RE: [Pyatcron-devel-list] Cron and the "*/45" entry

[Childers, Matthew]

> -----Original Message-----
> From: NICOLOVICI Xavier [mailto:address@hidden
> Sent: Thursday, November 20, 2003 10:09 AM
> To: address@hidden
> Subject: [Pyatcron-devel-list] Cron and the "*/45" entry
> 
> > > I tried the cron task, and set it up with my schedule
> > looking like this:
> > >
> > > */45 * * * * /bin/mycommand
> > >
> > > I watched my email, and noticed that it is firing the task
> > at the top of
> > > every hour and at the 45th minute of every hour.  It is NOT,
running
> > > every 45 minutes like I would expect it to.
> > >
> > > I'm starting to think that */n in the minutes column actually
means:
> > > 0-59 and step by n minutes.  And if n = 45 then it would
> > run at 0 and 45
> > > minutes on every hour (assuming the hour field is *).  And if n =
10
> > > then it would run at 0,10,20,30,40,50.  So before we just
> > assume that
> > > */45 means run every 45 minutes, and before we start crafting a
GUI
> > > based on this assumption, we may want to do a little more
> > research into
> > > it.  Did anyone else try this little experiment?
> > >
> >
> > I did a similar test (*/7) and it seems that you're right. It
doesn't
> > run every 7 minutes. It goes from min 56 to min 0 instead of min 3.
> >
> > We'll have to re-think about it I guess...
> >
> 
> 
> Hmm, not re-think, but get back to the first idea I guess, having list
of
> integers as parameters.
> 
> Explanation: I went through the way Cron works, and in fact, for each
> time/date entry, it builds internally a list of "true" value. In other
> words, looking at the minute fields for example, Cron builds
internally a
> list of minute value when the task is allowed to run.
> 
> The "*", "nn-mm" or the "X/nn" representations are made to be human
> readable, but when Cron parse the crontab files, it builds list of
values.
> 
> The "*" becomes "1,2,3,4,5,6,7,8,9,10,...56,57,58,59", "20-25" becomes
> "20,21,22,23,24,25" and finally, "*/22" which means every minutes from
0
> with an increment step of 22 becomes "0,22,44"; This is really not
> "execute every 22 minutes" but "build a list of values from 0 to 59
with
> an increment step of 22 and use this list as true values for the
minute
> field".
> 
> So, in conclusion, if everyone agrees, I would like to fall back to
list
> of integers for the get/set functions of the Scheduler. Then, the role
of
> the GUI will be to map human suitable graphical objects with list of
> values.
> 

I think that will probably be the best way to do it.