Cron jobs on laptops/netbooks - is anacron needed?

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#1

Does anyone have much experience with cron jobs on laptops or netbooks, as in does setting MAX_NOT_RUN=1 in /etc/sysconfig/cron actually work well or is it better to just use anacron?

#2

On 2011-06-16 11:36, tk83 wrote:
>
> Does anyone have much experience with cron jobs on laptops or netbooks,
> as in does setting MAX_NOT_RUN=1 in /etc/sysconfig/cron actually work
> well or is it better to just use anacron?

The daily/weekly/monthly jobs will eventually work. You can not say exactly
when, but they will run.

Cron jobs, though, might not ever run.

There is a difference.

–
Cheers / Saludos,

Carlos E. R.
(from 11.4 x86_64 “Celadon” at Telcontar)

#3

So anacron is still a good idea then I guess. Does it require any configuration or can I just install the package and it works?

#4

On 2011-06-16 13:36, tk83 wrote:
>
> So anacron is still a good idea then I guess

Depends on your needs.

–
Cheers / Saludos,

Carlos E. R.
(from 11.4 x86_64 “Celadon” at Telcontar)

#5

Found this discussion last week, when wondering about the same issue, but I did not find the conclusions too convincing.

Now I have tried it myself for a week, so I can answer.

If you just want to make sure that a job runs once a day, regardless when you turn on the machine there is no need for anacron. Just add your “job” into /etc/cron.daily/ directory

This is not really a cron feature, but an OpenSUSE feature, if I got it correctly. Behaviour will be determined by /etc/sysconfig/cron. Default values (at least in my 11.3) are fine, no need to change anything.

## Type:         string
## Default:      ""
#
# At which time cron.daily should start. Default is 15 minutes after booting
# the system. Example setting would be "14:00".
# Due to the fact that cron script runs only every 15 minutes,
# it will only run on xx:00, xx:15, xx:30, xx:45, not at the accurate time
# you set.
DAILY_TIME=""

So the “jobs” from the /etc/cron.daily directory (they are not really cron jobs) run at the full quarter that follows 15 minutes after booting.

## Type:         integer
## Default:      5
#
# Maximum days not running when using a fixed time set in DAILY_TIME.
# 0 to skip this. This is for users who will power off their system.
#
# There is a fixed max. of 14 days set,  if you want to override this
# change MAX_NOT_RUN_FORCE in /usr/lib/cron/run-crons
MAX_NOT_RUN="5"

This parameter is not relevant if DAILY_TIME has not been specified.

Jobs would probably not be run reliably if your machine always runs for less than 30 minutes a day. Not a problem for me.

I only need daily jobs at the moment, so I haven’t thought about other frequencies would work.

#6

Actually when you want to see how it works, you can change one parameter:

## Type:        yesno
## Default:     no
#
# generate syslog message for all scripts in 
# cron.{hourly,daily,weekly,monthly} 
# even if they haven't returned an error? (yes/no)
#
SYSLOG_ON_NO_ERROR="yes"

(Days) Later you can do a

sudo grep cron /var/log/messages

to see when your “jobs” where executed.

#7

On 2011-07-10 16:36, geuder wrote:
> Now I have tried it myself for a week, so I can answer.

Yes, that is how it works :slight_smile:

–
Cheers / Saludos,

Carlos E. R.
(from 11.4 x86_64 “Celadon” at Telcontar)