This post very useful information about changing the timezone in Ubuntu, CentOS, Fedora, RHEL system. We have already discussed about manage timezones.

This page shows two different types to chnages the timezone in Linux sytems.

Type 1: 

For example establish time format in Ubuntu 15.04, now check your current time,

# date
Thu Nov 12 00:53:20 EST 2015

Open your terminal and run the below command,
#  dpkg-reconfigure tzdata

In configuration tzdata, select time zones in which they are located (use UP and DOWN arrow key) then hit the Enter Key.

Then select the city or region corresponding to your time zone. next hit the Enter Key.

Output :

Current default time zone: 'Asia/Kolkata'
Local time is now:      Thu Nov 12 11:24:14 IST 2015.
Universal Time is now:  Thu Nov 12 05:54:14 UTC 2015.

Finally check the currently system date and time.
# date
Thu Nov 12 11:24:17 IST 2015

Also you can use same format in Redhat, CentOS/Fedora,FreeBSD/Slackware using the below command,

 # redhat-config-date

# system-config-date

# tzselect

Note : If you could not found the command system-config-date, Its asking permission to you for  install that package in your system. then press 'y'.

bash: system-config-date: command not found...
Install package 'system-config-date' to provide command 'system-config-date'? [N/y] y

Type 2 :

The following commands can be support to change timezone fromat in CentOS 7, Fedora 23, Ubuntu 15.04

Syntax :

sudo timedatectl set-timezone <timeszone>

set timezone as EST:
# sudo timedatectl set-timezone EST

set timezone as UTC:
# sudo timedatectl set-timezone UTC

Do you want to set specific timezone format run the command,
# sudo timedatectl set-timezone  Asia/Kolkata

List all timezone formats.
# timedatectl list-timezones