title: Awk date validation
body: <p>I have an awk script where I need to validate a large number of lines containing dates.</p>
  
  <p>I'm currently using either a regex based solution to do a basic validation (without testing for leap years or ) or calling the UNIX date command to validate it more accurately. The date command works well, but calling a system command is pretty expensive in terms of performance.</p>
  
  <p>I was hoping that someone here might be able to suggest a solution that is both accurate and is fast.</p>
  
  <p>Here's an example of my data</p>
  
  <pre><code>20140804024614
  20140803190020
  20140803163320
  20140803083222
  20140803170321
  20140803234044
  20140804011857
  20140803204008
  20140803160026
  20140803140120
  </code></pre>
  
  <p>Thanks.</p>