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Easy Install is a python module (easy_install) bundled with setuptools that lets you automatically download, build, install, and manage Python packages.
(Please share your experiences with us! Whether you encountered success or difficulty installing a particular package, please add your notes to the Experience Reports page. You'll need to register for a Wiki ID if you don't already have one; you can do that from the User Preferences page. Thanks!)
(Also, if you'd like to learn about how you can use setuptools to make your own packages work better with EasyInstall, or provide EasyInstall-like features without requiring your users to use EasyInstall directly, you'll probably want to check out the full setuptools documentation as well.)
If you are behind an NTLM-based firewall that prevents Python programs from accessing the net directly, you may wish to first install and use the APS proxy server, which lets you get past such firewalls in the same way that your web browser(s) do.
If you do not have write access to your computer's site-packages directory, please also see the section below on Non-Root Installation for more detailed instructions on pre-configuring your system for the best usability with EasyInstall, then return here for the remaining steps.
Download ez_setup.py, and run it; this will download and install the appropriate setuptools egg for your Python version. (You will need at least Python 2.3.5, or if you are on a 64-bit platform, Python 2.4.)
You may receive a message telling you about an obsolete version of setuptools being present; if so, you must be sure to delete it entirely, along with the old pkg_resources module if it's present on sys.path.
An easy_install script will be installed in the normal location for Python scripts on your platform.
(Note: the ez_setup.py script accepts the same Command-Line Options and Configuration Files as easy_install itself, so you can use them to control its behavior. However, you should avoid using a custom installation directory or doing multi-version installs of the setuptools package, because this may make it impossible for scripts installed with EasyInstall to access it afterwards.)
On Windows, an easy_install.exe launcher will also be installed, so that you can just type easy_install as long as it's on your PATH. If typing easy_install at the command prompt doesn't work, check to make sure your PATH includes the appropriate C:\\Python2X\\Scripts directory. On most current versions of Windows, you can change the PATH by right-clicking "My Computer", choosing "Properties" and selecting the "Advanced" tab, then clicking the "Environment Variables" button. PATH will be in the "System Variables" section, and you will probably need to reboot for the change to take effect. Be sure to add a ; after the last item on PATH before adding the scripts directory to it.
Note that instead of changing your PATH to include the Python scripts directory, you can also retarget the installation location for scripts so they go on a directory that's already on the PATH. For more information see the sections below on Command-Line Options and Configuration Files. You can pass command line options (such as --script-dir) to ez_setup.py to control where easy_install.exe will be installed.
For basic use of easy_install, you need only supply the filename or URL of a source distribution or .egg file (Python Egg).
Example 1. Install a package by name, searching PyPI for the latest version, and automatically downloading, building, and installing it:
Example 2. Install or upgrade a package by name and version by finding links on a given "download page":
easy_install -f http://pythonpaste.org/package_index.html SQLObject
Example 3. Download a source distribution from a specified URL, automatically building and installing it:
Example 4. Install an already-downloaded .egg file:
Example 5. Upgrade an already-installed package to the latest version listed on PyPI:
easy_install --upgrade PyProtocols
Example 6. Install a source distribution that's already downloaded and extracted in the current directory (New in 0.5a9):
Example 7. (New in 0.6a1) Find a source distribution or Subversion checkout URL for a package, and extract it or check it out to ~/projects/sqlobject (the name will always be in all-lowercase), where it can be examined or edited. (The package will not be installed, but it can easily be installed with easy_install ~/projects/sqlobject. See Editing and Viewing Source Packages below for more info.):
easy_install --editable --build-directory ~/projects SQLObject
Easy Install accepts URLs, filenames, PyPI package names (i.e., distutils "distribution" names), and package+version specifiers. In each case, it will attempt to locate the latest available version that meets your criteria.
When downloading or processing downloaded files, Easy Install recognizes distutils source distribution files with extensions of .tgz, .tar, .tar.gz, .tar.bz2, or .zip. And of course it handles already-built .egg distributions as well as .win32.exe installers built using distutils.
By default, packages are installed to the running Python installation's site-packages directory, unless you provide the -d or --install-dir option to specify an alternative directory, or specify an alternate location using distutils configuration files. (See Configuration Files, below.)
By default, any scripts included with the package are installed to the running Python installation's standard script installation location. However, if you specify an installation directory via the command line or a config file, then the default directory for installing scripts will be the same as the package installation directory, to ensure that the script will have access to the installed package. You can override this using the -s or --script-dir option.
Packages installed to site-packages are added to an easy-install.pth file, so that Python will always use the most-recently-installed version of the package. If you would like to be able to select which version to use at runtime, you should use the -m or --multi-version option.
Note, however, that installing to a directory other than site-packages already implies the -m option, so if you cannot install to site-packages, please see the Command-Line Options section below (under --multi-version) to find out how to select packages at runtime.
You don't need to do anything special to upgrade a package: just install the new version, either by requesting a specific version, e.g.:
a version greater than the one you have now:
using the upgrade flag, to find the latest available version on PyPI:
easy_install --upgrade SomePackage
or by using a download page, direct download URL, or package filename:
easy_install -f http://example.com/downloads ExamplePackage easy_install http://example.com/downloads/ExamplePackage-2.0-py2.4.egg easy_install my_downloads/ExamplePackage-2.0.tgz
If you're using -m or --multi (or installing outside of site-packages), using the require() function at runtime automatically selects the newest installed version of a package that meets your version criteria. So, installing a newer version is the only step needed to upgrade such packages.
If you're installing to Python's site-packages directory (and not using -m), installing a package automatically replaces any previous version in the easy-install.pth file, so that Python will import the most-recently installed version by default. So, again, installing the newer version is the only upgrade step needed.
If you haven't suppressed script installation (using --exclude-scripts or -x), then the upgraded version's scripts will be installed, and they will be automatically patched to require() the corresponding version of the package, so that you can use them even if not installing to site-packages.
easy_install never actually deletes packages (unless you're installing a package with the same name and version number as an existing package), so if you want to get rid of older versions of a package, please see Uninstalling Packages, below.
If you've upgraded a package, but need to revert to a previously-installed version, you can do so like this:
Where 1.2.3 is replaced by the exact version number you wish to switch to. If a package matching the requested name and version is not already installed in a directory on sys.path, it will be located via PyPI and installed.
If you'd like to switch to the latest installed version of PackageName, you can do so like this:
This will activate the latest installed version. (Note: if you have set any find_links via distutils configuration files, those download pages will be checked for the latest available version of the package, and it will be downloaded and installed if it is newer than your current version.)
Note that changing the active version of a package will install the newly active version's scripts, unless the --exclude-scripts or -x option is specified.
If you have replaced a package with another version, then you can just delete the package(s) you don't need by deleting the PackageName-versioninfo.egg file or directory (found in the installation directory).
If you want to delete the currently installed version of a package (or all versions of a package), you should first run:
easy_install -m PackageName
This will ensure that Python doesn't continue to search for a package you're planning to remove. After you've done this, you can safely delete the .egg files or directories, along with any scripts you wish to remove.
Whenever you install, upgrade, or change versions of a package, EasyInstall automatically installs the scripts for the selected package version, unless you tell it not to with -x or --exclude-scripts. If any scripts in the script directory have the same name, they are overwritten.
Thus, you do not normally need to manually delete scripts for older versions of a package, unless the newer version of the package does not include a script of the same name. However, if you are completely uninstalling a package, you may wish to manually delete its scripts.
EasyInstall's default behavior means that you can normally only run scripts from one version of a package at a time. If you want to keep multiple versions of a script available, however, you can simply use the --multi-version or -m option, and rename the scripts that EasyInstall creates. This works because EasyInstall installs scripts as short code stubs that require() the matching version of the package the script came from, so renaming the script has no effect on what it executes.
For example, suppose you want to use two versions of the rst2html tool provided by the docutils package. You might first install one version:
easy_install -m docutils==0.3.9
then rename the rst2html.py to r2h_039, and install another version:
easy_install -m docutils==0.3.10
This will create another rst2html.py script, this one using docutils version 0.3.10 instead of 0.3.9. You now have two scripts, each using a different version of the package. (Notice that we used -m for both installations, so that Python won't lock us out of using anything but the most recently-installed version of the package.)
EasyInstall respects standard distutils Configuration Files, so you can use them to configure build options for packages that it installs from source. For example, if you are on Windows using the MinGW compiler, you can configure the default compiler by putting something like this:
[build] compiler = mingw32
into the appropriate distutils configuration file. In fact, since this is just normal distutils configuration, it will affect any builds using that config file, not just ones done by EasyInstall. For example, if you add those lines to distutils.cfg in the distutils package directory, it will be the default compiler for all packages you build. See Configuration Files below for a list of the standard configuration file locations, and links to more documentation on using distutils configuration files.
Sometimes a package's source distribution contains additional documentation, examples, configuration files, etc., that are not part of its actual code. If you want to be able to examine these files, you can use the --editable option to EasyInstall, and EasyInstall will look for a source distribution or Subversion URL for the package, then download and extract it or check it out as a subdirectory of the --build-directory you specify. If you then wish to install the package after editing or configuring it, you can do so by rerunning EasyInstall with that directory as the target.
Note that using --editable stops EasyInstall from actually building or installing the package; it just finds, obtains, and possibly unpacks it for you. This allows you to make changes to the package if necessary, and to either install it in development mode using setup.py develop (if the package uses setuptools, that is), or by running easy_install projectdir (where projectdir is the subdirectory EasyInstall created for the downloaded package.
In order to use --editable (-e for short), you must also supply a --build-directory (-b for short). The project will be placed in a subdirectory of the build directory. The subdirectory will have the same name as the project itself, but in all-lowercase. If a file or directory of that name already exists, EasyInstall will print an error message and exit.
Also, when using --editable, you cannot use URLs or filenames as arguments. You must specify project names (and optional version requirements) so that EasyInstall knows what directory name(s) to create. If you need to force EasyInstall to use a particular URL or filename, you should specify it as a --find-links item (-f for short), and then also specify the project name, e.g.:
easy_install -eb ~/projects \ -fhttp://prdownloads.sourceforge.net/ctypes/ctypes-0.9.6.tar.gz?download \ ctypes==0.9.6
EasyInstall installs distributions in a "managed" way, such that each distribution can be independently activated or deactivated on sys.path. However, packages that were not installed by EasyInstall are "unmanaged", in that they usually live all in one directory and cannot be independently activated or deactivated.
As a result, if you are using EasyInstall to upgrade an existing package, or to install a package with the same name as an existing package, EasyInstall will warn you of the conflict. (This is an improvement over setup.py install, becuase the distutils just install new packages on top of old ones, possibly combining two unrelated packages or leaving behind modules that have been deleted in the newer version of the package.)
By default, EasyInstall will stop the installation if it detects a conflict between an existing, "unmanaged" package, and a module or package in any of the distributions you're installing. It will display a list of all of the existing files and directories that would need to be deleted for the new package to be able to function correctly. You can then either delete these conflicting files and directories yourself and re-run EasyInstall, or you can just use the --delete-conflicting or --ignore-conflicts-at-my-risk options, as described under Command-Line Options, below.
Of course, once you've replaced all of your existing "unmanaged" packages with versions managed by EasyInstall, you won't have any more conflicts to worry about!
EasyInstall tries to install packages in zipped form, if it can. Zipping packages can significantly increase Python's overall import performance if you're installing to``site-packages`` and not using the --multi option, because Python processes zipfile entries on sys.path much faster than it does directories.
As of version 0.5a9, EasyInstall analyzes packages to determine whether they can be safely installed as a zipfile, and then acts on its analysis. (Previous versions would not install a package as a zipfile unless you used the --zip-ok option.)
The current analysis approach is very conservative; it currenly looks for:
- Any use of the __file__ or __path__ variables (which should be replaced with pkg_resources API calls)
- Possible use of inspect functions that expect to manipulate source files (e.g. inspect.getsource())
- Any data files or C extensions (this restriction will be removed in a future release, once the pkg_resources runtime has been hardened for multi-user environments)
If any of the above are found in the package being installed, EasyInstall will assume that the package cannot be safely run from a zipfile, and unzip it to a directory instead. You can override this analysis with the -zip-ok flag, which will tell EasyInstall to install the package as a zipfile anyway. Or, you can use the --always-unzip flag, in which case EasyInstall will always unzip, even if its analysis says the package is safe to run as a zipfile.
Normally, however, it is simplest to let EasyInstall handle the determination of whether to zip or unzip, and only specify overrides when needed to work around a problem. If you find you need to override EasyInstall's guesses, you may want to contact the package author and the EasyInstall maintainers, so that they can make appropriate changes in future versions.
(Note: If a package uses setuptools in its setup script, the package author has the option to declare the package safe or unsafe for zipped usage via the zip_safe argument to setup(). If the package author makes such a declaration, EasyInstall believes the package's author and does not perform its own analysis. However, your command-line option, if any, will still override the package author's choice.)
(New in 0.4a2)
You may specify default options for EasyInstall using the standard distutils configuration files, under the command heading easy_install. EasyInstall will look first for a setup.cfg file in the current directory, then a ~/.pydistutils.cfg or $HOME\\pydistutils.cfg (on Unix-like OSes and Windows, respectively), and finally a distutils.cfg file in the distutils package directory. Here's a simple example:
[easy_install] # set the default location to install packages install_dir = /home/me/lib/python # Notice that indentation can be used to continue an option # value; this is especially useful for the "--find-links" # option, which tells easy_install to use download links on # these pages before consulting PyPI: # find_links = http://sqlobject.org/ http://peak.telecommunity.com/dist/
In addition to accepting configuration for its own options under [easy_install], EasyInstall also respects defaults specified for other distutils commands. For example, if you don't set an install_dir for [easy_install], but have set an install_lib for the [install] command, this will become EasyInstall's default installation directory. Thus, if you are already using distutils configuration files to set default install locations, build options, etc., EasyInstall will respect your existing settings until and unless you override them explicitly in an [easy_install] section.
For more information, see also the current Python documentation on the use and location of distutils configuration files.
Don't install any packages as zip files, even if the packages are marked as safe for running as a zipfile. This can be useful if a package does something unsafe, but not in a way that EasyInstall can easily detect. EasyInstall's default analysis is currently very conservative, however, so you should only use this option if you've had problems with a particular package, and after reporting the problem to the package's maintainer and to the EasyInstall maintainers.
(Note: the -z/-Z options only affect the installation of newly-built or downloaded packages that are not already installed in the target directory; if you want to convert an existing installed version from zipped to unzipped or vice versa, you'll need to delete the existing version first, and re-run EasyInstall.)
"Multi-version" mode. Specifying this option prevents easy_install from adding an easy-install.pth entry for the package being installed, and if an entry for any version the package already exists, it will be removed upon successful installation. In multi-version mode, no specific version of the package is available for importing, unless you use pkg_resources.require() to put it on sys.path. This can be as simple as:
from pkg_resources import require require("SomePackage", "OtherPackage", "MyPackage")
which will put the latest installed version of the specified packages on sys.path for you. (For more advanced uses, like selecting specific versions and enabling optional dependencies, see the pkg_resources API doc.)
Note that if you install to a directory other than site-packages, this option is automatically in effect, because .pth files can only be used in site-packages (at least in Python 2.3 and 2.4). So, if you use the --install-dir or -d option (or they are set via configuration file(s)) you must also use require() to enable packages at runtime.
Set the installation directory. It is up to you to ensure that this directory is on sys.path at runtime, and to use pkg_resources.require() to enable the installed package(s) that you need.
(New in 0.4a2) If this option is not directly specified on the command line or in a distutils configuration file, the distutils default installation location is used. Normally, this would be the site-packages directory, but if you are using distutils configuration files, setting things like prefix or install_lib, then those settings are taken into account when computing the default installation directory.
Scan the specified "download pages" for direct links to downloadable eggs or source distributions. Any usable packages will be downloaded if they are required by a command line argument. For example, this:
easy_install -f http://peak.telecommunity.com/dist PyProtocols
will download and install the latest version of PyProtocols linked from the PEAK downloads page, but ignore the other download links on that page. If all requested packages can be found using links on the specified download pages, the Python Package Index will not be consulted. You can use a file: URL to reference a local HTML file containing links, or you can just use the name of a directory containing "distribution files" (source archives, eggs, Windows installers, etc.), and EasyInstall will then be aware of the files available there.
You may specify multiple URLs or directories with this option, separated by whitespace. Note that on the command line, you will probably have to surround the URL list with quotes, so that it is recognized as a single option value. You can also specify URLs in a configuration file; see Configuration Files, above; but note that this means the specified pages will be downloaded every time you use EasyInstall (unless overridden on the command line) and thus may make startup slower.
Set the directory used to build source packages. If a package is built from a source distribution or checkout, it will be extracted to a subdirectory of the specified directory. The subdirectory will have the same name as the extracted distribution's project, but in all-lowercase. If a file or directory of that name already exists in the given directory, a warning will be printed to the console, and the build will take place in a temporary directory instead.
This option is most useful in combination with the --editable option, which forces EasyInstall to only find and extract (but not build and install) source distributions. See Editing and Viewing Source Packages, above, for more information.
Specify one or more custom "site" directories (separated by commas). "Site" directories are directories where .pth files are processed, such as the main Python site-packages directory. By default, EasyInstall only knows about Python-defined "site" directories, not those that may be added by an OS distribution or site administrator calling site.addsitedir(). You should not normally need to use this option directly, as your system administrator should configure it in the distutils.cfg file of the Python installation. For example, if the administrator wants to make each user's ~/lib/python2.3 directory be a "site" directory, he or she should create an altinstall.pth file in the normal site-packages directory, containing this:
import os, site; site.addsitedir(os.path.expanduser('~/lib/python2.3'))
and a distutils.cfg file inside the distutils package directory, containing this:
[easy_install] site_dirs = ~/lib/python23
This will ensure that EasyInstall knows about the additional "site" directory, thereby allowing individual users to install their own Python packages via EasyInstall.
Restrict downloading and spidering to hosts matching the specified glob patterns. E.g. -H *.python.org restricts web access so that only packages listed and downloadable from machines in the python.org domain. The glob patterns must match the entire user/host/port section of the target URL(s). For example, *.python.org will NOT accept a URL like http://python.org/foo or http://www.python.org:8080/. Multiple patterns can be specified by separting them with commas. The default pattern is *, which matches anything.
In general, this option is mainly useful for blocking EasyInstall's web access altogether (e.g. -Hlocalhost), or to restrict it to an intranet or other trusted site. EasyInstall will do the best it can to satisfy dependencies given your host restrictions, but of course can fail if it can't find suitable packages. EasyInstall displays all blocked URLs, so that you can adjust your --allow-hosts setting if it is more strict than you intended. Some sites may wish to define a restrictive default setting for this option in their configuration files, and then manually override the setting on the command line as needed.
If you want to use EasyInstall on a computer where you do not have write access to Python's main site-packages directory, you may need to set up an alternate "home" location for Python, so that it uses a personal site-packages directory instead of the system-wide site-packages.
If you are on a Mac OS X machine, you should just use the ~/Library/Python2.x/site-packages directory (replacing the x with the appropriate number). Just make sure the directory exists, and use it as your installation location for all packages (including EasyInstall itself). To make the distutils install to this personal site-packages directory by default, you should create a ~/.pydistutils.cfg file with the following contents:
[install] install_lib = ~/Library/Python$py_version_short/site-packages
This will tell the distutils (and EasyInstall) to always install packages in the appropriate personal site-packages directory. (Note: do not replace $py_version_short with an actual Python version in the configuration file! The distutils will substitute the correct value at runtime, so that the above configuration file will work correctly no matter what Python version you use, now or in the future.)
If you are on a Linux, BSD, Cygwin, or other similar Unix-like operating system, you have a couple of different options. You can create a "virtual" Python installation, which uses its own library directories and some symlinks to the site-wide Python. Or, you can use a "traditional" PYTHONPATH-based installation, which isn't as flexible, but which you may find more familiar, especially if you already have a custom PYTHONPATH set up.
In the simplest case, your virtual Python installation will live under the ~/lib/python2.x, ~/include/python2.x, and ~/bin directories. Just download virtual-python.py and run it using the site-wide Python. If you want to customize the location, you can use the --prefix option to specify an installation base directory in place of ~. (Use --help to get the complete list of options.)
When you're done, you'll have a ~/bin/python executable that's linked to the local Python installation and inherits all its current libraries, but which allows you to add as many new libraries as you want. Simply use this new Python in place of your system-defined one, and you can modify it as you like without breaking anything that relies on the system Python. You'll also still need to follow the standard installation instructions to install setuptools and EasyInstall, using your new ~/bin/python executable in place of the system Python.
Note that if you were previously setting a PYTHONPATH and/or had other special configuration options in your ~/.pydistutils.cfg, you may need to remove these settings before running virtual-python.py. You should also make sure that the ~/bin directory (or whatever directory you choose) is on your PATH, because that is where EasyInstall will install new Python scripts.
If you'd prefer to do the installation steps by hand, or just want to know what the script will do, here are the steps. (If you don't care how it works, you can just skip the rest of this section.)
First, you will need to know your Python version's sys.prefix and sys.exec_prefix, which you can find out by running:
python -c "import sys; print sys.prefix; print sys.exec_prefix"
(Replace "python" with the right path or version for your platform.)
Assuming your sys.prefix is /usr/local, and you are working with Python 2.4, you need to then perform the following steps (possibly making adjustments for the tools available on your platform). First, you need to set up the local library directories, by symlinking to the system Python's libraries:
mkdir -p ~/lib/python2.4 ln -s /usr/local/lib/python2.4/* ~/lib/python2.4/ rm ~/lib/python2.4/site-packages mkdir ~/lib/python2.4/site-packages ln -s /usr/local/lib/python2.4/site-packages/* ~/lib/python2.4/site-packages mkdir -p ~/include/python2.4 ln -s /usr/local/include/python2.4/* ~/include/python2.4
If your sys.exec_prefix was different from your sys.prefix, you will also need to do this:
ln -s /execprefix/lib/python2.4/* ~/lib/python2.4/
replacing execprefix in the above with the value of sys.exec_prefix.
Finally, you will also need a private python executable, e.g.:
mkdir -p ~/bin ln /usr/local/bin/python2.4 ~/bin/python
Note that if hardlinking as shown doesn't work (e.g. because the system Python is on a different filesystem), you should use copy -p instead of ln. Do NOT use a symlink! The Python binary must be copied or hardlinked, otherwise it will use the system site-packages directory and not yours.
You can now proceed with the standard installation instructions.
This installation method is not as robust or as flexible as creating a "virtual" python installation, as it uses various tricks to fool Python into processing .pth files where it normally wouldn't. We suggest you try the virtual Python approach first, as we are providing this method mainly for people who just can't get past their unshakeable belief that creating a virtual python is somehow "Not Right", or that putting stuff on PYTHONPATH "Should Just Work, Darnit." So, if you're not one of those people, you don't need these instructions. :-)
Assuming that you want to install packages in a directory called ~/py-lib, and scripts in ~/bin, here's what you need to do:
First, edit ~/.pydistutils.cfg to include these settings:
[install] install_lib = ~/py-lib install_scripts = ~/bin [easy_install] site_dirs = ~/py_lib
Be sure to do this before you try to run the ez_setup.py installation script. Then, follow the standard installation instructions, but take careful note of the full pathname of the .egg file that gets installed, so that you can add it to your PYTHONPATH, along with ~/py_lib.
You must add the setuptools egg file to your PYTHONPATH manually, or it will not work, and neither will any other packages you install with EasyInstall. You will not, however, have to manually add any other packages to the PYTHONPATH; EasyInstall will take care of them for you, as long as the setuptools egg is explicitly listed in PYTHONPATH.