#!/bin/bash

for h in `seq 0 23` ; do
 for MM in "00" "20" "40" ; do
  HH=$h ; [ $h -le 9 ] && HH=0$h
  cp gap.sbd gap-$HH:$MM.sbd
  sed "s/00\:00/$HH\:$MM/g" gap-$HH:$MM.sbd > toto.dat
  mv  toto.dat              gap-$HH:$MM.sbd 
 done 
done
