TZSETUP
NAME SYNOPSIS DESCRIPTION A WORD OF WARNING Internals FILES DERIVATION SEE ALSO AUTHOR
tzsetup - set the local timezone
This manual page explains how you can use the tzsetup utility to set the local timezone. This is necessary to let your system know about the difference between system time and local time (the time in the real world). It is also necessary to make your system behave nicely when your location uses Daylight Savings Time.
A valid system time together with the correct local time zone will give you best performance and highest reliablility. It is especially important in a network environment, where even small time differences can make a mirror refetch a whole ftp site, or where time stamps on external file systems are used.
tzsetup is typically called without any parameters from the shell. Optionally, the -y parameter can be used, to make it always change your time zone without asking first. The -g parameter can also be used, to make it ask if the hardware clock is set to gmt or not.
After you made your choice, tzsetup will try to change the timezone for you. See the Internals section below for technical details. You must have root privilegies to actually change anything. Please use tzselect(1)? as a user space command to just look at the timezones. It will print the local time in any timezone recognized by the system.
What timezone is correct for your system? It depends on the geographical location of the machine. Getting the correct location is important, but the system must also know how your hardware clock is set. Most DOS based PCs set their hardware clock on Local Time, while most UNIX systems set their hardware clock to UTC.
The Debian GNU/Linux system gains its knowledge of this setting from the file /etc/default/rcS. This file contains either the line UTC=yes, which indicates that the hardware clock is set to UTC, or it contains the line UTC=no, which declares the hardware clock is set to Local Time. If these setting are correct, and the hardware clock is truely set as indicated, then configuring the proper timezone for the machine will cause the proper date and time to be displayed. If these are not set correctly, the the reported time will be quite incorrect. See hwclock(8) for more details on this topic.
The work done by tzsetup is actually pretty simple. It just updates the link /etc/localtime to point to the correct timezone installed in /usr/share/zoneinfo/.
There is nothing wrong with doing this manually. However, using tzsetup you don't have to remember the path to the timezones.
/etc/timezone /etc/localtime /usr/share/zoneinfo
This program is based on tzconfig(8)? -- the only major difference is that this program uses debconf for its user interface, and that it allows configuration of GMT.
hwclock(8) tzselect(8) rcS(5) tzconfig(8)?
Joey Hess
One page links to tzsetup(8):
