Add an User
Add an User "cent" as an example below.
Changing password for user cent.
New UNIX password:# set password
Retype new UNIX password:# confirm
passwd: all authentication tokens updated successfully.
 Try to switch to a user that was added above.
higuys login:cent # input user name
password: # password
Password: # root password
[root@higuys ~]# # just switched to root
Make a user be only a user who can switch to root as an administration user. (it's 'cent' in this example)
[root@higuys ~]#vi /etc/pam.d/su
To forward to emails for root user to another user, set like follows. (it's 'cent' in this example)
# Person who should get root's mail
[root@higuys ~]#newaliases # reload