比较数字大小

思路：1.先判断输入的是不是两个参数 2.判断输入的两个参数是不是数字 3.判断大小；

#!/bin/bash
a=$1
b=$2
if [ $# -ne 2 ];then
        echo "Usage:sh $0 num1 num2."
        exit 1
fi
[ -n "`echo "$1"|sed ‘s/[0-9]//g‘`" ]&&echo "Please Input 1 Number."&&exit 1
[ -n "`echo "$2"|sed ‘s/[0-9]//g‘`" ]&&echo "Please Input 2 Number."&&exit 1
if [ $a -gt $b ];then
        echo "$a > $b."
elif [ $a -lt $b ];then
        echo "$a < $b"
else
        echo "$a = $b"
fi