Core concepts: the shell, commands, filesystem hierarchy, and how distributions differ.
Linux File Permissions, Ownership & umask Explained
The rwx permission model, chmod symbolic vs. octal notation, chown/chgrp, setuid/setgid/sticky bits, and how umask sets your defaults.
Linux Interview Questions & Answers
Real questions asked in Linux SysAdmin, DevOps, and RHCSA-track interviews — filesystem, permissions, systemd, networking, storage, and troubleshooting.
Filesystem
The FHS layout, mount points, inodes, and navigating the filesystem like an administrator.
Permissions
Owners, groups, chmod/chown, and the sticky/SUID/SGID bits that trip up beginners.