"Europe/Prague” timezone is set by default. To change it, do the following:
Use command dpkg-reconfigure tzdata and select your option, e.g. Atlantic/Bermuda.
Then verify correct time with date
date
Fri Jul 19 12:42:56 CEST 2013
If time is correct timezone setup in Linux is done. Now you have to change timezone in PHP to have correct time in web interface, too.
Set it up in date.timezone item in /etc/php5/apache2/php.ini a /etc/php5/cli/php.ini. You will find the list of available timezones at: http://php.net/manual/en/timezones.php.
nano /etc/php5/apache2/php.ini
date.timezone = "America/Argentina/San_Juan"
Restart apache.
service apache2 restart