Re: crontab every 5 minutes?

[Joao Clemente <jpcl@rnl.ist.utl.pt>]

Andreas wrote:
> On Thu, Dec 23, 2004 at 08:02:55PM -0600, Lance Hoffmeyer wrote:
>
> > Hello,
> >
> > How do I get crontab to run a process every 5 minutes?
> > Currently, it is setup as:
> > 5,10,15,20,25,30,35,40,45,50,55 * * * 
> >
> > Surely, there is a more elegant approach?
> >
> > Lance
>
> sure
>
> */12 * * * *
> or
> 0-59/12 * * * *
>
> should do it.

Sorry to post over your answer, but Andreas, this is not correct: you 
should have written
*/5
or
0-59/5

(every 5 minutes... your versions was "every 12 minutes". The '/' is not 
"divide the time into y parts" but "every time 'x MOD y = 0' then run")

For who is not used to "MOD", this is the same as "%" in some 
programming languages: MOD = Remainder of division
0%5 = 0
1%5 = 1
2%5 = 2
3%5 = 3
4%5 = 4
5%5 = 0
6%5 = 1
...

(Someone has already posted the solution, I just reply to your mail so 
that this is lot left alone and (possibly) confusing someone)


Now, I must wonder: Is there a way to "shift" this by a wanted value? 
(for instance, when x MOD y = 1, something like putting into cron the 
instance (*/5)+1  ? It would run at 1,6,11,16,21, ... Is it possible?

Joao Clemente