Creating multiple isolated python environements on a single OS using virtualenv

If you're doing a lot of coding in python, you probably came to a situation where you had to maintain many projects concurrently. In such situations it is hard to provide apropriate dependant library versions    for each project (especially if by any chance those different versions of a particular library lack a compatible API, just like python 2.X and 3.X).

A naive solution would require creating a seperate user profile (or using a virtual machine) for each maintained project. Ok seriously - don't even consider it.

If you want to have mutliple python development/deplyoment envirements you should have a place to store each appropriate set of libraries and interpreters. Secondly you should implement some scripts that run your project with the right environment variables (using the right interpreter).

This approach is better, but it sounds like a lot of work. Happily someone made the job for you. All you need to do is install virtualenv:

~ $ sudo pip install virtualenv

Now to you can configure your isolated python environment:

~ $ virtualenv my_env --quiet --no-site-packages && find my_env -maxdepth 2

my_env/
my_env/local
my_env/local/lib
my_env/local/include
my_env/local/bin
my_env/lib
my_env/lib/python2.7
my_env/include
my_env/include/python2.7
my_env/bin
my_env/bin/activate_this.py
my_env/bin/pip-2.7
my_env/bin/easy_install
my_env/bin/pip
my_env/bin/activate
my_env/bin/activate.fish
my_env/bin/python
my_env/bin/activate.csh
my_env/bin/easy_install-2.7

This is a fully functional python environment, in order to activate  it you have to load it with source  command:

~ $ source my_env/bin/activate

You command prompt should now look similar to this:

(my_env) ~ $
  
The environment has now been activated, you may now install new  libraries using pip or easy install without root privileges. All files will be installed in an appropriate directory in my_env. Running the python command will run an interpreter from the currently active virtual environment.

When you're done having fun, and you want to resume your system environment, just run:

(my_env) ~ $ deactivate 

~ $ 

You can have as many virtual environments as you like, the current version should even support moving/copying the environment.

~KR