字符串使用

#!/bin/bash

read -p "情输入铜壶名：" user
[ -z $user ] && exit
stty -echo
read -p "情书人密码：" pass
stty -echo
[ -z $pass ] && echo 没有输入 && exit
echo ""
useradd "$user"
echo "$pass" | passwd --stdin $user

-z为空值     ！-z不为空值
&&，当-z执行成功后执行exit