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User Guide

Contents

Installing Packages

pip supports installing from PyPI, version control, local projects, and directly from distribution files.

The most common scenario is to install 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

For more information and examples, see the :ref:`pip install` reference.

Requirements Files

"Requirements files" are files containing a list of items to be installed using :ref:`pip install` like so:

pip install -r requirements.txt

Details on the format of the files are here: :ref:`Requirements File Format`.

Logically, a Requirements file is just a list of :ref:`pip install` arguments placed in a file. Note that you should not rely on the items in the file being installed by pip in any particular order.

In practice, there are 4 common uses of Requirements files:

  1. Requirements files are used to hold the result from :ref:`pip freeze` for the purpose of achieving :ref:`repeatable installations <Repeatability>`. In this case, your requirement file contains a pinned version of everything that was installed when pip freeze was run.

    pip freeze > requirements.txt
pip install -r requirements.txt

  2. Requirements files are used to force pip to properly resolve dependencies. As it is now, pip doesn't have true dependency resolution, but instead simply uses the first specification it finds for a project. E.g if pkg1 requires pkg3>=1.0 and pkg2 requires pkg3>=1.0,<=2.0, and if pkg1 is resolved first, pip will only use pkg3>=1.0, and could easily end up installing a version of pkg3 that conflicts with the needs of pkg2. To solve this problem, you can place pkg3>=1.0,<=2.0 (i.e. the correct specification) into your requirements file directly along with the other top level requirements. Like so:

    pkg1
pkg2
pkg3>=1.0,<=2.0

  3. Requirements files are used to force pip to install an alternate version of a sub-dependency. For example, suppose ProjectA in your requirements file requires ProjectB, but the latest version (v1.3) has a bug, you can force pip to accept earlier versions like so:

    ProjectA
ProjectB<1.3

  4. Requirements files are used to override a dependency with a local patch that lives in version control. For example, suppose a dependency, SomeDependency from PyPI has a bug, and you can't wait for an upstream fix. You could clone/copy the src, make the fix, and place it in VCS with the tag sometag. You'd reference it in your requirements file with a line like so:

    git+https://myvcs.com/some_dependency@sometag#egg=SomeDependency

    If SomeDependency was previously a top-level requirement in your requirements file, then replace that line with the new line. If SomeDependency is a sub-dependency, then add the new line.

It's important to be clear that pip determines package dependencies using install_requires metadata, not by discovering requirements.txt files embedded in projects.

See also:

Constraints Files

Constraints files are requirements files that only control which version of a requirement is installed, not whether it is installed or not. Their syntax and contents is nearly identical to :ref:`Requirements Files`. There is one key difference: Including a package in a constraints file does not trigger installation of the package.

Use a constraints file like so:

pip install -c constraints.txt

Constraints files are used for exactly the same reason as requirements files when you don't know exactly what things you want to install. For instance, say that the "helloworld" package doesn't work in your environment, so you have a local patched version. Some things you install depend on "helloworld", and some don't.

One way to ensure that the patched version is used consistently is to manually audit the dependencies of everything you install, and if "helloworld" is present, write a requirements file to use when installing that thing.

Constraints files offer a better way: write a single constraints file for your organisation and use that everywhere. If the thing being installed requires "helloworld" to be installed, your fixed version specified in your constraints file will be used.

Constraints file support was added in pip 7.1.

Installing from Wheels

"Wheel" is a built, archive format that can greatly speed installation compared to building and installing from source archives. For more information, see the Wheel docs , PEP427, and PEP425

Pip prefers Wheels where they are available. To disable this, use the :ref:`--no-binary <install_--no-binary>` flag for :ref:`pip install`.

If no satisfactory wheels are found, pip will default to finding source archives.

To install directly from a wheel archive:

pip install SomePackage-1.0-py2.py3-none-any.whl

For the cases where wheels are not available, pip offers :ref:`pip wheel` as a convenience, to build wheels for all your requirements and dependencies.

:ref:`pip wheel` requires the wheel package to be installed, which provides the "bdist_wheel" setuptools extension that it uses.

To build wheels for your requirements and all their dependencies to a local directory:

pip install wheel
pip wheel --wheel-dir=/local/wheels -r requirements.txt

And then to install those requirements just using your local directory of wheels (and not from PyPI):

pip install --no-index --find-links=/local/wheels -r requirements.txt

Uninstalling Packages

pip is able to uninstall most packages like so:

$ pip uninstall SomePackage

pip also performs an automatic uninstall of an old version of a package before upgrading to a newer version.

For more information and examples, see the :ref:`pip uninstall` reference.

Listing Packages

To list installed packages:

$ pip list
docutils (0.9.1)
Jinja2 (2.6)
Pygments (1.5)
Sphinx (1.1.2)

To list outdated packages, and show the latest version available:

$ pip list --outdated
docutils (Current: 0.9.1 Latest: 0.10)
Sphinx (Current: 1.1.2 Latest: 1.1.3)

To show details about an installed package:

$ pip show sphinx
---
Name: Sphinx
Version: 1.1.3
Location: /my/env/lib/pythonx.x/site-packages
Requires: Pygments, Jinja2, docutils

For more information and examples, see the :ref:`pip list` and :ref:`pip show` reference pages.

Searching for Packages

pip can search PyPI for packages using the pip search command:

$ pip search "query"

The query will be used to search the names and summaries of all packages.

For more information and examples, see the :ref:`pip search` reference.

Configuration

Config file

pip allows you to set all command line option defaults in a standard ini style config file.

The names and locations of the configuration files vary slightly across platforms. You may have per-user, per-virtualenv or site-wide (shared amongst all users) configuration:

Per-user:

There are also a legacy per-user configuration file which is also respected, these are located at:

You can set a custom path location for this config file using the environment variable PIP_CONFIG_FILE.

Inside a virtualenv:

Site-wide:

If multiple configuration files are found by pip then they are combined in the following order:

  1. Firstly the site-wide file is read, then
  2. The per-user file is read, and finally
  3. The virtualenv-specific file is read.

Each file read overrides any values read from previous files, so if the global timeout is specified in both the site-wide file and the per-user file then the latter value is the one that will be used.

The names of the settings are derived from the long command line option, e.g. if you want to use a different package index (--index-url) and set the HTTP timeout (--default-timeout) to 60 seconds your config file would look like this:

[global]
timeout = 60
index-url = http://download.zope.org/ppix

Each subcommand can be configured optionally in its own section so that every global setting with the same name will be overridden; e.g. decreasing the timeout to 10 seconds when running the freeze (Freezing Requirements) command and using 60 seconds for all other commands is possible with:

[global]
timeout = 60

[freeze]
timeout = 10

Boolean options like --ignore-installed or --no-dependencies can be set like this:

[install]
ignore-installed = true
no-dependencies = yes

To enable the boolean options --no-compile and --no-cache-dir, falsy values have to be used:

[global]
no-cache-dir = false

[install]
no-compile = no

Appending options like --find-links can be written on multiple lines:

[global]
find-links =
    http://download.example.com

[install]
find-links =
    http://mirror1.example.com
    http://mirror2.example.com

Environment Variables

pip's command line options can be set with environment variables using the format PIP_<UPPER_LONG_NAME> . Dashes (-) have to be replaced with underscores (_).

For example, to set the default timeout:

export PIP_DEFAULT_TIMEOUT=60

This is the same as passing the option to pip directly:

pip --default-timeout=60 [...]

To set options that can be set multiple times on the command line, just add spaces in between values. For example:

export PIP_FIND_LINKS="http://mirror1.example.com http://mirror2.example.com"

is the same as calling:

pip install --find-links=http://mirror1.example.com --find-links=http://mirror2.example.com

Config Precedence

Command line options have precedence over environment variables, which have precedence over the config file.

Within the config file, command specific sections have precedence over the global section.

Examples:

  • --host=foo overrides PIP_HOST=foo
  • PIP_HOST=foo overrides a config file with [global] host = foo
  • A command specific section in the config file [<command>] host = bar overrides the option with same name in the [global] config file section

Command Completion

pip comes with support for command line completion in bash and zsh.

To setup for bash:

$ pip completion --bash >> ~/.profile

To setup for zsh:

$ pip completion --zsh >> ~/.zprofile

Alternatively, you can use the result of the completion command directly with the eval function of your shell, e.g. by adding the following to your startup file:

eval "`pip completion --bash`"

Installing from local packages

In some cases, you may want to install from local packages only, with no traffic to PyPI.

First, download the archives that fulfill your requirements:

$ pip install --download DIR -r requirements.txt

Note that pip install --download will look in your wheel cache first, before trying to download from PyPI. If you've never installed your requirements before, you won't have a wheel cache for those items. In that case, if some of your requirements don't come as wheels from PyPI, and you want wheels, then run this instead:

$ pip wheel --wheel-dir DIR -r requirements.txt

Then, to install from local only, you'll be using :ref:`--find-links <--find-links>` and :ref:`--no-index <--no-index>` like so:

$ pip install --no-index --find-links=DIR -r requirements.txt

"Only if needed" Recursive Upgrade

pip install --upgrade is currently written to perform an eager recursive upgrade, i.e. it upgrades all dependencies regardless of whether they still satisfy the new parent requirements.

E.g. supposing:

  • SomePackage-1.0 requires AnotherPackage>=1.0
  • SomePackage-2.0 requires AnotherPackage>=1.0 and OneMorePackage==1.0
  • SomePackage-1.0 and AnotherPackage-1.0 are currently installed
  • SomePackage-2.0 and AnotherPackage-2.0 are the latest versions available on PyPI.

Running pip install --upgrade SomePackage would upgrade SomePackage and AnotherPackage despite AnotherPackage already being satisfied.

pip doesn't currently have an option to do an "only if needed" recursive upgrade, but you can achieve it using these 2 steps:

pip install --upgrade --no-deps SomePackage
pip install SomePackage

The first line will upgrade SomePackage, but not dependencies like AnotherPackage. The 2nd line will fill in new dependencies like OneMorePackage.

See :issue:`59` for a plan of making "only if needed" recursive the default behavior for a new pip upgrade command.

User Installs

With Python 2.6 came the "user scheme" for installation, which means that all Python distributions support an alternative install location that is specific to a user. The default location for each OS is explained in the python documentation for the site.USER_BASE variable. This mode of installation can be turned on by specifying the :ref:`--user <install_--user>` option to pip install.

Moreover, the "user scheme" can be customized by setting the PYTHONUSERBASE environment variable, which updates the value of site.USER_BASE.

To install "SomePackage" into an environment with site.USER_BASE customized to '/myappenv', do the following:

export PYTHONUSERBASE=/myappenv
pip install --user SomePackage

pip install --user follows four rules:

  1. When globally installed packages are on the python path, and they conflict with the installation requirements, they are ignored, and not uninstalled.
  2. When globally installed packages are on the python path, and they satisfy the installation requirements, pip does nothing, and reports that requirement is satisfied (similar to how global packages can satisfy requirements when installing packages in a --system-site-packages virtualenv).
  3. pip will not perform a --user install in a --no-site-packages virtualenv (i.e. the default kind of virtualenv), due to the user site not being on the python path. The installation would be pointless.
  4. In a --system-site-packages virtualenv, pip will not install a package that conflicts with a package in the virtualenv site-packages. The --user installation would lack sys.path precedence and be pointless.

To make the rules clearer, here are some examples:

From within a --no-site-packages virtualenv (i.e. the default kind):

$ pip install --user SomePackage
Can not perform a '--user' install. User site-packages are not visible in this virtualenv.

From within a --system-site-packages virtualenv where SomePackage==0.3 is already installed in the virtualenv:

$ pip install --user SomePackage==0.4
Will not install to the user site because it will lack sys.path precedence

From within a real python, where SomePackage is not installed globally:

$ pip install --user SomePackage
[...]
Successfully installed SomePackage

From within a real python, where SomePackage is installed globally, but is not the latest version:

$ pip install --user SomePackage
[...]
Requirement already satisfied (use --upgrade to upgrade)

$ pip install --user --upgrade SomePackage
[...]
Successfully installed SomePackage

From within a real python, where SomePackage is installed globally, and is the latest version:

$ pip install --user SomePackage
[...]
Requirement already satisfied (use --upgrade to upgrade)

$ pip install --user --upgrade SomePackage
[...]
Requirement already up-to-date: SomePackage

# force the install
$ pip install --user --ignore-installed SomePackage
[...]
Successfully installed SomePackage

Ensuring Repeatability

pip can achieve various levels of repeatability:

Pinned Version Numbers

Pinning the versions of your dependencies in the requirements file protects you from bugs or incompatibilities in newly released versions:

SomePackage == 1.2.3
DependencyOfSomePackage == 4.5.6

Using :ref:`pip freeze` to generate the requirements file will ensure that not only the top-level dependencies are included but their sub-dependencies as well, and so on. Perform the installation using :ref:`--no-deps <install_--no-deps>` for an extra dose of insurance against installing anything not explicitly listed.

This strategy is easy to implement and works across OSes and architectures. However, it trusts PyPI and the certificate authority chain. It also relies on indices and find-links locations not allowing packages to change without a version increase. (PyPI does protect against this.)

Hash-checking Mode

Beyond pinning version numbers, you can add hashes against which to verify downloaded packages:

FooProject == 1.2 --hash=sha256:2cf24dba5fb0a30e26e83b2ac5b9e29e1b161e5c1fa7425e73043362938b9824

This protects against a compromise of PyPI or the HTTPS certificate chain. It also guards against a package changing without its version number changing (on indexes that allow this). This approach is a good fit for automated server deployments.

Hash-checking mode is a labor-saving alternative to running a private index server containing approved packages: it removes the need to upload packages, maintain ACLs, and keep an audit trail (which a VCS gives you on the requirements file for free). It can also substitute for a vendor library, providing easier upgrades and less VCS noise. It does not, of course, provide the availability benefits of a private index or a vendor library.

For more, see :ref:`pip install\'s discussion of hash-checking mode <hash-checking mode>`.

Installation Bundles

Using :ref:`pip wheel`, you can bundle up all of a project's dependencies, with any compilation done, into a single archive. This allows installation when index servers are unavailable and avoids time-consuming recompilation. Create an archive like this:

$ tempdir=$(mktemp -d /tmp/wheelhouse-XXXXX)
$ pip wheel -r requirements.txt --wheel-dir=$tempdir
$ cwd=`pwd`
$ (cd "$tempdir"; tar -cjvf "$cwd/bundled.tar.bz2" *)

You can then install from the archive like this:

$ tempdir=$(mktemp -d /tmp/wheelhouse-XXXXX)
$ (cd $tempdir; tar -xvf /path/to/bundled.tar.bz2)
$ pip install --force-reinstall --ignore-installed --upgrade --no-index --no-deps $tempdir/*

Note that compiled packages are typically OS- and architecture-specific, so these archives are not necessarily portable across machines.

Hash-checking mode can be used along with this method to ensure that future archives are built with identical packages.

Warning

Finally, 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 protections. If you need to use such a package, see :ref:`Controlling setup_requires<controlling-setup-requires>`.