How to Confirm Admin Access in Mac OS X
To run Ruby on Mac OS X, you have to install Ruby and several developer tools. To install the needed Ruby developer tools for Mac OS X, you need to be logged in to your computer using an account with Admin access.
If you’re the only person using the computer, you’re usually an administrator by default. If you share a computer at home, school, or work, you may need help to get access to an administrative account. You can check your access level by going to the Users & Groups control panel inside the System Preferences application. You only need Admin access during setup.