[CentOS] crontab and/or anacrontab ?

Tony Molloy tony.molloy at ul.ie
Thu Mar 11 17:03:09 UTC 2010


On Thursday 11 March 2010 16:17:13 Timothy Murphy wrote:
> Alexander Dalloz wrote:
> > let's take the case that you have a power failure or a scheduled
> > maintenance with your system for instance in the early morning hours,
> > from 03:00am - 05:00am. cron.daily is set by default to run at 04:02am.
> > So in this case cron could not perform tasks like logwatch. logwatch will
> > miss in such a case, *if* there wouldn't be anacron which takes over the
> > task to run after the machine is up again (i.e. at 05:00am).
> 
> Thanks for your response.
> 
> Actually, I wouldn't mind in the slightest if cron.daily failed to run
> because the machine was down at the nominated time.
> It is not as though my world depends on cron.daily running every day.
> I certainly would not run another program in case that happened.
> 

You're world may not depend on it but those of us who run 10's of servers need
a bit more reassurance.  ;-)

> > How anacron handles jobs is documentend in "man 8 anacron". It uses
> > timestamp files in /var/spool/anacron/ to control, when a job was last
> > performed and whether it is pending.
> 
> Actually, "man 8 anacron" does not say that.
> It says "Anacron records the date in a special timestamp file",
> but it doesn't say where that file is.
> 

They're in /var/spool/anacron. Three files cron.daily .weekly .monthly.

> I see that there are actually files /var/spool/anacron/cron.daily , etc,
> on my machine listing the last day anacron ran (20100311)
> But it seems that this information is not used, in my case,
> I don't know why.
> 

That's the date anacron was last run.

> As I said, this duplication seems to have started recently,
> and I have taken no action on this machine for months
> apart from running "sudo yum update",
> so I assume some update had this effect.
> 

Yum probaably updated anacron and set it to running

On my laptop

#  rpm -qa --last | grep anacron
gives
cronie-anacron-1.4.3-4.fc12                   Sat Feb 27 11:05:52 2010

So it was updated last on 27th Feb.

> I have a second CentOS machine where this duplication does not occur,
> even though everything seems the same as on the first machine.
> 

Tony

-- 

Chief Technical Officer.                   Tel: +353 061-202778
Dept. of Comp. Sci.
University of Limerick.



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