linux添加用户和修改密码

[root@zabbix-server ~]# useradd -d /usr/sam  -m  sam
[root@zabbix-server ~]# id sam
uid=1004(sam) gid=1004(sam) groups=1004(sam)
[root@zabbix-server ~]# passwd sam
Changing password for user sam.
New password: 
BAD PASSWORD: The password is shorter than 8 characters
Retype new password: 
passwd: all authentication tokens updated successfully.
[root@zabbix-server ~]# su - sam
[sam@zabbix-server ~]$ exit
logout
[root@zabbix-server ~]#