title: Performing set operations using linux command
body: <p>I have the following two lists of numbers stored in two different files:</p>
  
  <pre><code>File A:
  7
  1
  2
  9
  
  File B:
  10
  8
  4
  9
  </code></pre>
  
  <p>Now I want to find out the set operation A-B (i.e. find only those numbers that are in A but not in B). Is there some way by which I may do the same using linux command (like sed). I know it is possible to do it using python, but I am just curious to know if it is possible to do the same using some linux command?</p>