Shell——计算器解决思路

通过脚本参数变量判断用户输入是否为整数，并进行计算

#!/bin/bash
#no.1

[ $# -ne 2 ]&&{
        echo $"USAGE $0 NUM1 NUM2"
        exit 1
}

#no.2
a=$1
b=$2

expr $a + $b + 110 &>/dev/null
if [ $? -ne 0 ];then
        echo "You must input two nums"
        exit 2
fi

#no.3
echo "a+b=$(($a+$b))"
echo "a-b=$(($a-$b))"
echo "a*b=$(($a*$b))"
echo "a/b=$(($a/$b))"
echo "a%b=$(($a%$b))"
echo "a**b=$(($a**$b))"