on Wed, Apr 25, 2001 at 04:53:46PM -0500, Bud Rogers ([EMAIL PROTECTED]) wrote: > "Karsten M. Self" <kmself@ix.netcom.com> writes: > > I've got a job I'd like to run once a month, on a set day of the week, > > say, the first Sunday of the month. Suggestions as to how to do this > > with cron? > > Could you wrap the job in a shell scrip? Run the script from cron every > Sunday. Have the script check if the date is within the first seven days of > the month. If so run the job, else exit quietly. Not very elegant, but it > would get the job done.
If you'll refer to my original post you'll see that this was one option
I'd considered.
In my case, I decided that the simplest heuristic was, at the start of
the period in question, to schedule a job for the desired weekday (a
time specification allowed under GNU at), for some time later in the day
than the likely execution time of the cron job.
Note that there is no guarantee of scheduling under cron or at, and
under anomolous circumstances (very high system load, downtime, etc.),
jobs may not run when scheduled, or complete within a reasonable time.
I'd selected a roughly 1.5 hour difference to provide some measure of
leeway.
Hence, my crontab recipie to execute a job on the first sunday of the
month is:
1 1 1 * * echo 'command -args' | at 1:35 sunday
...or
At one minute past midnight on the first of the month, schedule the
following job for the first following 1:35 am that occurs on a
Sunday, via the 'at' scheduler.
Even if the current day _is_ Sunday, it
isn't yet 1:35 am, so the job will run at this time.
For tasks scheduled for other weeks of the month, you'd select:
Week Day
---- ---
1 1
2 8
3 15
4 21
5 29
Yes, there are other ways of doing this, however, the method shown
- Works.
- Works correctly.
- Is immediately apparent within the crontab.
- Relies on existing logic for proper determination of date, time, and
weekday.
- Doesn't require independent implementation of checks for date, time,
and weekday, subject to error and nonstandard implementation.
Cheers.
--
Karsten M. Self <kmself@ix.netcom.com> http://kmself.home.netcom.com/
What part of "Gestalt" don't you understand? There is no K5 cabal
http://gestalt-system.sourceforge.net/ http://www.kuro5hin.org
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