Installing Rails 4 on Linux Ubuntu Server 12.04

Step 1: Install RVM

Before you install ruby, you need to install a few libraries by the components you are installing, enter the following command.

sudo apt-get install build-essential curl

\curl -L https://get.rvm.io | bash -s stable

after it installing is done, close your terminal and start new one to begin
check the 'rvm' command shell

rvm

in order to work, RVM has some of its own dependancies that need to be installed. To automatically install them:

rvm requirements

Step 2: Install Ruby

rvm install ruby

we need the system using the ruby current installed

rvm use ruby --default

Step 3: Install RubyGems

rvm rubygems current

Step 4: Install Rails

gem install rails