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Linux is a free, open-source operating system kernel that powers everything from personal laptops and servers to embedded devices and supercomputers. Whether you are administering a production server, setting up a home lab, or simply exploring the command line for the first time, understanding Linux fundamentals gives you the confidence and control to work effectively in any Unix-like environment. The topics in this section cover the practical skills you need most: navigating the file system, managing permissions, controlling processes, and working fluently in the shell.

File System

Understand the Linux Filesystem Hierarchy Standard and learn to navigate, create, move, and search for files and directories.

Permissions

Master file ownership and access control with chmod, chown, and chgrp, including octal notation and special permission bits.

Processes

View, monitor, and control running processes using ps, top, kill, nice, and job control commands.

Shell Basics

Work efficiently at the command line with essential commands, I/O redirection, pipes, environment variables, and shortcuts.
Linux follows the Unix philosophy: build small, focused tools that do one thing well, then compose them together through pipes and redirection. The more comfortable you become with these building blocks, the more powerful your workflows will be.