To Use Ubuntuubunt

1.rename PC;

　　modify the /etc/hostname.

2.Use root account;

1.set the password for root account:

sudo passwd root

2.edit file:

vi /usr/share/lightdm/lightdm.conf.d/50-ubuntu.conf

add the following line to the end:

greeter-show-manual-login=true

3.restart.