Re: turning off computer

[Ted.Harding@nessie.mcc.ac.uk (Ted Harding)]

( Re Message From: J.P.D. Kooij )
> 
> The solution with a file in /tmp is an elegant way around the the
> setuid-root scripts problems.  On the other hand, because /tmp is
> world-writable and many system processes write to it, it might create it's
> own backdoors

The point about using a root-owned script to watch /tmp for a "trigger"
file planted by another user is that unless the script is running, nothing
will happen, no matter what other users try to do.

So root is able to decide at any time whether the operation is available
to other users or not. This is more flexible than many other suggestions
that have been posted, which would normally involve relatively permanent
changes to the system setup.

The watch-script I posted was only an example. It can be souped up to do
more complicated things (e.g. to grep "ls -l /tmp/trigger_file" to see if
it is owned by a particular user or set of users). In fact the scheme is
a kind of infinitely customizable "cron".

Ted.                                    (Ted.Harding@nessie.mcc.ac.uk)