pawel /sync $ sudo addgroup --system root-sync
Adding group `root-sync' (GID 136) ...
Done.
pawel /sync $ sudo adduser root root-sync
Adding user `root' to group `root-sync' ...
Adding user root to group root-sync
Done.
pawel /sync $ sudo adduser pawel root-sync
Adding user `pawel' to group `root-sync' ...
Adding user pawel to group root-sync
Done.
pawel /sync $ sudo chown root:root-sync -R settings/
pawel /sync $ ls -l
total 4
drwxrwxr-x 2 root root-sync 4096 Jun 16 15:25 settings
pawel /sync $ cd settings
pawel /sync/settings $ touch testfile
touch: cannot touch `testfile': Permission denied