Automating System Administration with Perl, 2nd Edition

Chapter 4. User Activity

In the previous chapter, we explored the parts of a user’s identity and how to manage and store it. Now let’s talk about how to manage users while they are active on our systems and networks.

Typical user activities fall into four domains:

Processes

Users run processes that can be spawned, killed, paused, and resumed on the machines we manage. 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, and so on take place when a specific user process interacts with files and directories 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, and even some process control and network access operations 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 usage

Users can send and receive data over network interfaces on our machines. 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, ...