[Wolves] Restricting Users

[Simon Burke]

Bit of a wierd question.

I'm messing around a bit with my linux machine and (ubuntu, also the
mrs' machine)
Anyway does anyone know if it is possible to restrict users, as far as
not permitting them to leave their /home/$USER dir. (ie they can
navigate around the directories in their home directory but not go
above their /home/$USER directory.

I mean they can go 
/home/$USER/, /home/$USER/foo etc.

but they cant go /home, /etc, /usr et al.

Also is it possible to restrict the commands they can use, like stop
them from using df (as an example)
-- 
Theres no place like ::1

Thanks,
SimonB