[1] Set root password
trusty@dlp:~$sudo passwd root
Enter new UNIX password:
# set root password
Retype new UNIX password:
# confirm
passwd: password updated successfully
trusty@dlp:~$
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:~#
usermod -G adm trusty