which file control TIME Zone?

[Herta Van den Eynde]

David Tonhofer, m-plify S.A. wrote:
> --On Tuesday, March 28, 2006 11:59 PM +0800 mcclnx mcc 
> <mcclnx at yahoo.com.tw> wrote:
> 
>> I have been test  Daylight saving time on REDHAT AS
>> 3.6.  All cron jobs between 2:00 A.M. to 3:00 A.M.
>> will not execute.
>>
>> We also have SUN Solaris servers, but SUN understand
>> it and will execute  cron jobs .
>>
>> Does anyone know how to make it run on Redhat LINUX
>> system?
>>
>> which file control Time ZOne setup?
>>
>> Thanks.
> 
> 
> 
> Is'nt it normal that the cronjobs won't execute? After
> all, the time interval is missing.
> 
> The cron log:
> 
> Mar 26 01:55:01 yui crond[29681]
> Mar 26 01:59:01 yui crond[30949]
> Mar 26 01:59:01 yui crond[30950]
> Mar 26 03:00:01 yui crond[31249] <-- works
> Mar 26 03:00:01 yui crond[31254]
> Mar 26 03:00:01 yui crond[31255]
> 
> Using anacron would probabyl fix this.
> 
> This old message may help more. I had some problems with timezoning
> in RH ES 4.0, and:
> 
>> There is a new file "/etc/timezone" which contains the name
>> of the timezone selected during install ("Europe/Luxembourg")
> 
> 
>> The file that has been traditionally there "/etc/localtime",
>> which should contain a copy of the TimeZone structure dump
>> in /usr/share/zoneinfo/Europe/Luxembourg, was missing.
> 
> 
>> I copied /usr/share/zoneinfo/Europe/Luxembourg into /etc/localtime
>> and all was well.

from the "man 5 crontab" pages:

"Commands  are  executed by cron(8) when the
  minute, hour, and month of year fields match
  the current time, and when at least one of
  the two day fields (day of month, or day of week)
  match the current time (...).  Note that this
  means that  non-existant times, such as
  "missing hours" during daylight savings
  conversion, will never match, causing  jobs
  scheduled  during  the  "missing times"
  not to  be  run.   Similarly,  times that occur
  more than once (again, during daylight savings
  conversion) will cause matching jobs to
  be run twice."

Depending on what your system is used for, if you want to avoid "missing 
times" or duplicate times, you could copy one of the timezone files from 
/usr/share/zoneinfo/Etc/ to /etc/localtime, as they don't use daylight 
savings.
Alternatively, reschedule your cronjobs to avoid running during daylight 
savings conversions.  Or mark your calendar to reschedule them just for 
the nights the conversions take place.

Kind regards,

Herta

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