effective rights mask in action

setfacl.note.txt

[root@localhost ~]# getfacl /var/log/nginx
getfacl: Removing leading '/' from absolute path names
# file: var/log/nginx
# owner: nginx
# group: nginx
user::rwx
user:dev2:r-x		#effective:---
user:dev1:r-x			#effective:---
group::---
mask::---
other::---
[root@localhost ~]# ls -ld /var/log/nginx
drwx------+ 2 nginx nginx 20480 Feb  2 03:06 /var/log/nginx

[root@localhost ~]# setfacl -m m::rx /var/log/nginx
[root@localhost ~]# getfacl /var/log/nginx
getfacl: Removing leading '/' from absolute path names
# file: var/log/nginx
# owner: nginx
# group: nginx
user::rwx
user:dev2:r-x
user:dev1:r-x
group::---
mask::r-x
other::---

[root@localhost ~]# ls -ld /var/log/nginx
drwxr-x---+ 2 nginx nginx 20480 Feb  2 03:06 /var/log/nginx