Thus spake Perry E. Metzger
> You *can* put up easy instructions on the console, like "type 'halt'
> at the login: prompt to shut down" and set up a halt account with
> /sbin/halt as its shell...

If you instead create a halt program that only runs if the tty is the
console (or, better yet, check /etc/ttys to see if tty is secure) then
you don't even need a password on the account.  Anyone can do it as
long as they have physical access to the machine, a situation where
they can do anything they want anyway.

And it is certainly possible.  I did something similar at a location
for an app that sometimes needed to be restarted.  The app ran at a
plant which ran 24x7 and it was important that the supervisor had
some way to restart a controlling app without having to know a thing
about Unix.  I didn't need to check the tty for that but that should
be pretty simple.

-- 
D'Arcy J.M. Cain <darcy@{druid|vex}.net>   |  Democracy is three wolves
http://www.druid.net/darcy/                |  and a sheep voting on
+1 416 424 2871     (DoD#0082)    (eNTP)   |  what's for dinner.