Ungraceful shutdowns

[trinkle at purdue.edu]

We also have written a setuid shutdown.  However, rather than let anyone
use it, we have a shutdown.allow file that contains a list of valid
shutdown users.  When a user runs shutdown, it looks for the name in the
allow list.  If it finds the user, it prompts the user for their login
password and verifies it.  This prevents someone from using an unattended
user's terminal.  On workstations, it is easy to add the local user to the
allow list.

I also wrote a program that is used by shutdown (but is more general
purpose) to do the real work.  It takes a description file similar to
cron, but with times relative to the target (shutdown) time.  This makes
it easier to modify the shutdown behavior of various machines.  It was
very useful when we had a VAX8600 with a DEUNA that needed to be
ifconfig'ed down before UNIX actually halted.  It also would allow us to
send mail to specific users a few minutes before, etc.  It is the kind of
stuff you would never want to add to the program, but is easy enough with
a configuration file.

If there is enough interest, I can probably bundle it up and make it
available through the Sun-Spots archive.

[[ Sounds good!  I might be interested in it for around here:  our systems
group uses a variant of Stanford's "V" instead of Unix, so generic
students need to have the ability to gracefully shut down Unix so they can
boot V.  The local hack we run now is not very sophisticated.  --wnl ]]

Daniel Trinkle			trinkle at cs.purdue.edu			ARPA
Department of Computer Sciences	trinkle%purdue.edu at relay.cs.net		CSNET
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