Upload data every nine weeks?

[Neil Edwards]

Hi,

I have a requirement to automatically upload some data files to a remote server every 9 weeks (on a Monday at 8 AM) . I can't find a combination of crontab entries that will do this. I haven't wriitten the upload script but my problem now is simply getting cron to run anything on a nine-week interval.

Any ideas out there?

Thanks in advance for your time,
Neil

[Patrick Wallek]

You might want to take a look at 'at' to do the scheduling.

Once you run it the first time you could schedule it via 'at' to run again in 63 days.

Something like this:

at now + 63 days < /dir/script_to_run

[Pete Randall]

See John Poff's solution using at in this thread:

http://forums.itrc.hp.com/cm/QuestionAnswer/1,,0xce7187dc4d7dd5118ff00090279cd0f9,00.html


Pete

[A. Clay Stephenson · Accepted solution]

Cron on its own ain't gonna do this but we can easily run your script every Monday at 0800 and simply exit if this ain't the week.

Something like this:

#!/usr/bin/sh

PATH=${PATH}:/usr/local/bin
export PATH

typeset -i WK=$(( (($(caljd.sh) + 1) / 7) % 9 ))
if [[ ${WK} -eq 0 ]]
then
echo "Run Your Script"
else
echo "Do nothing"
exit 0
fi

The + 1 offset is used to make the weeks start on Sunday. We then divide by 7 to get the week number and then a mod 9. You may need to change the -eq 0 to some other value between 0 and 8 to do correct week. The advantage of this method is that it is going to work year-in, year-out without any changes.

[A. Clay Stephenson]

Ooops, I suppose I better attach caljd.sh, I typically install it in /usr/local/bin.

No points for this, please.

[Neil Edwards]

Hi guys and thanks for your answers. Clay's response made me realize that I could simply use `date '%U` % 9 to do the same thing and much easier. I will assign points to all.

Thanks again,
Neil

[A. Clay Stephenson]

Sorry Neil, date '+%U' will almost work and you won't know you have problems until the year changes (and some will work just fine). If the year starts on a Sunday, the week number is 1 but otherwise the week number of the days before the 1st Sunday is zero. Caljd.sh counts days sequentially from 4713BCE and avoids this problem.