shell 簡單改系統時間

#！/bin/bash
#haha
while [ 1 ]
do
        sleep 60
        hour=$(date +"%H")
        sum=`expr $hour + 0`
        #sum=hour
        #echo $sum

        if [ $sum == "24" ]; then
                sum=0
                #echo $sum
        fi
        changetime="$sum:59:50"
        #echo $changetime
        date -s $changetime
        #hw不設定的話,雖然系統時間已設定為正確,但是會突然變成hw clock
        hwclock -uw 
done