Tutorials
Setup datetime in linux from command line
To automaticaly configure datetime on a debian server, you'll need NTP server installed.
sudo apt-get install ntp
Reconfigure timezone
sudo dpkg-reconfigure tzdata
Automatic timezone configuration
export DEBIAN_FRONTEND=noninteractive
export DEBCONF_NONINTERACTIVE_SEEN=true
sudo ln -sf /usr/share/zoneinfo/Europe/Berlin /etc/localtime
dpkg-reconfigure --frontend noninteractive tzdata