In command prompt past the following lines:-

1)sudo apt-get update

2)sudo apt-get install curl

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

4)source ~/.rvm/scripts/rvm

5)rvm requirements

6)rvm install ruby 1.9.3

7)rvm use ruby 1.9.3

8)rvm gemset create new-rails

9)rvm use @new-rails --default

Precise, Trusty, Xenial and higher

There is now an official Ubuntu package: https://github.com/rvm/ubuntu_rvm

Install

1. Add the PPA and install the package

Open a terminal (Ctrl+Alt+T) and run:

sudo apt-add-repository -y ppa:rael-gc/rvm
sudo apt-get update
sudo apt-get install rvm

Add your user to rvm group ($USER will automatically insert your username):

sudo usermod -a -G rvm $USER

2. Change your terminal window

Now, in order to always load rvm, change the Gnome Terminal to always perform a login.

At terminal window, click Edit > Profile Preferences, click on Command tab and check Run command as login shell.

3. Logout and login

A lot of changes were made and in order to properly get all them working, you need to login and logout. This requires not only close terminal window, but really logout and login again.

4. Install a ruby

Now you're ready to install rubies. Open a terminal (Ctrl+Alt+T) and run:

rvm install ruby