title: PHP regex/search and replace multiline strings in multiple files
body: <p>I have several hundred <code>.markdown</code> files that I need to loop through and replace the following multiline strings:</p>
  
  <pre><code>---
  ---
  </code></pre>
  
  <p>I currently have the following code: </p>
  
  <pre><code>foreach (glob("*.markdown") as $filename)
  {
      $file = file_get_contents($filename);
      file_put_contents($filename, preg_replace("/regexhere/","replacement",$file));
  }
  </code></pre>
  
  <p>My question is, which regex do I need to remove the multi line strings in every file. </p>
  
  <p>Thanks</p>