.. _`pip install`:

pip install
-----------

.. contents::

Usage
*****

.. pip-command-usage:: install

Description
***********

.. pip-command-description:: install


Overview
++++++++

Pip install has several stages:

1. Identify the base requirements. The user supplied arguments are processed
   here.
2. Resolve dependencies. What will be installed is determined here.
3. Build wheels. All the dependencies that can be are built into wheels.
4. Install the packages (and uninstall anything being upgraded/replaced).

Argument Handling
+++++++++++++++++

When looking at the items to be installed, pip checks what type of item
each is, in the following order:

1. Project or archive URL.
2. Local directory (which must contain a ``setup.py``, or pip will report
   an error).
3. Local file (a sdist or wheel format archive, following the naming
   conventions for those formats).
4. A requirement, as specified in PEP 440.

Each item identified is added to the set of requirements to be satisfied by
the install.

Working Out the Name and Version
++++++++++++++++++++++++++++++++

For each candidate item, pip needs to know the project name and version. For
wheels (identified by the ``.whl`` file extension) this can be obtained from
the filename, as per the Wheel spec. For local directories, or explicitly
specified sdist files, the ``setup.py egg_info`` command is used to determine
the project metadata. For sdists located via an index, the filename is parsed
for the name and project version (this is in theory slightly less reliable
than using the ``egg_info`` command, but avoids downloading and processing
unnecessary numbers of files).

Any URL may use the ``#egg=name`` syntax (see :ref:`VCS Support`) to
explicitly state the project name.

Satisfying Requirements
+++++++++++++++++++++++

Once pip has the set of requirements to satisfy, it chooses which version of
each requirement to install using the simple rule that the latest version that
satisfies the given constraints will be installed (but see :ref:`here <Pre Release Versions>`
for an exception regarding pre-release versions). Where more than one source of
the chosen version is available, it is assumed that any source is acceptable
(as otherwise the versions would differ).

Installation Order
++++++++++++++++++

As of v6.1.0, pip installs dependencies before their dependents, i.e. in
"topological order".  This is the only commitment pip currently makes related
to order.  While it may be coincidentally true that pip will install things in
the order of the install arguments or in the order of the items in a
requirements file, this is not a promise.

In the event of a dependency cycle (aka "circular dependency"), the current
implementation (which might possibly change later) has it such that the first
encountered member of the cycle is installed last.

For instance, if quux depends on foo which depends on bar which depends on baz,
which depends on foo::

    pip install quux
    ...
    Installing collected packages baz, bar, foo, quux

    pip install bar
    ...
    Installing collected packages foo, baz, bar


Prior to v6.1.0, pip made no commitments about install order.

The decision to install topologically is based on the principle that
installations should proceed in a way that leaves the environment usable at each
step. This has two main practical benefits:

1. Concurrent use of the environment during the install is more likely to work.
2. A failed install is less likely to leave a broken environment.  Although pip
   would like to support failure rollbacks eventually, in the mean time, this is
   an improvement.

Although the new install order is not intended to replace (and does not replace)
the use of ``setup_requires`` to declare build dependencies, it may help certain
projects install from sdist (that might previously fail) that fit the following
profile:

1. They have build dependencies that are also declared as install dependencies
   using ``install_requires``.
2. ``python setup.py egg_info`` works without their build dependencies being
   installed.
3. For whatever reason, they don't or won't declare their build dependencies using
   ``setup_requires``.


.. _`Requirements File Format`:

Requirements File Format
++++++++++++++++++++++++

Each line of the requirements file indicates something to be installed,
and like arguments to :ref:`pip install`, the following forms are supported::

    [[--option]...]
    <requirement specifier> [; markers] [[--option]...]
    <archive url/path>
    [-e] <local project path>
    [-e] <vcs project url>

For details on requirement specifiers, see :ref:`Requirement Specifiers`.

See the :ref:`pip install Examples<pip install Examples>` for examples of all these forms.

A line that begins with ``#`` is treated as a comment and ignored. Whitespace
followed by a ``#`` causes the ``#`` and the remainder of the line to be
treated as a comment.

A line ending in an unescaped ``\`` is treated as a line continuation
and the newline following it is effectively ignored.

Comments are stripped *before* line continuations are processed.

The following options are supported:

  *  :ref:`-i, --index-url <--index-url>`
  *  :ref:`--extra-index-url <--extra-index-url>`
  *  :ref:`--no-index <--no-index>`
  *  :ref:`-f, --find-links <--find-links>`
  *  :ref:`--no-binary <install_--no-binary>`
  *  :ref:`--only-binary <install_--only-binary>`
  *  :ref:`--require-hashes <--require-hashes>`

For example, to specify :ref:`--no-index <--no-index>` and 2 :ref:`--find-links <--find-links>` locations:

::

--no-index
--find-links /my/local/archives
--find-links http://some.archives.com/archives


If you wish, you can refer to other requirements files, like this::

    -r more_requirements.txt

You can also refer to :ref:`constraints files <Constraints Files>`, like this::

    -c some_constraints.txt

.. _`Using Environment Variables`:

Using Environment Variables
~~~~~~~~~~~~~~~~~~~~~~~~~~~

Since version 10, pip supports the use of environment variables inside the
requirements file. You can now store sensitive data (tokens, keys, etc.) in
environment variables and only specify the variable name for your requirements,
letting pip lookup the value at runtime. This approach aligns with the commonly
used `12-factor configuration pattern <https://12factor.net/config>`_.

You have to use the POSIX format for variable names including brackets around
the uppercase name as shown in this example: ``${API_TOKEN}``. pip will attempt
to find the corresponding environment variable defined on the host system at
runtime.

.. note::

   There is no support for other variable expansion syntaxes such as
   ``$VARIABLE`` and ``%VARIABLE%``.


.. _`Example Requirements File`:

Example Requirements File
~~~~~~~~~~~~~~~~~~~~~~~~~

Use ``pip install -r example-requirements.txt`` to install::

    #
    ####### example-requirements.txt #######
    #
    ###### Requirements without Version Specifiers ######
    nose
    nose-cov
    beautifulsoup4
    #
    ###### Requirements with Version Specifiers ######
    #   See https://www.python.org/dev/peps/pep-0440/#version-specifiers
    docopt == 0.6.1             # Version Matching. Must be version 0.6.1
    keyring >= 4.1.1            # Minimum version 4.1.1
    coverage != 3.5             # Version Exclusion. Anything except version 3.5
    Mopidy-Dirble ~= 1.1        # Compatible release. Same as >= 1.1, == 1.*
    #
    ###### Refer to other requirements files ######
    -r other-requirements.txt
    #
    #
    ###### A particular file ######
    ./downloads/numpy-1.9.2-cp34-none-win32.whl
    http://wxpython.org/Phoenix/snapshot-builds/wxPython_Phoenix-3.0.3.dev1820+49a8884-cp34-none-win_amd64.whl
    #
    ###### Additional Requirements without Version Specifiers ######
    #   Same as 1st section, just here to show that you can put things in any order.
    rejected
    green
    #

.. _`Requirement Specifiers`:

Requirement Specifiers
++++++++++++++++++++++

pip supports installing from a package index using a :term:`requirement
specifier <pypug:Requirement Specifier>`. Generally speaking, a requirement
specifier is composed of a project name followed by optional :term:`version
specifiers <pypug:Version Specifier>`.  `PEP508`_ contains a full specification
of the format of a requirement (``pip`` does not support the ``url_req`` form
of specifier at this time).

Some examples:

 ::

  SomeProject
  SomeProject == 1.3
  SomeProject >=1.2,<.2.0
  SomeProject[foo, bar]
  SomeProject~=1.4.2

Since version 6.0, pip also supports specifiers containing `environment markers
<https://www.python.org/dev/peps/pep-0426/#environment-markers>`_ like so:

 ::

  SomeProject ==5.4 ; python_version < '2.7'
  SomeProject; sys_platform == 'win32'

Environment markers are supported in the command line and in requirements files.

.. note::

   Use quotes around specifiers in the shell when using ``>``, ``<``, or when
   using environment markers. Don't use quotes in requirement files. [1]_


.. _`Per-requirement Overrides`:

Per-requirement Overrides
+++++++++++++++++++++++++

Since version 7.0 pip supports controlling the command line options given to
``setup.py`` via requirements files. This disables the use of wheels (cached or
otherwise) for that package, as ``setup.py`` does not exist for wheels.

The ``--global-option`` and ``--install-option`` options are used to pass
options to ``setup.py``. For example:

 ::

    FooProject >= 1.2 --global-option="--no-user-cfg" \
                      --install-option="--prefix='/usr/local'" \
                      --install-option="--no-compile"

The above translates roughly into running FooProject's ``setup.py``
script as:

 ::

   python setup.py --no-user-cfg install --prefix='/usr/local' --no-compile

Note that the only way of giving more than one option to ``setup.py``
is through multiple ``--global-option`` and ``--install-option``
options, as shown in the example above. The value of each option is
passed as a single argument to the ``setup.py`` script. Therefore, a
line such as the following is invalid and would result in an
installation error.

::

   # Invalid. Please use '--install-option' twice as shown above.
   FooProject >= 1.2 --install-option="--prefix=/usr/local --no-compile"


.. _`Pre Release Versions`:

Pre-release Versions
++++++++++++++++++++

Starting with v1.4, pip will only install stable versions as specified by
`PEP426`_ by default. If a version cannot be parsed as a compliant `PEP426`_
version then it is assumed to be a pre-release.

If a Requirement specifier includes a pre-release or development version
(e.g. ``>=0.0.dev0``) then pip will allow pre-release and development versions
for that requirement. This does not include the != flag.

The ``pip install`` command also supports a :ref:`--pre <install_--pre>` flag
that will enable installing pre-releases and development releases.


.. _PEP426: http://www.python.org/dev/peps/pep-0426


.. _`VCS Support`:

VCS Support
+++++++++++

pip supports installing from Git, Mercurial, Subversion and Bazaar, and detects
the type of VCS using url prefixes: "git+", "hg+", "bzr+", "svn+".

pip requires a working VCS command on your path: git, hg, svn, or bzr.

VCS projects can be installed in :ref:`editable mode <editable-installs>` (using
the :ref:`--editable <install_--editable>` option) or not.

* For editable installs, the clone location by default is "<venv
  path>/src/SomeProject" in virtual environments, and "<cwd>/src/SomeProject"
  for global installs.  The :ref:`--src <install_--src>` option can be used to
  modify this location.
* For non-editable installs, the project is built locally in a temp dir and then
  installed normally. Note that if a satisfactory version of the package is
  already installed, the VCS source will not overwrite it without an `--upgrade`
  flag. VCS requirements pin the package version (specified in the `setup.py`
  file) of the target commit, not necessarily the commit itself.
* The :ref:`pip freeze` subcommand will record the VCS requirement specifier
  (referencing a specific commit) if and only if the install is done using the
  editable option.

The "project name" component of the url suffix "egg=<project name>-<version>"
is used by pip in its dependency logic to identify the project prior
to pip downloading and analyzing the metadata.  The optional "version"
component of the egg name is not functionally important.  It merely
provides a human-readable clue as to what version is in use. For projects
where setup.py is not in the root of project, "subdirectory" component
is used. Value of "subdirectory" component should be a path starting from root
of the project to where setup.py is located.

So if your repository layout is:

    - pkg_dir/

      - setup.py  # setup.py for package ``pkg``
      - some_module.py
    - other_dir/

      - some_file
    - some_other_file

You'll need to use ``pip install -e vcs+protocol://repo_url/#egg=pkg&subdirectory=pkg_dir``.


Git
~~~

pip currently supports cloning over ``git``, ``git+http``, ``git+https``,
``git+ssh``, ``git+git`` and ``git+file``:

Here are the supported forms::

    [-e] git://git.example.com/MyProject#egg=MyProject
    [-e] git+http://git.example.com/MyProject#egg=MyProject
    [-e] git+https://git.example.com/MyProject#egg=MyProject
    [-e] git+ssh://git.example.com/MyProject#egg=MyProject
    [-e] git+git://git.example.com/MyProject#egg=MyProject
    [-e] git+file:///home/user/projects/MyProject#egg=MyProject
    -e git+git@git.example.com:MyProject#egg=MyProject

Passing branch names, a commit hash or a tag name is possible like so::

    [-e] git://git.example.com/MyProject.git@master#egg=MyProject
    [-e] git://git.example.com/MyProject.git@v1.0#egg=MyProject
    [-e] git://git.example.com/MyProject.git@da39a3ee5e6b4b0d3255bfef95601890afd80709#egg=MyProject

When passing a commit hash, specifying a full hash is preferable to a partial
hash because a full hash allows pip to operate more efficiently (e.g. by
making fewer network calls).

Mercurial
~~~~~~~~~

The supported schemes are: ``hg+http``, ``hg+https``,
``hg+static-http`` and ``hg+ssh``.

Here are the supported forms::

    [-e] hg+http://hg.myproject.org/MyProject#egg=MyProject
    [-e] hg+https://hg.myproject.org/MyProject#egg=MyProject
    [-e] hg+ssh://hg.myproject.org/MyProject#egg=MyProject
    [-e] hg+file:///home/user/projects/MyProject#egg=MyProject

You can also specify a revision number, a revision hash, a tag name or a local
branch name like so::

    [-e] hg+http://hg.example.com/MyProject@da39a3ee5e6b#egg=MyProject
    [-e] hg+http://hg.example.com/MyProject@2019#egg=MyProject
    [-e] hg+http://hg.example.com/MyProject@v1.0#egg=MyProject
    [-e] hg+http://hg.example.com/MyProject@special_feature#egg=MyProject

Subversion
~~~~~~~~~~

pip supports the URL schemes ``svn``, ``svn+svn``, ``svn+http``, ``svn+https``, ``svn+ssh``.

You can also give specific revisions to an SVN URL, like so::

    [-e] svn+svn://svn.example.com/svn/MyProject#egg=MyProject
    [-e] svn+http://svn.example.com/svn/MyProject/trunk@2019#egg=MyProject

which will check out revision 2019.  ``@{20080101}`` would also check
out the revision from 2008-01-01. You can only check out specific
revisions using ``-e svn+...``.

Bazaar
~~~~~~

pip supports Bazaar using the ``bzr+http``, ``bzr+https``, ``bzr+ssh``,
``bzr+sftp``, ``bzr+ftp`` and ``bzr+lp`` schemes.

Here are the supported forms::

    [-e] bzr+http://bzr.example.com/MyProject/trunk#egg=MyProject
    [-e] bzr+sftp://user@example.com/MyProject/trunk#egg=MyProject
    [-e] bzr+ssh://user@example.com/MyProject/trunk#egg=MyProject
    [-e] bzr+ftp://user@example.com/MyProject/trunk#egg=MyProject
    [-e] bzr+lp:MyProject#egg=MyProject

Tags or revisions can be installed like so::

    [-e] bzr+https://bzr.example.com/MyProject/trunk@2019#egg=MyProject
    [-e] bzr+http://bzr.example.com/MyProject/trunk@v1.0#egg=MyProject

Using Environment Variables
~~~~~~~~~~~~~~~~~~~~~~~~~~~

Since version 10, pip also makes it possible to use environment variables which
makes it possible to reference private repositories without having to store
access tokens in the requirements file. For example, a private git repository
allowing Basic Auth for authentication can be refenced like this::

    [-e] git+http://${AUTH_USER}:${AUTH_PASSWORD}@git.example.com/MyProject#egg=MyProject
    [-e] git+https://${AUTH_USER}:${AUTH_PASSWORD}@git.example.com/MyProject#egg=MyProject

.. note::

   Only ``${VARIABLE}`` is supported, other formats like ``$VARIABLE`` or
   ``%VARIABLE%`` won't work.

Finding Packages
++++++++++++++++

pip searches for packages on `PyPI`_ using the
`http simple interface <https://pypi.org/simple/>`_,
which is documented `here <https://setuptools.readthedocs.io/en/latest/easy_install.html#package-index-api>`_
and `there <http://www.python.org/dev/peps/pep-0301/>`_

pip offers a number of Package Index Options for modifying how packages are found.

pip looks for packages in a number of places, on PyPI (if not disabled via
```--no-index```), in the local filesystem, and in any additional repositories
specified via ```--find-links``` or ```--index-url```. There is no ordering in
the locations that are searched, rather they are all checked, and the "best"
match for the requirements (in terms of version number - see `PEP440`_ for
details) is selected.

See the :ref:`pip install Examples<pip install Examples>`.


.. _`SSL Certificate Verification`:

SSL Certificate Verification
++++++++++++++++++++++++++++

Starting with v1.3, pip provides SSL certificate verification over https, to
prevent man-in-the-middle attacks against PyPI downloads.


.. _`Caching`:

Caching
+++++++

Starting with v6.0, pip provides an on-by-default cache which functions
similarly to that of a web browser. While the cache is on by default and is
designed do the right thing by default you can disable the cache and always
access PyPI by utilizing the ``--no-cache-dir`` option.

When making any HTTP request pip will first check its local cache to determine
if it has a suitable response stored for that request which has not expired. If
it does then it simply returns that response and doesn't make the request.

If it has a response stored, but it has expired, then it will attempt to make a
conditional request to refresh the cache which will either return an empty
response telling pip to simply use the cached item (and refresh the expiration
timer) or it will return a whole new response which pip can then store in the
cache.

When storing items in the cache, pip will respect the ``CacheControl`` header
if it exists, or it will fall back to the ``Expires`` header if that exists.
This allows pip to function as a browser would, and allows the index server
to communicate to pip how long it is reasonable to cache any particular item.

While this cache attempts to minimize network activity, it does not prevent
network access altogether. If you want a local install solution that
circumvents accessing PyPI, see :ref:`Installing from local packages`.

The default location for the cache directory depends on the Operating System:

Unix
  :file:`~/.cache/pip` and it respects the ``XDG_CACHE_HOME`` directory.
macOS
  :file:`~/Library/Caches/pip`.
Windows
  :file:`<CSIDL_LOCAL_APPDATA>\\pip\\Cache`


.. _`Wheel cache`:

Wheel Cache
~~~~~~~~~~~

Pip will read from the subdirectory ``wheels`` within the pip cache directory
and use any packages found there. This is disabled via the same
``--no-cache-dir`` option that disables the HTTP cache. The internal structure
of that is not part of the pip API. As of 7.0, pip makes a subdirectory for
each sdist that wheels are built from and places the resulting wheels inside.

Pip attempts to choose the best wheels from those built in preference to
building a new wheel. Note that this means when a package has both optional
C extensions and builds `py` tagged wheels when the C extension can't be built
that pip will not attempt to build a better wheel for Pythons that would have
supported it, once any generic wheel is built. To correct this, make sure that
the wheels are built with Python specific tags - e.g. pp on PyPy.

When no wheels are found for an sdist, pip will attempt to build a wheel
automatically and insert it into the wheel cache.


.. _`hash-checking mode`:

Hash-Checking Mode
++++++++++++++++++

Since version 8.0, pip can check downloaded package archives against local
hashes to protect against remote tampering. To verify a package against one or
more hashes, add them to the end of the line::

    FooProject == 1.2 --hash=sha256:2cf24dba5fb0a30e26e83b2ac5b9e29e1b161e5c1fa7425e73043362938b9824 \
                      --hash=sha256:486ea46224d1bb4fb680f34f7c9ad96a8f24ec88be73ea8e5a6c65260e9cb8a7

(The ability to use multiple hashes is important when a package has both
binary and source distributions or when it offers binary distributions for a
variety of platforms.)

The recommended hash algorithm at the moment is sha256, but stronger ones are
allowed, including all those supported by ``hashlib``. However, weaker ones
such as md5, sha1, and sha224 are excluded to avoid giving a false sense of
security.

Hash verification is an all-or-nothing proposition. Specifying a ``--hash``
against any requirement not only checks that hash but also activates a global
*hash-checking mode*, which imposes several other security restrictions:

* Hashes are required for all requirements. This is because a partially-hashed
  requirements file is of little use and thus likely an error: a malicious
  actor could slip bad code into the installation via one of the unhashed
  requirements. Note that hashes embedded in URL-style requirements via the
  ``#md5=...`` syntax suffice to satisfy this rule (regardless of hash
  strength, for legacy reasons), though you should use a stronger
  hash like sha256 whenever possible.
* Hashes are required for all dependencies. An error results if there is a
  dependency that is not spelled out and hashed in the requirements file.
* Requirements that take the form of project names (rather than URLs or local
  filesystem paths) must be pinned to a specific version using ``==``. This
  prevents a surprising hash mismatch upon the release of a new version
  that matches the requirement specifier.
* ``--egg`` is disallowed, because it delegates installation of dependencies
  to setuptools, giving up pip's ability to enforce any of the above.

.. _`--require-hashes`:

Hash-checking mode can be forced on with the ``--require-hashes`` command-line
option::

    $ pip install --require-hashes -r requirements.txt
        ...
        Hashes are required in --require-hashes mode (implicitly on when a hash is
        specified for any package). These requirements were missing hashes,
        leaving them open to tampering. These are the hashes the downloaded
        archives actually had. You can add lines like these to your requirements
        files to prevent tampering.
            pyelasticsearch==1.0 --hash=sha256:44ddfb1225054d7d6b1d02e9338e7d4809be94edbe9929a2ec0807d38df993fa
            more-itertools==2.2 --hash=sha256:93e62e05c7ad3da1a233def6731e8285156701e3419a5fe279017c429ec67ce0

This can be useful in deploy scripts, to ensure that the author of the
requirements file provided hashes. It is also a convenient way to bootstrap
your list of hashes, since it shows the hashes of the packages it fetched. It
fetches only the preferred archive for each package, so you may still need to
add hashes for alternatives archives using :ref:`pip hash`: for instance if
there is both a binary and a source distribution.

The :ref:`wheel cache <Wheel cache>` is disabled in hash-checking mode to
prevent spurious hash mismatch errors. These would otherwise occur while
installing sdists that had already been automatically built into cached wheels:
those wheels would be selected for installation, but their hashes would not
match the sdist ones from the requirements file. A further complication is that
locally built wheels are nondeterministic: contemporary modification times make
their way into the archive, making hashes unpredictable across machines and
cache flushes. Compilation of C code adds further nondeterminism, as many
compilers include random-seeded values in their output. However, wheels fetched
from index servers are the same every time. They land in pip's HTTP cache, not
its wheel cache, and are used normally in hash-checking mode. The only downside
of having the wheel cache disabled is thus extra build time for sdists, and
this can be solved by making sure pre-built wheels are available from the index
server.

Hash-checking mode also works with :ref:`pip download` and :ref:`pip wheel`. A
:ref:`comparison of hash-checking mode with other repeatability strategies
<Repeatability>` is available in the User Guide.

.. warning::
    Beware of the ``setup_requires`` keyword arg in :file:`setup.py`. The
    (rare) packages that use it will cause those dependencies to be downloaded
    by setuptools directly, skipping pip's hash-checking. If you need to use
    such a package, see :ref:`Controlling
    setup_requires<controlling-setup-requires>`.

.. warning::
    Be careful not to nullify all your security work when you install your
    actual project by using setuptools directly: for example, by calling
    ``python setup.py install``, ``python setup.py develop``, or
    ``easy_install``. Setuptools will happily go out and download, unchecked,
    anything you missed in your requirements file—and it’s easy to miss things
    as your project evolves. To be safe, install your project using pip and
    :ref:`--no-deps <install_--no-deps>`.

    Instead of ``python setup.py develop``, use... ::

        pip install --no-deps -e .

    Instead of ``python setup.py install``, use... ::

        pip install --no-deps .


Hashes from PyPI
~~~~~~~~~~~~~~~~

PyPI provides an MD5 hash in the fragment portion of each package download URL,
like ``#md5=123...``, which pip checks as a protection against download
corruption. Other hash algorithms that have guaranteed support from ``hashlib``
are also supported here: sha1, sha224, sha384, sha256, and sha512. Since this
hash originates remotely, it is not a useful guard against tampering and thus
does not satisfy the ``--require-hashes`` demand that every package have a
local hash.


.. _`editable-installs`:

"Editable" Installs
+++++++++++++++++++

"Editable" installs are fundamentally `"setuptools develop mode"
<https://setuptools.readthedocs.io/en/latest/setuptools.html#development-mode>`_
installs.

You can install local projects or VCS projects in "editable" mode::

$ pip install -e path/to/SomeProject
$ pip install -e git+http://repo/my_project.git#egg=SomeProject

(See the :ref:`VCS Support` section above for more information on VCS-related syntax.)

For local projects, the "SomeProject.egg-info" directory is created relative to
the project path.  This is one advantage over just using ``setup.py develop``,
which creates the "egg-info" directly relative the current working directory.


.. _`controlling-setup-requires`:

Controlling setup_requires
++++++++++++++++++++++++++

Setuptools offers the ``setup_requires`` `setup() keyword
<https://setuptools.readthedocs.io/en/latest/setuptools.html#new-and-changed-setup-keywords>`_
for specifying dependencies that need to be present in order for the `setup.py`
script to run.  Internally, Setuptools uses ``easy_install`` to fulfill these
dependencies.

pip has no way to control how these dependencies are located.  None of the
Package Index Options have an effect.

The solution is to configure a "system" or "personal" `Distutils configuration
file
<http://docs.python.org/2/install/index.html#distutils-configuration-files>`_ to
manage the fulfillment.

For example, to have the dependency located at an alternate index, add this:

::

  [easy_install]
  index_url = https://my.index-mirror.com

To have the dependency located from a local directory and not crawl PyPI, add this:

::

  [easy_install]
  allow_hosts = ''
  find_links = file:///path/to/local/archives/


Build System Interface
++++++++++++++++++++++

In order for pip to install a package from source, ``setup.py`` must implement
the following commands::

    setup.py egg_info [--egg-base XXX]
    setup.py install --record XXX [--single-version-externally-managed] [--root XXX] [--compile|--no-compile] [--install-headers XXX]

The ``egg_info`` command should create egg metadata for the package, as
described in the setuptools documentation at
https://setuptools.readthedocs.io/en/latest/setuptools.html#egg-info-create-egg-metadata-and-set-build-tags

The ``install`` command should implement the complete process of installing the
package to the target directory XXX.

To install a package in "editable" mode (``pip install -e``), ``setup.py`` must
implement the following command::

    setup.py develop --no-deps

This should implement the complete process of installing the package in
"editable" mode.

All packages will be attempted to built into wheels::

    setup.py bdist_wheel -d XXX

One further ``setup.py`` command is invoked by ``pip install``::

    setup.py clean

This command is invoked to clean up temporary commands from the build. (TODO:
Investigate in more detail when this command is required).

No other build system commands are invoked by the ``pip install`` command.

Installing a package from a wheel does not invoke the build system at all.

.. _PyPI: https://pypi.org/
.. _setuptools extras: https://setuptools.readthedocs.io/en/latest/setuptools.html#declaring-extras-optional-features-with-their-own-dependencies



.. _`pip install Options`:

Options
*******

.. pip-command-options:: install

.. pip-index-options::


.. _`pip install Examples`:

Examples
********

#. Install `SomePackage` and its dependencies from `PyPI`_ using :ref:`Requirement Specifiers`

    ::

      $ pip install SomePackage            # latest version
      $ pip install SomePackage==1.0.4     # specific version
      $ pip install 'SomePackage>=1.0.4'     # minimum version


#. Install a list of requirements specified in a file.  See the :ref:`Requirements files <Requirements Files>`.

    ::

      $ pip install -r requirements.txt


#. Upgrade an already installed `SomePackage` to the latest from PyPI.

    ::

      $ pip install --upgrade SomePackage


#. Install a local project in "editable" mode. See the section on :ref:`Editable Installs <editable-installs>`.

    ::

      $ pip install -e .                     # project in current directory
      $ pip install -e path/to/project       # project in another directory


#. Install a project from VCS in "editable" mode. See the sections on :ref:`VCS Support <VCS Support>` and :ref:`Editable Installs <editable-installs>`.

    ::

      $ pip install -e git+https://git.repo/some_pkg.git#egg=SomePackage          # from git
      $ pip install -e hg+https://hg.repo/some_pkg.git#egg=SomePackage            # from mercurial
      $ pip install -e svn+svn://svn.repo/some_pkg/trunk/#egg=SomePackage         # from svn
      $ pip install -e git+https://git.repo/some_pkg.git@feature#egg=SomePackage  # from 'feature' branch
      $ pip install -e "git+https://git.repo/some_repo.git#egg=subdir&subdirectory=subdir_path" # install a python package from a repo subdirectory

#. Install a package with `setuptools extras`_.

    ::

      $ pip install SomePackage[PDF]
      $ pip install git+https://git.repo/some_pkg.git#egg=SomePackage[PDF]
      $ pip install SomePackage[PDF]==3.0
      $ pip install -e .[PDF]==3.0  # editable project in current directory
      $ pip install SomePackage[PDF,EPUB]  # multiple extras


#. Install a particular source archive file.

    ::

      $ pip install ./downloads/SomePackage-1.0.4.tar.gz
      $ pip install http://my.package.repo/SomePackage-1.0.4.zip


#. Install from alternative package repositories.

   Install from a different index, and not `PyPI`_ ::

     $ pip install --index-url http://my.package.repo/simple/ SomePackage

   Search an additional index during install, in addition to `PyPI`_ ::

     $ pip install --extra-index-url http://my.package.repo/simple SomePackage

   Install from a local flat directory containing archives (and don't scan indexes)::

     $ pip install --no-index --find-links=file:///local/dir/ SomePackage
     $ pip install --no-index --find-links=/local/dir/ SomePackage
     $ pip install --no-index --find-links=relative/dir/ SomePackage


#. Find pre-release and development versions, in addition to stable versions.  By default, pip only finds stable versions.

    ::

      $ pip install --pre SomePackage

----

.. [1] This is true with the exception that pip v7.0 and v7.0.1 required quotes
       around specifiers containing environment markers in requirement files.

.. _PEP440: http://www.python.org/dev/peps/pep-0440
.. _PEP508: http://www.python.org/dev/peps/pep-0508
