title: How to update system Ruby to 1.9.2 on Mac?
body: <p>I saw an answer saying I should use RVM. But I don't know how even after: </p>
  
  <pre><code>$ rvm system
  $ rvm current
  system
  
  $ ruby -v
  ruby 1.8.7 (2009-06-12 patchlevel 174) [universal-darwin10.0]
  </code></pre>