title: Compares lines in two files
body: <p>how could we compare lines in two files using a shell script.</p>
  
  <p>I want to compare line in one file with the line in other.<code>diff</code> will give me all the differences in two files at a time.i want a line in the first file to be compared with all the lines in the second file and get the common lines as the output. with the line numbers where the lines are present in the second file.</p>