Ubuntu/Debian Quick Reference: How To Change Your Server’s UTC Timezone on the command line

Just Type…
sudo dpkg-reconfigure tzdata

…and follow the instructions on screen.

The process should look something like the following:

Select your Region

Select a city on your time zone

You’re done.

Tip
You can always check the status of your configuration using
sudo debconf-show tzdata

You could for example map that command via ssh to several machines and grep for “*”, that way you could easily spot servers with wrong timezones very quickly.