Question: Create two groups: students and profs
	- Add two users: natasha and harry to students group
	- Add two users: amy and anna to profs group
	- Create two directories: /data/students and /data/profs so that:
		- all students have read/write access to /data/students
		- all profs have read/write access to /data/profs
		- others have no access to /data/students and /data/profs
		- files created under /data/students and /data/profs are owned by respective groups
		- Only the owner of the file can delete the file created under /data/profs and /data/students
		- User anna is the head master and have full read and write access to both directories /data/students and /data/profs
		- Also make sure that members of group profs have read access to /data/students

Credit:: Sander van Vugt, question from his video course. 

Solution:

groupadd students
groupadd profs

useradd natasha
useradd harry
useradd amy
useradd anna

usermod -aG students natasha
usermod -aG students harry

# Verify group students
lid -g students

usermod -aG profs anna
usermod -aG profs amy

# Verify group profs
lid -g profs

mkdir -p /data/students
mkdir -p /data/profs

cd /data/

# Check current permissions
ls -ltr

# Sticky bit: 1, Owned by group: 2 --> Total: 1+2=3
chmod 3770 students
chmod 3770 profs

# Anna being head master
chown anna:students students
chown anna:profs profs

# Check current permissions
ls -ltr

# Now we need to give ACL on students directory for profs group:
getfacl students/

setfacl -m d:g:profs:rx students
setfacl -m g:profs:rx students

# Verify the ACLs
getfacl students/

# Do little unit testing if time permits :)
