r.mapcalc expr="map1 = 1" 
r.mapcalc expr="map2 = 3" 
r.mapcalc expr="map3 = 5" 

t.register type=rast maps=map1 start=2012-08-20 end=2012-08-21
t.register type=rast maps=map2 start=2012-08-22 end=2012-08-23
t.register type=rast maps=map3 start=2012-08-24 end=2012-08-25

t.create type=strds temporaltype=absolute \
         output=precipitation_daily \
         title="Daily precipitation" \
         description="Test dataset with daily precipitation"
         
t.register type=rast input=precipitation_daily maps=map1,map2,map3

t.rast.list -h input=precipitation_daily columns=name,start_time,min,max

name    start_time  min max
map1    2012-08-20 00:00:00 1.0 1.0
map2    2012-08-22 00:00:00 3.0 3.0
map3    2012-08-24 00:00:00 5.0 5.0

t.rast.list -h input=precipitation_daily method=deltagaps

id  name    mapset  start_time  end_time    interval_length distance_from_begin
map1@soeren map1    soeren  2012-08-20 00:00:00 2012-08-21 00:00:00 1.0 0.0
None        None    None    2012-08-21 00:00:00 2012-08-22 00:00:00 1.0 1.0
map2@soeren map2    soeren  2012-08-22 00:00:00 2012-08-23 00:00:00 1.0 2.0
None        None    None    2012-08-23 00:00:00 2012-08-24 00:00:00 1.0 3.0
map3@soeren map3    soeren  2012-08-24 00:00:00 2012-08-25 00:00:00 1.0 4.0

t.rast.gapfill input=precipitation_daily base=gap

t.rast.list -h input=precipitation_daily columns=name,start_time,min,max

name    start_time  min max
map1    2012-08-20 00:00:00 1.0 1.0
gap_6   2012-08-21 00:00:00 2.0 2.0
map2    2012-08-22 00:00:00 3.0 3.0
gap_7   2012-08-23 00:00:00 4.0 4.0
map3    2012-08-24 00:00:00 5.0 5.0