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<title>Debian Python Policy - Python Programs</title>

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<link href="ch-python3.html" rel="chapter" title="1 On the move to Python 3">
<link href="ch-python.html" rel="chapter" title="2 Python Packaging">
<link href="ch-module_packages.html" rel="chapter" title="3 Packaged Modules">
<link href="ch-programs.html" rel="chapter" title="4 Python Programs">
<link href="ch-embed.html" rel="chapter" title="5 Programs Embedding Python">
<link href="ch-other.html" rel="chapter" title="6 Interaction with Locally Installed Python Versions">
<link href="ap-build_dependencies.html" rel="appendix" title="A Build Dependencies">
<link href="ap-packaging_tools.html" rel="appendix" title="B Packaging Tools">
<link href="ap-upgrade.html" rel="appendix" title="C Upgrade Procedure">
<link href="ch-python.html#s-versions" rel="section" title="2.1 Versions">
<link href="ch-python.html#s-base" rel="section" title="2.2 Main packages">
<link href="ch-python.html#s-minimal" rel="section" title="2.3 Minimal packages">
<link href="ch-python.html#s-interpreter" rel="section" title="2.4 Python Interpreter">
<link href="ch-python.html#s-paths" rel="section" title="2.5 Module Path">
<link href="ch-python.html#s-runtimes_hooks" rel="section" title="2.6 Hooks for updates to installed runtimes">
<link href="ch-python.html#s-docs" rel="section" title="2.7 Documentation">
<link href="ch-module_packages.html#s3.1" rel="section" title="3.1 Types of Python Modules">
<link href="ch-module_packages.html#s-wheels" rel="section" title="3.2 Wheels">
<link href="ch-module_packages.html#s-package_names" rel="section" title="3.3 Module Package Names">
<link href="ch-module_packages.html#s-specifying_versions" rel="section" title="3.4 Specifying Supported Versions">
<link href="ch-module_packages.html#s-dependencies" rel="section" title="3.5 Dependencies">
<link href="ch-module_packages.html#s-provides" rel="section" title="3.6 Provides">
<link href="ch-module_packages.html#s-byte_compilation" rel="section" title="3.7 Modules Byte-Compilation">
<link href="ch-programs.html#s-version_indep_progs" rel="section" title="4.1 Programs using the default python">
<link href="ch-programs.html#s-version_dep_progs" rel="section" title="4.2 Programs Using a Particular Python Version">
<link href="ch-embed.html#s-build_embedded" rel="section" title="5.1 Building Embedded Programs">
<link href="ch-embed.html#s-embedded_deps" rel="section" title="5.2 Embedded Python Dependencies">
<link href="ap-packaging_tools.html#s-distutils" rel="section" title="B.1 distutils">
<link href="ap-packaging_tools.html#s-pysupport" rel="section" title="B.2 python-support (deprecated)">
<link href="ap-packaging_tools.html#s-pycentral" rel="section" title="B.3 python-central (removed)">
<link href="ap-packaging_tools.html#s-cdbs" rel="section" title="B.4 CDBS">
<link href="ap-packaging_tools.html#s-dh_python2_3" rel="section" title="B.5 dh_python2 and dh_python3">
<link href="ch-python.html#s-interpreter_name" rel="subsection" title="2.4.1 Interpreter Name">
<link href="ch-python.html#s-interpreter_loc" rel="subsection" title="2.4.2 Interpreter Location">
<link href="ch-programs.html#s-current_version_progs" rel="subsection" title="4.1.1 Programs Shipping Private Modules">

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[ <a href="ap-build_dependencies.html">A</a> ]
[ <a href="ap-packaging_tools.html">B</a> ]
[ <a href="ap-upgrade.html">C</a> ]
[ <a href="ch-embed.html">next</a> ]
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<h1>
Debian Python Policy
<br>Chapter 4 - Python Programs
</h1>

<hr>

<h2 id="s-version_indep_progs">4.1 Programs using the default python</h2>

<p>
Programs that can run with any version of Python must begin with
<samp>#!/usr/bin/python</samp> or <samp>#!/usr/bin/env python</samp> (the
former is strongly preferred).  They must also specify a dependency on
<code>python</code>, with a versioned dependency if necessary.
</p>

<p>
If the program needs the python module <samp>foo</samp>, it must depend on the
real package providing this module, usually <code>python-foo</code> but this
name might vary when the package ships multiple modules.
</p>

<hr>

<h3 id="s-current_version_progs">4.1.1 Programs Shipping Private Modules</h3>

<p>
A program using <code>/usr/bin/python</code> as interpreter can come up with
private Python modules.  These modules should be installed in
<samp>/usr/share/<var>module</var></samp>, or
<samp>/usr/lib/<var>module</var></samp> if the modules are
architecture-dependent (e.g.  extensions).
</p>

<p>
The rules explained in <a
href="ch-module_packages.html#s-byte_compilation">Modules Byte-Compilation,
Section 3.7</a> apply to those private modules: the byte-compiled modules must
not be shipped with the binary package, they should be generated in the
package's postinst, using the current default Python version, and removed in
the prerm.  Modules should be byte-compiled using the current default Python
version.
</p>

<p>
Programs that have private compiled extensions must either handle multiple
version support themselves, or declare a tight dependency on the current Python
version (e.g.  <samp>Depends: python (&gt;= 2.6), python (&lt;&lt; 2.7)</samp>.
No tools currently exist to alleviate this situation.
</p>

<hr>

<h2 id="s-version_dep_progs">4.2 Programs Using a Particular Python Version</h2>

<p>
A program which requires a specific version of Python must begin with
<samp>#!/usr/bin/python<var>X</var>.<var>Y</var></samp> (or
<samp>#!/usr/bin/env python<var>X</var>.<var>Y</var></samp>).  It must also
specify a dependency on <code>python<var>X</var>.<var>Y</var></code> and on any
<code>python<var>X</var>.<var>Y</var>-foo</code> package providing necessary
modules.  It should not depend on any <code>python-foo</code> package, unless
it requires a specific version of the package (since virtual packages cannot be
versioned).  If this is the case, it should depend on both the virtual package
and the main package (e.g.  <samp>Depends: python2.7-foo, python-foo (&gt;=
1.0)</samp>).
</p>

<p>
The notes on installation directories and byte-compilation for programs that
support any version of Python also apply to programs supporting only a single
Python version.  Modules to be byte-compiled should use the same Python version
as the package itself.
</p>

<hr>

<p>
[ <a href="ch-module_packages.html">previous</a> ]
[ <a href="index.html#contents">Contents</a> ]
[ <a href="ch-python3.html">1</a> ]
[ <a href="ch-python.html">2</a> ]
[ <a href="ch-module_packages.html">3</a> ]
[ 4 ]
[ <a href="ch-embed.html">5</a> ]
[ <a href="ch-other.html">6</a> ]
[ <a href="ap-build_dependencies.html">A</a> ]
[ <a href="ap-packaging_tools.html">B</a> ]
[ <a href="ap-upgrade.html">C</a> ]
[ <a href="ch-embed.html">next</a> ]
</p>

<hr>

<p>
Debian Python Policy
</p>

<address>
version 0.10.0.2<br>
<br>
Neil Schemenauer <code><a href="mailto:nas@debian.org">mailto:nas@debian.org</a></code><br>
Matthias Klose <code><a href="mailto:doko@debian.org">mailto:doko@debian.org</a></code><br>
Gregor Hoffleit <code><a href="mailto:flight@debian.org">mailto:flight@debian.org</a></code><br>
Josselin Mouette <code><a href="mailto:joss@debian.org">mailto:joss@debian.org</a></code><br>
Joe Wreschnig <code><a href="mailto:piman@debian.org">mailto:piman@debian.org</a></code><br>
Lo&iuml;c Minier <code><a href="mailto:lool@debian.org">mailto:lool@debian.org</a></code><br>
Scott Kitterman <code><a href="mailto:scott@kitterman.com">mailto:scott@kitterman.com</a></code><br>
Barry Warsaw <code><a href="mailto:barry@debian.org">mailto:barry@debian.org</a></code><br>
<br>
</address>
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