How Linux Works: A Simplified Overview for Beginners 🐧

If you’ve ever wondered how Linux works under the hood, here’s a step-by-step breakdown of its boot process and core components. Let’s take a journey from the moment you power on your system to the point where you can interact with your favorite Linux apps.

1️⃣ Power On: The Beginning

It all starts when you press the power button. This triggers the BIOS (Basic Input/Output System), which is stored in ROM. The BIOS is responsible for running a system check and ensuring that all hardware is functioning correctly.

2️⃣ The Master Boot Record (MBR)

Once the BIOS has done its job, it loads the Master Boot Record (MBR) from the hard disk. The MBR contains the bootloader, which is a critical program that knows how to load the next important piece of the puzzle: the Linux Kernel.

3️⃣ Bootloader: Loading the Kernel

The Bootloader (commonly GRUB or LILO) loads the Linux Kernel into RAM. The kernel is the heart of the operating system, managing everything from hardware communication to process handling.

4️⃣ Kernel Takes Control

Once the Kernel is loaded into memory, it immediately takes charge. It initializes system components like the CPU, memory, and all connected devices (such as hard drives and network adapters).

5️⃣ /sbin/init and systemd: The First Process

The first process started by the kernel is /sbin/init (nowadays handled by systemd). This process is responsible for starting all other essential system services and daemons.

It’s like the conductor of an orchestra — ensuring everything plays in harmony.

6️⃣ User Space: Where You Come In

After the kernel is up and running, the system moves into user space, where the magic happens. The Shell (CLI) and GUI are loaded, giving you the ability to interact with the system.

You can now run applications, type commands, and access files. The user space is isolated, meaning it has limited access to the system’s core components, keeping the OS safe and stable.

7️⃣ Kernel Space: The Heart of Linux

While you’re busy using the user interface, the Kernel is working behind the scenes in privileged mode. It directly manages:

• Process Management: Scheduling tasks for the CPU.
• Memory Management: Allocating and optimizing RAM usage.
• Device Drivers: Interacting with hardware devices like your hard disk, printers, etc.
• File System Management: Managing file systems for data storage and retrieval.
• System Calls: Handling requests from user applications to perform tasks like opening files or executing commands.

8️⃣ System Calls: How User Apps Talk to the Kernel

Every time you run a program or execute a command, you are indirectly interacting with the kernel. This is done via System Calls (API calls) that let your application request services like reading data from a file or accessing network resources.

9️⃣ Managing Resources: The Kernel’s Role

The kernel manages essential hardware components:

• CPU: It allocates processing time to different programs.
• Memory: Manages the distribution and utilization of RAM.
• Hard Disk: Reads and writes data efficiently to storage.
• Network: Manages network interfaces for communication with other devices.

In Summary:

Linux operates through a well-coordinated series of events, starting with the BIOS, moving to the bootloader and kernel, and ending with you interacting with the system in user space. The Kernel works tirelessly behind the scenes, managing system resources, handling user requests, and keeping everything running smoothly.

Now you know what happens when you hit that power button! 🔌👨‍💻

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