[root@ok ~]# vim /etc/pam.d/su

#%PAM-1.0auth      sufficient   pam_rootok.so# Uncomment the following line to implicitly trust users in the "wheel" group.#auth      sufficient   pam_wheel.so trust use_uid# Uncomment the following line to require a user to be in the "wheel" group.#auth      required    pam_wheel.so use_uidauth      include     system-authaccount     sufficient   pam_succeed_if.so uid = 0 use_uid quietaccount     include     system-authpassword    include     system-authsession     include     system-authsession     optional    pam_xauth.so

[root@ok ok]# usermod -G wheel ok[ok@ok ~]$ su [root@ok ok]#