In Linux, the system time zone is determined by the symbolic link /etc/localtime. This symbolic link points to a time zone data file located at either /usr/share/zoneinfo or /usr/lib/zoneinfo depending on Linux distribution. So changing the system timezone is just a simple job of updating this symbolic link.

Run the following command to view the list of regions

ls -l /usr/share/zoneinfo

Choose the most appropriate region.

Suppose we have to set the system timezone as UK timezone, so we pick up “Europe” as the region. “Europe” is a directory in /usr/share/zoneinfo.

Now run following ls command to view the city listing and choose an appropriate one.

ls -l /usr/share/zoneinfo/Europe

We choose London for our example.

Next step is to update the symbolic link, so run the following command

ln -sf /usr/share/zoneinfo/Europe/London /etc/localtime

If you wish you could have taken a backup before updating the symbolic link as below

mv /etc/localtime /etc/localtime-bck

In CentOS, you might need to also edit /etc/sysconfig/clock. This file contains an entry as shown below

ZONE="Europe/London"

Now verify whether timezone has been updated or not by running the date command.

[wbs@DVSRVR001 ~]$ date
Mon Jul 14 18:21:40 BST 2014
[wbs@DVSRVR001 ~]$

BST stands for “British Summer Time”.

To change the timezone for the current user session only, you can set the environment variable TZ as shown below

export TZ="Europe/London"

One more method of changing the system timezone is to run one of the following commands based on your Linux distribution you may.

Ubuntu: dpkg-reconfigure tzdata
Redhat: redhat-config-date
CentOS/Fedora: system-config-date
FreeBSD/Slackware: tzselect

This method will open an ASCII menu that will allow you to choose your timezone. Current timezone is selected by default when the menu opens.

Running the command “dpkg-reconfigure tzdata” in Ubuntu displays the screen shown in the image below