date manupulation strangeness

[Eugene Grosbein]

On Sun, Oct 28, 2007 at 07:20:11PM +0100, Holger Kipp wrote:

> > # unixtime=1193511599
> > # LC_ALL=C TZ=Asia/Krasnoyarsk date -jr $unixtime
> > Sun Oct 28 02:59:59 KRAT 2007

Here it shows 'Sun Oct 28 02:59:59 KRAST 2007' really
(cut-n-paste error, mea culpa). Take a note of zone name,
KRAST stands for 'KRAsnoyarsk Summer Time' and
KRAT stands for 'KRAsnoyarsk Time' (winter one).

> > That's last second of Summer time in this time zone.
> > 
> > # LC_ALL=C TZ=Asia/Krasnoyarsk date -f %s $unixtime
> > Sun Oct 28 02:59:59 KRAT 2007
> > 
> > That's an hour later after the switch from Summer time,
> > but how can it be? It is a bug?
> 
> I haven't checked, but usually during switch from summer
> to winter time, you change the clock back from 03:00 to
> 02:00, so you have the same hour twice.
> 
> So you have 02:59:59 summer time and then you have
> (instead of 03:00:00) 02:00:00 winter time a second
> later, so one hour later you end up with 02:59:59 again.

Yes, but "02:59:59 KRAT" is one hour (minus one second) later
than "02:00:00 KRAT", the latter equals to "03:00:00 KRAST",
so the first invocation of 'date' command shows time an hour
before time the second invocation shows. However,
unixtime is the same. That bothers me, something is wrong.

Eugene