Enter the root user under a common user

Log on to Linux as a root user and log on to Linux as a normal user. To enable root for the first time, perform the following operations: XX :~ $ Sudo passwd root [sudo] password for XX: enter the password for confirmation: enter the password to prompt that the password is successfully updated. At this time, the root user is enabled. The root operation is as follows: XX :~ $ Su root Password: enter the password and you can perform the root operation. You can also use the su common user name to switch to the common user for operations. You do not need to enter the password. I use ubuntu Linux 12.10. All of the above are verified by myself. In this method, the system can only be logged on from a common user, and then the root user can be logged on from the terminal using the su root operation.