title: Display a message using msg in PHP
body: <p>I have to redirect a to a page and say x already exist.</p>
  
  <p>I am doing some think like this:</p>
  
  <pre><code>header('location:newcategory.php'?msg=category exists);
  </code></pre>
  
  <p>I would prefer to do this from PHP, rather than in JavaScript.</p>