pseudo-newbie exec scripts and session-time

[Charles Gregory]

Greetings!

I've been cruising the archives and pages and don't quite see
what I am looking for. I am hoping someone can point me to a nice
simple HOWTO or MAN page for specifying an 'exec' script
in radiusd.conf that will set the Session-Timeout and return
it to the NAS.

I'm thinking:
     Session-Timeout := %{exec:timecalc}

Or something like that. Also, where exactly should this go in the
'authorize' section? I'm presuming at the end, but have found no
examples....

Our dialups have a couple of diffrent time parameters, including
a user-option file, so while I appreciate any info on the radius
'counter' function, I don't think it will meet all my needs.

Hmmm. While I'm here, if I set Session-Timeout to ZERO, what will happen?

Thanks in advance!

- Charles