At first, we need Ruby, at least a 1.8.7 version for Rails 3 installation. Also we need a database, here which is MySQL and the necessary RubyGems.
All these dependencies and Rails can be installed in a single command,
$ yum install rubygem-rails ruby-devel mysql-devel ruby-mysql -y
The above command installs MySQL, Ruby 1.8.7, Rubygems, and Rails 2.3.8. But we need Rails 3, isn’t it? So, type this command after running the previous one.
$ gem install rails
This will install the Rails 3 framework.