#!/bin/bash
while getopts ":a:b:c:" arg #选项后面的冒号表示该选项需要参数
do
	echo  "arg":$arg
        case $arg in
             a)
                echo "a‘s arg:$OPTARG --- $OPTIND" #参数存在$OPTARG中
                ;;
             b)
                echo "b‘s arg:$OPTARG ---  $OPTIND"
                ;;
             c)
                echo "c‘s arg:$OPTARG --- $OPTIND"
		;;
	     ?)  #当有不认识的选项的时候arg为?
            echo "unkonw argument"
        exit 1
        ;;
        esac
done