wry1224@ubuntu:~$ sudo passwd
[sudo] password for wry1224:
Enter new UNIX password: //此时的密码为root的新密码
Retype new UNIX password: //确认输入
passwd: password updated successfully
wry1224@ubuntu:~$ su root
Password: //上面输入的密码
[sudo] password for wry1224:
Enter new UNIX password: //此时的密码为root的新密码
Retype new UNIX password: //确认输入
passwd: password updated successfully
wry1224@ubuntu:~$ su root
Password: //上面输入的密码