[Lias] linux time

[Andrew Dorrell]

Parkes High School wrote:
> One every Linux machine I have so far set up I end up with the wrong 
> time – I have not set the cmos time to GMT.
> 
> On most machines I have set up I have a dual boot with Windows – Windows 
> time is OK but Linux is always out – I have set time zone to Australia – 
> NSW.
> 
>  
> 
> I’m doing something simple wrong obviously. 
> 
> (Loving the idea of Linux but feeling frustrated)

Dual booting always gives you time problems because these two systems 
deal with time differently.  In particular, windows assume the HW clock 
is set to the local time.  When daylight savings time arrives it duely 
changes the time as stored in the HW clock.  Linux on the other hand 
assumes the HW clock carries some reference time and adjusts for any 
local modifications during daylight savings (and doesn't change the 
value in the HW clock).  The practical upshot of this is:

1. You need to tell linux that the value in the HW clock is the local 
time (on RH this is set in /etc/sysconfig/clock (set UTC=false))

2. At daylight savings changeover, reboot in windows to have the HW 
clock adjusted for the new localtime (do not adjust it under linux as 
windows will adjust it again when it reboots)

(Loving the idea of dual boot but acknowledging the problems it can cause)
-- 
Andrew Dorrell PhD.        Senior Research Engineer
Canon Information Systems Research Australia     Phone: 61 2 9805 2224
1 Thomas Holt Drive,  North Ryde,  NSW 2113.     Fax:   61 2 9805 2865