bash script按格式输出数字

#!/bin/bash

if [ $# != 1 ]
then
	echo please input one number
	exit 1
fi


result=""

intFra()
{
	unset yushu
	unset var
	var=$1

	# result=""
	while [ "$yushu" != 0 ]
	do
		yushu=$(expr $var % 1000)
		var=$(expr $var / 1000)
		if [ $yushu != 0 ]
		then
			if [ "$result" = "" ]
			then
				result=$yushu 
			else
				result="$yushu,$result"
			fi
		fi
	done

}

IFS='.'
read -ra arr <<< "$1"

integer=${arr[0]}
decimal=${arr[1]}
#echo $integer $decimal

intFra $integer

echo $result\.$decimal