shell脚本：时差

Question

这是我的脚本来计算现在和我的约会之间的时差。 有没有其他方法可以更有效地进行相同的操作？

#!/bin/bash

mydate=20141224 # yyyymmdd
mytime=00:00:00 #hh:mm:ss


current=$(date +%s)
target=$(date -d "$mydate $mytime" +%s)
diff=$((target-current))

day=$((diff / 86400))
left=$((diff - (day*86400)))

diff=$((left))

hour=$((diff / 3600))
left=$((diff - (hour * 3600)))

diff=$((left))

min=$((diff / 60))
left=$((diff -(min * 60)))

diff=$((left))

sec=$((diff))

echo $day"d" $hour"h" $min"min" $sec"sec"