User, Group, and Permission Management

Create, modify, and delete user accounts using command-line tools

Create, modify, and delete groups and manage group membership

Interpret the structure and contents of /etc/passwd, /etc/shadow, and /etc/group files

Interpret file permissions using symbolic and numeric notation

Modify file permissions using chmod and set default permissions with umask

Change file ownership and group assignment using chown and chgrp

Apply special permissions (setuid, setgid, sticky bit) to files and directories