title: Unix timestamp to days, hours, minutes
body: <p>So, I have a field in my users table named <code>last_active</code> which updates every time a user reloads a page.<br> It's stored in unix timestamp. </p>
  
  <p>I would like to output it like this: <code>Last online: 4 d 18 h 19 m ago</code></p>
  
  <p>How would one do that? Can you do it with php's date()?</p>
  
  <p>Thank you.</p>