How can different users who are not the owner of the file be given different access?

Question

linux

How can different users who are not the owner of the file be given different access?
For user 1 to be the owner, user 2 can both read and write, and 3 can only read. they are all in the same group

Answer 1

help.ubuntu.ru/wiki/access_control_list

Answer 2

If you do not go into ACL, but use only standard rights, then like this:

# Первый пользователь
useradd user1
# Второй пользователь
useradd user2
# Третий пользователь
useradd user3
# Создаем группу usersgroup
addgroup usersgroup
# Добавляем туда пользователей user1 и user2
adduser user1 user2 usersgroup
# Выдаем права на файл
chown user1:usersgroup file
chmod u=rwx,g=rw,o=r file

Something like this