title: how to set ruby1.9.1 as default version on debian squeeze
body: <p>I am using Debian Squeeze as my OS and am trying to develop a Ruby on Rails projects. For that I first installed some ruby packages.</p>
  
  <p>My ruby versions are: ruby1.8, ruby1.9.1</p>
  
  <p>Then I uninstalled ruby1.8 to make ruby1.9.1 my default ruby.</p>
  
  <p>Now if I run:</p>
  
  <pre><code>$ which ruby
  </code></pre>
  
  <p>it displays nothing.</p>
  
  <p>If I run:</p>
  
  <pre><code>$ which ruby1.9.1
  /usr/bin/ruby1.9.1
  </code></pre>
  
  <p>However:</p>
  
  <pre><code>$ rails new testApp
  bash: /usr/bin/rails: /usr/bin/ruby1.8: bad interpreter: No such file or directory
  </code></pre>
  
  <p>I don't know what to do. Please guide me.</p>