TZSETUP(8) MidnightBSD System Manager’s Manual TZSETUP(8)


tzsetup — set local timezone


tzsetup [−n] [default]


The tzsetup utility reads a database of timezone information and presents a menu allowing the user to select a specific zone without knowing the details of the database layout. The selected zone is installed as the system default zone. The tzsetup utility also determines whether any adjustment is necessary for systems where the hardware clock does not keep UTC.

The following option is available:


Do not create or copy files.

It is possible to short-circuit the menu system by specifying a default on the command line; this is intended mainly for pre-configured installation scripts.


The contents of the timezone database are indexed by /usr/share/zoneinfo/ This file lists, for each timezone data file, the ISO 3166 territory code, approximate geographical coordinates (in ISO 6709 format), and location within the territory.

The maintainers of the database maintain the following policies:


At least one zone for every country or inhabited geographical territory.


One zone for every distinct, documented timezone history since the beginning of the UNIX epoch (January 1, 1970, GMT).


Each zone is named for the most populous city therein. (Where possible, the database includes pre-1970 history for its city.)

The source code to the database (/usr/src/share/zoneinfo/[a-z]*) contains many additional comments and documentation references for the historically minded.


current time zone file


see adjkerntz(8).


mapping of ISO 3166 territory codes to names


directory for zoneinfo files


mapping of timezone file to country and location


date(1), adjtime(2), ctime(3), timezone(3), tzfile(5), adjkerntz(8), zdump(8), zic(8)


The representation of certain localities as being associated with certain countries and/or territories is for the purposes of identification only, and does not imply any endorsement or rejection on the part of the FreeBSD Project of the territorial claims of any entity.


Programs which are already running when tzsetup creates or updates /etc/localtime will not reflect the updated timezone. When the system is first configured for a non-UTC hardware clock, it is necessary to run adjkerntz(8) (which normally happens as a part of system startup) in order to update the kernel’s idea of the correct timezone offset.

MidnightBSD 0.3 January 24, 1996 MidnightBSD 0.3