I have two versions of Compass, 0.12 and 0.13.alpha. The default version is 0.13.alpha but sometimes I need to switch to 0.12.
What command will permit this, please?
If you are switching versions for different projects, I recommend using either RVM (Ruby) or virtualenv with some help (Python) or something similar to manage gems and versions. Bundler will help make either solution simpler to maintain.
If you are switching versions within a project, I recommend reconsidering your approach.