title: Delete empty lines from a file
body: <p>I need to delete empty lines from a file (with spaces only - not null records).</p>
  
  <p>The following command works only for null rows, but not in case of
  spaces:</p>
  
  <p><code>sed '/^$/d' filename</code></p>
  
  <p>Can it be done using grep?</p>