Installing Python 3 by Kenneth Reitz & Real Python. Copy for people who could't reach source website: docs.python-guide.org/

linux.md

Installing Python 3 on Linux

This document describes how to install Python 3.6 on Ubuntu Linux machines.

To see which version of Python 3 you have installed, open a command prompt and run

$ python3 --version

If you are using Ubuntu 16.10 or newer, then you can easily install Python 3.6 with the following commands:

$ sudo apt-get update
$ sudo apt-get install python3.6

If you’re using another version of Ubuntu (e.g. the latest LTS release), we recommend using the deadsnakes PPA to install Python 3.6:

$ sudo apt-get install software-properties-common
$ sudo add-apt-repository ppa:deadsnakes/ppa
$ sudo apt-get update
$ sudo apt-get install python3.6

If you are using other Linux distribution, chances are you already have Python 3 pre-installed as well. If not, use your distribution’s package manager. For example on Fedora, you would use dnf:

$ sudo dnf install python3

Note that if the version of the python3 package is not recent enough for you, there may be ways of installing more recent versions as well, depending on you distribution. For example installing the python36 package on Fedora 25 to get Python 3.6. If you are a Fedora user, you might want to read about multiple Python versions available in Fedora.

Working with Python 3

At this point, you may have system Python 2.7 available as well.

$ python

This will launch the Python 2 interpreter.

$ python3

This will launch the Python 3 interpreter.

Setuptools & Pip

The two most crucial third-party Python packages are setuptools and pip.

Once installed, you can download, install and uninstall any compliant Python software product with a single command. It also enables you to add this network installation capability to your own Python software with very little work.

Python 2.7.9 and later (on the python2 series), and Python 3.4 and later include pip by default.

To see if pip is installed, open a command prompt and run

$ command -v pip

To install pip, follow the official pip installation guide - this will automatically install the latest version of setuptools.

Note that on some Linux distributions including Ubuntu and Fedora the pip command is meant for Python 2, while the pip3 command is meant for Python 3.

$ command -v pip3

However, when using virtual environments (described below), you don’t need to care about that.

Pipenv & Virtual Environments

The next step is to install Pipenv, so you can install dependencies and manage virtual environments.

A Virtual Environment is a tool to keep the dependencies required by different projects in separate places, by creating virtual Python environments for them. It solves the “Project X depends on version 1.x but, Project Y needs 4.x” dilemma, and keeps your global site-packages directory clean and manageable.

For example, you can work on a project which requires Django 1.10 while also maintaining a project which requires Django 1.8.

So, onward! To the Pipenv & Virtual Environments docs!

osx.md

Installing Python 3 on Mac OS X

The latest version of Mac OS X, High Sierra, comes with Python 2.7 out of the box.

You do not need to install or configure anything else to use Python 2. These instructions document the installation of Python 3.

The version of Python that ships with OS X is great for learning, but it’s not good for development. The version shipped with OS X may be out of date from the official current Python release, which is considered the stable production version.

Doing it Right

Let’s install a real version of Python.

Before installing Python, you’ll need to install GCC. GCC can be obtained by downloading XCode, the smaller Command Line Tools (must have an Apple account) or the even smaller OSX-GCC-Installer package.

Note: If you already have XCode installed, do not install OSX-GCC-Installer. In combination, the software can cause issues that are difficult to diagnose.

Note: If you perform a fresh install of XCode, you will also need to add the commandline tools by running xcode-select --install on the terminal.

While OS X comes with a large number of UNIX utilities, those familiar with Linux systems will notice one key component missing: a package manager. Homebrew fills this void.

To install Homebrew, open Terminal or your favorite OSX terminal emulator and run

$ ruby -e "$(curl -fsSL https://raw.githubusercontent.com/Homebrew/install/master/install)"

The script will explain what changes it will make and prompt you before the installation begins. Once you’ve installed Homebrew, insert the Homebrew directory at the top of your PATH environment variable. You can do this by adding the following line at the bottom of your ~/.profile file

export PATH="/usr/local/opt/python/libexec/bin:$PATH"

If you have OS X 10.12 (Sierra) or older use this line instead

export PATH=/usr/local/bin:/usr/local/sbin:$PATH

Now, we can install Python 3:

$ brew install python

This will take a minute or two.

Pip

Homebrew installs pip pointing to the Homebrew’d Python 3 for you.

Working with Python 3

At this point, you have the system Python 2.7 available, potentially the Homebrew version of Python 2 installed, and the Homebrew version of Python 3 as well.

$ python

will launch the homebrew-installed Python 3 interpreter.

$ python2

will launch the homebrew-installed Python 2 interpreter (if any).

$ python3

will launch the homebrew-installed Python 3 interpreter.

If the Homebrew version of Python 2 is installed then pip2 will point to Python 2. If the Homebrew version of Python 3 is installed then pip will point to Python 3.

The rest of the guide will assume that python references Python 3.

# Do I have a Python 3 installed?
$ python --version
Python 3.7.1 # Success!

Pipenv & Virtual Environments

The next step is to install Pipenv, so you can install dependencies and manage virtual environments.

A Virtual Environment is a tool to keep the dependencies required by different projects in separate places, by creating virtual Python environments for them. It solves the “Project X depends on version 1.x but, Project Y needs 4.x” dilemma, and keeps your global site-packages directory clean and manageable.

For example, you can work on a project which requires Django 1.10 while also maintaining a project which requires Django 1.8.

So, onward! To the Pipenv & Virtual Environments docs!

windows.md

Installing Python 3 on Windows

First, follow the installation instructions for Chocolatey. It’s a community system packager manager for Windows 7+. (It’s very much like Homebrew on OSX.)

Once done, installing Python 3 is very simple, because Chocolatey pushes Python 3 as the default.

choco install python

Once you’ve run this command, you should be able to launch Python directly from to the console. (Chocolatey is fantastic and automatically adds Python to your path.)

Setuptools + Pip

The two most crucial third-party Python packages are setuptools and pip, which let you download, install and uninstall any compliant Python software product with a single command. It also enables you to add this network installation capability to your own Python software with very little work.

All supported versions of Python 3 include pip, so just make sure it’s up to date:

python -m pip install -U pip

Pipenv & Virtual Environments

The next step is to install Pipenv, so you can install dependencies and manage virtual environments.

A Virtual Environment is a tool to keep the dependencies required by different projects in separate places, by creating virtual Python environments for them. It solves the “Project X depends on version 1.x but, Project Y needs 4.x” dilemma, and keeps your global site-packages directory clean and manageable.

For example, you can work on a project which requires Django 1.10 while also maintaining a project which requires Django 1.8.

So, onward! To the Pipenv & Virtual Environments docs!