Date command will display your current date time with time zone.
date Fri Apr 21 13:59:49 IST 2016
To change date and time
date -s "21APR2017 10:06:00"
To change only date
date +%Y%m%d -s "20170421"
To change only time
date +%T -s "11:14:00"
How to change time zone
First take backup of existing localtime file
cp /etc/localtime /backup/localtime_backup
Copy and overwrite existing /etc/localtime file by selecting your prefer timezone file which present in /usr/share/zoneinfo/ directory. eg. I want set timezone to Kolkata.
cp /usr/share/zoneinfo/Asia/Kolkata /etc/localtime
Hardware clock know as Real Time Clock (RTC)
If hardware clock is different timezone from system timezone then edit file /etc/sysconfig/clock.
update below timezone
ZONE="Asia/Kolkata" UTC=true ARC=false
you can also set using cli.
hwclock --set --date "21 Oct 2017 21:17" --IST
Then verify both time zone system as well as hardware type
note: It is always advised to reboot the system after changing date time or time zone because some of the services currently running will be holding old time. eg. cronjob, MySQL.