According to the upstream package maintainer in Debian (Aurelien Jarno), /etc/localtime is the authoritive source of information, while /etc/timezone is just a Debian-specific artifact.
Thus the preferred approach for changing the timzone is indeed the change of the /etc/localtime symlink, followed by dpkg-reconfigure. See https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=813226#10 and https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=848143#10. ** Bug watch added: Debian Bug tracker #813226 https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=813226 ** Bug watch added: Debian Bug tracker #848143 https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=848143 -- You received this bug notification because you are a member of Ubuntu Touch seeded packages, which is subscribed to tzdata in Ubuntu. https://bugs.launchpad.net/bugs/1554806 Title: Change of behavior: "dpkg-reconfigure -f noninteractive" unconditionally overwrites /etc/timezone now Status in tzdata package in Ubuntu: Confirmed Bug description: In previous versions it was possible to set the system's timezone by editing /etc/timezone before running "dpkg-reconfigure -f noninteractive tzdata". This behavior changed, /etc/timezone gets overwritten unconditionally during "dpkg-reconfigure -f noninteractive tzdata": --- root@xenial:/# echo "Europe/Berlin" > /etc/timezone root@xenial:/# cat /etc/timezone Europe/Berlin root@xenial:/# dpkg-reconfigure -f noninteractive tzdata Current default time zone: 'Etc/UTC' Local time is now: Tue Mar 8 23:09:39 UTC 2016. Universal Time is now: Tue Mar 8 23:09:39 UTC 2016. root@xenial:/# cat /etc/timezone Etc/UTC --- As a workaround to programmatically set the timezone one now needs to point "/etc/localtime" to the new timezone: --- root@xenial:/# ln -fs /usr/share/zoneinfo/Europe/Berlin /etc/localtime root@xenial:/# ll /etc/localtime lrwxrwxrwx 1 root root 33 Mar 9 00:48 /etc/localtime -> /usr/share/zoneinfo/Europe/Berlin root@xenial:/# cat /etc/timezone Etc/UTC root@xenial:/# dpkg-reconfigure -f noninteractive tzdata Current default time zone: 'Europe/Berlin' Local time is now: Wed Mar 9 00:49:05 CET 2016. Universal Time is now: Tue Mar 8 23:49:05 UTC 2016. root@xenial:/# cat /etc/timezone Europe/Berlin --- To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/tzdata/+bug/1554806/+subscriptions -- Mailing list: https://launchpad.net/~touch-packages Post to : touch-packages@lists.launchpad.net Unsubscribe : https://launchpad.net/~touch-packages More help : https://help.launchpad.net/ListHelp
