title: Bash compare file last modification date with another date
body: <p>I need to check if the last modification date of a file if greater than a date saved in a variable like this:</p>
  
  <pre><code>variable=$date
  
  if [ $file_last_modified_date -gt $variable ]; then.......
  </code></pre>
  
  <p>The error I get: <code>[: too many arguments</code></p>
  
  <p>I'm afraid, the error is because the two formats are different:</p>
  
  <ul>
  <li><code>file_last_modified_date</code>: <code>2016-11-01 23:00:00.000000000 +0100</code></li>
  <li><code>variable</code>: <code>Wed Nov 2 16:10:52 CET 2016</code></li>
  </ul>
  
  <p>How can I make them comparable?</p>