判断用户是否存在，类型是否为管理员

[root@localhost ~]# vim /tmp/uidex.sh

#!/bin/bash
username=$1

if [ "$username" = "" ];then
echo "Please input a username"
exit 1
fi

if id $username &> /dev/null;then
userid=$(id -u $username)
if [ $userid -lt 500 ]; then
echo "$username is a admin user"
else
echo "$username is a normal user"
fi
else
echo "$username is not exit"
useradd $username
if [ $? -eq 0 ]; then  #判断用户是否添加成功
echo "Add user $username."
else
echo "Can not add $username."
fi
fi