Set a Volume's permissions to group write for all files and folders To me this seems like it should be easy but I'm having a hard time finding a very good answer that seems definitive to me.
I have a I have a hard drive mounted that my wife and I share (internal drive).  My wife are I both in admin group and this drive's group ownership is also admin.
This volume's current permissions are: drwxrwx---.  My wife and I can both add and create files, however, these new files are not inheriting the parent volumes permissions.  If I create a new folder or file, the g+w bit is not being set.  It's read only.
I don't really want to change my umask from 022 to 002 because it's only this volume I want the g+w bit set.  I guess I can if that's the only solution.
I want to ensure that any file created, copied, or moved to this Volume (anywhere on the volume) has the correct permissions.  Is this possible?
Or do I need to fall back on umask and a cron job to reset permissions?
edit - first attempt with ACLs
Here is what I tried, as a test.  It didn't carry it forward to the next file I created though.  I don't think I fully understand how this is supposed to work ...
$ mkdir test-acl
$ chmod 770 test-acl
$ ls -le
total 0
drwxrwx---  2 damon  admin  68 Jan 13 09:50 test-acl
$ chmod +a &quot;admin allow list,add_file,search,delete,add_subdirectory,delete_child,readattr,writeattr,readextattr,writeextattr,readsecurity,file_inherit,directory_inherit&quot; test-acl
$ ls -le
total 0
drwxrwx---+ 2 damon  admin  68 Jan 13 09:50 test-acl
 0: group:admin allow list,add_file,search,delete,add_subdirectory,delete_child,readattr,writeattr,readextattr,writeextattr,readsecurity,file_inherit,directory_inherit
$ cd test-acl
test-acl$  touch test.txt
test-acl$  ls -le
total 0
-rw-r--r--+ 1 damon  admin  0 Jan 13 09:50 test.txt
 0: group:admin inherited allow read,write,execute,delete,append,readattr,writeattr,readextattr,writeextattr,readsecurity
You can fix this on a folder on the drive using an Access Control List (ACL) to set the right permissions.

Check the man page for chmod(1) and you will need to set 'file_inherit' and 'directory_inherit' on the parent folder and then set permissions on it to read and write the group but nothing for all users.

You may also need to turn on the use of ACLs for SMB sharing if you are sharing via SMB rather than AppleShare.