On Ubutu:
If you get 0.system for the version, this means you have the version that PHP shipped with. For a newer version, you must upgrade via the PECL extension (sudo pecl install timezonedb)
http://pecl.php.net/package/timezonedb
(PHP 5 >= 5.3.0, PHP 7)
timezone_version_get — Gets the version of the timezonedb
Returns the current version of the timezonedb.
Returns a string.
Example #1 Getting the timezonedb version
<?php
echo timezone_version_get();
?>
以上例程的输出类似于：
2009.7
On Ubutu:
If you get 0.system for the version, this means you have the version that PHP shipped with. For a newer version, you must upgrade via the PECL extension (sudo pecl install timezonedb)
http://pecl.php.net/package/timezonedb