title: grep for multiple strings in file on different lines (ie. whole file, not line based search)?
body: <p>I want to grep for files containing the words <code>Dansk</code>, <code>Svenska</code> or  <code>Norsk</code> on any line, with a usable returncode (as I really only like to have the info that the strings are contained, my one-liner goes a little further then this).</p>
  
  <p>I have many files with lines in them like this:</p>
  
  <pre><code>Disc Title: unknown
  Title: 01, Length: 01:33:37.000 Chapters: 33, Cells: 31, Audio streams: 04, Subpictures: 20
          Subtitle: 01, Language: ar - Arabic, Content: Undefined, Stream id: 0x20, 
          Subtitle: 02, Language: bg - Bulgarian, Content: Undefined, Stream id: 0x21, 
          Subtitle: 03, Language: cs - Czech, Content: Undefined, Stream id: 0x22, 
          Subtitle: 04, Language: da - Dansk, Content: Undefined, Stream id: 0x23, 
          Subtitle: 05, Language: de - Deutsch, Content: Undefined, Stream id: 0x24, 
  (...)
  </code></pre>
  
  <p>Here is the pseudocode of what I want:</p>
  
  <pre><code>for all files in directory;
   if file contains "Dansk" AND "Norsk" AND "Svenska" then
   then echo the filename
  end
  </code></pre>
  
  <p>What is the best way to do this?  Can it be done on one line?</p>