title: Crontab Formatting - every 15 minutes
body: <p>I'm trying to get a simple crontab job to run every 15 minutes and am having trouble deciding how to format the timing.</p>
  
  <p>What I've been putting down is the following:</p>
  
  <pre><code>15 * * * * ------------------------
  </code></pre>
  
  <p>I'm pretty sure this just runs the first 15 minutes of every hour.</p>
  
  <p>I think that crontab allows users to specify exact times to run, namely:</p>
  
  <pre><code>0, 15,30,45 * * * * -------------------------
  </code></pre>
  
  <p>But if I wanted to run the crontab every 15 minutes from the moment I start it, (which may not necessarily be on a value divisible by 15), how would I go about formatting that/is that possible?</p>