Ubuntu® Linux® Bible

Chapter 21. Managing Users, Groups, Authentication, and Advanced Permissions

IN THIS CHAPTER

• Creating users and groups

• Understanding standard Linux authentication

• Configuring the sudo command

• Using ACLs from the command line

• Editing ACLs graphically

Though many people install and use Ubuntu as the operating system on a truly personal computer, Linux is designed and implemented as a multiuser computer system from the group up. Even if you're the only user of an Ubuntu system, that system still has multiple user and group accounts and runs many processes using the rights granted to those accounts. Similarly, the login process seems simple, but actually invokes several user and group checks under the hood, as do other commands that require specific permissions.

This chapter explains how to manage users and groups on Ubuntu systems. Chapter 4 provided a basic introduction to the classical Ubuntu and general Linux concepts of users, groups, file permissions, and performing privileged operations. Following is a quick review:

• The section of Chapter 4 entitled "Basic Concepts: Users and Groups" provided an overview of how users and groups work on Ubuntu and other Unix-like systems, explaining the content and organization of the system files that hold user and group information.

• The section of Chapter 4 entitled "File and Directory Permissions Under Linux" introduced file and directory permissions and explained what the cryptic protection entries in a long file listing actually mean.

• The section of ...