Your post is in Linux-General forum, so I will give you a general answer.
Every distribution has a specific method or user interface to deal with the time zones, and you may have interest in find the way for your distro.
Anyway,
The date format is controlled by a binary file with the definitions for your local time (daylight saving range, name of your zone, distance from the UTC, etc).
This file is /etc/localtime.
To change to another zone, simply copy or link it from files in /usr/share/zoneinfo/.
In you case, you can:
Code:
# cp /usr/share/zoneinfo/EST /etc/localtime
(or)
# rm /etc/localtime
# ln -s /usr/share/zoneinfo/EST /etc/localtime
Some distro have a file named /etc/sysconfig/clock or /etc/sysconfig/timezone
where you set the default localtime. have a look. It is read at boot time and set the localtime for process started at this time.
