Subject: Re: Timezone Setting (was A couple of problems)
To: None <perry@imsi.com>
From: Terry Moore <tmm@uunet.uu.net>
List: current-users
Date: 07/27/1995 03:26:46
> This should be a FAQ.
> 
> Stefano Gobbo writes:
> > 2  Timezone setting. I just rebuild my kernel and I wanted to
> >    adjust timezone to MET (since now, it is set to the some US TZ).
> >    Which values must I give to the TIMEZONE and DST entry in the config
> >    file? I've read somwhere thah it needs the time shift expressed in 
> >    minutes. Is it true? Since MET is +1 hour to GMT but seems to me that
> >    TZ=0 is set up to an US TZ, how must I behave?
> 
> The kernel setting isn't what you use -- thats an ancient bit of
> residue -- don't touch it. Timezone isn't in the kernel any more.

Actually, I did touch it, and it was helpful.  The kernel setting
controls what the kernel assumes about the time zone for the CMOS
battery-backed clock in the hardware, both getting and setting.
For many people, having the timezone for the clock be different than
local standard time is just too confusing.  So, for my group, I build
kernels to use local time for the hardware clock.

> You simply link /etc/localtime to the appropriate file in
> /usr/share/zoneinfo. The only stuff that cares are userland programs
> and their localtime() calls check that ZIC file to figure out what to
> do.

There are two mappings:

	CMOS <=> Kernel GMT time

and 

	Kernel GMT time <=> local time as reported by "date", for example.

The kernel config file setting controls the former; the /etc/localtime
setting controls the latter.

--Terry Moore
tmm@mcci.com