Introduction to Linux
Table of contents
- What is Linux?
- History and open source philosophy
- Linux distributions
- Where is Linux used?
- Why learn Linux?
1 - What is Linux?
Linux is a free and open source operating system (OS). Like Windows or macOS, it lets your computer run and execute applications.
Technical definition
Linux is actually the kernel of the operating system. The kernel is the core that manages hardware resources (CPU, RAM, disks) and lets applications communicate with the hardware.
Linux vs GNU/Linux
| Term | Description |
|---|---|
| Linux | The kernel created by Linus Torvalds |
| GNU | The tools and utilities (shell, commands) |
| GNU/Linux | The complete system (kernel + tools) |
In everyday language, "Linux" is used to refer to the complete GNU/Linux system. That is what we will do in this course.
Main characteristics
| Characteristic | Description |
|---|---|
| Open Source | Source code accessible and modifiable |
| Free | Downloadable and usable without a license |
| Multi-user | Several users simultaneously |
| Multitasking | Several programs at the same time |
| Stable | Runs for years without rebooting |
| Secure | Strict permissions, few viruses |
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2 - History and open source philosophy
The birth of Linux
The key players
| Person | Contribution |
|---|---|
| Ken Thompson & Dennis Ritchie | Creators of Unix (1969) |
| Richard Stallman | GNU project and GPL license |
| Linus Torvalds | Creator of the Linux kernel (1991) |
The message that started it all
In 1991, Linus Torvalds, a 21-year-old Finnish student, posted this message:
"I'm doing a (free) operating system (just a hobby, won't be big and professional like gnu)..."
This "hobby" is today used by 96.3% of web servers in the world!
The Open Source philosophy
The 4 freedoms of free software:
- Freedom 0: Use the program for any purpose
- Freedom 1: Study how it works and modify it
- Freedom 2: Redistribute copies
- Freedom 3: Distribute modified versions
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3 - Linux distributions
A distribution (or "distro") is a complete system based on the Linux kernel, with preinstalled software and a package manager.
Distribution families
Comparison of the main distributions
| Distribution | Usage | Package manager | Ideal for |
|---|---|---|---|
| Ubuntu | Desktop/Server | apt | Beginners, DevOps |
| Debian | Server | apt | Maximum stability |
| CentOS/Rocky | Enterprise server | yum/dnf | Production |
| Fedora | Desktop | dnf | Latest technologies |
| Arch Linux | Advanced desktop | pacman | Experienced users |
Which distribution to choose?
We will use Ubuntu because it is the most widespread distribution, well documented, and perfect for learning.
| Your profile | Recommended distribution |
|---|---|
| Complete beginner | Ubuntu Desktop |
| Learning DevOps | Ubuntu Server |
| Developer | Fedora or Ubuntu |
| Production server | Debian, Rocky Linux, Ubuntu LTS |
| Maximum customization | Arch Linux |
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4 - Where is Linux used?
Linux is everywhere, even if you don't see it!
Market shares
Areas of use
| Domain | Examples |
|---|---|
| Web Servers | Apache, Nginx on Linux |
| Cloud Computing | AWS, Google Cloud, Azure |
| Containers | Docker, Kubernetes |
| DevOps | CI/CD, automation |
| IoT | Raspberry Pi, connected devices |
| Smartphones | Android (based on Linux) |
| Supercomputers | 100% of the TOP500 |
| Embedded | Cars, TVs, routers |
Companies using Linux
| Company | Usage |
|---|---|
| All servers, Android | |
| Amazon | AWS, Kindle |
| Facebook/Meta | Entire infrastructure |
| Netflix | Global streaming |
| Tesla | Embedded systems |
| NASA | Space stations |
Even if you are on Windows or Mac, every time you use the Internet, you are probably interacting with Linux servers.
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5 - Why learn Linux?
Professional reasons
| Reason | Explanation |
|---|---|
| Market demand | 90% of DevOps/Cloud job offers require Linux |
| Salaries | Linux skills = better compensation |
| Universality | Same principles everywhere (cloud, containers) |
| Automation | The foundation of all DevOps |
Technical reasons
| Advantage | Detail |
|---|---|
| Stability | Servers that run for years |
| Performance | Lightweight, fast, efficient |
| Security | Robust permissions model |
| Control | Full mastery of the system |
| Free | No license to pay for |
Skills developed
By learning Linux, you develop:
- Systems thinking: understand how an OS works
- Command line: efficiency and automation
- Scripting: automate tasks
- Networking: configure and diagnose
- Security: best practices
Linux is essential for a career in DevOps, Cloud, or system administration. Not mastering it closes many doors.
The DevOps and Linux path
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Key takeaways
- Linux is an open source operating system created in 1991
- There are many distributions (Ubuntu, Debian, CentOS, etc.)
- Linux is used by 96% of web servers in the world
- It is an indispensable skill for DevOps and Cloud
- Ubuntu is the recommended distribution for getting started