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Re: system time


On Fri, 07 Sep 2007, daniele pendenza wrote:

> It's time :-) to understand why my DEBIAN/GNU/LINUX system thinks that 
> the "BIOS time" is set up as the GMT time and shift it to the "local" time.
> 1- what part of the system controls this behavior ? is there only a flag 
> somewhere whose value could be only  GMT or LOCAL ?
> 2- how can i change this behavior ?


there is
- BIOS Time
- Linux Time & MS Windows Time

normally the thing works like this:

pc turned of, bios time is running
pc is turned of
os is booted
os reads the bios time, ONE TIME
os is running
os is shutting down
bios is running its time

the bios time has no relevance if you use linux&windows, its only purpose is
to store the time, while the OS is turned off, or the OS is sleeping.

Linux vs. Windows

Linux shows each user his local time. Thats done by calculating time for the
user. Each user can have its different TimeZone.

Of Course there is also a System-Default-Timezone..

And the question remains, should linux store the time into the bios clock
using the system-default-timezone or should it store gmt?

Windows on the otherside.. is _always_ using local time, and calculates the
timezones from it. So if you run a german windows its default ist GMT+2, so
is the bios set. if you run windows in greenwitch, windows uses GMT and
stores GMT into the bios.

so .. if you want to use dual boot, linux windows, its a good idea to run
linux with its system-default-timezone same as windows, and let linux store
the bios time this way.

and.. to change such things, run 'tzconfig'.

Florian Reitmeir

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