I installed ubuntu12.04 directly on my computer before and found the following problems:
In the graphical interface (ctrl + alt + f7 mode), you cannot log in directly with the root user name and password. You can only enter root mode with su. But this is sometimes inconvenient.
The following is a method I found to solve this problem, which has been verified by myself and can be used.
1. First enter your current user;
2. Open a terminal and enter the command:
su or sudo -s or su root
3. Then enter the root password
Enter the root account
4. Enter the following commands:
vi /etc/lightdm/lightdm.conf
5. After opening the configuration file, add a line at the bottom:
greeter-show-manual-login=true /* Open the way to manually enter account and password */
6. Finally restart the machine, you can choose the user to log in.
Attached:
What is lightdm?
LightDM, namely: Light Display Manager, is a new, lightweight desktop display manager for Linux desktops, while traditional Ubuntu uses GNOME desktop standard GDM.
Article about introducing lightDM: http://imtx.me/archives/1662.html