title: trigger firing based on date difference with current date
body: <p>I have an item which is a trap that is returning an Epoch time like so:</p>
  
  <pre><code>1539302400
  </code></pre>
  
  <p>This represents as <code>2018-10-11 20:00:00</code></p>
  
  <p>What I want to be able to do is have a zabbix trigger that if the value on that Epoch time is less than 32 days from the current date to send an alert.</p>
  
  <p>So if the current date is <code>2018-10-01 20:00:00</code> I want the trigger to fire, but if the current date is <code>2018-09-01 20:00:00</code> then the trigger would not fire.</p>