title: Windows CMD: List files in dir & subdir WITHOUT given extensions
body: <p>I'd like to recursively search a directory and find files, which have NOT a certain extension, or precisely, which have NOT a certain set of extensions.</p>
  
  <p><strong>Sketch: find in "dir" all files without "ext1", "ext2", "ext3" and print results to .txt</strong></p>
  
  <p>I tried around several hours with DIR and ATTRIB, but unfortunately without bigger success.</p>
  
  <p>Your consideration is highly regarded! Thanks.</p>