多账户登录ubuntu 15.10

编辑文件/usr/share/lightdm/lightdm.conf.d/50-ubuntu.conf
donald_draper@rain:~$ sudo vim /usr/share/lightdm/lightdm.conf.d/50-ubuntu.conf
添加如下行：
greeter-show-manual-login=true
donald_draper@rain:~$ cat /usr/share/lightdm/lightdm.conf.d/50-ubuntu.conf
[Seat:*]
user-session=ubuntu
greeter-show-manual-login=true
修改root密码：
donald_draper@rain:~$ sudo passwd root
Enter new UNIX password:
Retype new UNIX password:
passwd: password updated successfully
donald_draper@rain:~$