bash autologout feature?

[Tony Nugent]

I've been looking for an "autologout" facility in bash, but it
doesn't seem to have one.  I'm sure that it used to be there (or
perhaps I'm recalling tcsh from way back).

The idea is to set an environment variable to an idle timeout value
so that an interactive shell will automatically exit when the
timeout occurs.

Does bash 1.x or 2.x have this functionality?  If so, how to enable
it?

Cheers
Tony