Understanding the Linux Kernel: Core Concepts, Versioning, and Key Functions

01 Introduction

The Linux kernel, with over 13 million lines of code, is one of the largest open‑source projects in the world. This article explains what the Linux kernel is and what it is used for.

02 What is the Linux Kernel?

Linux kernel

is the core of the Linux operating system. It is a system core program maintained by Linus Torvalds that provides hardware abstraction, disk and file‑system control, and multitasking capabilities.

The Linux operating system is a product composed of the Linux kernel and various common software.

03 Linux Kernel Version Naming Rules

Linux kernel versions come in two types: stable and development.

The version number consists of three numbers: r.x.y

r: the main kernel version currently released.

x: even numbers indicate stable versions; odd numbers indicate development versions.

y: the number of bug‑fix releases.

Running uname -a on a host displays the system name, node name, OS release, kernel version, etc.

System name: Linux

Node name: qll

OS release: 3.10.0-1127.el7.x86_64

Naming rule:

Main version: 3
Sub version: 10 (odd = development, even = stable)
Revision: 0 (number of modifications)
Nth modification of this version: 1127
el7: Red Hat Enterprise Linux 7
x86_64: 64‑bit architecture

Kernel version: #1 SMP Tue Mar 31 23:36:51 UTC 2020

Hardware platform: x86_64

Machine hardware name: x86_64

Processor architecture: x86_64

Operating system: GNU/Linux

Linux kernel version naming has varied over time; in the 2.X series odd X indicated development and even X indicated stable. From 2.6.X and 3.X onward there is no strict convention.

04 Main Functions of the Linux Kernel

The Linux kernel, written in C and conforming to the POSIX standard, is the core that implements the system’s functionality.

Key functions include process management, memory management, file management, device management, and network management.

Process management: The kernel creates and destroys processes, schedules them, and provides inter‑process communication, enabling multiple processes to share processor resources.

Memory management: The kernel allows safe sharing of memory among processes, provides each process with a virtual address space, and separates hardware‑independent and hardware‑dependent code.

File management: The kernel presents a unified virtual file system, abstracting hardware details and supporting many file‑system types such as ext3.

Device management: The kernel includes drivers for virtually all hardware devices, providing a uniform interface for device control.

Network management: The kernel implements network protocol stacks and device drivers, supporting protocols like TCP/IP and communication with network hardware.