No need to change the primary group. I successfully use a group strategy that uses BSD style group permissions.
Originally Posted by RogerTX
I have all users that need to access the the directory in a common group. I have the umask set to 0002. This sets the default system create to 0775 for directories and 0664 for files.
Then I set the directory in question to 3775. This means that whenever you create a file or directory the group is set as the one defined in that root directory. This in effect is how BSD manages groups (e.g based on the group not the owner (user)). I have set the sticky bit but I don't know that it really matters.
At this point you can access the directory make files and subdirectories and so can the other users in the group.
You do not have worry about primary groups. It really is more a matter of controlling the permissions of items created in the first directory. Here is what my shared folder looks like
Here are some files inside that shared directory
drwxrwsr-t 8 bab smbusers 4.0K 2012-04-15 18:40 share
Membership in the group smbusers controls access. Note how all the files have 0664 permissions.
-rw-rw-r-- 1 bab smbusers 2.4M 2011-05-30 16:18 Time After Time.mp3
-rw-rw-r-- 1 egb smbusers 3.0M 2011-05-01 17:41 boats.jpg
-rw-rw-r-- 1 ajo smbusers 634K 2011-05-02 07:39 scan1.jpg