[gentoo-user] Sending console messages on Users

[Mick]

Hi All,

What is the way to send a console warning to anyone logged on a machine before 
I reboot it?

If the user is logged on a console I will only need to send it to the console; 
in addition if the user is running webmin, or phpadmin, then I would really 
like a popup of sorts to alert them to log out (something like the net send 
command on MS Windows running with the messenger service).

Is there such a thing?
-- 
Regards,
Mick