Perl for System Administration

Chapter 4. User Activity

In the previous chapter, we explored the identity of a user and how this identity is managed and stored. Now let’s talk about how to manage users while they are active on our systems and network.

The significant actions of users fall into four domains:

Processes

Users can spawn, kill, pause, and resume processes on our machines. These processes compete for a computer’s finite processing power, adding resource issues to the list of problems a system administrator needs to mediate.

File operations

Most of the time, operations like writing, reading, creating, deleting, etc., take place when some user process interacts with files in a filesystem. But under Unix, there’s more to this picture. Unix uses the filesystem as a gateway to more than just file storage. Device control, input/output channels, and even some process control and network access are file operations. We dealt with filesystem administration in Chapter 2, but in this chapter we’ll approach this topic from a user administration perspective.

Network

Users can send and receive data over network interfaces on our machine. There is material elsewhere in this book on networking, but we’ll address this issue here from a different perspective.

OS-specific activities

This last domain is a catchall for the OS-specific features that users can access via different APIs. Included in this list are things like GUI element controls, shared memory usage, file sharing APIs, sound, etc. This category is so diverse ...