Introduction to Linux Operating System: A Comprehensive Guide for Beginners

UNIX and Linux Flavours

Over the years, numerous operating systems have emerged, deriving inspiration from UNIX and Linux:

Derived from UNIX:	Derived from Linux:
Linux	Red Hat Enterprise Linux (RHEL)
HP-UX	CentOS
IBM AIX	Fedora
macOS	Ubuntu
Sun Solaris (now Oracle Solaris)	Kali Linux

Linux Operating System Community and Family Connections

The Linux ecosystem is powered by strong community support and contributions. Here’s how the communities are interlinked:

• Fedora, CentOS, and Red Hat: Fedora acts as the testing ground for innovations that eventually shape RHEL and CentOS.
• Debian Family: Debian serves as the backbone for distributions like Ubuntu, Kali Linux, and Linux Mint, providing a stable foundation for various use cases offering stability and a wide range of applications.

Key Features of UNIX and Linux Operating System

Both UNIX and Linux are celebrated for their exceptional features:

• Robust Security: Multiple layers of security, including firewalls and two-factor authentication (2FA), protect users.
• Virus Resistance: Automatic execution permissions are disabled by default, reducing vulnerabilities to malware.
• Stability: Linux supports older hardware and remains a favourite for critical systems.
• Free and Open-Source Availability: Most Linux distributions are free, making them accessible to everyone.
• Versatile File System Support: Linux supports a wide range of file systems for flexibility.
• Efficient Resource Management: The operating system is optimized for better utilization of system resources.
• Customizability: Users can tailor Linux to suit their specific needs.

Use of UNIX and Linux

UNIX and Linux power some of the most demanding applications in the tech world:

• Supercomputers: Most of the world’s supercomputers run on Linux.
• Servers: Linux dominates the server market due to its reliability and security.
• Cloud Computing: It is the backbone of many cloud platforms and infrastructure services.

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Linux Kernel: The Heart of the Operating System

The kernel is often referred to as the heart of the operating system. It is responsible for managing and executing all hardware-related tasks. Here’s how it works:

Linux Kernel and Its Components

The operating system is composed of three main parts:

Kernel:

• The heart of the operating system, responsible for communicating with the hardware.
• The kernel acts as an intermediary, ensuring that hardware tasks are executed as requested.
• It manages hardware resources such as CPU, memory, and I/O devices.

Shell:

• The interface between the user and the kernel, enabling users to interact with the operating system.
• Users pass commands via the shell, which then relays these instructions to the kernel.
• The shell can be likened to a command prompt in Windows but offers far greater flexibility and functionality.

Built-In Utilities:

• Provide users with essential tools and commands to perform tasks such as file manipulation, process management, and system configuration.

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Understanding the UNIX/Linux Shell

The UNIX/Linux shell is a powerful interface that unlocks the full potential of the operating system. Here’s what you need to know:

What is the Shell?

• The shell is a command-line interface that allows users to interact directly with the operating system.
• It is used to manipulate data, run applications, and automate tasks based on specific conditions.

Comparison to Windows/DOS Systems

• While it’s similar to the old Command Prompt in Windows/DOS, the shell in UNIX/Linux is far more robust and versatile.
• It supports advanced scripting, automation, and system-level control that goes beyond basic commands.

Different Flavors of Shells

• UNIX/Linux systems come with multiple shell types, such as Bash, C Shell, and tcsh.
• Each shell performs the same core functions but offers unique features or syntax variations.

Types of Shells

Linux supports various types of shells, each offering unique features:

• Bash (Bourne Again Shell): The most widely used shell in Linux.
• C Shell (csh): Known for its syntax resembling the C programming language.
• tcsh: An enhanced version of C Shell with additional features.

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Is Linux the Same as UNIX?

YES, Linux is Like UNIX Because:

1. Look and Feel:
   • Linux has a similar interface and functionality to traditional UNIX systems.
   • Users familiar with UNIX can easily navigate Linux due to its shared principles and design.
2. Compatibility:
   • Linux can run nearly any program designed for UNIX systems.
   • It adheres to conventions like POSIX (Portable Operating System Interface), ensuring interoperability with UNIX applications.

NO, Linux is Not Exactly UNIX Because:

1. Kernel Differences:
   • The Linux kernel introduces many new features and innovations that go beyond the classical UNIX design.
   • It is written independently from scratch, without using UNIX code.
2. Licensing and Philosophy:
   • UNIX is proprietary in many of its implementations, whereas Linux is open-source and freely available under the GPL (GNU General Public License).

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What is GNU?

Without GNU, the Linux operating system as we know it wouldn’t exist. The tools developed under the GNU Project provide the essential functionality needed for system operation and user interaction, making GNU an integral part of Linux distributions.

• It represents a collection of free software tools that, combined with the Linux kernel, create a fully functional operating system.
• While Linus Torvalds developed the Linux kernel, many essential tools that make Linux usable (e.g., compilers, shell, text editors) come from the GNU Project. Together, the GNU tools and the Linux kernel form what we often call a Linux distribution.
• The GNU Public License (GPL) ensures that: You can freely use, study, and modify the software. You can redistribute the modified software, provided it remains under the GPL terms.

The Free Software Foundation (FSF)`

• The GNU Project was initiated by Richard Stallman, who founded the Free Software Foundation (FSF).
• The goal of the FSF is to promote the development and use of software that can be freely shared and modified.

The Significance of GNU Public License (GPL)

• The GPL defines how software and its source code can be shared, ensuring the freedom to modify and redistribute the software under the same license.
• This licensing philosophy underpins the collaborative nature of Linux and many other open-source projects.

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Linux Booting Process: A Simple Explanation

The process of booting a Linux system involves several stages, each with a unique role in preparing the system for use. Here’s a step-by-step explanation:

1. Bootloader:
   • It is software that manages the start-up process. It identifies the operating system to load.
   • Finds and loads the Linux kernel into memory.
2. Kernel
   • It manages hardware resources such as the CPU, memory, and peripheral devices (like hard drives, printers, etc.) to start the system.
   • Acts as a bridge between the hardware and the rest of the system.
3. Init System
   • Once the kernel is loaded, control is handed over to the init system.
   • The init system starts user-space processes and manages background services (called daemons).
   • It ensures necessary services are running and the system is ready for the user.
4. Daemons
   • They are background services that handle system tasks like printing, managing sound, or scheduling.
   • These services start automatically during boot or after you log in.
   • It keep the system functional behind the scenes.
5. Graphical Server
   • Commonly known as the X server or just X which is responsible for displaying graphics on your monitor.
   • It provides the interface for your desktop environment to interact with the hardware.
   • Enables the graphical user interface (GUI).
6. Desktop Environment
   • The desktop environment is what users interact with on the screen.
   • It comes with built-in tools like file managers, configuration utilities, and web browsers.
   • It provides a user-friendly interface for interacting with the system.
7. Applications
   • The applications are the programs you use, such as web browsers, office suites, and media players.
   • Linux distributions often include app store-like tools (e.g., Ubuntu Software Centre) for easy installation of additional software.
   • It extend the functionality of the system to meet user needs.

Also Read: How to Install Red Hat Enterprise Linux