title: grep for exact match
body: <p>I have a file that looks like this:</p>
  
  <pre><code>1   2HE MET 1.8493
  1   3HE MET 1.3568
  2   H   GLN 6.1731
  2   HA  GLN 4.2384
  2   2HB GLN 2.2204
  2   3HB GLN 1.3062
  </code></pre>
  
  <p>I use the grep command: <code>grep H file</code> and get all the lines as shown above. I would like to only retrieve the line <code>2   H   GLN 6.1731</code>.
  I've used <code>grep 'H$'file</code> as well as <code>grep -x H processed_shifts.out</code> but do not get any output with these commands. How could I modify the grep command to only get line 3 as the output?</p>