Enable root user

	The root user in Ubuntu is disabled by default because his password is not set. But if you'd like to use root user by some reason, enable it like follows.
[1]	Set root password

pangolin@dlp:~$ sudo passwd root Enter new UNIX password: # set root password Retype new UNIX password: # confirm passwd: password updated successfully pangolin@dlp:~$ su - Password: # root password root@dlp:~# # just switched

*	The examples on this site show as a root user from now. If you use sudo, add "sudo" at the head of commands.

[2]	If you enable root, limit users to switch to root.

root@dlp:~#

vi /etc/pam.d/su

# line 15: uncomment and add a group that can switch to root

auth   required   pam_wheel.so  

group=adm

root@dlp:~#

vi /etc/group

adm:x:4:

pangolin