3 of 6 edited body

What relationships do tie ACL mask and standard group permission on a file?

At first I create a file and check it's standard permissions and ACL entries:

$ touch file; ls -l file; getfacl file
-rw-r--r-- 1 user user 0 Jul 30 16:26 file
# file: file
# owner: user
# group: user
user::rw-
group::r--
other::r--

Then I set the ACL mask on the file and again check it's standard permissions and ACL entries:

$ setfacl -m mask:rwx file
$ ls -l file; getfacl file
-rw-rwxr--+ 1 user user 0 Jul 30 16:26 file
# file: file
# owner: user
# group: user
user::rw-
group::r--
mask::rwx
other::r--

Note that along with ACL mask standard group permission on the file also changed.

  1. Why does this happen?
  2. What did developers mean to show by this change?
  3. What connection does exist between ACL mask and standard group permission?

The distribution in question is Debian Linux 7.6.