런닝타임 구하는 쉘 스크립트

#!/bin/sh

time1_total=`date +%s.%N`

echo "####################################"
echo "##  01. ㅌㅌㅌ                        ##"
echo "####################################"
time1=`date +%s.%N`
echo "##  START : "`date +'%Y%m%d%H%M%S'`
/쉘프로그램.sh
echo "##  END   : "`date +'%Y%m%d%H%M%S'`
time2=`date +%s.%N`
diff=`echo "$time2 - $time1" | bc`
htime=`echo "$diff/3600" | bc`
mtime=`echo "($diff/60) - ($diff * 60)" | bc`
stime=`echo "$diff - (($diff/60) * 60)" | bc`
echo "##  RUNNING TIME : ${htime}시간 ${mtime}분 ${stime}초"

echo "####################################"
echo "##  02. ㅋㅋㅋ           ##"
echo "####################################"
time1=`date +%s.%N`
echo "##  START : "`date +'%Y%m%d%H%M%S'`
/쉘프로그램.sh
echo "##  END   : "`date +'%Y%m%d%H%M%S'`
time2=`date +%s.%N`
diff=`echo "$time2 - $time1" | bc`
htime=`echo "$diff/3600" | bc`
mtime=`echo "($diff/60) - ($diff * 60)" | bc`
stime=`echo "$diff - (($diff/60) * 60)" | bc`
echo "##  RUNNING TIME : ${htime}시간 ${mtime}분 ${stime}초"

echo "####################################"
echo "##  TOTAL RUNNING TIME            ##"
echo "####################################"
echo "##  START        : "$time1_total
echo "##  END          : "$time2_total
time2_total=`date +%s.%N`
diff=`echo "$time2_total - $time1_total" | bc`
htime=`echo "$diff/3600" | bc`
mtime=`echo "($diff/60) - ($diff * 60)" | bc`
stime=`echo "$diff - (($diff/60) * 60)" | bc`
echo "##  RUNNING TIME : ${htime}시간 ${mtime}분 ${stime}초"

exit 0