title: Web crawler: Checking multiple webpages' subpages for a specific string
body: <p>How would one go about this:<br>
  <strong>I have a list that contains approx 160 pages, each with ±5 submenues. In total, I have to check for a specific tag in 800 pages and return the pages where a specific tag is missing.</strong></p>
  
  <p>I came up with this pseudo-code (thinking in Python) so far</p>
  
  <pre><code>for each URL in URL_list
      fetch pagesource
      for each submenu_link in pagesource
          fetch pagesource
          if string "&lt;h2 class=\"subtitle\"&gt;" is not in pagesource:
          print submenu_link + "subtitle missing"
  </code></pre>
  
  <p>What do you think? Wrong approach?<br>Don't know which web crawler lib/module I should use or programming language for that matter - recommendations are welcome!</p>