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Re: Clock/Time issues



On Mon, 25 Apr 2005, Charles Malespin wrote:

I forgot to mention that I am running a dual boot with XP on the other
side.  Does this mean that I cant use the UTC option?  Is there
something else that I can do since I am using XP?  Thanks,
Charles

You can set Linux to expect the hardware clock to contain local time (using system-config-date), but the switch back and forth between standard time and daylight time is a pain. Linux only updates the hardware clock for daylight time if it is running when the switch is made. Windows updates the first time it's booted after the switch whether Linux updated it or not. In Windows, each user can set the update flag individually. On a multi-boot, multi-user system, chaos ensues when the changeover occurs.


I have a dual-boot FC/XP system. I don't use the XP side much, so I did the following:

(1) Set up Linux so the hardware clock uses UTC and Linux uses my timezone (US Eastern).

(2) Set up Windows to use timezone GMT (GMT standard time is the same as UTC).

(3) Turn off daylight savings time auto-adjust for all Windows users.

(4) Live with the fact that Windows time is 4-5 hours later than local time. If I want to know what time it is when in Windows, I look at my watch.



On Mon, 2005-04-25 at 15:32 -0400, Deron Meranda wrote:
On 4/25/05, Bruno Wolff III <bruno wolff to> wrote:
On Mon, Apr 25, 2005 at 11:51:59 -0500,
  Charles Malespin <charles malespin gmail com> wrote:
Hi all,
   I am running FC3 with the newest kernel 2.6.11 but am having some
clock issues.  Every time I boot up the clock is set back 5 hours from
what the actual time is.

This is usually caused by the bios having the clock set to local time, but linux is assuming it is GMT.

The right way to do this is to have the BIOS clock set to GMT, but I don't
think this works well with Windows if you are dual booting the machine.

Yes, you want the BIOS hardware clock to be set to UTC time. The only reason to ever leave the BIOS in "local" time is if you are dual-booting with Windows which can not deal with timezones correctly. As long as you're all Unix/Linux/BSD: hardware clock should always be UTC.

The system-config-date GUI has a checkbox for "system clock uses UTC".
As well, you can just edit the config file /etc/sysconfig/clock and set the
UTC= variable to true

UTC=true

then reboot.  Also you may want to set up NTP, or at least one-shot
set the clock with a command like following,

ntpdate 0.pool.ntp.org





-- Matthew Saltzman

Clemson University Math Sciences
mjs AT clemson DOT edu
http://www.math.clemson.edu/~mjs


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