As we've stated before, Linux is inherently a multi-user system, especially in the context of a Linux server, where these systems are often administered not by a single user, but often a (large) team. Each user on a server has it own set of permissions. Imagine, for example, a server where three departments need to be development, operations, and security. Development and operations both have their own stuff there, but also need to share some other things. The security department needs to be able to view everything to ensure proper compliance and adherence to security guidelines. How could we arrange such a structure? Let's make it happen!
First, we need to create some users. For each department, we will create a single user, but since we're going to ensure permissions on the group level, this will work just as well for 5, 10, or...