title: Crawl a website, then download all files of a specific type based on the occurrence of a text string on a page
body: <p>I believe I have a rather unique question. Or at least I was unable to find a solution to a similar problem. </p>
  
  <p>I want to crawl a website and then on each page I want to search for a particular text string. If the text string is found I want to download all files of a specific type (PDF) that are linked to that page. </p>
  
  <p>I would appreciate a complete answer but if anybody could just point me in the direction of the necessary software or framework that could to accomplish this it would be greatly appreciated.   </p>