Chron curiosity

[Geoffrey Leach]

I have this line in /etc/crontab:

30 23 * * * geoff /usr/local/bin/fp.pl

which executes the program every day at 2330.  The script terminates by 
executing system 'sudo systemctl start poweroff.target';

Generally this works as expected.

However, when I realize that the shutdown happened too soon, and I 
restart the system, it re-executes the script.

Any suggestions as to where I've gone wrong?

Thanks.

[Wolfgang S. Rupprecht]

Geoffrey Leach  writes:
> I have this line in /etc/crontab:
>
> 30 23 * * * geoff /usr/local/bin/fp.pl
>
> which executes the program every day at 2330.  The script terminates by 
> executing system 'sudo systemctl start poweroff.target';
>
> Generally this works as expected.
>
> However, when I realize that the shutdown happened too soon, and I 
> restart the system, it re-executes the script.
>
> Any suggestions as to where I've gone wrong?

You didn't wait a minute for before restarting the computer? ;-)

Look at the top of /etc/cron.hourly/0anacron and add logic just like
this to your script.  Cron is stateless across reboots (as far as I
know) and has no way to tell if it already ran.  You have to record that
fact yourself.

-wolfgang

[Tom Horsley]

On Fri, 28 Jun 2013 12:25:02 -0700
Wolfgang S. Rupprecht wrote:
> Look at the top of /etc/cron.hourly/0anacron

Speaking of anacron, you may want to eradicate all the
anacron junk if you actually want jobs to run at the
times you specified rather than at random times
anacron picks to be as inconvenient as possible.

[Reindl Harald]

Am 28.06.2013 21:41, schrieb Tom Horsley:
> On Fri, 28 Jun 2013 12:25:02 -0700
> Wolfgang S. Rupprecht wrote:
> > Look at the top of /etc/cron.hourly/0anacron
>
> Speaking of anacron, you may want to eradicate all the
> anacron junk if you actually want jobs to run at the
> times you specified rather than at random times
> anacron picks to be as inconvenient as possible

*no* you can configure it to *not* use random times
and then you can be sure that the system is aware
that a job did run

the random-default is perfectly for most environments
especially if you are in the world of virtualization
__________________________________________________________

# /etc/anacrontab: configuration file for anacron
# See anacron(8) and anacrontab(5) for details.

SHELL=/usr/bin/bash
PATH=/usr/sbin:/usr/bin
MAILTO=root

# the maximal random delay added to the base delay of the jobs
RANDOM_DELAY=5

# the jobs will be started during the following hours only
START_HOURS_RANGE=0-12

#period in days   delay in minutes   job-identifier   command
1                 5                  cron.daily       nice -n 19 run-parts /etc/cron.daily
7                 25                 cron.weekly      nice -n 19 run-parts /etc/cron.weekly
@monthly          45                 cron.monthly     nice -n 19 run-parts /etc/cron.monthly