Introduction to Linux
Lesson 1 of 11
1Introduction to Linux
What the picture shows: The kernel in the middle, and every program around it sending its requests.
No background needed. If you know Linux, jump to Myth vs Reality and then the quiz.
Map of this part
The concepts in order, click any one to jump to it:
Two ways into the same idea
The kernel is like a car engine: you do not drive an engine alone but a whole car with a wheel and seats. Linux is the engine, and a distribution like Ubuntu is a full car built around it. Servers have no screen or mouse, so you drive by typing short commands instead of clicking buttons.
Linux is an open-source kernel; a distribution (Ubuntu, Debian, Fedora) bundles it with GNU tools, a package manager and defaults. Working in text through a shell is repeatable, scriptable and works remotely over ssh, which is why it is the language of servers and containers.
Before You Start
🧭The operating system lesson
You know what a kernel and a process are. Here we name the kernel you will work on.
☁️The word "server"
A server is a computer in a data centre with no screen, serving thousands of devices over the network. You will hear it a lot.
The Core Idea
1Linux is a kernel, and the system is bigger than it
The word Linux means exactly the kernel: the program that manages the processor, memory, files and network. Linus Torvalds wrote it in 1991 and released it to everyone.
Follow the picture: the browser, the editor and the terminal are all programs around the kernel, sending it requests. What you call "a Linux system" is the kernel plus hundreds of tools around it.
There is no screen and no windows in the kernel itself. The graphical interface is an extra program, and servers do without it entirely.
2A distribution: the kernel with chosen tools
Because the kernel alone is not enough, different groups bundle the kernel with tools, settings and a package manager, and call the bundle a distribution. Ubuntu, Debian and Fedora are the best known.
The kernel is nearly the same in all of them; the difference is in the bundled tools and the update policy. What you learn here works on all of them.
An Android phone is a distribution too: a Linux kernel with Google's interface on top. You have been using Linux for years without knowing.
3Why text and not clicks
A server has no screen, so the only way to work with it is typing: a text command goes out and text comes back. That is what the rest of this track teaches.
The Unix philosophy Linux inherited: each tool does one thing and does it well, reads text and writes text, so you can connect one tool to another.
Text is also repeatable: the command you typed today you save in a file and run tomorrow on a thousand servers. A click cannot be saved or repeated.
How It Works, Step by Step: How your command reaches the kernel
You type a command in the terminal, say to list a folder's contents.
A program called the shell reads what you typed and works out which tool you mean.
The tool asks the kernel to read the folder through a system call.
The kernel reads the disk and returns the names, and the tool prints them for you.
Try it without code
Myth vs Reality
| Myth | Reality |
|---|---|
| Linux is for experts only. | The kernel itself is in your phone, your router and your TV. The hard part is the commands, and those you learn step by step. |
| Ubuntu and Linux are two different things. | Ubuntu is a distribution: the Linux kernel with chosen tools. Distributions differ in tools, not in the kernel. |
| Without a graphical interface nothing can be done. | The servers that run the whole internet are managed in text only, and it is faster, more precise and repeatable. |
Try it yourself
Which of these is a distribution rather than a kernel?
Ubuntu is a complete bundle: the Linux kernel with tools, a package manager and settings. Linux 6.x is a version number of the kernel itself.
Quick review cards
Check Your Understanding
Why can so many companies build their systems on Linux?
Because the kernel's source is open under a licence that allows modification and distribution, so each builds its own distribution.
If you update the distribution, does the kernel necessarily change?
Not necessarily; the tools alone may update, and the kernel has its own separate updates.
What makes a text command stronger than a click in daily work?
It can be saved in a file, repeated, chained with other commands, and run remotely on a machine with no screen.
Resources for this lesson
Grouped by type. Start with the official docs for precision, or an article or video for the explanation.
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