[CentOS] {Q} Relate to daylight saving time on Nov. 6 cron job

Mon Oct 10 21:08:49 UTC 2011
Bowie Bailey <Bowie_Bailey at BUC.com>

On 10/10/2011 5:04 PM, mcclnx mcc wrote:
> We have CENTOS 4.X and 5.X on DELL servers.  On Nov. 6, 2:00 A.M. will change to 1:00 A.M.
> If I have cron job on 1:20 A.M., will it run twice?

$ man cron


   Daylight Saving Time and other time changes
       Local time changes of less than three hours, such as those caused
by the start or end of Daylight Saving Time,
       are handled specially.  This only applies to jobs that run at a
specific time and jobs that  are  run  with  a
       granularity greater than one hour.  Jobs that run more frequently
are scheduled normally.

       If  time  has  moved forward, those jobs that would have run in
the interval that has been skipped will be run
       immediately.  Conversely, if time has moved backward, care is
taken to avoid running jobs twice.

       Time changes of more than 3 hours are considered to be
corrections to the clock or timezone, and the new  time
       is used immediately.