[ntp:questions] Re: OT: zone source file syntax

mike michael.no.spam.cook at wanadoo.fr
Tue Aug 9 09:57:56 UTC 2005


Ben Fitzgerald wrote:
> Hi,
> 
> I realise this is an ntp news group, but I couldn't find one for zone
> info files, so here goes.
> 
> On linux I didn't have my timezone source files. On a solaris box I did
> have one for europe. It has the following:
> 
> # Zone  NAME            GMTOFF  RULES   FORMAT  [UNTIL]
> Zone    Europe/London   -0:01:15 -      LMT     1847 Dec  1
>                          0:00   GB-Eire %s      1968 Oct 27
>                          1:00   -       BST	1971 Oct 31 2:00u
> 			 0:00	GB-Eire %s	1996
> 			 0:00   EU      GMT/BST
> 
> # Zone  NAME            GMTOFF  RULES  FORMAT  [UNTIL]
> Rule    EU   1981  max     -       Mar     lastSun  1:00u  1:00 S
> Rule    EU   1996  max     -       Oct     lastSun  1:00u  0    -
> 
> As I understand it the last line of the zone means that for the present
> day the EU rules should be used and that London's offset from GMT is 0.
> 
> The EU rules state:
> on the last Sun of March at 01:00UTC add one hour.
> on the last Sun of October at 01:00UTC do nothing.
> 
> It's the last part I don't get. I'd expect to see -1:00 here. My grasp
> of this is clearly not quite right. Can help explain this?
> 
> Thanks in advance for any pointers,
> 
> Ben.
> 
   Unix expects to have its clock running UTC (aka GMT) so the rules are 
ok. The library calls do the add/subtract/do-nothing as required.




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