Why sudo does it ?

[shaulk@netvision.net.il (shaul)]

[01:50:34 shaul]# cat /etc/sudoers
# sudoers file (/etc/sudoers).
#
# This file MUST be edited with the 'visudo' command as root.
#
# See the man page for the details on how to write a sudoers file.
#

# Host alias specification

# User alias specification

##
# Cmnd alias specification
##
Cmnd_Alias      HALT=/sbin/halt
Cmnd_Alias      REBOOT=/sbin/shutdown -r "now"
Cmnd_Alias      SHUTDOWN=/sbin/shutdown -h "now"

##
# User privilege specification
##

# root can run anything on any machine as any user
root	ALL=(ALL) ALL

# shaul may run these commands:
shaul   ALL=HALT,REBOOT,SHUTDOWN
[01:51:33 shaul]# exit
[01:53:38 shaul]$ sudo -l
You may run the following commands on this host:
    (root) /sbin/halt
    (root) /sbin/shutdown -r "now"
    (root) /sbin/shutdown -h "now"
[01:55:05 shaul]$ sudo rebbot
sudo: rebbot: command not found
[01:55:14 shaul]$ sudo reboot
Sorry, user shaul is not allowed to execute "/sbin/reboot" as root on rakefet.

[01:55:21 shaul]$ 

BTW: My sudo group is empty, if that matter.