gistfile1.txt

-bash-4.2$ getfacl test.txt
# file: test.txt
# owner: justin.harris
# group: dnn
user::rw-
group::r--
mask::r--
other::r--

-bash-4.2$ getfacl .
# file: .
# owner: root
# group: dnn
# flags: ss-
user::rwx
group::rwx
group:dnn:rwx
group:dnnfed:rwx
mask::rwx
other::r-x
default:user::rwx
default:group::rwx
default:group:dnn:rwx
default:group:dnnfed:rwx
default:mask::rwx
default:other::r-x

-bash-4.2$ newgrp dnnfed
bash-4.2$ groups
dnnfed test
bash-4.2$ echo "" > test.txt
bash: test.txt: Permission denied