Summary

In this chapter, you learned about usernames, user ID numbers, group names, and group ID numbers. The password and group database access routines were covered in detail. You now should have a clear understanding of the role of real, effective, and saved user ID and group ID identifiers. The chapter concluded with supplementary groups and how to control them.

The next chapter digs into the topic of library functions. You'll start with static libraries and then leap into the exciting functionality of shared and dynamically loaded libraries.