TimeZone in Linux

Unix time, or POSIX time, is a system for describing points in time: it is the number of seconds elapsed since midnight UTC on the morning of January 1, 1970, not counting leap seconds.

Generic procedure to change timezone

Change directory to /etc

# cd /etc

Create a symlink to file localtime e.g. 

if you want to set up it to IST (Asia/Calcutta):

# ln -sf /usr/share/zoneinfo/Asia/Calcutta localtime

Please mote that in above example you need to use directory structure i.e. if you want to set the timezone to Calcutta (India) which is located in the Asia directory you will then have to setup using as above

Please do check with date command:

$ date

Output:

Mon Oct  8 16:39:56 IST 2012

Use of environment variable

You can use TZ environment variable to display date and time according to your or other timezones:

$ export TZ=Asia/Calcutta

$ date

Output:

Mon Oct  8 16:39:56 IST 2012

Here is the small script to check TIME from US-Chicago,Shanghai and India.

#!/bin/bash

echo -ne "India\t\t\c \t"

export TZ=Asia/Calcutta

date

echo -ne "Shanghai\t\c \t"

export TZ=Asia/Shanghai

date

echo -ne "US-Chicago\t\c \t"

export TZ=America/Chicago

date