This tutorial will guide you through installing Python 3 on a CentOS 7  system using the Software Collections (SCL) alongside the distribution  default Python version 2.7. We will also show you how to create a Python  virtual environment.

Python is one of the most popular  programming languages in the world. With its simple and easy to learn  syntax Python is a great choice for beginners and experienced  developers. Python is a quite versatile programming language. You can  use it to do almost anything you want, write small scripts, build games,  develop websites, create machine learning algorithms, analyze data, and  more.

Many  popular applications and websites, including YouTube, DropBox, Reddit,  Quora, Instagram, Pinterest have been developed using Python.

Python 2 support ends in 2020. Python 3 is the present and future of the language.

Enable Software Collections (SCL)

Software Collections,  also known as SCL is a community project that allows you to build,  install, and use multiple versions of software on the same system,  without affecting system default packages. By enabling SCL you will gain  access to the newer versions of programming languages and services  which are not available in the core repositories.

CentOS  7 ships with Python 2.7.5 which is a critical part of the CentOS base  system. SCL allows you to install newer versions of python 3.x alongside  the default python v2.7.5 so that system tools such as yum will continue to work properly.

To  enable SCL, you need to install the CentOS SCL release file. It is part  of the CentOS extras repository and can be installed by running the  following command:

sudo yum install centos-release-scl

Installing Python 3 on CentOS 7

Now  that you have access to the SCL repository, you can install any Python  3.x version you need. Currently, the following Python 3 collections are  available:

  • Python 3.3
  • Python 3.4
  • Python 3.5
  • Python 3.6

In  this tutorial, we will install Python 3.6, which is the latest version  available at the time of writing. To do so type the following command on  your CentOS 7 terminal:

sudo yum install rh-python36

Using Python 3

Once the package rh-python36 is installed, check the Python version by typing:

python --version
Python 2.7.5

You will notice that Python 2.7 is the default Python version in your current shell.

To access Python 3.6 you need to launch a new shell instance using the Software Collection scl tool:

scl enable rh-python36 bash

What the command above does is calling the script /opt/rh/rh-python36/enable, which changes the shell environment variables.

If you check the Python version again, you’ll notice that Python 3.6 is the default version in your current shell now.

python --version
Python 3.6.3

It is important to point out that Python 3.6 is set as  the default Python version only in this shell session. If you exit the  session or open a new session from another terminal Python 2.7 will be  the default Python version.

Installing Development Tools

Development tools are required for building Python modules. To install the necessary tools and libraries type:

sudo yum groupinstall 'Development Tools'

Creating a Virtual Environment

Python Virtual Environments allows you to install Python modules in an isolated location for a  specific project, rather than being installed globally. This way, you do  not have to worry about affecting other Python projects.

The preferred way to create a new virtual environment in Python 3 is by executing the venv command.

Let’s say you want to create a new Python 3 project called my_new_project inside your user home directory and matching virtual environment.

First, create the project directory and switch to it:

mkdir ~/my_new_project

Activate Python 3.6 using the scl tool:

scl enable rh-python36 bash

From inside the project root run the following command to create a virtual environment named my_project_venv:

python -m venv my_project_venv

To start using the virtual environment, activate it by typing:

source my_project_venv/bin/activate

After activating the environment, the shell prompt will be prefixed with the name of the environment:

(my_project_venv) user@host:~/my_new_project$

Copy

Starting with Python 3.4, when creating virtual environments pip, the package manager for Python is installed by default.

Conclusion

You  should now have Python 3 programming environment set up on your CentOS 7  machine, and you can start developing your Python 3 project.

You can also read about how to install Odoo 11 on CentOS 7 and see an example of how to use Python 3 virtual environment to run Python software on a CentOS 7 server.

If you have any questions or feedback, feel free to comment below.