title: Questions about ruby directory install
body: <p>I'm installing ruby on my system and I'm getting an error <code>You don't have write permissions for the /Library/Ruby/Gems/2.0.0 directory</code>. </p>
  
  <p>As far as I understand, there is a local version of ruby that the system uses already on my machine. How can I ensure that I'm not trying to write to that directory as opposed to the new one? </p>