Perl for System Administration

Chapter 3. User Accounts

Here’s a short pop quiz. If it wasn’t for users, system administration would be:

a) More pleasant.

b) Nonexistent.

Despite the comments from system administrators on their most beleaguered days, b) is the best answer to this question. As I mentioned in the first chapter, ultimately system administration is about making it possible for people to use the available technology.

Why all the grumbling then? Users introduce two things into the systems and networks we administer that make them significantly more complex: nondeterminism and individuality. We’ll address the nondeterminism issues when we discuss user activity in the next chapter, but for now let’s focus on individuality.

In most cases, users want to retain their own separate identities. Not only do they want a unique name, but they want unique “stuff” too. They want to be able to say, “These are my files. I keep them in my directories. I print them with my print quota. I make them available from my home page on the Web.” Modern operating systems keep an account of all of these details for each user.

But who keeps track of all of the accounts on a system or network of systems? Who is ultimately responsible for creating, protecting, and disposing of these little shells for individuals? I’d hazard a guess and say "you, dear reader” — or if not you personally, then tools you’ll build to act as your proxy. This chapter is designed to help you with that responsibility.

Let’s begin our discussion of users by addressing ...