This document is being retained solely until the
independently covers all of the relevant information currently included here.
This guide only covers the basic tools for building and distributing extensions that are provided as part of this version of Python. Third party tools offer easier to use and more secure alternatives. Refer to the [https://packaging.python.org/guides/tool-recommendations/ quick recommendations section] in the Python Packaging User Guide for more information.
In Python 2.0, the
distutils API was first added to the standard library.
This provided Linux distro maintainers with a standard way of converting
Python projects into Linux distro packages, and system administrators with a
standard way of installing them directly onto target systems.
In the many years since Python 2.0 was released, tightly coupling the build
system and package installer to the language runtime release cycle has turned
out to be problematic, and it is now recommended that projects use the
pip package installer and the
setuptools build system, rather than
This legacy documentation is being retained only until we’re confident that the
setuptools documentation covers everything needed.
If you download a module source distribution, you can tell pretty quickly if it
was packaged and distributed in the standard way, i.e. using the Distutils.
First, the distribution’s name and version number will be featured prominently
in the name of the downloaded archive, e.g.
widget-0.9.7.zip. Next, the archive will unpack into a similarly-named
widget-0.9.7. Additionally, the
distribution will contain a setup script
setup.py, and a file named
README.txt or possibly just
README, which should explain that
building and installing the module distribution is a simple matter of running
one command from a terminal:
python setup.py install
For Windows, this command should be run from a command prompt window ():
If all these things are true, then you already know how to build and install the modules you’ve just downloaded: Run the command above. Unless you need to install things in a non-standard way or customize the build process, you don’t really need this manual. Or rather, the above command is everything you need to get out of this manual.
As described in section Distutils based source distributions, building and installing a module distribution using the Distutils is usually one simple command to run from a terminal:
python setup.py install
You should always run the setup command from the distribution root directory,
i.e. the top-level subdirectory that the module source distribution unpacks
into. For example, if you’ve just downloaded a module source distribution
foo-1.0.tar.gz onto a Unix system, the normal thing to do is:
gunzip -c foo-1.0.tar.gz | tar xf - # unpacks into directory foo-1.0 cd foo-1.0 python setup.py install
On Windows, you’d probably download
foo-1.0.zip. If you downloaded the
archive file to
C:\Temp, then it would unpack into
C:\Temp\foo-1.0; you can use either an archive manipulator with a
graphical user interface (such as WinZip) or a command-line tool (such as
unzip or pkunzip) to unpack the archive. Then, open a
command prompt window and run:
cd c:\Temp\foo-1.0 python setup.py install
setup.py install builds and installs all modules in one run. If you
prefer to work incrementally—especially useful if you want to customize the
build process, or if things are going wrong—you can use the setup script to do
one thing at a time. This is particularly helpful when the build and install
will be done by different users—for example, you might want to build a module
distribution and hand it off to a system administrator for installation (or do
it yourself, with super-user privileges).
For example, you can build everything in one step, and then install everything in a second step, by invoking the setup script twice:
python setup.py build python setup.py install
If you do this, you will notice that running the install command
first runs the build command, which—in this case—quickly notices
that it has nothing to do, since everything in the
build directory is
You may not need this ability to break things down often if all you do is install modules downloaded off the ‘net, but it’s very handy for more advanced tasks. If you get into distributing your own Python modules and extensions, you’ll run lots of individual Distutils commands on their own.
As implied above, the build command is responsible for putting the
files to install into a build directory. By default, this is
under the distribution root; if you’re excessively concerned with speed, or want
to keep the source tree pristine, you can change the build directory with the
--build-base option. For example:
python setup.py build --build-base=/path/to/pybuild/foo-1.0
(Or you could do this permanently with a directive in your system or personal Distutils configuration file; see section Distutils Configuration Files.) Normally, this isn’t necessary.
The default layout for the build tree is as follows:
--- build/ --- lib/ or --- build/ --- lib.<plat>/ temp.<plat>/
<plat> expands to a brief description of the current OS/hardware
platform and Python version. The first form, with just a
is used for “pure module distributions”—that is, module distributions that
include only pure Python modules. If a module distribution contains any
extensions (modules written in C/C++), then the second form, with two
directories, is used. In that case, the
temp.plat directory holds
temporary files generated by the compile/link process that don’t actually get
installed. In either case, the
contains all Python modules (pure Python and extensions) that will be installed.
In the future, more directories will be added to handle Python scripts, documentation, binary executables, and whatever else is needed to handle the job of installing Python modules and applications.
After the build command runs (whether you run it explicitly, or the
install command does it for you), the work of the install
command is relatively simple: all it has to do is copy everything under
build/lib.plat) to your chosen installation
If you don’t choose an installation directory—i.e., if you just run
setup.py install—then the install command installs to the standard
location for third-party Python modules. This location varies by platform and
by how you built/installed Python itself. On Unix (and Mac OS X, which is also
Unix-based), it also depends on whether the module distribution being installed
is pure Python or contains extensions (“non-pure”):
|Platform||Standard installation location||Default value||Notes|
exec-prefixare usually both
/usron Linux. If you build Python yourself on Linux (or any Unix-like system), the default
C:\Program Files\Pythonunder Python 1.6a1, 1.5.2, and earlier.
exec-prefix stand for the directories that Python
is installed to, and where it finds its libraries at run-time. They are always
the same under Windows, and very often the same under Unix and Mac OS X. You
can find out what your Python installation uses for
exec-prefix by running Python in interactive mode and typing a few
simple commands. Under Unix, just type
python at the shell prompt. Under
Windows, choose . Once the interpreter is started, you type Python code
at the prompt. For example, on my Linux system, I type the three Python
statements shown below, and get the output as shown, to find out my
Python 2.4 (#26, Aug 7 2004, 17:19:02) Type "help", "copyright", "credits" or "license" for more information. >>> import sys >>> sys.prefix '/usr' >>> sys.exec_prefix '/usr'
A few other placeholders are used in this document:
X.Y stands for the
version of Python, for example
abiflags will be replaced by
the value of
sys.abiflags or the empty string for platforms which don’t
define ABI flags;
distname will be replaced by the name of the module
distribution being installed. Dots and capitalization are important in the
paths; for example, a value that uses
python3.2 on UNIX will typically use
Python32 on Windows.
If you don’t want to install modules to the standard location, or if you don’t have permission to write there, then you need to read about alternate installations in section Alternate Installation. If you want to customize your installation directories more heavily, see section Custom Installation on custom installations.
Often, it is necessary or desirable to install modules to a location other than the standard location for third-party Python modules. For example, on a Unix system you might not have permission to write to the standard third-party module directory. Or you might wish to try out a module before making it a standard part of your local Python installation. This is especially true when upgrading a distribution already present: you want to make sure your existing base of scripts still works with the new version before actually upgrading.
The Distutils install command is designed to make installing module distributions to an alternate location simple and painless. The basic idea is that you supply a base directory for the installation, and the install command picks a set of directories (called an installation scheme) under this base directory in which to install files. The details differ across platforms, so read whichever of the following sections applies to you.
Note that the various alternate installation schemes are mutually exclusive: you
--install-platbase, but you can’t mix from these
This scheme is designed to be the most convenient solution for users that don’t have write permission to the global site-packages directory or don’t want to install into it. It is enabled with a simple option:
python setup.py install --user
Files will be installed into subdirectories of
userbase hereafter). This scheme installs pure Python modules and
extension modules in the same location (also known as
Here are the values for UNIX, including Mac OS X:
|Type of file||Installation directory|
And here are the values used on Windows:
|Type of file||Installation directory|
The advantage of using this scheme compared to the other ones described below is
that the user site-packages directory is under normal conditions always included
site for more information), which means that
there is no additional step to perform after running the
to finalize the installation.
The build_ext command also has a
--user option to add
userbase/include to the compiler search path for header files and
userbase/lib to the compiler search path for libraries as well as to
the runtime search path for shared C libraries (rpath).
The idea behind the “home scheme” is that you build and maintain a personal
stash of Python modules. This scheme’s name is derived from the idea of a
“home” directory on Unix, since it’s not unusual for a Unix user to make their
home directory have a layout similar to
This scheme can be used by anyone, regardless of the operating system they
are installing for.
Installing a new module distribution is as simple as
python setup.py install --home=<dir>
where you can supply any directory you like for the
--home option. On
Unix, lazy typists can just type a tilde (
~); the install command
will expand this to your home directory:
python setup.py install --home=~
--home option defines the installation base directory. Files are
installed to the following directories under the installation base as follows:
|Type of file||Installation directory|
(Mentally replace slashes with backslashes if you’re on Windows.)
The “prefix scheme” is useful when you wish to use one Python installation to perform the build/install (i.e., to run the setup script), but install modules into the third-party module directory of a different Python installation (or something that looks like a different Python installation). If this sounds a trifle unusual, it is—that’s why the user and home schemes come before. However, there are at least two known cases where the prefix scheme will be useful.
First, consider that many Linux distributions put Python in
than the more traditional
/usr/local. This is entirely appropriate,
since in those cases Python is part of “the system” rather than a local add-on.
However, if you are installing Python modules from source, you probably want
them to go in
/usr/local/lib/python2.X rather than
/usr/lib/python2.X. This can be done with
/usr/bin/python setup.py install --prefix=/usr/local
Another possibility is a network filesystem where the name used to write to a
remote directory is different from the name used to read it: for example, the
Python interpreter accessed as
/usr/local/bin/python might search for
/usr/local/lib/python2.X, but those modules would have to
be installed to, say,
/mnt/@server/export/lib/python2.X. This could
be done with
/usr/local/bin/python setup.py install --prefix=/mnt/@server/export
In either case, the
--prefix option defines the installation base, and
--exec-prefix option defines the platform-specific installation
base, which is used for platform-specific files. (Currently, this just means
non-pure module distributions, but could be expanded to C libraries, binary
executables, etc.) If
--exec-prefix is not supplied, it defaults to
--prefix. Files are installed as follows:
|Type of file||Installation directory|
There is no requirement that
actually point to an alternate Python installation; if the directories listed
above do not already exist, they are created at installation time.
Incidentally, the real reason the prefix scheme is important is simply that a
standard Unix installation uses the prefix scheme, but with
--exec-prefix supplied by Python itself as
sys.exec_prefix. Thus, you might think you’ll never use the prefix scheme,
but every time you run
python setup.py install without any other options,
you’re using it.
Note that installing extensions to an alternate Python installation has no
effect on how those extensions are built: in particular, the Python header files
Python.h and friends) installed with the Python interpreter used to run
the setup script will be used in compiling extensions. It is your
responsibility to ensure that the interpreter used to run extensions installed
in this way is compatible with the interpreter used to build them. The best way
to do this is to ensure that the two interpreters are the same version of Python
(possibly different builds, or possibly copies of the same build). (Of course,
--exec-prefix don’t even point to an
alternate Python installation, this is immaterial.)
Windows has no concept of a user’s home directory, and since the standard Python
installation under Windows is simpler than under Unix, the
option has traditionally been used to install additional packages in separate
locations on Windows.
python setup.py install --prefix="\Temp\Python"
to install modules to the
\Temp\Python directory on the current drive.
The installation base is defined by the
--prefix option; the
--exec-prefix option is not supported under Windows, which means that
pure Python modules and extension modules are installed into the same location.
Files are installed as follows:
|Type of file||Installation directory|
Sometimes, the alternate installation schemes described in section Alternate Installation just don’t do what you want. You might want to tweak just one or two directories while keeping everything under the same base directory, or you might want to completely redefine the installation scheme. In either case, you’re creating a custom installation scheme.
To create a custom installation scheme, you start with one of the alternate schemes and override some of the installation directories used for the various types of files, using these options:
|Type of file||Override option|
These override options can be relative, absolute,
or explicitly defined in terms of one of the installation base directories.
(There are two installation base directories, and they are normally the
same—they only differ when you use the Unix “prefix scheme” and supply
--exec-prefix options; using
will override values computed or given for
--install-platlib, and is recommended for schemes that don’t make a
difference between Python and extension modules.)
For example, say you’re installing a module distribution to your home directory
under Unix—but you want scripts to go in
~/scripts rather than
~/bin. As you might expect, you can override this directory with the
--install-scripts option; in this case, it makes most sense to supply
a relative path, which will be interpreted relative to the installation base
directory (your home directory, in this case):
python setup.py install --home=~ --install-scripts=scripts
Another Unix example: suppose your Python installation was built and installed
with a prefix of
/usr/local/python, so under a standard installation
scripts will wind up in
/usr/local/python/bin. If you want them in
/usr/local/bin instead, you would supply this absolute directory for the
python setup.py install --install-scripts=/usr/local/bin
(This performs an installation using the “prefix scheme”, where the prefix is
whatever your Python interpreter was installed with—
in this case.)
If you maintain Python on Windows, you might want third-party modules to live in
a subdirectory of
prefix, rather than right in
itself. This is almost as easy as customizing the script installation
directory—you just have to remember that there are two types of modules
to worry about, Python and extension modules, which can conveniently be both
controlled by one option:
python setup.py install --install-lib=Site
The specified installation directory is relative to
course, you also have to ensure that this directory is in Python’s module
search path, such as by putting a
.pth file in a site directory (see
site). See section Modifying Python’s Search Path to find out how to modify
Python’s search path.
If you want to define an entire installation scheme, you just have to supply all
of the installation directory options. The recommended way to do this is to
supply relative paths; for example, if you want to maintain all Python
module-related files under
python in your home directory, and you want a
separate directory for each platform that you use your home directory from, you
might define the following installation scheme:
python setup.py install --home=~ \ --install-purelib=python/lib \ --install-platlib=python/lib.$PLAT \ --install-scripts=python/scripts --install-data=python/data
python setup.py install --home=~/python \ --install-purelib=lib \ --install-platlib='lib.$PLAT' \ --install-scripts=scripts --install-data=data
$PLAT is not (necessarily) an environment variable—it will be expanded by
the Distutils as it parses your command line options, just as it does when
parsing your configuration file(s).
Obviously, specifying the entire installation scheme every time you install a new module distribution would be very tedious. Thus, you can put these options into your Distutils config file (see section Distutils Configuration Files):
[install] install-base=$HOME install-purelib=python/lib install-platlib=python/lib.$PLAT install-scripts=python/scripts install-data=python/data
[install] install-base=$HOME/python install-purelib=lib install-platlib=lib.$PLAT install-scripts=scripts install-data=data
Note that these two are not equivalent if you supply a different installation base directory when you run the setup script. For example,
python setup.py install --install-base=/tmp
would install pure modules to
/tmp/python/lib in the first case, and
/tmp/lib in the second case. (For the second case, you probably
want to supply an installation base of
You probably noticed the use of
$PLAT in the sample
configuration file input. These are Distutils configuration variables, which
bear a strong resemblance to environment variables. In fact, you can use
environment variables in config files on platforms that have such a notion but
the Distutils additionally define a few extra variables that may not be in your
environment, such as
$PLAT. (And of course, on systems that don’t have
environment variables, such as Mac OS 9, the configuration variables supplied by
the Distutils are the only ones you can use.) See section Distutils Configuration Files
When a virtual environment is activated, any options that change the installation path will be ignored from all distutils configuration files to prevent inadvertently installing projects outside of the virtual environment.
When the Python interpreter executes an
import statement, it searches
for both Python code and extension modules along a search path. A default value
for the path is configured into the Python binary when the interpreter is built.
You can determine the path by importing the
sys module and printing the
$ python Python 2.2 (#11, Oct 3 2002, 13:31:27) [GCC 2.96 20000731 (Red Hat Linux 7.3 2.96-112)] on linux2 Type "help", "copyright", "credits" or "license" for more information. >>> import sys >>> sys.path ['', '/usr/local/lib/python2.3', '/usr/local/lib/python2.3/plat-linux2', '/usr/local/lib/python2.3/lib-tk', '/usr/local/lib/python2.3/lib-dynload', '/usr/local/lib/python2.3/site-packages'] >>>
The null string in
sys.path represents the current working directory.
The expected convention for locally installed packages is to put them in the
…/site-packages/ directory, but you may want to install Python
modules into some arbitrary directory. For example, your site may have a
convention of keeping all software related to the web server under
Add-on Python modules might then belong in
/www/python, and in order to
import them, this directory must be added to
sys.path. There are several
different ways to add the directory.
The most convenient way is to add a path configuration file to a directory
that’s already on Python’s path, usually to the
directory. Path configuration files have an extension of
.pth, and each
line must contain a single path that will be appended to
the new paths are appended to
sys.path, modules in the added directories
will not override standard modules. This means you can’t use this mechanism for
installing fixed versions of standard modules.)
Paths can be absolute or relative, in which case they’re relative to the
directory containing the
.pth file. See the documentation of
site module for more information.
A slightly less convenient way is to edit the
site.py file in Python’s
standard library, and modify
site.py is automatically
imported when the Python interpreter is executed, unless the
is supplied to suppress this behaviour. So you could simply edit
site.py and add two lines to it:
import sys sys.path.append('/www/python/')
However, if you reinstall the same major version of Python (perhaps when
upgrading from 2.2 to 2.2.2, for example)
site.py will be overwritten by
the stock version. You’d have to remember that it was modified and save a copy
before doing the installation.
There are two environment variables that can modify
PYTHONHOME sets an alternate value for the prefix of the Python
installation. For example, if
PYTHONHOME is set to
the search path will be set to
[, '/www/python/lib/pythonX.Y/', '/www/python/lib/pythonX.Y/plat-linux2', ...].
PYTHONPATH variable can be set to a list of paths that will be
added to the beginning of
sys.path. For example, if
/www/python:/opt/py, the search path will begin with
['/www/python', '/opt/py']. (Note that directories must exist in order to
be added to
site module removes paths that don’t
sys.path is just a regular Python list, so any Python application
can modify it by adding or removing entries.
As mentioned above, you can use Distutils configuration files to record personal or site preferences for any Distutils options. That is, any option to any command can be stored in one of two or three (depending on your platform) configuration files, which will be consulted before the command-line is parsed. This means that configuration files will override default values, and the command-line will in turn override configuration files. Furthermore, if multiple configuration files apply, values from “earlier” files are overridden by “later” files.
The names and locations of the configuration files vary slightly across platforms. On Unix and Mac OS X, the three configuration files (in the order they are processed) are:
|Type of file||Location and filename||Notes|
And on Windows, the configuration files are:
|Type of file||Location and filename||Notes|
On all platforms, the “personal” file can be temporarily disabled by passing the –no-user-cfg option.
prefix/lib/python1.5/site-packages/distutils, so the system configuration file should be put there under Python 1.5.2.
HOMEenvironment variable is not defined, the user’s home directory will be determined with the
getpwuid()function from the standard
pwdmodule. This is done by the
os.path.expanduser()function used by Distutils.
C:\Python, so the system configuration file is normally
C:\Python\Lib\distutils\distutils.cfg. Under Python 1.5.2, the default prefix was
C:\Program Files\Python, and the Distutils were not part of the standard library—so the system configuration file would be
C:\Program Files\Python\distutils\distutils.cfgin a standard Python 1.5.2 installation under Windows.
HOMEenvironment variable is not defined,
HOMEPATHwill be tried. This is done by the
os.path.expanduser()function used by Distutils.
The Distutils configuration files all have the same syntax. The config files
are grouped into sections. There is one section for each Distutils command,
global section for global options that affect every command. Each
section consists of one option per line, specified as
For example, the following is a complete config file that just forces all commands to run quietly by default:
If this is installed as the system config file, it will affect all processing of
any Python module distribution by any user on the current system. If it is
installed as your personal config file (on systems that support them), it will
affect only module distributions processed by you. And if it is used as the
setup.cfg for a particular module distribution, it affects only that
You could override the default “build base” directory and make the build* commands always forcibly rebuild all files with the following:
[build] build-base=blib force=1
which corresponds to the command-line arguments
python setup.py build --build-base=blib --force
except that including the build command on the command-line means that command will be run. Including a particular command in config files has no such implication; it only means that if the command is run, the options in the config file will apply. (Or if other commands that derive values from it are run, they will use the values in the config file.)
You can find out the complete list of options for any command using the
--help option, e.g.:
python setup.py build --help
and you can find out the complete list of global options by using
--help without a command:
python setup.py --help
See also the “Reference” section of the “Distributing Python Modules” manual.
Whenever possible, the Distutils try to use the configuration information made
available by the Python interpreter used to run the
For example, the same compiler and linker flags used to compile Python will also
be used for compiling extensions. Usually this will work well, but in
complicated situations this might be inappropriate. This section discusses how
to override the usual Distutils behaviour.
This subsection describes the necessary steps to use Distutils with the Borland
C++ compiler version 5.5. First you have to know that Borland’s object file
format (OMF) is different from the format used by the Python version you can
download from the Python or ActiveState Web site. (Python is built with
Microsoft Visual C++, which uses COFF as the object file format.) For this
reason you have to convert Python’s library
python25.lib into the
Borland format. You can do this as follows:
coff2omf python25.lib python25_bcpp.lib
coff2omf program comes with the Borland compiler. The file
python25.lib is in the
Libs directory of your Python
installation. If your extension uses other libraries (zlib, …) you have to
convert them too.
The converted files have to reside in the same directories as the normal libraries.
How does Distutils manage to use these libraries with their changed names? If
the extension needs a library (eg.
foo) Distutils checks first if it
finds a library with suffix
foo_bcpp.lib) and then
uses this library. In the case it doesn’t find such a special library it uses
the default name (
To let Distutils compile your extension with Borland C++ you now have to type:
python setup.py build --compiler=bcpp
If you want to use the Borland C++ compiler as the default, you could specify this in your personal or system-wide configuration file for Distutils (see section Distutils Configuration Files.)
This section describes the necessary steps to use Distutils with the GNU C/C++ compilers in their Cygwin and MinGW distributions. 2 For a Python interpreter that was built with Cygwin, everything should work without any of these following steps.
Not all extensions can be built with MinGW or Cygwin, but many can. Extensions most likely to not work are those that use C++ or depend on Microsoft Visual C extensions.
To let Distutils compile your extension with Cygwin you have to type:
python setup.py build --compiler=cygwin
and for Cygwin in no-cygwin mode 3 or for MinGW type:
python setup.py build --compiler=mingw32
If you want to use any of these options/compilers as default, you should consider writing it in your personal or system-wide configuration file for Distutils (see section Distutils Configuration Files.)
The following instructions only apply if you’re using a version of Python inferior to 2.4.1 with a MinGW inferior to 3.0.0 (with binutils-2.13.90-20030111-1).
These compilers require some special libraries. This task is more complex than for Borland’s C++, because there is no program to convert the library. First you have to create a list of symbols which the Python DLL exports. (You can find a good program for this task at https://sourceforge.net/projects/mingw/files/MinGW/Extension/pexports/).
pexports python25.dll >python25.def
The location of an installed
python25.dll will depend on the
installation options and the version and language of Windows. In a “just for
me” installation, it will appear in the root of the installation directory. In
a shared installation, it will be located in the system directory.
Then you can create from these information an import library for gcc.
/cygwin/bin/dlltool --dllname python25.dll --def python25.def --output-lib libpython25.a
The resulting library has to be placed in the same directory as
python25.lib. (Should be the
libs directory under your Python
If your extension uses other libraries (zlib,…) you might have to convert them too. The converted files have to reside in the same directories as the normal libraries do.