tzsetup - set the local timezone
tzsetup [-y] [-g]
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 tzse-
lect(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
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(1) rcS(5) tzconfig(8)
Joey Hess <firstname.lastname@example.org>
Debian 11 June 2001 TZSETUP(8)
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