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<section id="module-runpy">
<span id="runpy-locating-and-executing-python-modules"></span><h1><code class="xref py py-mod docutils literal notranslate"><span class="pre">runpy</span></code> — Locating and executing Python modules<a class="headerlink" href="#module-runpy" title="Link to this heading"></a></h1>
<p><strong>Source code:</strong> <a class="extlink-source reference external" href="https://github.com/python/cpython/tree/3.13/Lib/runpy.py">Lib/runpy.py</a></p>
<hr class="docutils" />
<p>The <a class="reference internal" href="#module-runpy" title="runpy: Locate and run Python modules without importing them first."><code class="xref py py-mod docutils literal notranslate"><span class="pre">runpy</span></code></a> module is used to locate and run Python modules without
importing them first. Its main use is to implement the <a class="reference internal" href="../using/cmdline.html#cmdoption-m"><code class="xref std std-option docutils literal notranslate"><span class="pre">-m</span></code></a> command
line switch that allows scripts to be located using the Python module
namespace rather than the filesystem.</p>
<p>Note that this is <em>not</em> a sandbox module - all code is executed in the
current process, and any side effects (such as cached imports of other
modules) will remain in place after the functions have returned.</p>
<p>Furthermore, any functions and classes defined by the executed code are not
guaranteed to work correctly after a <a class="reference internal" href="#module-runpy" title="runpy: Locate and run Python modules without importing them first."><code class="xref py py-mod docutils literal notranslate"><span class="pre">runpy</span></code></a> function has returned.
If that limitation is not acceptable for a given use case, <a class="reference internal" href="importlib.html#module-importlib" title="importlib: The implementation of the import machinery."><code class="xref py py-mod docutils literal notranslate"><span class="pre">importlib</span></code></a>
is likely to be a more suitable choice than this module.</p>
<p>The <a class="reference internal" href="#module-runpy" title="runpy: Locate and run Python modules without importing them first."><code class="xref py py-mod docutils literal notranslate"><span class="pre">runpy</span></code></a> module provides two functions:</p>
<dl class="py function">
<dt class="sig sig-object py" id="runpy.run_module">
<span class="sig-prename descclassname"><span class="pre">runpy.</span></span><span class="sig-name descname"><span class="pre">run_module</span></span><span class="sig-paren">(</span><em class="sig-param"><span class="n"><span class="pre">mod_name</span></span></em>, <em class="sig-param"><span class="n"><span class="pre">init_globals</span></span><span class="o"><span class="pre">=</span></span><span class="default_value"><span class="pre">None</span></span></em>, <em class="sig-param"><span class="n"><span class="pre">run_name</span></span><span class="o"><span class="pre">=</span></span><span class="default_value"><span class="pre">None</span></span></em>, <em class="sig-param"><span class="n"><span class="pre">alter_sys</span></span><span class="o"><span class="pre">=</span></span><span class="default_value"><span class="pre">False</span></span></em><span class="sig-paren">)</span><a class="headerlink" href="#runpy.run_module" title="Link to this definition"></a></dt>
<dd><p id="index-0">Execute the code of the specified module and return the resulting modules
globals dictionary. The modules code is first located using the standard
import mechanism (refer to <span class="target" id="index-1"></span><a class="pep reference external" href="https://peps.python.org/pep-0302/"><strong>PEP 302</strong></a> for details) and then executed in a
fresh module namespace.</p>
<p>The <em>mod_name</em> argument should be an absolute module name.
If the module name refers to a package rather than a normal
module, then that package is imported and the <a class="reference internal" href="__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> submodule within
that package is then executed and the resulting module globals dictionary
returned.</p>
<p>The optional dictionary argument <em>init_globals</em> may be used to pre-populate
the modules globals dictionary before the code is executed.
<em>init_globals</em> will not be modified. If any of the special global variables
below are defined in <em>init_globals</em>, those definitions are
overridden by <a class="reference internal" href="#runpy.run_module" title="runpy.run_module"><code class="xref py py-func docutils literal notranslate"><span class="pre">run_module()</span></code></a>.</p>
<p>The special global variables <code class="docutils literal notranslate"><span class="pre">__name__</span></code>, <code class="docutils literal notranslate"><span class="pre">__spec__</span></code>, <code class="docutils literal notranslate"><span class="pre">__file__</span></code>,
<code class="docutils literal notranslate"><span class="pre">__cached__</span></code>, <code class="docutils literal notranslate"><span class="pre">__loader__</span></code> and <code class="docutils literal notranslate"><span class="pre">__package__</span></code> are set in the globals
dictionary before the module code is executed. (Note that this is a
minimal set of variables - other variables may be set implicitly as an
interpreter implementation detail.)</p>
<p><code class="docutils literal notranslate"><span class="pre">__name__</span></code> is set to <em>run_name</em> if this optional argument is not
<a class="reference internal" href="constants.html#None" title="None"><code class="xref py py-const docutils literal notranslate"><span class="pre">None</span></code></a>, to <code class="docutils literal notranslate"><span class="pre">mod_name</span> <span class="pre">+</span> <span class="pre">'.__main__'</span></code> if the named module is a
package and to the <em>mod_name</em> argument otherwise.</p>
<p><code class="docutils literal notranslate"><span class="pre">__spec__</span></code> will be set appropriately for the <em>actually</em> imported
module (that is, <code class="docutils literal notranslate"><span class="pre">__spec__.name</span></code> will always be <em>mod_name</em> or
<code class="docutils literal notranslate"><span class="pre">mod_name</span> <span class="pre">+</span> <span class="pre">'.__main__'</span></code>, never <em>run_name</em>).</p>
<p><code class="docutils literal notranslate"><span class="pre">__file__</span></code>, <code class="docutils literal notranslate"><span class="pre">__cached__</span></code>, <code class="docutils literal notranslate"><span class="pre">__loader__</span></code> and <code class="docutils literal notranslate"><span class="pre">__package__</span></code> are
<a class="reference internal" href="../reference/datamodel.html#import-mod-attrs"><span class="std std-ref">set as normal</span></a> based on the module spec.</p>
<p>If the argument <em>alter_sys</em> is supplied and evaluates to <a class="reference internal" href="constants.html#True" title="True"><code class="xref py py-const docutils literal notranslate"><span class="pre">True</span></code></a>,
then <code class="docutils literal notranslate"><span class="pre">sys.argv[0]</span></code> is updated with the value of <code class="docutils literal notranslate"><span class="pre">__file__</span></code> and
<code class="docutils literal notranslate"><span class="pre">sys.modules[__name__]</span></code> is updated with a temporary module object for the
module being executed. Both <code class="docutils literal notranslate"><span class="pre">sys.argv[0]</span></code> and <code class="docutils literal notranslate"><span class="pre">sys.modules[__name__]</span></code>
are restored to their original values before the function returns.</p>
<p>Note that this manipulation of <a class="reference internal" href="sys.html#module-sys" title="sys: Access system-specific parameters and functions."><code class="xref py py-mod docutils literal notranslate"><span class="pre">sys</span></code></a> is not thread-safe. Other threads
may see the partially initialised module, as well as the altered list of
arguments. It is recommended that the <code class="docutils literal notranslate"><span class="pre">sys</span></code> module be left alone when
invoking this function from threaded code.</p>
<div class="admonition seealso">
<p class="admonition-title">See also</p>
<p>The <a class="reference internal" href="../using/cmdline.html#cmdoption-m"><code class="xref std std-option docutils literal notranslate"><span class="pre">-m</span></code></a> option offering equivalent functionality from the
command line.</p>
</div>
<div class="versionchanged">
<p><span class="versionmodified changed">Changed in version 3.1: </span>Added ability to execute packages by looking for a <a class="reference internal" href="__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> submodule.</p>
</div>
<div class="versionchanged">
<p><span class="versionmodified changed">Changed in version 3.2: </span>Added <code class="docutils literal notranslate"><span class="pre">__cached__</span></code> global variable (see <span class="target" id="index-2"></span><a class="pep reference external" href="https://peps.python.org/pep-3147/"><strong>PEP 3147</strong></a>).</p>
</div>
<div class="versionchanged">
<p><span class="versionmodified changed">Changed in version 3.4: </span>Updated to take advantage of the module spec feature added by
<span class="target" id="index-3"></span><a class="pep reference external" href="https://peps.python.org/pep-0451/"><strong>PEP 451</strong></a>. This allows <code class="docutils literal notranslate"><span class="pre">__cached__</span></code> to be set correctly for modules
run this way, as well as ensuring the real module name is always
accessible as <code class="docutils literal notranslate"><span class="pre">__spec__.name</span></code>.</p>
</div>
<div class="versionchanged">
<p><span class="versionmodified changed">Changed in version 3.12: </span>The setting of <code class="docutils literal notranslate"><span class="pre">__cached__</span></code>, <code class="docutils literal notranslate"><span class="pre">__loader__</span></code>, and
<code class="docutils literal notranslate"><span class="pre">__package__</span></code> are deprecated. See
<a class="reference internal" href="importlib.html#importlib.machinery.ModuleSpec" title="importlib.machinery.ModuleSpec"><code class="xref py py-class docutils literal notranslate"><span class="pre">ModuleSpec</span></code></a> for alternatives.</p>
</div>
</dd></dl>
<dl class="py function">
<dt class="sig sig-object py" id="runpy.run_path">
<span class="sig-prename descclassname"><span class="pre">runpy.</span></span><span class="sig-name descname"><span class="pre">run_path</span></span><span class="sig-paren">(</span><em class="sig-param"><span class="n"><span class="pre">path_name</span></span></em>, <em class="sig-param"><span class="n"><span class="pre">init_globals</span></span><span class="o"><span class="pre">=</span></span><span class="default_value"><span class="pre">None</span></span></em>, <em class="sig-param"><span class="n"><span class="pre">run_name</span></span><span class="o"><span class="pre">=</span></span><span class="default_value"><span class="pre">None</span></span></em><span class="sig-paren">)</span><a class="headerlink" href="#runpy.run_path" title="Link to this definition"></a></dt>
<dd><p id="index-4">Execute the code at the named filesystem location and return the resulting
modules globals dictionary. As with a script name supplied to the CPython
command line, <em>file_path</em> may refer to a Python source file, a
compiled bytecode file or a valid <a class="reference internal" href="sys.html#sys.path" title="sys.path"><code class="xref py py-data docutils literal notranslate"><span class="pre">sys.path</span></code></a> entry containing a
<a class="reference internal" href="__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
(e.g. a zipfile containing a top-level <code class="file docutils literal notranslate"><span class="pre">__main__.py</span></code> file).</p>
<p>For a simple script, the specified code is simply executed in a fresh
module namespace. For a valid <a class="reference internal" href="sys.html#sys.path" title="sys.path"><code class="xref py py-data docutils literal notranslate"><span class="pre">sys.path</span></code></a> entry (typically a zipfile or
directory), the entry is first added to the beginning of <code class="docutils literal notranslate"><span class="pre">sys.path</span></code>. The
function then looks for and executes a <a class="reference internal" href="__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 using the
updated path. Note that there is no special protection against invoking
an existing <code class="docutils literal notranslate"><span class="pre">__main__</span></code> entry located elsewhere on <code class="docutils literal notranslate"><span class="pre">sys.path</span></code> if
there is no such module at the specified location.</p>
<p>The optional dictionary argument <em>init_globals</em> may be used to pre-populate
the modules globals dictionary before the code is executed.
<em>init_globals</em> will not be modified. If any of the special global variables
below are defined in <em>init_globals</em>, those definitions are
overridden by <a class="reference internal" href="#runpy.run_path" title="runpy.run_path"><code class="xref py py-func docutils literal notranslate"><span class="pre">run_path()</span></code></a>.</p>
<p>The special global variables <code class="docutils literal notranslate"><span class="pre">__name__</span></code>, <code class="docutils literal notranslate"><span class="pre">__spec__</span></code>, <code class="docutils literal notranslate"><span class="pre">__file__</span></code>,
<code class="docutils literal notranslate"><span class="pre">__cached__</span></code>, <code class="docutils literal notranslate"><span class="pre">__loader__</span></code> and <code class="docutils literal notranslate"><span class="pre">__package__</span></code> are set in the globals
dictionary before the module code is executed. (Note that this is a
minimal set of variables - other variables may be set implicitly as an
interpreter implementation detail.)</p>
<p><code class="docutils literal notranslate"><span class="pre">__name__</span></code> is set to <em>run_name</em> if this optional argument is not
<a class="reference internal" href="constants.html#None" title="None"><code class="xref py py-const docutils literal notranslate"><span class="pre">None</span></code></a> and to <code class="docutils literal notranslate"><span class="pre">'&lt;run_path&gt;'</span></code> otherwise.</p>
<p>If <em>file_path</em> directly references a script file (whether as source
or as precompiled byte code), then <code class="docutils literal notranslate"><span class="pre">__file__</span></code> will be set to
<em>file_path</em>, and <code class="docutils literal notranslate"><span class="pre">__spec__</span></code>, <code class="docutils literal notranslate"><span class="pre">__cached__</span></code>, <code class="docutils literal notranslate"><span class="pre">__loader__</span></code> and
<code class="docutils literal notranslate"><span class="pre">__package__</span></code> will all be set to <a class="reference internal" href="constants.html#None" title="None"><code class="xref py py-const docutils literal notranslate"><span class="pre">None</span></code></a>.</p>
<p>If <em>file_path</em> is a reference to a valid <a class="reference internal" href="sys.html#sys.path" title="sys.path"><code class="xref py py-data docutils literal notranslate"><span class="pre">sys.path</span></code></a> entry, then
<code class="docutils literal notranslate"><span class="pre">__spec__</span></code> will be set appropriately for the imported <a class="reference internal" href="__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 (that is, <code class="docutils literal notranslate"><span class="pre">__spec__.name</span></code> will always be <code class="docutils literal notranslate"><span class="pre">__main__</span></code>).
<code class="docutils literal notranslate"><span class="pre">__file__</span></code>, <code class="docutils literal notranslate"><span class="pre">__cached__</span></code>, <code class="docutils literal notranslate"><span class="pre">__loader__</span></code> and <code class="docutils literal notranslate"><span class="pre">__package__</span></code> will be
<a class="reference internal" href="../reference/datamodel.html#import-mod-attrs"><span class="std std-ref">set as normal</span></a> based on the module spec.</p>
<p>A number of alterations are also made to the <a class="reference internal" href="sys.html#module-sys" title="sys: Access system-specific parameters and functions."><code class="xref py py-mod docutils literal notranslate"><span class="pre">sys</span></code></a> module. Firstly,
<a class="reference internal" href="sys.html#sys.path" title="sys.path"><code class="xref py py-data docutils literal notranslate"><span class="pre">sys.path</span></code></a> may be altered as described above. <code class="docutils literal notranslate"><span class="pre">sys.argv[0]</span></code> is updated
with the value of <em>file_path</em> and <code class="docutils literal notranslate"><span class="pre">sys.modules[__name__]</span></code> is updated
with a temporary module object for the module being executed. All
modifications to items in <a class="reference internal" href="sys.html#module-sys" title="sys: Access system-specific parameters and functions."><code class="xref py py-mod docutils literal notranslate"><span class="pre">sys</span></code></a> are reverted before the function
returns.</p>
<p>Note that, unlike <a class="reference internal" href="#runpy.run_module" title="runpy.run_module"><code class="xref py py-func docutils literal notranslate"><span class="pre">run_module()</span></code></a>, the alterations made to <a class="reference internal" href="sys.html#module-sys" title="sys: Access system-specific parameters and functions."><code class="xref py py-mod docutils literal notranslate"><span class="pre">sys</span></code></a>
are not optional in this function as these adjustments are essential to
allowing the execution of <a class="reference internal" href="sys.html#sys.path" title="sys.path"><code class="xref py py-data docutils literal notranslate"><span class="pre">sys.path</span></code></a> entries. As the thread-safety
limitations still apply, use of this function in threaded code should be
either serialised with the import lock or delegated to a separate process.</p>
<div class="admonition seealso">
<p class="admonition-title">See also</p>
<p><a class="reference internal" href="../using/cmdline.html#using-on-interface-options"><span class="std std-ref">Interface options</span></a> for equivalent functionality on the
command line (<code class="docutils literal notranslate"><span class="pre">python</span> <span class="pre">path/to/script</span></code>).</p>
</div>
<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 3.4: </span>Updated to take advantage of the module spec feature added by
<span class="target" id="index-5"></span><a class="pep reference external" href="https://peps.python.org/pep-0451/"><strong>PEP 451</strong></a>. This allows <code class="docutils literal notranslate"><span class="pre">__cached__</span></code> to be set correctly in the
case where <code class="docutils literal notranslate"><span class="pre">__main__</span></code> is imported from a valid <a class="reference internal" href="sys.html#sys.path" title="sys.path"><code class="xref py py-data docutils literal notranslate"><span class="pre">sys.path</span></code></a> entry rather
than being executed directly.</p>
</div>
<div class="versionchanged">
<p><span class="versionmodified changed">Changed in version 3.12: </span>The setting of <code class="docutils literal notranslate"><span class="pre">__cached__</span></code>, <code class="docutils literal notranslate"><span class="pre">__loader__</span></code>, and
<code class="docutils literal notranslate"><span class="pre">__package__</span></code> are deprecated.</p>
</div>
</dd></dl>
<div class="admonition seealso">
<p class="admonition-title">See also</p>
<dl class="simple">
<dt><span class="target" id="index-6"></span><a class="pep reference external" href="https://peps.python.org/pep-0338/"><strong>PEP 338</strong></a> Executing modules as scripts</dt><dd><p>PEP written and implemented by Nick Coghlan.</p>
</dd>
<dt><span class="target" id="index-7"></span><a class="pep reference external" href="https://peps.python.org/pep-0366/"><strong>PEP 366</strong></a> Main module explicit relative imports</dt><dd><p>PEP written and implemented by Nick Coghlan.</p>
</dd>
<dt><span class="target" id="index-8"></span><a class="pep reference external" href="https://peps.python.org/pep-0451/"><strong>PEP 451</strong></a> A ModuleSpec Type for the Import System</dt><dd><p>PEP written and implemented by Eric Snow</p>
</dd>
</dl>
<p><a class="reference internal" href="../using/cmdline.html#using-on-general"><span class="std std-ref">Command line and environment</span></a> - CPython command line details</p>
<p>The <a class="reference internal" href="importlib.html#importlib.import_module" title="importlib.import_module"><code class="xref py py-func docutils literal notranslate"><span class="pre">importlib.import_module()</span></code></a> function</p>
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