[Remind-Fans] reminder every half hour

[Reid Thompson]

On Wed, Jan 20, 2010 at 12:07:38AM +0000, Tarlika Elisabeth Schmitz wrote:
> >From 10:00 to midnight, I would like a 1/2-hourly reminder to check
> whether I need to put another log on the fire.
> 
> I tried REM AT 10:00 *30 MSG check fire
> 
> but that doesn't do anything. Am I missing something obvious?
> 

from  http://www.linuxjournal.com/article/3529
Here's an example of a timed reminder:

REM Mon Tue Wed Thu Fri AT 17:00 +15 *3 MSG Go home!

The AT keyword introduces an AT clause.   The 17:00 means that the
trigger time is 5:00 PM. The +15 means Remind starts carping at you
fifteen minutes ahead of time, and the *3 means it annoys you every
three minutes. 

so i think you want

REM AT 12:00 +120 *30 MSG check fire