Setting up a virtual environment from scratch

Dependencies, if necessary:
$ easy_install pip
$ pip virtualenv

Create virtual environment:
$ mkdir ~/env
$ mkdir ~/env/RIS
$ virtualenv -p /usr/local/bin/python3.4 env/RIS

Enter virtual environment and install libraries:
source env/RIS/bin/activate
(RIS) $ pip install yolk3k
(RIS) $ pip install Flask

Query for packages already installed:
(RIS) $ yolk -l

Create the requirements.txt:
(RIS) $ pip freeze > requirements.txt

Finally:
(RIS) $ deactivate