pip supports installing from PyPI, version control, local projects, and directly from distribution files.
$ 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 pip install reference.
“Requirements files” are files containing a list of items to be installed using pip install like so:
pip install -r requirements.txt
Details on the format of the files are here: Requirements File Format.
Logically, a Requirements file is just a list of pip install arguments placed in a file.
In practice, there are 4 common uses of Requirements files:
Requirements files are used to hold the result from pip freeze for the purpose of achieving repeatable installations. 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
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
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:
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:
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.
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 pip wheel as a convenience, to build wheels for all your requirements and dependencies.
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
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 pip uninstall reference.
To list installed packages:
$ pip list Pygments (1.5) docutils (0.9.1) Sphinx (1.1.2) Jinja2 (2.6)
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
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 pip search reference.
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.
- On Unix and Mac OS X the configuration file is: $HOME/.pip/pip.conf
- On Windows, the configuration file is: %HOME%\pip\pip.ini
You can set a custom path location for the config file using the environment variable PIP_CONFIG_FILE.
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
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
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:
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
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.
- --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
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 you shell, e.g. by adding the following to your startup file:
eval "`pip completion --bash`"
Often, you will want a fast install from local archives, without probing PyPI.
First, download the archives that fulfill your requirements:
$ pip install --download <DIR> -r requirements.txt
$ pip install --no-index --find-links=[file://]<DIR> -r requirements.txt
pip install --upgrade is currently written to perform a recursive upgrade.
- SomePackage-1.0 requires AnotherPackage>=1.0
- SomePackage-2.0 requires AnotherPackage>=1.0 and OneMorePoject==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 satisifed.
If you would like to perform a non-recursive upgrade perform 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.
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 –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:
- When globally installed packages are on the python path, and they conflict with the installation requirements, they are ignored, and not uninstalled.
- 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).
- 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.
- 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
Three things are required to fully guarantee a repeatable installation using requirements files.
- The requirements file was generated by pip freeze or you’re sure it only contains requirements that specify a specific version.
- The installation is performed using –no-deps. This guarantees that only what is explicitly listed in the requirements file is installed.
- The installation is performed against an index or find-links location that is guaranteed to not allow archives to be changed and updated without a version increase. Unfortunately, this is not true on PyPI. It is possible for the same pypi distribution to have a different hash over time. Project authors are allowed to delete a distribution, and then upload a new one with the same name and version, but a different hash. See Issue #1175 for plans to add hash confirmation to pip, or a new “lock file” notion, but for now, know that the peep project offers this feature on top of pip using requirements file comments.