Linux shell脚本示例（三）

example No. 1
做为shell编写人员，要避免使用者输入数据的格式不正确，也就是要在shell脚本发布前拦截可能的错误；本示例是对使用者输入的数据（或位置变量）进行判断是否可用，而后在符合条件时调用代码块；

#!/bin/bash
#shell name: shell_vaild.sh
#used：输入密码后判断密码是不是由数字和字母组成，判断输入的IP是否合法等
#author by woon
#定义函数
vaild_pass() 
{
    decide=$(echo $1 | sed -e "s/[^[:alnum:]]//g")
    if [ "$decide" != "$pass" ];then
        return 1
    else
        return 0
    fi
}

#
read -t 10 -p "Please input IP address:" ipaddr
read -s -p "Please input the password:" pass
echo
#判断输入是否为空；空退出程序
if [ -z $ipaddr] || [ -z $pass ];then
    echo "输入错误\n"
    exit 2
fi
if  ! vaild_pass "$pass";then
    echo "Your inpur must consist of only letters and numbers.">&2
else
    echo "Your password is vaild!"
fi

yn=$(echo $ipaddr|awk -F "." '{if($1<255&&$2<255&&$3<255&&$4<255){print "0"}else{print "1"}}')
    if [ $yn == "0" ];then
        echo "Your Ipaddr is vaild"
    else
        echo "Your IPADDR is not vaild."
        exit 1
    fi