Installing additional Python packages using pip

Nowadays, a lot of operating systems come with Python as a standard component. Most Linux distributions and UNIX-based systems, such as FreeBSD, NetBSD, OpenBSD, or macOS, come with Python either installed by default or available through system package repositories. Many of them even use it as part of some core components – Python powers the installers of Ubuntu (Ubiquity), Red Hat Linux (Anaconda), and Fedora (Anaconda again). Unfortunately, the preinstalled system version of Python is often Python 2.7, which is fairly outdated.

Due to Python's popularity as an operating system component, a lot of packages from PyPI are also available as native packages managed by the system's package management tools, such as apt-get (Debian, Ubuntu), rpm (Red Hat Linux), or emerge (Gentoo). It should be remembered, however, that the list of available libraries is very limited, and they are mostly outdated compared to PyPI. This is the reason why pip should always be used to obtain new packages in the latest version, as recommended by the Python Packaging Authority (PyPA). Although it is an independent package, starting from version 2.7.9 and 3.4 of CPython, it is bundled with every new release by default. Installing the new package is as simple as this:

pip install <package-name>

Among other features, pip allows specific versions of packages to be forced (using the pip install package-name==version syntax) and upgraded to the latest version available (using the --upgrade switch). The full usage description for most of the command-line tools presented in the book can be easily obtained simply by running the command with the -h or --help switch, but here is an example session that demonstrates the most commonly used options:

$ pip show pip
Name: pip
Version: 18.0
Summary: The PyPA recommended tool for installing Python packages.
Home-page: https://pip.pypa.io/
Author: The pip developers
Author-email: pypa-dev@groups.google.com
License: MIT
Location: /Users/swistakm/.envs/epp-3rd-ed/lib/python3.7/site-packages
Requires: 
Required-by:

$ pip install 'pip>=18.0'
Requirement already satisfied: pip>=18.0 in (...)/lib/python3.7/site-packages (18.0) 

$ pip install --upgrade pip
Requirement already up-to-date: pip in (...)/lib/python3.7/site-packages (18.0)

In some cases, pip may not be available by default. From Python 3.4 onward (and also Python 2.7.9), it can always be bootstrapped using the ensurepip module:

$ python -m ensurepip
Looking in links: /var/folders/z6/3m2r6jgd04q0m7yq29c6lbzh0000gn/T/tmp784u9bct
Requirement already satisfied: setuptools in /Users/swistakm/.envs/epp-3rd-ed/lib/python3.7/site-packages (40.4.3)
Collecting pip
Installing collected packages: pip
Successfully installed pip-10.0.1

The most up-to-date information on how to install pip for older Python versions is available on the project's documentation page at https://pip.pypa.io/en/stable/installing/.