Permissions, Ownership and Users

Who may do what on a Linux server: the mode in ls -l and stat, chmod with letters and with numbers, read, write and execute on a directory, umask, the setuid, setgid and sticky bits; id and groups, chgrp, chown through exact sudo rules and owner:group; getent, useradd, usermod -aG, passwd -S and sudo -u.

Labs in this module

Chapter 20, Part 1. Permissions, Ownership and Users: ls -l, stat, chmod, umask and the special bits - Part 1 of 3: the mode in ls -l and stat, chmod with letters and with numbers, read, write and execute on a directory, umask, and the setuid,
Chapter 20, Part 2. Permissions, Ownership and Users: id, chgrp, chown and sudo -l - Part 2 of 3: id and the groups of an account, the permission check, chgrp, chown through the exact sudo rules of the server, and owner:group
Chapter 20, Part 3. Permissions, Ownership and Users: getent, useradd, usermod, passwd -S and sudo -u - Final test: Chapter 20, Permissions, Ownership and Users. Twenty-five objectives on a real Debian 12 server covering all three parts: ls -l,