[ec2-user@ip-10-118-22-125 ~]$ sudo yum install ruby-devel
Loaded plugins: priorities, update-motd, upgrade-helper
amzn-main/2013.09                                                                                                                                                                                                      | 2.1 kB     00:00
amzn-updates/2013.09                                                                                                                                                                                                   | 2.3 kB     00:00
Package ruby-devel-1.8.7.374-2.11.amzn1.x86_64 already installed and latest version
Nothing to do