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Note The entire See also Installing Python ModulesThe up to date module installation documentation. For regular Python usage, you almost certainly want that document rather than this one. Note 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 quick recommendations section in the Python Packaging User Guide for more information. Introduction¶In Python 2.0, the 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 See Installing Python Modules and Distributing Python Modules for more details. This legacy documentation is being retained only until we’re confident that the Distutils based source distributions¶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. 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. Standard Build and Install¶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: Platform variations¶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 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 cd c:\Temp\foo-1.0 python setup.py install Splitting the job up¶Running 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 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. How building works¶As implied above, the build command is responsible for putting the files to install into a build directory. By default, this is 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. where 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. How installation works¶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 If you don’t choose an installation directory—i.e., if you just run
Notes:
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: 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. Alternate Installation¶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 can pass Alternate installation: the user scheme¶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
And here are the values used on Windows:
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 in The build_ext command also has a Alternate installation: the home scheme¶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 Installing a new module distribution is as simple as python setup.py install --home= where you can supply any directory you like for the python setup.py install --home=~ To make Python find the distributions installed with this scheme, you may have to
modify Python’s search path or edit The
(Mentally replace slashes with backslashes if you’re on Windows.) Alternate installation: Unix (the prefix scheme)¶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 /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 setup.py install --prefix=/mnt/@server/export In either case, the
There is no requirement that Incidentally, the real reason the prefix scheme is important is simply that a standard Unix installation uses the prefix scheme, but with Note that installing extensions to an alternate Python installation has no effect on how those extensions are built: in particular, the Python header files ( Alternate installation: Windows (the prefix scheme)¶Windows has no concept of a user’s home directory, and since the standard Python installation under Windows is simpler than under Unix, the python setup.py install --prefix="\Temp\Python" to install modules to the The installation base is defined by the
Custom Installation¶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:
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 different For example, say you’re installing a module distribution to your home directory under Unix—but you want scripts to go in python setup.py install --home=~ --install-scripts=scripts Another Unix example: suppose your Python
installation was built and installed with a prefix of 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— If you maintain Python on Windows, you might want third-party modules to live in
a subdirectory of python setup.py install --install-lib=Site The specified installation directory is relative to 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 setup.py install --home=~ \ --install-purelib=python/lib \ --install-platlib=python/lib.$PLAT \ --install-scripts=python/scripts --install-data=python/data or, equivalently, python setup.py install --home=~/python \ --install-purelib=lib \ --install-platlib='lib.$PLAT' \ --install-scripts=scripts --install-data=data
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 or, equivalently, [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 You probably noticed the use of Note 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. Modifying Python’s Search Path¶When the Python interpreter executes an $ 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 The expected convention for locally installed packages is to put them in the The most convenient way is to add a path configuration file to a directory that’s already on Python’s path, usually to
the Paths can be absolute or relative, in which case they’re relative to the directory containing the A slightly less convenient way is to edit the 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) There are two environment variables that can modify The
Finally, Distutils Configuration Files¶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. Location and names of config files¶The names and locations of the configuration files vary slightly across platforms. On Unix and macOS, the three configuration files (in the order they are processed) are:
And on Windows, the configuration files are:
On all platforms, the “personal” file can be temporarily disabled by passing the –no-user-cfg option. Notes:
Syntax of config files¶The Distutils configuration files all have the same syntax. The config files are grouped into sections. There is one section for each Distutils command, plus a 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 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 python setup.py build --help and you can find out the complete list of global options by using See also the “Reference” section of the “Distributing Python Modules” manual. Building Extensions: Tips and Tricks¶Whenever possible, the Distutils try to use the configuration information made available by the Python interpreter used to run the Tweaking compiler/linker flags¶Compiling a Python extension written in C or C++ will sometimes require specifying custom flags for the compiler and linker in order to use a particular library or produce a special kind of object code. This is especially true if the extension hasn’t been tested on your platform, or if you’re trying to cross-compile Python. In the most general case, the extension author might have foreseen that compiling the extensions would be complicated, and provided a A module ... [sourcefile ...] [cpparg ...] [library ...] Let’s examine each of the fields in turn.
If a particular platform requires a special library on your platform, you can add it by editing the must be linked with the math library Arbitrary switches intended for the compiler or the linker can be supplied with the foo foomodule.c -Xcompiler -o32 -Xlinker -shared -lm The next option after Compiler flags can also be supplied through setting the Using non-Microsoft compilers on Windows¶Borland/CodeGear C++¶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 coff2omf python25.lib python25_bcpp.lib The 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. 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.) GNU C / Cygwin / MinGW¶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.) Older Versions of Python and MinGW¶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 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 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. Footnotes 1This also means you could replace all existing COFF-libraries with OMF-libraries of the same name. 2Check https://www.sourceware.org/cygwin/ for more information 3Then you have no POSIX emulation available, but you also don’t need |