Switch Ruby Version In Your Terminal with rbenv

How can you switch between Ruby versions in Terminal? Say you want to give jruby a test-drive. Once it is bundled up, you use this command to switch for your current session:

rbenv shell jruby-1.7.18

To verify that switch did indeed work:

ruby -v

Which will give you the output:

jruby 1.7.18 (1.9.3p551) 2014-12-22 625381c on Java HotSpot(TM) 64-Bit Server VM 1.8.0_25-b17 +jit [darwin-x86_64]

To switch to any Ruby version, you do not specify Ruby explicitly, but instead reference it by the version number:

rbenv shell 2.2.0