title: How do I install ruby gems on Mac
body: <p>How do I install RubyGems on my Mac?</p>
  
  <p>I tried to run <code>$ gem install rubygems-update</code> with no luck . It returns</p>
  
  <pre><code>ERROR:  While executing gem ... (Gem::FilePermissionError)
      You don't have write permissions for the /Library/Ruby/Gems/2.0.0 directory.
  </code></pre>
  
  <p>Any help would be great. Thanks</p>