1.进入root用户提示su: Authentication failure
roots@ubuntu:~$ su -
Password:
su: Authentication failure
2.通过sudo更改root密码就可以了
roots@ubuntu:~$ sudo passwd root
[sudo] password for roots:
Enter new UNIX password:
Retype new UNIX password:
passwd: password updated successfully
roots@ubuntu:~$ su -
Password:
root@ubuntu:~#