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>Yup, but *for cron* something does happen. What's the exact behaviour?
>Does cron wake up each minute, checks date, and makes actions? This would
>mean that an action scheduled for 2:30 each Sunday night was not executed
>when DST started (because cron found that after 1:59 there was 3:00) and
>will be executed twice when it will end?
No, cron keeps a list of actions and whenever an action is started it will
schedule also the next event.
The DST changes are never handled very well in cron, though.
Different things should happen to jobs that:
run every n minutes (no problem there)
run every hour (should run twice at 2:00 am when summertime ends?,
and only 23 times in a day when DST starts)
run every day/week/month during the "lost hour"
(should be run exactly once, even when DST changes)
I don't think cron does all that, nor do I know what standards say on this.
What cron typically does is compute the time for the next run/
Then when a job is being run, cron checks whether it's permitted to
run at the time it wakes up; if not, it reschedules.
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