rails binary package in Ubuntu Precise amd64

 Rails is a full-stack, open-source web framework in Ruby for writing
 real-world applications.
 .
 Being a full-stack framework means that all layers are built to work
 seamlessly together. That way you don't repeat yourself and you can
 use a single language from top to bottom. Everything from templates to
 control flow to business logic is written in Ruby.
 .
 This is (almost) empty dependency package which provide the rails
 command which runs the defaults version of the rails. If you need
 a specific version of rails, you need to depend on ruby-rails-VERSION
 package.

Source package