title: Cron job every day from 8AM to 8PM at 20 minutes interval
body: <p>How to run <code>cron job</code> every day from <code>8:00 AM</code> to <code>8:00 PM</code> at 20 minutes interval eg cron job  should start at <code>8:00 AM</code> every day, then run at <code>8:20 AM</code> then <code>8:40 AM</code> then <code>9:00 AM</code> up to <code>8:00 PM</code>. Thanks.</p>
  
  <p><strong>EDIT:</strong> How to Implement it with ruby <code>whenever</code> gem.</p>