[Wolves] Cron question

Steve Parkes sparkes at westmids.biz
Tue Jun 21 17:41:43 BST 2005

Wayne Morris wrote:

> 1)Is stuff in a cron file executed simultaneously or one by one where 
> two items have the same time entry?

impossible on a single processor machine ;-), a less pedantic answer to 
your question is they can happen in any order and can be interupted by 
other processes so I wouldn't think the order is at all trustworthy and 
to all intents and purposes things will appear to happen at the same 
time but if they if one is dependant on the anything to do with the 
other they should be combined in a one liner.

> 2)If you start to tar a bunch of files in a directory, then add files 
> to directory once tar process has begun, are these files tarred or
> left alone?

I would think that's entirely dependant on the implimentation of tar but 
shouldn't bugger things up either way.

> so should
> 00,30 tar job
> 00,30 streamer job
> result in the tar operation being completed, before streamer starts , 
> or not?

probably not.  The processes are sent to the schedualer by cron when it 
finds them and then the kernel doles them out time slices until they finish

To make sure streamer job isn't started until tar job is finished 
combine them.  If tar job takes too long to finish and there is a gap 
use different directories for the streamer job each time it runs  
(something like pid?)

> (if I start streamer a minute later, then I lose a minute of footage 
> every half hour.
is there anyway to predict when that minute in and what's the combo to 
your safe ;-)

> ideas?

lot's but my admin foo is weak.  It's a small bash/perl script for 
someone with the process knowhow.  or a dirty hacking session for the 
rest of us.


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