title: Can't use Rails
body: <p>I've installed new Rails 3.1.3 using <code>gem</code></p>
  
  <pre><code># gem install rails
  </code></pre>
  
  <p>Then type:</p>
  
  <pre><code>wbednarski@mbp13:~$ rails
  Rails is not currently installed on this system.
  To get the latest version, simply type:
  
  $ sudo gem install rails
  
  You can then rerun your "rails" command.
  </code></pre>
  
  <p>More WTF:</p>
  
  <pre><code>wbednarski@mbp13:~$ which rails
  /usr/bin/rails
  </code></pre>
  
  <p>How is it possible that command <code>rails</code> exist but Rails is not installed and how to fix it?</p>
  
  <p><strong>EDIT:</strong></p>
  
  <pre><code>wbednarski@mbp13:~$ sudo gem install rails
  Password:
  Successfully installed rails-3.1.3
  1 gem installed
  Installing ri documentation for rails-3.1.3...
  Installing RDoc documentation for rails-3.1.3...
  </code></pre>
  
  <p>then</p>
  
  <pre><code>wbednarski@mbp13:~$ rails -v
  Rails is not currently installed on this system. To get the latest version, simply type:
  
      $ sudo gem install rails
  
  You can then rerun your "rails" command.
  </code></pre>