-ref">Opt-in EncodingWarning</span></a> for details.</p>
|
||
<div class="versionadded">
|
||
<p><span class="versionmodified added">Added in version 3.10.</span></p>
|
||
</div>
|
||
</dd></dl>
|
||
|
||
<dl class="std envvar">
|
||
<dt class="sig sig-object std" id="envvar-PYTHONNODEBUGRANGES">
|
||
<span class="sig-name descname"><span class="pre">PYTHONNODEBUGRANGES</span></span><a class="headerlink" href="#envvar-PYTHONNODEBUGRANGES" title="Link to this definition">¶</a></dt>
|
||
<dd><p>If this variable is set, it disables the inclusion of the tables mapping
|
||
extra location information (end line, start column offset and end column
|
||
offset) to every instruction in code objects. This is useful when smaller
|
||
code objects and pyc files are desired as well as suppressing the extra visual
|
||
location indicators when the interpreter displays tracebacks.</p>
|
||
<div class="versionadded">
|
||
<p><span class="versionmodified added">Added in version 3.11.</span></p>
|
||
</div>
|
||
</dd></dl>
|
||
|
||
<dl class="std envvar">
|
||
<dt class="sig sig-object std" id="envvar-PYTHONPERFSUPPORT">
|
||
<span class="sig-name descname"><span class="pre">PYTHONPERFSUPPORT</span></span><a class="headerlink" href="#envvar-PYTHONPERFSUPPORT" title="Link to this definition">¶</a></dt>
|
||
<dd><p>If this variable is set to a nonzero value, it enables support for
|
||
the Linux <code class="docutils literal notranslate"><span class="pre">perf</span></code> profiler so Python calls can be detected by it.</p>
|
||
<p>If set to <code class="docutils literal notranslate"><span class="pre">0</span></code>, disable Linux <code class="docutils literal notranslate"><span class="pre">perf</span></code> profiler support.</p>
|
||
<p>See also the <a class="reference internal" href="#cmdoption-X"><code class="xref std std-option docutils literal notranslate"><span class="pre">-X</span> <span class="pre">perf</span></code></a> command-line option
|
||
and <a class="reference internal" href="../howto/perf_profiling.html#perf-profiling"><span class="std std-ref">Python support for the Linux perf profiler</span></a>.</p>
|
||
<div class="versionadded">
|
||
<p><span class="versionmodified added">Added in version 3.12.</span></p>
|
||
</div>
|
||
</dd></dl>
|
||
|
||
<dl class="std envvar">
|
||
<dt class="sig sig-object std" id="envvar-PYTHON_PERF_JIT_SUPPORT">
|
||
<span class="sig-name descname"><span class="pre">PYTHON_PERF_JIT_SUPPORT</span></span><a class="headerlink" href="#envvar-PYTHON_PERF_JIT_SUPPORT" title="Link to this definition">¶</a></dt>
|
||
<dd><p>If this variable is set to a nonzero value, it enables support for
|
||
the Linux <code class="docutils literal notranslate"><span class="pre">perf</span></code> profiler so Python calls can be detected by it
|
||
using DWARF information.</p>
|
||
<p>If set to <code class="docutils literal notranslate"><span class="pre">0</span></code>, disable Linux <code class="docutils literal notranslate"><span class="pre">perf</span></code> profiler support.</p>
|
||
<p>See also the <a class="reference internal" href="#cmdoption-X"><code class="xref std std-option docutils literal notranslate"><span class="pre">-X</span> <span class="pre">perf_jit</span></code></a> command-line option
|
||
and <a class="reference internal" href="../howto/perf_profiling.html#perf-profiling"><span class="std std-ref">Python support for the Linux perf profiler</span></a>.</p>
|
||
<div class="versionadded">
|
||
<p><span class="versionmodified added">Added in version 3.13.</span></p>
|
||
</div>
|
||
</dd></dl>
|
||
|
||
<dl class="std envvar">
|
||
<dt class="sig sig-object std" id="envvar-PYTHON_CPU_COUNT">
|
||
<span class="sig-name descname"><span class="pre">PYTHON_CPU_COUNT</span></span><a class="headerlink" href="#envvar-PYTHON_CPU_COUNT" title="Link to this definition">¶</a></dt>
|
||
<dd><p>If this variable is set to a positive integer, it overrides the return
|
||
values of <a class="reference internal" href="../library/os.html#os.cpu_count" title="os.cpu_count"><code class="xref py py-func docutils literal notranslate"><span class="pre">os.cpu_count()</span></code></a> and <a class="reference internal" href="../library/os.html#os.process_cpu_count" title="os.process_cpu_count"><code class="xref py py-func docutils literal notranslate"><span class="pre">os.process_cpu_count()</span></code></a>.</p>
|
||
<p>See also the <a class="reference internal" href="#cmdoption-X"><code class="xref std std-option docutils literal notranslate"><span class="pre">-X</span> <span class="pre">cpu_count</span></code></a> command-line option.</p>
|
||
<div class="versionadded">
|
||
<p><span class="versionmodified added">Added in version 3.13.</span></p>
|
||
</div>
|
||
</dd></dl>
|
||
|
||
<dl class="std envvar">
|
||
<dt class="sig sig-object std" id="envvar-PYTHON_FROZEN_MODULES">
|
||
<span class="sig-name descname"><span class="pre">PYTHON_FROZEN_MODULES</span></span><a class="headerlink" href="#envvar-PYTHON_FROZEN_MODULES" title="Link to this definition">¶</a></dt>
|
||
<dd><p>If this variable is set to <code class="docutils literal notranslate"><span class="pre">on</span></code> or <code class="docutils literal notranslate"><span class="pre">off</span></code>, it determines whether or not
|
||
frozen modules are ignored by the import machinery. A value of <code class="docutils literal notranslate"><span class="pre">on</span></code> means
|
||
they get imported and <code class="docutils literal notranslate"><span class="pre">off</span></code> means they are ignored. The default is <code class="docutils literal notranslate"><span class="pre">on</span></code>
|
||
for non-debug builds (the normal case) and <code class="docutils literal notranslate"><span class="pre">off</span></code> for debug builds.
|
||
Note that the <code class="xref py py-mod docutils literal notranslate"><span class="pre">importlib_bootstrap</span></code> and
|
||
<code class="xref py py-mod docutils literal notranslate"><span class="pre">importlib_bootstrap_external</span></code> frozen modules are always used, even
|
||
if this flag is set to <code class="docutils literal notranslate"><span class="pre">off</span></code>.</p>
|
||
<p>See also the <a class="reference internal" href="#cmdoption-X"><code class="xref std std-option docutils literal notranslate"><span class="pre">-X</span> <span class="pre">frozen_modules</span></code></a> command-line option.</p>
|
||
<div class="versionadded">
|
||
<p><span class="versionmodified added">Added in version 3.13.</span></p>
|
||
</div>
|
||
</dd></dl>
|
||
|
||
<dl class="std envvar">
|
||
<dt class="sig sig-object std" id="envvar-PYTHON_COLORS">
|
||
<span class="sig-name descname"><span class="pre">PYTHON_COLORS</span></span><a class="headerlink" href="#envvar-PYTHON_COLORS" title="Link to this definition">¶</a></dt>
|
||
<dd><p>If this variable is set to <code class="docutils literal notranslate"><span class="pre">1</span></code>, the interpreter will colorize various kinds
|
||
of output. Setting it to <code class="docutils literal notranslate"><span class="pre">0</span></code> deactivates this behavior.
|
||
See also <a class="reference internal" href="#using-on-controlling-color"><span class="std std-ref">Controlling color</span></a>.</p>
|
||
<div class="versionadded">
|
||
<p><span class="versionmodified added">Added in version 3.13.</span></p>
|
||
</div>
|
||
</dd></dl>
|
||
|
||
<dl class="std envvar">
|
||
<dt class="sig sig-object std" id="envvar-PYTHON_BASIC_REPL">
|
||
<span class="sig-name descname"><span class="pre">PYTHON_BASIC_REPL</span></span><a class="headerlink" href="#envvar-PYTHON_BASIC_REPL" title="Link to this definition">¶</a></dt>
|
||
<dd><p>If this variable is set to any value, the interpreter will not attempt to
|
||
load the Python-based <a class="reference internal" href="../glossary.html#term-REPL"><span class="xref std std-term">REPL</span></a> that requires <a class="reference internal" href="../library/curses.html#module-curses" title="curses: An interface to the curses library, providing portable terminal handling. (Unix)"><code class="xref py py-mod docutils literal notranslate"><span class="pre">curses</span></code></a> and
|
||
<a class="reference internal" href="../library/readline.html#module-readline" title="readline: GNU readline support for Python. (Unix)"><code class="xref py py-mod docutils literal notranslate"><span class="pre">readline</span></code></a>, and will instead use the traditional parser-based
|
||
<a class="reference internal" href="../glossary.html#term-REPL"><span class="xref std std-term">REPL</span></a>.</p>
|
||
<div class="versionadded">
|
||
<p><span class="versionmodified added">Added in version 3.13.</span></p>
|
||
</div>
|
||
</dd></dl>
|
||
|
||
<dl class="std envvar">
|
||
<dt class="sig sig-object std" id="envvar-PYTHON_HISTORY">
|
||
<span class="sig-name descname"><span class="pre">PYTHON_HISTORY</span></span><a class="headerlink" href="#envvar-PYTHON_HISTORY" title="Link to this definition">¶</a></dt>
|
||
<dd><p>This environment variable can be used to set the location of a
|
||
<code class="docutils literal notranslate"><span class="pre">.python_history</span></code> file (by default, it is <code class="docutils literal notranslate"><span class="pre">.python_history</span></code> in the
|
||
user’s home directory).</p>
|
||
<div class="versionadded">
|
||
<p><span class="versionmodified added">Added in version 3.13.</span></p>
|
||
</div>
|
||
</dd></dl>
|
||
|
||
<dl class="std envvar">
|
||
<dt class="sig sig-object std" id="envvar-PYTHON_GIL">
|
||
<span class="sig-name descname"><span class="pre">PYTHON_GIL</span></span><a class="headerlink" href="#envvar-PYTHON_GIL" title="Link to this definition">¶</a></dt>
|
||
<dd><p>If this variable is set to <code class="docutils literal notranslate"><span class="pre">1</span></code>, the global interpreter lock (GIL) will be
|
||
forced on. Setting it to <code class="docutils literal notranslate"><span class="pre">0</span></code> forces the GIL off (needs Python configured with
|
||
the <a class="reference internal" href="configure.html#cmdoption-disable-gil"><code class="xref std std-option docutils literal notranslate"><span class="pre">--disable-gil</span></code></a> build option).</p>
|
||
<p>See also the <a class="reference internal" href="#cmdoption-X"><code class="xref std std-option docutils literal notranslate"><span class="pre">-X</span> <span class="pre">gil</span></code></a> command-line option, which takes
|
||
precedence over this variable, and <a class="reference internal" href="../whatsnew/3.13.html#whatsnew313-free-threaded-cpython"><span class="std std-ref">Free-threaded CPython</span></a>.</p>
|
||
<div class="versionadded">
|
||
<p><span class="versionmodified added">Added in version 3.13.</span></p>
|
||
</div>
|
||
</dd></dl>
|
||
|
||
<section id="debug-mode-variables">
|
||
<h3><span class="section-number">1.2.1. </span>Debug-mode variables<a class="headerlink" href="#debug-mode-variables" title="Link to this heading">¶</a></h3>
|
||
<dl class="std envvar">
|
||
<dt class="sig sig-object std" id="envvar-PYTHONDUMPREFS">
|
||
<span class="sig-name descname"><span class="pre">PYTHONDUMPREFS</span></span><a class="headerlink" href="#envvar-PYTHONDUMPREFS" title="Link to this definition">¶</a></dt>
|
||
<dd><p>If set, Python will dump objects and reference counts still alive after
|
||
shutting down the interpreter.</p>
|
||
<p>Needs Python configured with the <a class="reference internal" href="configure.html#cmdoption-with-trace-refs"><code class="xref std std-option docutils literal notranslate"><span class="pre">--with-trace-refs</span></code></a> build option.</p>
|
||
</dd></dl>
|
||
|
||
<dl class="std envvar">
|
||
<dt class="sig sig-object std" id="envvar-PYTHONDUMPREFSFILE">
|
||
<span class="sig-name descname"><span class="pre">PYTHONDUMPREFSFILE</span></span><a class="headerlink" href="#envvar-PYTHONDUMPREFSFILE" title="Link to this definition">¶</a></dt>
|
||
<dd><p>If set, Python will dump objects and reference counts still alive
|
||
after shutting down the interpreter into a file under the path given
|
||
as the value to this environment variable.</p>
|
||
<p>Needs Python configured with the <a class="reference internal" href="configure.html#cmdoption-with-trace-refs"><code class="xref std std-option docutils literal notranslate"><span class="pre">--with-trace-refs</span></code></a> build option.</p>
|
||
<div class="versionadded">
|
||
<p><span class="versionmodified added">Added in version 3.11.</span></p>
|
||
</div>
|
||
</dd></dl>
|
||
|
||
<dl class="std envvar">
|
||
<dt class="sig sig-object std" id="envvar-PYTHON_PRESITE">
|
||
<span class="sig-name descname"><span class="pre">PYTHON_PRESITE</span></span><a class="headerlink" href="#envvar-PYTHON_PRESITE" title="Link to this definition">¶</a></dt>
|
||
<dd><p>If this variable is set to a module, that module will be imported
|
||
early in the interpreter lifecycle, before the <a class="reference internal" href="../library/site.html#module-site" title="site: Module responsible for site-specific configuration."><code class="xref py py-mod docutils literal notranslate"><span class="pre">site</span></code></a> module is
|
||
executed, and before the <a class="reference internal" href="../library/__main__.html#module-__main__" title="__main__: The environment where top-level code is run. Covers command-line interfaces, import-time behavior, and ``__name__ == '__main__'``."><code class="xref py py-mod docutils literal notranslate"><span class="pre">__main__</span></code></a> module is created.
|
||
Therefore, the imported module is not treated as <a class="reference internal" href="../library/__main__.html#module-__main__" title="__main__: The environment where top-level code is run. Covers command-line interfaces, import-time behavior, and ``__name__ == '__main__'``."><code class="xref py py-mod docutils literal notranslate"><span class="pre">__main__</span></code></a>.</p>
|
||
<p>This can be used to execute code early during Python initialization.</p>
|
||
<p>To import a submodule, use <code class="docutils literal notranslate"><span class="pre">package.module</span></code> as the value, like in
|
||
an import statement.</p>
|
||
<p>See also the <a class="reference internal" href="#cmdoption-X"><code class="xref std std-option docutils literal notranslate"><span class="pre">-X</span> <span class="pre">presite</span></code></a> command-line option,
|
||
which takes precedence over this variable.</p>
|
||
<p>Needs Python configured with the <a class="reference internal" href="configure.html#cmdoption-with-pydebug"><code class="xref std std-option docutils literal notranslate"><span class="pre">--with-pydebug</span></code></a> build option.</p>
|
||
<div class="versionadded">
|
||
<p><span class="versionmodified added">Added in version 3.13.</span></p>
|
||
</div>
|
||
</dd></dl>
|
||
|
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</section>
|
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|
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<li><a class="reference internal" href="#interface-options">1.1.1. Interface options</a></li>
|
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|
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<li><a class="reference internal" href="#miscellaneous-options">1.1.3. Miscellaneous options</a></li>
|
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<li><a class="reference internal" href="#controlling-color">1.1.4. Controlling color</a></li>
|
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|
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|
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|
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|
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