File Sharing - Default Group Permissions

[kiezpro]

I want to use an old Mac Mini with a regular Lion install as a small file server, using the built-in File Sharing. All my users are in the group "Staff". I'm sharing a single folder, /Users/Shared for them all. Unfortunately, when a user creates a file or folder on the server, the permissions are rw-r--r-- or rwxr-xr-x, respectively. Thus, the other users don't have write access to files or folders one user creates. Of course, I'd rather have new files and folders group writable by default.
I've searched the Web a lot, but I couldn't find a working solution for this problem. What can I do to have new files and folders group writable by default?

[agentx]

You need to add an ACL (access control list) for R/W for group staff to folder or change umask for systems.

Paste this into Terminal

sudo chmod +a "group:staff allow list,add_file,search,delete,add_subdirectory,delete_child,readattr,writeattr,readextattr,writeextattr,readsecurity,writesecurity,chown,file_inherit,directory_inherit" /Users/Shared

You might want to add -R (recursive) to command if you have lots of sub folders and files you want to correct.

sudo chmod -R +a "group:staff allow list,add_file,search,delete,add_subdirectory,delete_child,readattr,writeattr,readextattr,writeextattr,readsecurity,writesecurity,chown,file_inherit,directory_inherit" /Users/Shared

[kiezpro]

Weirdly enough, this doesn't set the proper Unix permissions (newly created files/folders still aren't group writable according to ls -al), but nonetheless it works. Thanks!

[agentx]

POSIX on OS X is crap you have to adjust umask settings on Server/Client side to get POSIX to work how you want.

ACL just works ;-)

POSIX and ACL are complementary but ACL trumps POSIX.

[agentx]

BTW ls -lea will show ACLs

[agentx]

you can also set POSIX permissions on /Users/Shared if you want.

sudo chown root:staff /Users/Shared ; chmod 775 /Users/Shared