tcsh had a builtin command for this

       The autologout shell variable can be set to log out or lock the shell
	after a given number of minutes of inactivity.

       autologout (+)
               The first word is the number of minutes of inactivity before
		automatic logout.  The optional  second word is the number
               	of minutes of inactivity before automatic locking.  When the
               	shell automatically logs out, it prints 
uto-logout', sets
               	the variable logout to 
utomatic' and exits.  When the shell
               	automatically locks, the user is required to enter his
               	password to continue working.  Five incorrect attempts
               	result in automatic logout.  Set to (automatic logout after
               	60 minutes, and no locking) by default in login and
               	superuser shells, but not if the shell thinks it is running
               	under a window system (i.e., the DISPLAY environment
               	variable is set), the tty is a pseudo-tty (pty) or the shell
               	was not so compiled (see the version shell variable).  See
               	also the afsuser and logout shell variables.

Another nice command is the watch command. I don't remember how it handles
SU's or login's from something other than telnet, but it was a good way to
see if your friend logged on.... or a hacker??? now that you don't see many
tty sessions.

TO get a process to run when you log out you can suspend it normaly ^z then
type bg (background) Some programs will still run on logout some will not.
Perhaps it was just something funny I did and the shell/tty didn't know it
was disconnected. Because I have lost a connection and re-logged in after
rebooting the client pc and seen the previous session still running. But I
know I have seen the program running after the shell died and I had issued
the bg command.

> 
> On Sat, 7 Dec 2002, Jonathan Hutchins wrote:
> 
> > > -----Original Message-----
> > > From: Jason Clinton [mailto:clintonj@umkc.edu]
> > 
> > > 2. How can I lock a console while I'm away without logging out and 
> > > killing everything running under that virtual terminal?
> > 
> > There is a screensaver/console lock, but I don't recall at the moment.  I
> > think I used to have it set up in case the cat walked on the keyboard, but
> > with a KVM I just toggle to a null input when I step away.
> 
> I used to use vlock for this. I think it's still available.
> 
> -- 
> Dave Hull
> http://insipid.com
> 
> You cite it, you bite it.  I don't need someone else to help randomize my
> bits; we're full up on sparse lookup services.  Sell thin citation someplace
> else.
> -- Steve Nordquist, Re: Clarification: Jesux, 09/25/99
> 
> 
> 
>