Files and Directory Permissions in Linux with special type of permission implementation such as sticky bit , acl(access control list)

we are implementing file and directory permission with special type of permission  such as  sticky bit and acl
(1) Add 4 users
useradd u1
useradd  u2
useradd u3
useradd u3
useradd u4

(2) Now add 2 groups
groupadd linux
groupadd oracle

(3) Now add the users to the group linux  and oracle
usermod -G  linux u1
usermod -G  linux u2
usermod -G  oracle u3
usermod -G  oracle u4

(4) After that make 2 directory
mkdir  /linux
mkdir  /oracle

(5)  Change group of both the directory
chgrp oracle  /oracle
chgrp linux  /linux

(6) Now change the permissions of both  the directory only group members can access the directory
chmod 770  /oracle
chmod 770  /linux

(8) Now login from user  u1
su - u1

(9) Now create direcory a directory /linux/u1
mkdir /linux/u1
#successful

(10) Now create a directory /oracle/abc
mkdir /oracle /abc
#permission denied
# user u1 can't have permission to make file and directory  in /oracle directory

(11) Now login from user u2
su - u2
rm - rf  /linux/u1
#sucessful

(12) To  prevent this we implement sticky bit only root user and owner of the file can implement in the Directory
chmod 1770 /linux/u1

(13)  To check it
 su -  u2
rm -rf  /linux/u1
#permission denied
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There is an another type of permission that is ACL (acces control list)
that is implemented as
setfacl  -m  u:u1:rwx  /linux
setfacl -m u:u2:rw-   /linux