Introduction to Linux

Linux is a versatile and powerful open-source operating system that forms the backbone of countless technological infrastructures, from servers and desktops to mobile devices and embedded systems. Known for its stability, security, and flexibility, Linux provides a robust platform that can be customized to suit a wide range of applications. It is supported by a vibrant global community of developers and users, which contributes to its continuous evolution and ensures a rich ecosystem of software and tools. Whether for personal use, enterprise environments, or innovative tech projects, Linux offers a reliable and adaptable solution for modern computing needs.

What is Operating System?

 
                      +-------+
                      | User  |
                      +-------+
                          |
          -----------------------------------
          |                |               |
   +-------------+  +-------------+  +-------------+
   | Application |  | Application |  | Application |
   +-------------+  +-------------+  +-------------+
          \             |              /
           \            |             /
            \           |            /
             +-----------------------+
             |   Operating System    |
             +-----------------------+
                |       |        |
     +----------+-------+--------+----------+
     |          |       |        |          |
   +-----+   +-----+  +---------+  +------+
   | RAM |   | CPU |  | Input/  |  |  ... |
   |     |   |     |  | Output  |  |      |
   +-----+   +-----+  +---------+  +------+

OS manages:

Memory (MMU)
Process
Devices (Drivers)
Storage
CPU (Scheduling)
Networking

Operating systems are the fundamental layer that enables communication between computer hardware and user applications, evolving over time through a rich interplay of design philosophies and technological innovations. The Unix family, known for its modularity and robust design principles, has given rise to a diverse range of systems that embody both traditional and modern approaches to computing. Alongside this evolution, systems like Linux have emerged, driven by community collaboration and adaptability, offering a dynamic platform that continuously reshapes the computing landscape. In parallel, alternative paradigms, such as those seen in the Windows ecosystem, highlight different methodologies and priorities, collectively creating a broad and intricate tapestry of technologies that support everything from personal devices to complex enterprise infrastructures.

 
Operating Systems
├── Unix & Unix-like Systems
│   ├── Original Unix
│   │   ├── AT&T Unix (System V)
│   │   │   ├── Solaris (SunOS)
│   │   │   ├── AIX (IBM)
│   │   │   └── HP-UX (HP)
│   │   └── BSD Unix
│   │       ├── FreeBSD
│   │       ├── NetBSD
│   │       ├── OpenBSD
│   │       └── Darwin (forms the core of macOS)
│   └── Linux (Unix-like)
│       ├── Debian Family
│       │   ├── Ubuntu
│       │   └── Others (e.g., Linux Mint)
│       ├── Red Hat Family
│       │   ├── Fedora
│       │   ├── CentOS
│       │   └── RHEL (Red Hat Enterprise Linux)
│       └── Other Distributions (e.g., Arch, SUSE)
└── Non-Unix Systems
    ├── Windows Family (NT-based and earlier)
    └── Others (e.g., DOS, AmigaOS)

Why Learn Linux?

Linux has demonstrated consistent growth over the past three decades, affirming its enduring relevance in the technology industry and maintaining its popularity among professionals and enthusiasts.
The versatility of Linux is showcased by its use across a wide range of systems, including web servers, supercomputers, IoT devices, and even Tesla's electric cars. Additionally, many operating systems, such as Android and Unix-like systems like Playstation OS, Mac OS, and OS X, are either based on or inspired by Linux, underlining its widespread influence.
The Linux kernel is engineered to support a vast array of hardware types, from personal computers and servers to mobile devices and embedded systems, making it a highly adaptable operating system for various applications.
Linux offers a rich selection of native software, and many popular applications from Windows and Mac platforms have been ported to run on it, ensuring a broad spectrum of software availability for users.
Due to its open-source and modular nature, Linux can be tailored to meet a wide range of requirements, facilitating diverse applications across different sectors.
The Linux community is robust and continuously contributes to its development and improvement. This community, along with an extensive ecosystem that includes forums, educational resources, tools, and conferences, provides ample support for users seeking to learn and solve problems.
For businesses, especially startups, Linux is a cost-effective solution. It enables the efficient running of websites, databases, and applications without the hefty licensing fees associated with other operating systems. Its ease of installation, use, upgrade, deployment, and maintenance makes it an attractive choice for optimizing operational efficiency.

Before Linux

 
       Multics          Unix            GNU           Linux
        (1960s)         (1970s)         (1983)         (1991)
          |               |               |               |
          |               |               |               |
-----------------------------------------------------------------

I. Multics (Multiplexed Information and Computer Services):

An early time-sharing operating system.

II. Unix (Uniplexed Information and Computer Services, or Unics):

Developed to overcome many of Multics’ problems.
Provides a hierarchical file system
Manages processes
Offers a command-line interface
Includes a wide range of utilities

III. POSIX (Portable Operating System Interface):

An IEEE 1003.1 standard from the 1980s
Defines the language interface between application programs and the UNIX operating system, ensuring portability
Specifies the C library, system interfaces and headers, as well as various commands and utilities

IV. GNU (GNU’s Not Unix):

Introduced in 1983 to promote the Free Software concept
Embodies the freedoms to run, study, modify, and redistribute software
Uses the GNU General Public License (GPL) to protect these freedoms
Aims to create a complete free-software operating system, including projects such as the shell, core utilities (e.g., ls), compilers, and libraries (e.g., the C library)

V. Linux Kernel:

Introduced by Linus Torvalds
Licensed under GPL version 2 (GPLv2)
Compiled using GNU GCC
Provides a Unix-like operating system with advantages such as low cost, full control, and strong community support
Serves as the kernel that the GNU project required

The History of Linux

In 1971, UNIX was released by Ken Thompson and Dennis Ritchie, serving as a pioneering operating system that laid the foundation for many future systems, including Linux.
The GNU Project was established in 1983 by Richard Stallman with the goal of creating a completely free and open-source operating system, setting the stage for the development of Linux.
In 1987, Andrew S. Tanenbaum introduced MINIX, a simplified UNIX-like system designed for academic purposes, which later inspired Linus Torvalds in the creation of Linux.
1991 marked the release of the first version of the Linux kernel by Linus Torvalds, a student at the University of Helsinki, as a small, experimental project initially compatible only with his own computer.
In 1992, Linus Torvalds agreed to license the Linux kernel under the GNU General Public License (GPL), ensuring that it would remain free and open-source as part of the Free Software ecosystem.
The release of Red Hat Linux in 1994 became a pivotal moment, as it emerged as one of the most popular and influential Linux distributions, contributing significantly to the growth of Linux in the enterprise market.
The Linux Foundation was formed in 2007, bringing together various organizations supporting Linux and sponsoring the work of Linus Torvalds, while also leading collaborative development on the Linux kernel and other open-source projects.
In 2008, the Android operating system, based on the Linux kernel, was officially released by Google. Android quickly became the dominant operating system for smartphones and tablets, significantly expanding the use and visibility of Linux in the consumer market.
2011 saw the release of the Linux 3.0 kernel, a major milestone in Linux development that introduced significant advancements in process and network management, file systems, and driver support.
The Linux 4.0 kernel was released in 2015, featuring live kernel patching and numerous enhancements that made Linux more suitable for cloud-based applications.
In 2017, the Linux 4.14 kernel introduced improved security features, broader hardware support, and enhanced file system handling, further advancing the operating system's capabilities.
The release of Ubuntu 18.04 LTS in 2018 marked a significant moment for one of the most popular Linux distributions. This version included support for the GNOME desktop environment by default, replacing Unity, and emphasized improvements in security and stability.
The Linux 5.10 kernel, released in 2020 as a long-term support (LTS) version, brought several major improvements, including enhanced system security, hardware support, and overall performance enhancements.
In 2023, the Linux kernel reached version 6.0, representing a new phase in the evolution of the kernel with major updates in hardware support, security features, and optimizations for modern computing environments, including cloud and edge computing.

Understanding a Linux Distribution

A Linux distribution, often simply referred to as a "distro," is a particular variant of Linux that packages together the Linux kernel and a variety of additional software to create a fully functional operating system.

Each distribution includes:

The Linux Kernel, which is the core component responsible for managing hardware, processes, memory, and peripherals.
Libraries are included in each distribution, providing standard functions like input/output processing, mathematical computations, and other functionalities that various programs can use.
System Daemons are background services that start up during boot time to offer essential system functionalities, such as logging, task scheduling, and network management.
The inclusion of Development and Packaging Tools is essential for compiling and managing software packages, facilitating software installation and updates.
Each distribution also comes with Life-cycle Management Utilities that help manage system updates, configure system settings, and monitor the overall health of the system.

Before a distribution is released, all of these components are thoroughly tested together for compatibility and interoperability. This ensures a seamless user experience and functionality.

Linux distributions can be installed and run on a wide range of hardware, including servers, desktops, laptops, and more. They come in numerous variants each tailored for specific user groups or usage scenarios.

Examples of popular Linux distributions include:

Ubuntu is known for its user-friendly nature, making it a popular recommendation for Linux beginners.
The Debian distribution is renowned for its stability, often used in server environments and serving as the base for other distributions like Ubuntu.
As a cutting-edge distribution, Fedora includes the latest software technologies and is sponsored by Red Hat.
openSUSE is recognized for its robustness and versatility, making it suitable for both server and desktop environments.
Cumulus Linux is a specialized Linux distribution designed specifically for networking hardware.