title: Comparing two files in linux terminal
body: <p>There are two files called <strong>"a.txt"</strong> and <strong>"b.txt"</strong> both have a list of words. Now I want to check which words are extra in <strong>"a.txt"</strong> and  are not in <strong>"b.txt"</strong>. </p>
  
  <p>I need a efficient algorithm as I need to compare two dictionaries.</p>