title: Homebrew - bad interpreter: No such file or directory
body: <p>Like an idiot, I managed to delete my system ruby install.</p>
  
  <p>I've re-installed xcode, and also installed RVM</p>
  
  <p>Doing this:  </p>
  
  <pre><code>$ which ruby
  </code></pre>
  
  <p>returns this:  </p>
  
  <pre><code>/Users/alex/.rvm/bin/ruby
  </code></pre>
  
  <p>However, Homebrew still seems to be broken:</p>
  
  <pre><code>$ brew  
  -bash: /usr/local/bin/brew: /usr/bin/ruby: bad interpreter: No such file or directory
  </code></pre>