crontab - help with advanced settings

[chrismyers]

Hi Guys,

I am having trouble finding the correct syntax to create a cronjob that will run every 6 weeks (or 8 times a year). Even better if this will run on a Monday, but not essential.

I can't quite work this one out. It would be nice if @yearly/8 worked, but it doesn't.

Any help would be greatly appreciated.

[mikewhatever]

I am not a cron expert, but it seems that this particular task would be easier to accomplish with 8 separate cron jobs.

[chrismyers]

I was hoping you wouldn't say that.. I have about 30 jobs to create on a 6 week rota..

That would mean 240 cron jobs!

Any other suggstions anyone?

[CharlesA]

I don't think there is any way to have it run every 6 weeks. You can do it monthly, but if you wanted to do it every 6 weeks, I don't think that's possible.

Well unless you wanted to hack it with a script that sleeps for 2 weeks.. but that may cause more problems then not. Set cron to run a script in 4 weeks, and have a command to let the script sleep for 2 weeks. Nasty hack but it might be better then setting 30 + cronjobs a week.

Anyhow, if the jobs are predefined, you can just import them into cron at scheduled intervals, worth a shot I guess.

Anyhow, you can replace the current crontab with a file by running this:

crontab -u username somefile

See here for some more infos.

[matt_symes]

Hi

Here's another idea.

If this is a server that is not often rebooted then what about scheduling it using the at command.

The script you run could schedule another run for itself by calculating the date in 6 weeks time.

This could be abstracted into a script that calls your main worker script.

You could hook it into cron using the @reboot option. Rescheduling after a reboot could be handled by storing the date it needs to run in a file and using that to pass to the at command again.

I have not attempted this and i don't know if it's feasible so maybe someone like Charles could comment on it as i would not want to lead you up the proverbial garden path

Kind regards

[CharlesA]

Hi

Here's another idea.

If this is a server that is not often rebooted then what about scheduling it using the at command.

The script you run could schedule another run for itself by calculating the date in 6 weeks time.

This could be abstracted into a script that calls your main worker script.

That's actually a good idea. I have used @reboot scripts before, but not in that matter.

My idea was to have a script wait 2 weeks and then run, but that might work too.