So you want to try ruby 1.9 and rails 3? Awesome! You’ve come to the right place. Before installing ruby 1.9 or rails 3 you want to install RVM (Ruby Version Manager). RVM is a handy tool which allows you to have multiple version of Ruby installed on your system (along with gems, which include Rails).
RVM — Ruby Version Manager
Straight from the RVM Website:
RVM is a command line tool which allows us to easily install, manage and work with multiple ruby environments from interpreters to sets of gems. RVM itself is easy to install!
I couldn’t have explained it better my self. So let’s get started! In order to install RVM just download the gem
sudo gem install rvm