title: best way to convert timestamps to unix to find time delta, then put back to human readable format?
body: <p>Real world example: using this (bash) tool to determine average time to backup databases in production.</p>
  
  <p>Log format is:</p>
  
  <pre><code>YYMMDD HH:MM:SS
  </code></pre>
  
  <p>example:</p>
  
  <pre><code>140809 04:22:45
  </code></pre>
  
  <p>Making it into unix for easy subtraction isn't a problem. But how do I go about passing this along as an argument to the date command, and how can I put the diff into a hours, minutes, seconds delta? </p>