title: Linux date command, finding seconds to next hour
body: <p>How do I find the seconds to the next hour using date? I know I can do </p>
  
  <pre><code>date -d "next hour"
  </code></pre>
  
  <p>but that just adds 1 hour to the present time. I want it to show the seconds to the next full hour. For example if the current time is <code>9:39am</code> I want to find the number of seconds to <code>10am</code></p>