aaron@rome /srv $ sudo setfacl -m d:g:www-rw:rwX /srv/www
aaron@rome /srv $ sudo getfacl /srv/www
getfacl: Removing leading '/' from absolute path names
# file: srv/www
# owner: root
# group: root
# flags: -s-
user::rwx
group::rwx
group:www-ro:r-x
group:www-rw:rwx
mask::rwx
other::---
default:user::rwx
default:group::rwx
default:group:www-ro:r-x
default:group:www-rw:rwx
default:mask::rwx
default:other::---