shell两数之间的算术运算

#!/bin/bash
read -p "请输入第一个数：" a
read -p "请输入第二个数：" b
echo "$a+$b=$[$a+$b]"
echo "$a-$b=$[$a-$b]"
echo "$a×$b=$[$a*$b]"
echo "$a/$b=$[$a/$b]"
echo "$a%$b=$[$a%$b]"