如果su在提示时输入密码to ,则输入密码无效sudo su。另外,当使用命令执行命令时sudo (command),sudo会默认自动由root自动执行该命令(因为手册页显示sudo, sudoedit - execute a command as another user michaelxu@michaelxu-server:~$ su Password: su: Authentication failure michaelxu@michaelxu-server:~$ sudo su [sudo] password for michaelxu: root@michaelxu-server:/home/michaelxu# exit