updatedb : how to disable its (an)cron job ?
ben darby
ben at cvrse.com
Fri Dec 8 10:39:30 UTC 2006
* Vincent Trouilliez wrote:
> ben darby <ben at cvrse.com> wrote:
> > im not sure what you mean by "properly" as i would consider changing the
> > permissions -x on
>
> Hmm, I was thinking "proper" as in "remove the schedule job", just like
> your remove/uninstall an application and not just remove its icon from
> the menu ;-)
anacron uses run-parts to run all the executable scripts in relevant directories
whether it be daily, weekly, or monthly. along the same lines as the /etc/rcX.d
directories. so removing execution privileges from the file will remove it from
the schedule.
> Ah, looks like you over-estimated my understanding of cron...thanks for
> the starting point !
> I need a beginners guide, an overview of how cron works, what files are
> involved, how to remove a job, what commands and utility (if any) are
> used to work with cron, etc, etc.
> Also, cron is not enough. ISTR that updatedb nowadays on Ubuntu is
> triggered by anacron, not cron. So, on top of cron, I need to have a
> working knowledge of anacron as well, and what is the relation between
> the two... if any.
i think your being confused by the naming scheme used, or the way that
cron is configured by default in ubuntu means cron wont execute those
directories if anacron is installed (see /etc/crontab)
cron will execute at a specific time, day, + interval if the computer isn't
running at that time the job will not execute until the next time that
combination comes around. therefore has its disadvantages on a desktop
machine that wont necessarily be available 24/7 and possibly never actually
be running when the jobs are scheduled. that's where anacron comes in...
anacron doesn't run at a specific time, but will ensure that its jobs are run
as close to the intervals specified as possible (IE. job specified to be run
daily but the machine is only active every second, it will just run the job
once every second day) and the jobs + frequencies are specified by their
location(daily, weekly, monthly) + presence of an executable script.
cron uses /etc/crontab + a crontab for any user that creates one in
/var/spool/cron/crontabs to edit/create a schedule for your user use
'crontab -e' for the file format 'man 5 crontab'
hopefully i've covered all your questions there.
--
ben darby
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