Chapter 6: Users and groups

Create and manage local user accounts and groups, give administrators controlled root access with sudo, and set password policies.

What you will learn

• Explain users, groups, UIDs and GIDs, and read the account databases /etc/passwd, /etc/group and /etc/shadow.
• Become root with su or run commands as root with sudo, and grant sudo access with drop-in files checked by visudo.
• Create, modify and delete user accounts and groups, including supplementary group membership.
• Set, lock and age passwords, force a change at the next login, and make accounts expire.

Sections

1. Users, groups and the account files
2. Become root safely
3. Exercise: Grant limited root access
4. Manage accounts and groups
5. Exercise: Set up a web team
6. Passwords and password ageing
7. Exercise: Onboard and offboard an intern
8. Exercise: Users and groups review
9. Linux users and groups quiz
10. Linux users and groups cheat sheet