title: Extract text from url using Nginx
body: <p>I am trying to find a way to extract some text from a url to be used in alias. 
  The url is something like:</p>
  
  <pre><code>/test/user_code_name/
  </code></pre>
  
  <p>and the alias should be</p>
  
  <pre><code>/test1/user_name/
  </code></pre>
  
  <p>So the idea is to just remove the part between _ and _ and use it like a variable.</p>
  
  <p>Thx
  L.</p>