# Uncomment the following line to require a user to be in the "wheel" group.
#auth required /lib/security/$ISA/pam_wheel.so use_uid

auth required /lib/security/$ISA/pam_wheel.so use_uid

• wheel group only to be able to su.
• Other than the wheel group is not accustomed to a non-root user with su.

auth required /lib/security/$ISA/pam_wheel.so use_uid root_only

• wheel group only get used to root su. .
• Other than the wheel group , get used to other users in su command.