cron question / process queue

[Kent Johnson]

Hi,

I have a server that runs regular daily, weekly and monthly updates, all 
scheduled with cron.

The updates are lengthy - the weekly update now takes about 8 hours - 
and I would like for them not to overlap. I also want them to run at 
night, for some reasonable value of night, so I can't just schedule them 
far apart.

I can use the historical run times to schedule the jobs to prevent them 
overlapping, but I was wondering if there is a more robust and flexible 
way to do this; some way to say
   daily - queue the daily update
   weekly - queue the weekly update
   monthly - queue the monthly update
and have the updates run sequentially.

I guess it would not be hard to write a Python program to do determine 
which updates to run and start the correct processes, but I'm wondering 
if there is some system facility that would help.

Thanks,
Kent