The root Account in Ubuntu is disabled by default because his password is not set. But if you'd like to use root Account by some reason, it's possible to use like follows.
[1] The user account added during installation is set an administrative account with Sudo, so it's easy to get root account's shell like follows.
xerus@dlp:~$ sudo -s
[sudo] password for xerus: # own password
root@dlp:~# # switched
Or it's possible to switch to root account with su command to set root account's password.
xerus@dlp:~$ sudo passwd root [sudo] password for xerus: # own password Enter new UNIX password: # set root password Retype new UNIX password: # confirm passwd: password updated successfully xerus@dlp:~$ su - Password:# input root password root@dlp:~## switched
* The examples on this site shows as a root account. If you use Sudo, add "sudo" on the head of commands. It had better to limit user if you enable root account. For using by Sudo, it's possible to limit to prohibit shells in sudoers config, refer to details about Sudo Settings. [3] For limit to do su command, set like follows.
root@dlp:~# vi /etc/pam.d/su
# line 15: uncomment and add a group which is allow to do su command
auth required pam_wheel.so group=adm
root@dlp:~# usermod -G adm ubuntu
