title: "Minus" operation on two files using Linux commands
body: <p>I have 4 files sorted alphabetically, A, B, C, and D.
  These files contain a single string on each line.
  Essentially, what needs to happen is that anything in B gets deleted from A.
  The result of that will then be stripped of anything in C.
  And similarly, the result of that will be stripped of D.</p>
  
  <p>Is there a way to this using Linux commands?</p>