Introduction

Why Linux?

Linux is the operating system that runs the world. It powers web servers, cloud infrastructure, Android phones, supercomputers, and embedded systems. If you write software professionally, you will work with Linux every day.

  • Free and open source -- The kernel source code is public, auditable, and modifiable. You own your system.
  • Dominant in servers -- Over 96% of the world's web servers run Linux. AWS, Google Cloud, and Azure are built on Linux.
  • The developer's OS -- Package managers, shell scripting, SSH, containers, and deployment pipelines all assume Linux fluency.
  • Stable and secure -- Linux powers critical infrastructure because it is reliable, configurable, and has a strong security model.

The Story

Linus Torvalds was a 21-year-old Finnish student in 1991 when he announced on a Usenet newsgroup: "I'm doing a (free) operating system (just a hobby, won't be big and professional like GNU)." That project became the Linux kernel — today one of the largest collaborative software projects in history, with contributions from thousands of developers and companies including Google, Intel, Red Hat, and Microsoft.

The GNU Project, started by Richard Stallman in 1983, had already created most of the user-space tools (shell, compiler, coreutils). Combined with Torvalds' kernel, the result was a complete free operating system: GNU/Linux.

The Shell

At the heart of Linux is the shell — a text interface where you type commands. The default shell on most systems is Bash (Bourne Again SHell). The shell is not just a way to run programs; it is a full scripting language for automating tasks.

This course runs your shell commands in an in-browser Linux simulator. You get a real shell experience — a virtual filesystem, common commands, pipes, variables, and scripting — without needing to install anything.

What You Will Learn

This course contains 17 lessons organized into 4 chapters:

  1. The Shell -- echo, pwd, ls, cd, and cat. The fundamental commands for navigating and reading files.
  2. Working with Files -- mkdir, touch, cp, mv, and rm. Creating, copying, moving, and deleting files and directories.
  3. Text Processing -- head, grep, pipes, and wc. Reading parts of files, searching, and combining commands with the pipe operator.
  4. Shell Scripting -- Variables, for loops, and if/else conditionals. Writing scripts that automate work.

Each lesson explains a concept, demonstrates it with examples, and gives you an exercise to practice in the browser.

Let's get started.

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