TZSETUP (8) | System administration commands and daemons | Unix Manual Pages | :man▋
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:
|-n || 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/zone.tab. 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:
The source code to the database (/usr/src/share/zoneinfo/[a-z]*) contains many additional comments and documentation references for the historically minded.
- 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.)
| /etc/localtime || current time zone file |
| /etc/wall_cmos_clock || see adjkerntz(8). |
| /usr/share/misc/iso3166 || mapping of ISO 3166 territory codes to names |
| /usr/share/zoneinfo || directory for zoneinfo files |
| /usr/share/zoneinfo/zone.tab |
| || mapping of timezone file to country and location |
date(1), adjtime(2), ctime(3), timezone(3), tzfile(5), adjkerntz(8), zdump(8), zic(8)