Virtualenv

Virtual Python Environment or venv is a Python environment which will help you to install different versions of Python modules in a local directory using which you can develop and test your code without requiring to install everything systemwide.

Installation

In Python3 we can use the venv module to create virtual environments.

Usage

We will create a directory call virtual inside which we will have two different virtual environment.

The following commands will create an env called virt1.

$ cd virtual
$ python3 -m venv virt1
$

Now we can activate the virt1 environment.

$ source virt1/bin/activate
(virt1)[user@host]$

The first part of the prompt is now the name of the virtual environment, it will help you identify which environment you are in when you have multiple environments.

To deactivate the environment use deactivate command.

(virt1)$ deactivate
$

So, now we will install a Python module called redis.

(virt1)$ pip install redis
Collecting redis
  Downloading redis-2.10.5-py2.py3-none-any.whl (60kB)
    100% |████████████████████████████████| 61kB 607kB/s
Installing collected packages: redis
Successfully installed redis-2.10.5

Now we will create another virtual environment virt2 where we will install the same redis module but an old 2.4 version of it.

$ python3 -m venv virt2
$ source virt2/bin/activate
(virt2)$
(virt2)$ pip install redis==2.4
Downloading/unpacking redis
Downloading redis-2.4.0.tar.gz
Running setup.py egg_info for package redis
Installing collected packages: redis
Running setup.py install for redis
Successfully installed redis
Cleaning up...

This way you can have many different environments for all of your development needs.

Note

Always remember to create virtualenvs while developing new applications. This will help you keep the system modules clean.