In this post I’ll cover setting up a virtual environment in Python 2.7 in preparation for working out a RESTful app in Flask.

Installation

So, I’ll assume you’re running a Debian flavor of Linux. You’ll need curl, so if you don’t already have that, run the following from the command line:

sudo apt-get install curl

Then, using curl, you can install pip.

curl --silent --show-error --retry 5 https://bootstrap.pypa.io/get-pip.py | sudo python2.7

Then, using pip, you can install virtualenv.

sudo pip install virtualenv

Now, we’re good to go.

Creating a Virtual Environment

First create a directory to hold your virtual environments.

mkdir venvs

Next, create a virtual environment by specifying the root directory of that environment. By default, no site-packages are installed.

virtualenv venvs/one

This creates a virtual environment in ./venvs/one/. To activate this environment, use the command,

source venvs/one/bin/activate

This will change your command line to reflect that you are working in a virtual environment. To get out of the virtual environment, execute the following:

deactivate

Seeing What is Installed

To see what is installed in your virtual envrionment, use the yolk utility. First install using apt-get

sudo apt-get install yolk

And then use the following from inside the virtual environment to see what you have installed.

yolk -l