To install ruby2.1 just follow these instructions.
/ubuntu/vivid/main///install/index.html Interpreter of object-oriented scripting language Ruby Ubuntu 15.04 ruby 2.1.2-2ubuntu3
sudo apt-get install ruby2.1
Which will install ruby2.1 and any other packages on which it depends.
Package | ruby2.1 |
Version | 2.1.2-2ubuntu3 |
Maintainer | Ubuntu Developers |
Description | Interpreter of object-oriented scripting language Ruby |
Distro | ubuntu |
Release | vivid |
Repo | main |
Section | ruby |