Date/Time setting
Fritz Whittington
f.whittington at att.net
Wed Mar 2 23:31:01 UTC 2005
On or about 2005-03-02 14:40, Fritz Whittington whipped out a trusty #2 pencil
and scribbled:
> On or about 2005-03-02 06:14, Alan McDonald whipped out a trusty #2
> pencil and scribbled:
>
>> I synchronise some files across an ftp connection. The files comes from a
>> computer with the current date/time set, and my PC is also set with
>> correct
>> time (both clock and hwclock return the correct time). But the files
>> which
>> are writtin into the ftp directory are 13 hours ascew.. How can I correct
>> this? Where is the magic setting for making files writen to disk obey the
>> curret clock?
>> thanks
>> Alan
>>
>>
> I'm presuming that this involves moving files from a Windows machine to
> Linux, or vv. Both Windows and Linux use UTC for timestamps. The
> difference is, in Windows you set the hardware clock to your local time,
> tell it which timezone you're in, and it converts to UTC when stamping
> file times. Likewise, it converts timestamps back to local time for
> DISPLAY purposes when you list the directory.
> Linux/Unix do it the other way. The hardware clock is usually set to
> UTC, you tell it what time zone you're in, and the DISPLAY of times will
> be in local, but timestamps on files will be in UTC.
>
> As a convenience to those who have one machine with a dual-boot of
> Windows/Linux, most distros allow you to declare that the hardware clock
> is actually not UTC, but local. Then when Linux boots, it reads the
> hardware clock, applies the TZ correction, then sets the system clock to
> UTC. If you tell Linux the hardware clock is UTC, then it doesn't apply
> the correction on boot, just sets the system clock to the hardware
> clock, and goes on as usual.
>
> Windows of course, has no facility to be told that the hardware clock is
> on UTC, and to correct for local time zone on booting. So for Windows
> you must set local time on the hardware clock.
> Another problem is that you can have your Windows time zone set
> incorrectly, and someone has set the hardware clock to compensate. So
> if I in the US Central TZ set my Windows system to the Greenwich time
> zone, then fiddle with the clock setting so that the time "looks
> correct", then Windows will think it does not need to apply any
> correction to get UTC, but all it's timestamps will then be off by 6
> hours. (A file created at 8:00 am local time would actually be stamped
> as 0800 UTC, when it really should be stamped as 0200 UTC.)
Oooops! That should be 1400 UTC, not 0200 UTC. Sorry if the example caused
even more confusion...
> Similar things of course can happen in Linux, in the opposite direction,
> if you don't have your TZ data set correctly and just force the clock to
> look like correct local time.
>
--
Fritz Whittington
Man is by nature a political animal. (Aristotle, Politics)
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