Timezone info

[Lunt, Nick]

Thanks for your help, but how do I see what time change rules are in the zone file ?

My /etc/localtime is a symlink to /usr/share/zoneinfo/Europe/London.

$ strings /etc/localtime
TZif
BDST
$

>From that output I cannot tell that the time will change at 2am. 

man tzfile and man tzset do not seem to show me how to change the time at which I would like the machine to start interpreting daylight savings time.

>>If zoneinfo file contains correct rules it will be the
>>same moment as set by the government. Therefore, you will not have any
>>problems with the time change.


This is important because we have Oracle running on these machines, and Oracle does not react well to time changes.

On our HPUX boxes we have a /usr/lib/tztab file in which we can specify at what time to move over to daylight saving, and we schedule Oracle to be down at this time. 
Am I correct in thinking that we do not have this functionality on RH ?

Thanks,
Nick .


> -----Original Message-----
> From: A.Fadyushin at it-centre.ru [mailto:A.Fadyushin at it-centre.ru]
> Sent: 28 October 2005 14:54
> To: redhat-list at redhat.com
> Subject: RE: Timezone info
> 
> 
> The rules for time changes are described in zoneinfo files. So, if you
> use the correct link '/etc/localtime' and that link points to the
> up-to-date file (i.e. the file /usr/share/zoneinfo/Europe/London
> contains officially declared time change rules which is currently in
> force) your boxes will change the time exactly at the moment set in
> zoneinfo files. If zoneinfo file contains correct rules it will be the
> same moment as set by the government. Therefore, you will not have any
> problems with the time change.
> 
> Also, you do not need to reboot the system for the change to take
> effect. The internal clock in the Linux kernel always uses UTC,
> regardless of tile zone. The localtime is then produced from 
> the UTC on
> the proccesses' requests in accordance with time zone 
> information (e.g.
> from /etc/localtime). At the moment of time change the kernel 
> clock will
> not be changed, only the rules for computation of local time will be
> changed.
> 
> Alexey Fadyushin.
> Brainbench MVP for Linux.
> http://www.brainbench.com
> 
> 
> > -----Original Message-----
> > From: redhat-list-bounces at redhat.com [mailto:redhat-list-
> > bounces at redhat.com] On Behalf Of Lunt, Nick
> > Sent: Friday, October 28, 2005 2:24 PM
> > To: Redhat (E-mail)
> > Subject: Timezone info
> > 
> > Hi folks,
> > 
> > This Sunday in the UK the time will be going backwards one hour. I
> need to
> > know if I can tell the system when to make this change or how I can
> find
> > out when this change is scheduled for.
> > 
> > All our boxes use a local timeserver which punts out the 
> UTC time and
> our
> > linux boxes convert that into the localtime for the box.
> > 
> > Here's some info from one of my boxes
> > 
> > # date
> > Fri Oct 28 11:18:27 BST 2005
> > # date -u
> > Fri Oct 28 10:18:29 UTC 2005
> > 
> > Our /etc/localtime is pointing to /usr/share/zoneinfo/Europe/London.
> > After the time change on Sunday `date` and `date -u` will output the
> same
> > time (I hope ;)
> > 
> > Can anyone give me any pointers on finding out when/how the 
> boxes will
> go
> > back an hour please ?
> > 
> > It seems that the machine will only pick up the new time after a
> reboot  -
> > can anyone confirm this ?
> > 
> > I've tried googling with not much luck.
> > I've also browsed the archives for last year around October 
> but didn't
> see
> > anything there either.
> > 
> > Cheers
> > Nick .
> > 
> > 
> > 
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