I've got a directory (/var/shared) that is owned by root:shared, and is
in mode 770. Two users (glen and ewan) are members of the 'shared'
group. If I do `touch /var/shared/foo` as 'glen', then the file 'foo' is
owned by glen:glen. Is there any way to configure the directory so that
the new file is automagically owned by root:shared, or at least