shell脚本实现希尔（shell)排序

#! /bin/bash
arr=("5" "7" "1" "4" "3" "6" "8" "9")
size=${#arr[@]}
gap=$size
echo "before arr:" ${arr[*]}
while [ $gap -gt 1 ]
do
((gap=(gap/3)+1))
for((i=gap;i<size;i+=gap ))
do
let temp=${arr[$i]}
let start=i-gap
while [ $start -ge 0 -a $temp -lt ${arr[$start]} ]
do
let sum=start+gap
let arr[$sum]=${arr[$start]}
let start-=gap
if [ $start -lt 0 ];then
break;
fi
done
let arr[$start+$gap]=$temp
done
done
echo "after arr :" ${arr[*]}