> ls -la /tmp/testshare
drwxrws---  5 main smbusers 4096 Dec 24 17:29 .
drwxrwxrwt 12 root root     4096 Dec 24 17:28 ..
drwxrws---  2 main smbusers 4096 Dec 24 17:29 bar
drwxrws---  2 main smbusers 4096 Dec 24 17:29 foo
drwxrws---  2 main smbusers 4096 Dec 24 17:28 Public

[global]
    server string = %h server (Samba, Ubuntu)
    server role = standalone server
    os level = 20
    workgroup = WORKGROUP
    writeable = yes
    security = user
    map to guest = bad password
    force user = main
    force group = smbusers
    create mask = 0660
    force create mode = 0660
    directory mask = 0770
    force directory mode = 0770
    encrypt passwords = yes
    unix password sync = yes
    passdb backend = tdbsam
    passwd chat = *Entersnews*spassword:* %nn *Retypesnews*spassword:* %nn *passwordsupdatedssuccessfully* .
    passwd program = /usr/bin/passwd %u
    pam password change = yes
    obey pam restrictions = yes
    panic action = /usr/share/samba/panic-action %d
    max log size = 1000
    log file = /var/log/samba/log.%m
    dns proxy = no
    socket options = TCP_NODELAY

[Public]
    path = /tmp/testshare/public
    guest ok = yes

[bar]
    path = /tmp/testshare/bar
    valid users = bar

[foo]
    path = /tmp/testshare/foo
    valid users = foo

> ls -lA /tmp/testshare/public
-rw-r----- 1 main smbusers    0 Dec 24 19:43 New Text Document.txt
drwxr-s--- 2 main smbusers 4096 Dec 24 19:43 New Folder
> ls -lA /tmp/testshare/bar
-rw-r----- 1 main smbusers    0 Dec 24 19:43 New Text Document.txt
drwxr-s--- 2 main smbusers 4096 Dec 24 19:43 New Folder