Subsections

- 1.1 Best case: trivial installation
- 1.2 The new standard: Distutils
- 1.3 The old way: no standards

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1 Introduction

Although Python's extensive standard library covers many programming needs, there often comes a time when you need to add some new functionality to your Python installation in the form of third-party modules. This might be necessary to support your own programming, or to support an application that you want to use and that happens to be written in Python.

In the past, there has been little support for adding third-party modules to an existing Python installation. With the introduction of the Python Distribution Utilities (Distutils for short) in Python 2.0, this is starting to change. Not everything will change overnight, though, so while this document concentrates on installing module distributions that use the Distutils, we will also spend some time dealing with the old ways.

This document is aimed primarily at the people who need to install third-party Python modules: end-users and system administrators who just need to get some Python application running, and existing Python programmers who want to add some new goodies to their toolbox. You don't need to know Python to read this document; there will be some brief forays into using Python's interactive mode to explore your installation, but that's it. If you're looking for information on how to distribute your own Python modules so that others may use them, see the Distributing Python Modules manual.

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1.1 Best case: trivial installation

In the best case, someone will have prepared a special version of the module distribution you want to install that is targeted specifically at your platform and is installed just like any other software on your platform. For example, the module developer might make an executable installer available for Windows users, an RPM package for users of RPM-based Linux systems (Red Hat, SuSE, Mandrake, and many others), a Debian package for users of Debian-based Linux systems (Debian proper, Caldera, Corel, etc.), and so forth.

In that case, you would download the installer appropriate to your platform and do the obvious thing with it: run it if it's an executable installer, `rpm -install` it if it's an RPM, etc. You don't need to run Python or a setup script, you don't need to compile anything--you might not even need to read any instructions (although it's always a good idea to do so anyways).

Of course, things will not always be that easy. You might be interested in a module distribution that doesn't have an easy-to-use installer for your platform. In that case, you'll have to start with the source distribution released by the module's author/maintainer. Installing from a source distribution is not too hard, as long as the modules are packaged in the standard way. The bulk of this document is about building and installing modules from standard source distributions.

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1.2 The new standard: Distutils

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. foo-1.0.tar.gz or widget-0.9.7.zip. Next, the archive will unpack into a similarly-named directory: foo-1.0 or widget-0.9.7. Additionally, the distribution will contain a setup script setup.py, and a README.txt (or possibly README), which should explain that building and installing the module distribution is a simple matter of running

      python setup.py install

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.

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1.3 The old way: no standards

Before the Distutils, there was no infrastructure to support installing third-party modules in a consistent, standardized way. Thus, it's not really possible to write a general manual for installing Python modules that don't use the Distutils; the only truly general statement that can be made is, ``Read the module's own installation instructions.''

However, if such instructions exist at all, they are often woefully inadequate and targeted at experienced Python developers. Such users are already familiar with how the Python library is laid out on their platform, and know where to copy various files in order for Python to find them. This document makes no such assumptions, and explains how the Python library is laid out on three major platforms (Unix, Windows, and MacOS), so that you can understand what happens when the Distutils do their job and know how to install modules manually when the module author fails to provide a setup script.

Additionally, while there has not previously been a standard installation mechanism, Python has had some standard machinery for building extensions on Unix since Python 1.4. This machinery (the Makefile.pre.in file) is superseded by the Distutils, but it will no doubt live on in older module distributions for a while. This Makefile.pre.in mechanism is documented in the Extending & Embedding Python manual, but that manual is aimed at module developers--hence, we include documentation for builders/installers here.

All of the pre-Distutils material is tucked away in section .