Ask Ubuntu is a question and answer site for Ubuntu users and developers. Join them; it only takes a minute:

Sign up
Here's how it works:
  1. Anybody can ask a question
  2. Anybody can answer
  3. The best answers are voted up and rise to the top

Please correct me if I am wrong here....

When I change my system clock this changes the file /usr/share/zoneinfo immediately, HOWEVER, the actual system time doesn't change until the next reboot because /etc/localtime then re-reads /usr/share/zoneinfo?

I have seen behaviour similar to the above, whereby /usr/share/zoneinfo/ was accessed but the system time did not change until after the system had rebooted

share|improve this question

Every process knows the time zone (you can alter it on a per-process basis by setting the TZ environment variable). When you change the system time zone, only newly launched processes will "see" the new time zone setting. This is why it seems to only fully take effect with a reboot. If you restart applications and services they should pick up the change

Notably, your system logging daemon will continue to write logs in the old timezone until it is restarted.

share|improve this answer

Your Answer


By posting your answer, you agree to the privacy policy and terms of service.

Not the answer you're looking for? Browse other questions tagged or ask your own question.