From Sigmon

format_time

   function format_time($s) {
      $rem = $s;

      $days = intval($rem / 86400);
      $rem = $rem % 86400;

      $hour = intval( $rem / 3600 );
      $rem = $rem % 3600;

      $min  = intval( $rem / 60 );
      $rem = $rem % 60;

      $sec = $rem;

      $r = '';
      if ($day > 0)     $r .= ($day).'d ';
      if ($hour > 0)    $r .= ($hour).'h ';
      if ($min > 0)     $r .= ($min).'m ';
      if ($sec > 0)     $r .= ($sec).'s ';

      return $r;
   }