What is RVM?
RVM stands for Ruby Version Manager.
Why use RVM?
When you start making a ton of websites with Ruby and Rails, you’ll have a lot of versions of Ruby and Rails. For example, your honor society’s website might have been built with Ruby 1.9.2/Rails 3.2.0. Your club sports team’s website might have been built with Ruby 1.9.1/Rails 3.1.0. If you don’t have RVM on your computer, you can only have ONE version of Ruby and ONE version of Rails on your computer. With RVM, you can have multiple versions of Ruby/Rails.
How to install Ruby 1.9.2 on your computer
rvm install 1.9.2
How to create and use a new gemset named “blog” for Ruby 1.9.2
rvm --create use 1.9.2@blog
How to list all the gemsets managed by RVM
rvm gemset list
How to list all the versions of Ruby managed by RVM
How to delete a gemset email@example.com
rvm gemset delete firstname.lastname@example.org
How to use JRuby 1.6.5
rvm use jruby-1.6.5