When you getting following warning message while execute PHP file, need to configure timezone database in sever.

PHP Warning:  Unknown: It is not safe to rely on the system's timezone settings. You are *required* to use the date.timezone setting or the date_default_timezone_set() function. In case you used any of those methods and you are still getting this warning, you most likely misspelled the timezone identifier. We selected 'Asia/Calcutta' for 'IST/5.0/no DST' instead in Unknown on line 0

Configure the data.timezone on php.ini to disappear the PHP warning message,
# vim /etc/php.ini

date.timezone = "Asia/Jakarta"