file and directory permissions question...

[Eric Walstad <debian@ericwalstad.com>]

Hi All,

I'm trying to set up some restrictions to a couple of directories and 
their files and just can't seem to get it right.  Here's what I'm 
trying to do:
/foo   - Only folks in the 'users' group can read, write and delete 
files/dirs.  
/bar   - Only folks in the 'admin' group can read, write and delete 
files/dirs.

For both:
New files/dirs are created as owner=the person that created it.  New 
files/dirs are created as group='users'|'admin', respectively.

User fred is in groups fred,user
User barney is in group barney
User betty is in groups betty,user,admin

I'd like Betty to be able to read/write in both foo and bar.
Barney is hosed, he cannot read or write in neither foo nor bar
I'd like Fred to be able to read/write only in foo.

I've tried logging in as betty and touching a new file in bar, but no 
luck (permission denied), even when 
drwxrwx--T   13 admin     admin         4096 Nov 05 10:52 bar

Can someone enlighten me with a chmod command or two that'll make this 
happen?  Do I need to change the groups to which the users belong?

It probably doesn't matter, but I'm running Debain 'unstable'.

Many thanks in advance.

Eric.