path: root/EasyInstall.txt

============
Easy Install
============

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! If you encounter difficulty installing
a package, please contact us via the `distutils mailing list
<http://mail.python.org/pipermail/distutils-sig/>`_.  (Note: please DO NOT send
private email directly to the author of setuptools; it will be discarded.  The
mailing list is a searchable archive of previously-asked and answered
questions; you should begin your research there before reporting something as a
bug -- and then do so via list discussion first.)

(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.)

.. contents:: **Table of Contents**


Using "Easy Install"
====================


.. _installation instructions:

Installing "Easy Install"
-------------------------

Please see the `setuptools PyPI page <http://pypi.python.org/pypi/setuptools>`_
for download links and basic installation instructions for each of the
supported platforms.

You will need at least Python 2.3.5, or if you are on a 64-bit platform, Python
2.4.  An ``easy_install`` script will be installed in the normal location for
Python scripts on your platform.

Note that the instructions on the setuptools PyPI page assume that you are
are installling to Python's primary ``site-packages`` directory.  If this is
not the case, you should consult the section below on `Custom Installation
Locations`_ before installing.  (And, on Windows, you should not use the
``.exe`` installer when installing to an alternate location.)

Note that ``easy_install`` normally works by downloading files from the
internet.  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 <http://ntlmaps.sf.net/>`_, which lets you get past such
firewalls in the same way that your web browser(s) do.

(Alternately, if you do not wish easy_install to actually download anything, you
can restrict it from doing so with the ``--allow-hosts`` option; see the
sections on `restricting downloads with --allow-hosts`_ and `command-line
options`_ for more details.)


Troubleshooting
~~~~~~~~~~~~~~~

If EasyInstall/setuptools appears to install correctly, and you can run the
``easy_install`` command but it fails with an ``ImportError``, the most likely
cause is that you installed to a location other than ``site-packages``,
without taking any of the steps described in the `Custom Installation
Locations`_ section below.  Please see that section and follow the steps to
make sure that your custom location will work correctly.  Then re-install.

Similarly, if you can run ``easy_install``, and it appears to be installing
packages, but then you can't import them, the most likely issue is that you
installed EasyInstall correctly but are using it to install packages to a
non-standard location that hasn't been properly prepared.  Again, see the
section on `Custom Installation Locations`_ for more details.


Windows Notes
~~~~~~~~~~~~~

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 need to exit and restart your command shell
(command.com, cmd.exe, bash, or other) 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.



Downloading and Installing a Package
------------------------------------

For basic use of ``easy_install``, you need only supply the filename or URL of
a source distribution or .egg file (`Python Egg`__).

__ http://peak.telecommunity.com/DevCenter/PythonEggs

**Example 1**. Install a package by name, searching PyPI for the latest
version, and automatically downloading, building, and installing it::

    easy_install SQLObject

**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::

    easy_install http://example.com/path/to/MyPackage-1.2.3.tgz

**Example 4**. Install an already-downloaded .egg file::

    easy_install /my_downloads/OtherPackage-3.2.1-py2.3.egg

**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)::

    easy_install .

**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.

Installed packages are added to an ``easy-install.pth`` file in the install
directory, 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.


Upgrading a Package
-------------------

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.::

    easy_install "SomePackage==2.0"

a version greater than the one you have now::

    easy_install "SomePackage>2.0"

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-version`` , 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 a directory on PYTHONPATH, or a configured "site"
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 they are installed in multi-version
mode.

``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.


Changing the Active Version
---------------------------

If you've upgraded a package, but need to revert to a previously-installed
version, you can do so like this::

    easy_install PackageName==1.2.3

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::

    easy_install PackageName

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.


Uninstalling Packages
---------------------

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 -mxN 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.


Managing Scripts
----------------

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 <http://docutils.sf.net/>`_ 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.)



Tips & Techniques
-----------------


Multiple Python Versions
~~~~~~~~~~~~~~~~~~~~~~~~

As of version 0.6a11, EasyInstall installs itself under two names:
``easy_install`` and ``easy_install-N.N``, where ``N.N`` is the Python version
used to install it.  Thus, if you install EasyInstall for both Python 2.3 and
2.4, you can use the ``easy_install-2.3`` or ``easy_install-2.4`` scripts to
install packages for Python 2.3 or 2.4, respectively.

Also, if you're working with Python version 2.4 or higher, you can run Python
with ``-m easy_install`` to run that particular Python version's
``easy_install`` command.


Restricting Downloads with ``--allow-hosts``
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

You can use the ``--allow-hosts`` (``-H``) option to restrict what domains
EasyInstall will look for links and downloads on.  ``--allow-hosts=None``
prevents downloading altogether.  You can also use wildcards, for example
to restrict downloading to hosts in your own intranet.  See the section below
on `Command-Line Options`_ for more details on the ``--allow-hosts`` option.

By default, there are no host restrictions in effect, but you can change this
default by editing the appropriate `configuration files`_ and adding::

    [easy_install]
    allow_hosts = *.myintranet.example.com,*.python.org

The above example would then allow downloads only from hosts in the
``python.org`` and ``myintranet.example.com`` domains, unless overridden on the
command line.


Installing on Un-networked Machines
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Just copy the eggs or source packages you need to a directory on the target
machine, then use the ``-f`` or ``--find-links`` option to specify that
directory's location.  For example::

    easy_install -H None -f somedir SomePackage

will attempt to install SomePackage using only eggs and source packages found
in ``somedir`` and disallowing all remote access.  You should of course make
sure you have all of SomePackage's dependencies available in somedir.

If you have another machine of the same operating system and library versions
(or if the packages aren't platform-specific), you can create the directory of
eggs using a command like this::

    easy_install -zmaxd somedir SomePackage

This will tell EasyInstall to put zipped eggs or source packages for
SomePackage and all its dependencies into ``somedir``, without creating any
scripts or .pth files.  You can then copy the contents of ``somedir`` to the
target machine.  (``-z`` means zipped eggs, ``-m`` means multi-version, which
prevents .pth files from being used, ``-a`` means to copy all the eggs needed,
even if they're installed elsewhere on the machine, and ``-d`` indicates the
directory to place the eggs in.)

You can also build the eggs from local development packages that were installed
with the ``setup.py develop`` command, by including the ``-l`` option, e.g.::

    easy_install -zmaxld somedir SomePackage

This will use locally-available source distributions to build the eggs.


Packaging Others' Projects As Eggs
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Need to distribute a package that isn't published in egg form?  You can use
EasyInstall to build eggs for a project.  You'll want to use the ``--zip-ok``,
``--exclude-scripts``, and possibly ``--no-deps`` options (``-z``, ``-x`` and
``-N``, respectively).  Use ``-d`` or ``--install-dir`` to specify the location
where you'd like the eggs placed.  By placing them in a directory that is
published to the web, you can then make the eggs available for download, either
in an intranet or to the internet at large.

If someone distributes a package in the form of a single ``.py`` file, you can
wrap it in an egg by tacking an ``#egg=name-version`` suffix on the file's URL.
So, something like this::

    easy_install -f "http://some.example.com/downloads/foo.py#egg=foo-1.0" foo

will install the package as an egg, and this::

    easy_install -zmaxd. \
        -f "http://some.example.com/downloads/foo.py#egg=foo-1.0" foo

will create a ``.egg`` file in the current directory.


Creating your own Package Index
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

In addition to local directories and the Python Package Index, EasyInstall can
find download links on most any web page whose URL is given to the ``-f``
(``--find-links``) option.  In the simplest case, you can simply have a web
page with links to eggs or Python source packages, even an automatically
generated directory listing (such as the Apache web server provides).

If you are setting up an intranet site for package downloads, you may want to
configure the target machines to use your download site by default, adding
something like this to their `configuration files`_::

    [easy_install]
    find_links = http://mypackages.example.com/somedir/
                 http://turbogears.org/download/
                 http://peak.telecommunity.com/dist/

As you can see, you can list multiple URLs separated by whitespace, continuing
on multiple lines if necessary (as long as the subsequent lines are indented.

If you are more ambitious, you can also create an entirely custom package index
or PyPI mirror.  See the ``--index-url`` option under `Command-Line Options`_,
below, and also the section on `Package Index "API"`_.


Password-Protected Sites
~~~~~~~~~~~~~~~~~~~~~~~~

If a site you want to download from is password-protected using HTTP "Basic"
authentication, you can specify your credentials in the URL, like so::

    http://some_userid:some_password@some.example.com/some_path/

You can do this with both index page URLs and direct download URLs.  As long
as any HTML pages read by easy_install use *relative* links to point to the
downloads, the same user ID and password will be used to do the downloading.


Controlling Build Options
~~~~~~~~~~~~~~~~~~~~~~~~~

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.


Editing and Viewing Source Packages
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

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


Dealing with Installation Conflicts
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

(NOTE: As of 0.6a11, this section is obsolete; it is retained here only so that
people using older versions of EasyInstall can consult it.  As of version
0.6a11, installation conflicts are handled automatically without deleting the
old or system-installed packages, and without ignoring the issue.  Instead,
eggs are automatically shifted to the front of ``sys.path`` using special
code added to the ``easy-install.pth`` file.  So, if you are using version
0.6a11 or better of setuptools, you do not need to worry about conflicts,
and the following issues do not apply to you.)

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!


Compressed Installation
~~~~~~~~~~~~~~~~~~~~~~~

EasyInstall tries to install packages in zipped form, if it can.  Zipping
packages can improve Python's overall import performance if you're not using
the ``--multi-version`` 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 fairly 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()``)

 * Top-level modules that might be scripts used with ``python -m`` (Python 2.4)

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.)


Reference Manual
================

Configuration Files
-------------------

(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 <http://docs.python.org/inst/config-syntax.html>`_.


Command-Line Options
--------------------

``--zip-ok, -z``
    Install all packages as zip files, even if they are marked as unsafe for
    running as a zipfile.  This can be useful when EasyInstall's analysis
    of a non-setuptools package is too conservative, but keep in mind that
    the package may not work correctly.  (Changed in 0.5a9; previously this
    option was required in order for zipped installation to happen at all.)

``--always-unzip, -Z``
    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, -m``
    "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.)

    Changed in 0.6a10: this option is no longer silently enabled when
    installing to a non-PYTHONPATH, non-"site" directory.  You must always
    explicitly use this option if you want it to be active.

``--upgrade, -U``   (New in 0.5a4)
    By default, EasyInstall only searches online if a project/version
    requirement can't be met by distributions already installed
    on sys.path or the installation directory.  However, if you supply the
    ``--upgrade`` or ``-U`` flag, EasyInstall will always check the package
    index and ``--find-links`` URLs before selecting a version to install.  In
    this way, you can force EasyInstall to use the latest available version of
    any package it installs (subject to any version requirements that might
    exclude such later versions).

``--install-dir=DIR, -d DIR``
    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, as is the
    ``--prefix`` option.

``--script-dir=DIR, -s DIR``
    Set the script installation directory.  If you don't supply this option
    (via the command line or a configuration file), but you *have* supplied
    an ``--install-dir`` (via command line or config file), then this option
    defaults to the same directory, so that the scripts will be able to find
    their associated package installation.  Otherwise, this setting defaults
    to the location where the distutils would normally install scripts, taking
    any distutils configuration file settings into account.

``--exclude-scripts, -x``
    Don't install scripts.  This is useful if you need to install multiple
    versions of a package, but do not want to reset the version that will be
    run by scripts that are already installed.

``--always-copy, -a``   (New in 0.5a4)
    Copy all needed distributions to the installation directory, even if they
    are already present in a directory on sys.path.  In older versions of
    EasyInstall, this was the default behavior, but now you must explicitly
    request it.  By default, EasyInstall will no longer copy such distributions
    from other sys.path directories to the installation directory, unless you
    explicitly gave the distribution's filename on the command line.

    Note that as of 0.6a10, using this option excludes "system" and
    "development" eggs from consideration because they can't be reliably
    copied.  This may cause EasyInstall to choose an older version of a package
    than what you expected, or it may cause downloading and installation of a
    fresh copy of something that's already installed.  You will see warning
    messages for any eggs that EasyInstall skips, before it falls back to an
    older version or attempts to download a fresh copy.

``--find-links=URLS_OR_FILENAMES, -f URLS_OR_FILENAMES``
    Scan the specified "download pages" or directories for direct links to eggs
    or other distributions.  Any existing file or directory names or direct
    download URLs are immediately added to EasyInstall's search cache, and any
    indirect URLs (ones that don't point to eggs or other recognized archive
    formats) are added to a list of additional places to search for download
    links.  As soon as EasyInstall has to go online to find a package (either
    because it doesn't exist locally, or because ``--upgrade`` or ``-U`` was
    used), the specified URLs will be downloaded and scanned for additional
    direct links.

    Eggs and archives found by way of ``--find-links`` are only downloaded if
    they are needed to meet a requirement specified on the command line; links
    to unneeded packages are ignored.

    If all requested packages can be found using links on the specified
    download pages, the Python Package Index will not be consulted unless you
    also specified the ``--upgrade`` or ``-U`` option.

    (Note: if you want to refer to a local HTML file containing links, you must
    use a ``file:`` URL, as filenames that do not refer to a directory, egg, or
    archive are ignored.)

    You may specify multiple URLs or file/directory names 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.

    Changed in 0.6a10: previously all URLs and directories passed to this
    option were scanned as early as possible, but from 0.6a10 on, only
    directories and direct archive links are scanned immediately; URLs are not
    retrieved unless a package search was already going to go online due to a
    package not being available locally, or due to the use of the ``--update``
    or ``-U`` option.

``--delete-conflicting, -D`` (Removed in 0.6a11)
    (As of 0.6a11, this option is no longer necessary; please do not use it!)

    If you are replacing a package that was previously installed *without*
    using EasyInstall, the old version may end up on ``sys.path`` before the
    version being installed with EasyInstall.  EasyInstall will normally abort
    the installation of a package if it detects such a conflict, and ask you to
    manually remove the conflicting files or directories.  If you specify this
    option, however, EasyInstall will attempt to delete the files or
    directories itself, and then proceed with the installation.

``--ignore-conflicts-at-my-risk`` (Removed in 0.6a11)
    (As of 0.6a11, this option is no longer necessary; please do not use it!)

    Ignore conflicting packages and proceed with installation anyway, even
    though it means the package probably won't work properly.  If the
    conflicting package is in a directory you can't write to, this may be your
    only option, but you will need to take more invasive measures to get the
    installed package to work, like manually adding it to ``PYTHONPATH`` or to
    ``sys.path`` at runtime.

``--index-url=URL, -i URL`` (New in 0.4a1; default changed in 0.6c7)
    Specifies the base URL of the Python Package Index.  The default is
    http://pypi.python.org/simple if not specified.  When a package is requested
    that is not locally available or linked from a ``--find-links`` download
    page, the package index will be searched for download pages for the needed
    package, and those download pages will be searched for links to download
    an egg or source distribution.

``--editable, -e`` (New in 0.6a1)
    Only find and download source distributions for the specified projects,
    unpacking them to subdirectories of the specified ``--build-directory``.
    EasyInstall will not actually build or install the requested projects or
    their dependencies; it will just find and extract them for you.  See
    `Editing and Viewing Source Packages`_ above for more details.

``--build-directory=DIR, -b DIR`` (UPDATED in 0.6a1)
    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.

``--verbose, -v, --quiet, -q`` (New in 0.4a4)
    Control the level of detail of EasyInstall's progress messages.  The
    default detail level is "info", which prints information only about
    relatively time-consuming operations like running a setup script, unpacking
    an archive, or retrieving a URL.  Using ``-q`` or ``--quiet`` drops the
    detail level to "warn", which will only display installation reports,
    warnings, and errors.  Using ``-v`` or ``--verbose`` increases the detail
    level to include individual file-level operations, link analysis messages,
    and distutils messages from any setup scripts that get run.  If you include
    the ``-v`` option more than once, the second and subsequent uses are passed
    down to any setup scripts, increasing the verbosity of their reporting as
    well.

``--dry-run, -n`` (New in 0.4a4)
    Don't actually install the package or scripts.  This option is passed down
    to any setup scripts run, so packages should not actually build either.
    This does *not* skip downloading, nor does it skip extracting source
    distributions to a temporary/build directory.

``--optimize=LEVEL``, ``-O LEVEL`` (New in 0.4a4)
    If you are installing from a source distribution, and are *not* using the
    ``--zip-ok`` option, this option controls the optimization level for
    compiling installed ``.py`` files to ``.pyo`` files.  It does not affect
    the compilation of modules contained in ``.egg`` files, only those in
    ``.egg`` directories.  The optimization level can be set to 0, 1, or 2;
    the default is 0 (unless it's set under ``install`` or ``install_lib`` in
    one of your distutils configuration files).

``--record=FILENAME``  (New in 0.5a4)
    Write a record of all installed files to FILENAME.  This is basically the
    same as the same option for the standard distutils "install" command, and
    is included for compatibility with tools that expect to pass this option
    to "setup.py install".

``--site-dirs=DIRLIST, -S DIRLIST``   (New in 0.6a1)
    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.  As of 0.6a10, EasyInstall
    automatically detects whether a given directory processes ``.pth`` files
    (or can be made to do so), so you should not normally need to use this
    option.  It is is now only necessary if you want to override EasyInstall's
    judgment and force an installation directory to be treated as if it
    supported ``.pth`` files.

    (If you want to *make* a non-``PYTHONPATH`` directory support ``.pth``
    files, please see the `Administrator Installation`_ section below.)

``--no-deps, -N``  (New in 0.6a6)
    Don't install any dependencies.  This is intended as a convenience for
    tools that wrap eggs in a platform-specific packaging system.  (We don't
    recommend that you use it for anything else.)

``--allow-hosts=PATTERNS, -H PATTERNS``   (New in 0.6a6)
    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.

``--prefix=DIR`` (New in 0.6a10)
    Use the specified directory as a base for computing the default
    installation and script directories.  On Windows, the resulting default
    directories will be ``prefix\\Lib\\site-packages`` and ``prefix\\Scripts``,
    while on other platforms the defaults will be
    ``prefix/lib/python2.X/site-packages`` (with the appropriate version
    substituted) for libraries and ``prefix/bin`` for scripts.

    Note that the ``--prefix`` option only sets the *default* installation and
    script directories, and does not override the ones set on the command line
    or in a configuration file.

``--local-snapshots-ok, -l`` (New in 0.6c6)
    Normally, EasyInstall prefers to only install *released* versions of
    projects, not in-development ones, because such projects may not
    have a currently-valid version number.  So, it usually only installs them
    when their ``setup.py`` directory is explicitly passed on the command line.
    
    However, if this option is used, then any in-development projects that were
    installed using the ``setup.py develop`` command, will be used to build
    eggs, effectively upgrading the "in-development" project to a snapshot
    release.  Normally, this option is used only in conjunction with the
    ``--always-copy`` option to create a distributable snapshot of every egg
    needed to run an application.

    Note that if you use this option, you must make sure that there is a valid
    version number (such as an SVN revision number tag) for any in-development
    projects that may be used, as otherwise EasyInstall may not be able to tell
    what version of the project is "newer" when future installations or
    upgrades are attempted.


.. _non-root installation:

Custom Installation Locations
-----------------------------

EasyInstall manages what packages are active using Python ``.pth`` files, which
are normally only usable in Python's main ``site-packages`` directory.  On some
platforms (such as Mac OS X), there are additional ``site-packages``
directories that you can use besides the main one, but usually there is only
one directory on the system where you can install packages without extra steps.

There are many reasons, however, why you might want to install packages
somewhere other than the ``site-packages`` directory.  For example, you might
not have write access to that directory.  You may be working with unstable
versions of packages that you don't want to install system-wide.  And so on.

The following sections describe various approaches to custom installation; feel
free to choose which one best suits your system and needs.

`Administrator Installation`_
    This approach is for when you have write access to ``site-packages`` (or
    another directory where ``.pth`` files are processed), but don't want to
    install packages there.  This can also be used by a system administrator
    to enable each user having their own private directories that EasyInstall
    will use to install packages.

`Mac OS X "User" Installation`_
    This approach produces a result similar to an administrator installation
    that gives each user their own private package directory, but on Mac OS X
    the hard part has already been done for you.  This is probably the best
    approach for Mac OS X users.

`Creating a "Virtual" Python`_
    This approach is for when you don't have "root" or access to write to the
    ``site-packages`` directory, and would like to be able to set up one or
    more "virtual python" executables for your projects.  This approach
    gives you the benefits of multiple Python installations, but without having
    to actually install Python more than once and use up lots of disk space.
    (Only the Python executable is copied; the libraries will be symlinked
    from the systemwide Python.)

    If you don't already have any ``PYTHONPATH`` customization or
    special distutils configuration, and you can't use either of the preceding
    approaches, this is probably the best one for you.

`"Traditional" PYTHONPATH-based Installation`_
    If you already have a custom ``PYTHONPATH``, and/or a custom distutils
    configuration, and don't want to change any of your existing setup, you may
    be interested in this approach.  (If you're using a custom ``.pth`` file to
    point to your custom installation location, however, you should use
    `Administrator Installation`_ to enable ``.pth`` processing in the custom
    location instead, as that is easier and more flexible than this approach.)


Administrator Installation
~~~~~~~~~~~~~~~~~~~~~~~~~~

If you have root access to your machine, you can easily configure it to allow
each user to have their own directory where Python packages can be installed
and managed by EasyInstall.

First, create an ``altinstall.pth`` file in Python's ``site-packages``
directory,  containing the following line (substituting the correct Python
version)::

    import os, site; site.addsitedir(os.path.expanduser('~/lib/python2.3'))

This will automatically add each user's ``~/lib/python2.X`` directory to
``sys.path`` (if it exists), *and* it will process any ``.pth`` files in that
directory -- which is what makes it usable with EasyInstall.

The next step is to create or modify ``distutils.cfg`` in the ``distutils``
directory of your Python library.  The correct directory will be something like
``/usr/lib/python2.X/distutils`` on most Posix systems and something like
``C:\\Python2X\Lib\distutils`` on Windows machines.  Add the following lines
to the file, substituting the correct Python version if necessary::

    [install]
    install_lib = ~/lib/python2.3

    # This next line is optional but often quite useful; it directs EasyInstall
    # and the distutils to install scripts in the user's "bin" directory.  For
    # Mac OS X framework Python builds, you should use /usr/local/bin instead,
    # because neither ~/bin nor the default script installation location are on
    # the system PATH.
    #
    install_scripts = ~/bin

This will configure the distutils and EasyInstall to install packages to the
user's home directory by default.

Of course, you aren't limited to using a ``~/lib/python2.X`` directory with
this approach.  You can substitute a specific systemwide directory if you like.
You can also edit ``~/.pydistutils.cfg`` (or ``~/pydistutils.cfg`` on Windows)
instead of changing the master ``distutils.cfg`` file.  The true keys of this
approach are simply that:

1. any custom installation directory must be added to ``sys.path`` using a
   ``site.addsitedir()`` call from a working ``.pth`` file or
   ``sitecustomize.py``.

2. The active distutils configuration file(s) or ``easy_install`` command line
   should include the custom directory in the ``--site-dirs`` option, so that
   EasyInstall knows that ``.pth`` files will work in that location.  (This is
   because Python does not keep track of what directories are or aren't enabled
   for ``.pth`` processing, in any way that EasyInstall can find out.)

As long as both of these things have been done, your custom installation
location is good to go.


Mac OS X "User" Installation
~~~~~~~~~~~~~~~~~~~~~~~~~~~~

If you are on a Mac OS X machine, you should just use the
``~/Library/Python/2.x/site-packages`` directory as your custom installation
location, because it is already configured to process ``.pth`` files, and
EasyInstall already knows this.

Before installing EasyInstall/setuptools, just create a ``~/.pydistutils.cfg``
file with the following contents (or add this to the existing contents)::

    [install]
    install_lib = ~/Library/Python/$py_version_short/site-packages
    install_scripts = ~/bin

This will tell the distutils and EasyInstall to always install packages in
your personal ``site-packages`` directory, and scripts to ``~/bin``.  (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 should work correctly no matter
what Python version you use, now or in the future.)

Once you have done this, you can follow the normal `installation instructions`_
and use ``easy_install`` without any other special options or steps.

(Note, however, that ``~/bin`` is not in the default ``PATH``, so you may have
to refer to scripts by their full location.  You may want to modify your shell
startup script (likely ``.bashrc`` or ``.profile``) or your
``~/.MacOSX/environment.plist`` to include ``~/bin`` in your ``PATH``.


Creating a "Virtual" Python
~~~~~~~~~~~~~~~~~~~~~~~~~~~

If you are on a Linux, BSD, Cygwin, or other similar Unix-like operating
system, but don't have root access, you can create your own "virtual"
Python installation, which uses its own library directories and some symlinks
to the site-wide Python.

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.)

.. _virtual-python.py: http://peak.telecommunity.com/dist/virtual-python.py

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``.  This is because
your new Python executable will not need *any* custom configuration for the
distutils or EasyInstall; everything will go to the correct ``~/lib`` and
``~/bin`` directories automatically.

You should, however, also make sure that the ``bin`` subdirectory of your
installation prefix (e.g. ``~/bin``) is on your ``PATH``, because that is where
EasyInstall and the distutils will install new Python scripts.


"Traditional" ``PYTHONPATH``-based Installation
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

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 at least
consider using one of the other approaches, as they will generally result in
a cleaner, more usable Python configuration.  However, if for some reason you
can't or won't use one of the other approaches, here's how to do it.

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, if you don't
already have them::

    [install]
    install_lib = ~/py-lib
    install_scripts = ~/bin

Be sure to do this *before* you try to run the ``ez_setup.py`` installation
script.  Then, follow the standard `installation instructions`_, but make
sure that ``~/py-lib`` is listed in your ``PYTHONPATH`` environment variable.

Your library installation directory *must* be in listed in ``PYTHONPATH``,
not only when you install packages with EasyInstall, but also when you use
any packages that are installed using EasyInstall.  You will probably want to
edit your ``~/.profile`` or other configuration file(s) to ensure that it is
set, if you haven't already got this set up on your machine.


Package Index "API"
-------------------

Custom package indexes (and PyPI) must follow the following rules for
EasyInstall to be able to look up and download packages:

1. Except where stated otherwise, "pages" are HTML or XHTML, and "links"
   refer to ``href`` attributes.

2. Individual project version pages' URLs must be of the form
   ``base/projectname/version``, where ``base`` is the package index's base URL.

3. Omitting the ``/version`` part of a project page's URL (but keeping the
   trailing ``/``) should result in a page that is either:

   a) The single active version of that project, as though the version had been
      explicitly included, OR

   b) A page with links to all of the active version pages for that project.

4. Individual project version pages should contain direct links to downloadable
   distributions where possible.  It is explicitly permitted for a project's
   "long_description" to include URLs, and these should be formatted as HTML
   links by the package index, as EasyInstall does no special processing to
   identify what parts of a page are index-specific and which are part of the
   project's supplied description.

5. Where available, MD5 information should be added to download URLs by
   appending a fragment identifier of the form ``#md5=...``, where ``...`` is
   the 32-character hex MD5 digest.  EasyInstall will verify that the
   downloaded file's MD5 digest matches the given value.

6. Individual project version pages should identify any "homepage" or
   "download" URLs using ``rel="homepage"`` and ``rel="download"`` attributes
   on the HTML elements linking to those URLs. Use of these attributes will
   cause EasyInstall to always follow the provided links, unless it can be
   determined by inspection that they are downloadable distributions. If the
   links are not to downloadable distributions, they are retrieved, and if they
   are HTML, they are scanned for download links. They are *not* scanned for
   additional "homepage" or "download" links, as these are only processed for
   pages that are part of a package index site.

7. The root URL of the index, if retrieved with a trailing ``/``, must result
   in a page containing links to *all* projects' active version pages.

   (Note: This requirement is a workaround for the absence of case-insensitive
   ``safe_name()`` matching of project names in URL paths. If project names are
   matched in this fashion (e.g. via the PyPI server, mod_rewrite, or a similar
   mechanism), then it is not necessary to include this all-packages listing
   page.)

8. If a package index is accessed via a ``file://`` URL, then EasyInstall will
   automatically use ``index.html`` files, if present, when trying to read a
   directory with a trailing ``/`` on the URL.


Backward Compatibility
~~~~~~~~~~~~~~~~~~~~~~

Package indexes that wish to support setuptools versions prior to 0.6b4 should
also follow these rules:

* Homepage and download links must be preceded with ``"<th>Home Page"`` or
  ``"<th>Download URL"``, in addition to (or instead of) the ``rel=""``
  attributes on the actual links.  These marker strings do not need to be
  visible, or uncommented, however!  For example, the following is a valid
  homepage link that will work with any version of setuptools::

    <li>
     <strong>Home Page:</strong>
     <!-- <th>Home Page -->
     <a rel="homepage" href="http://sqlobject.org">http://sqlobject.org</a>
    </li>

  Even though the marker string is in an HTML comment, older versions of
  EasyInstall will still "see" it and know that the link that follows is the
  project's home page URL.

* The pages described by paragraph 3(b) of the preceding section *must*
  contain the string ``"Index of Packages</title>"`` somewhere in their text.
  This can be inside of an HTML comment, if desired, and it can be anywhere
  in the page.  (Note: this string MUST NOT appear on normal project pages, as
  described in paragraphs 2 and 3(a)!)

In addition, for compatibility with PyPI versions that do not use ``#md5=``
fragment IDs, EasyInstall uses the following regular expression to match PyPI's
displayed MD5 info (broken onto two lines for readability)::

    <a href="([^"#]+)">([^<]+)</a>\n\s+\(<a href="[^?]+\?:action=show_md5
    &amp;digest=([0-9a-f]{32})">md5</a>\)


Release Notes/Change History
============================

0.7a1
 * You can now use "python -m easy_install" with Python 2.4 and above.

 * Better ambiguity management: accept ``#egg`` name/version even if processing
   what appears to be a correctly-named distutils file, and ignore ``.egg``
   files with no ``-``, since valid Python ``.egg`` files always have a version
   number (but Scheme eggs often don't).

 * Support ``file://`` links to directories in ``--find-links``, so that
   easy_install can build packages from local source checkouts.

 * Ignore bdist_dumb distributions when looking at download URLs.

 * Don't install or update a ``site.py`` patch when installing to a
   ``PYTHONPATH`` directory with ``--multi-version``, unless an
   ``easy-install.pth`` file is already in use there.


Future Plans
============

* Additional utilities to list/remove/verify packages
* Signature checking?  SSL?  Ability to suppress PyPI search?
* Display byte progress meter when downloading distributions and long pages?
* Redirect stdout/stderr to log during run_setup?