Operating Systems and Linux Basic, Intermediate and Advance

#linux #devops #ubuntu #advance

Module 1: Foundations of Linux and Operating Systems

What is an OS and how does it work?
An Operating System (OS) is system software that acts as an intermediary between computer hardware and the user. It manages hardware resources and provides a set of services for computer programs.

Key Functions of an OS
1. Process Management
2. Memory Management
3. File System Management
4. Device Management
5. User Interface (UI)
6. Security and Access Control

How Does an OS Work?
Imagine you want to open a web browser.
1. You click the icon.
2. The OS:

Allocates memory to load the program.
Tells the CPU to start running the browser process.
Uses the file system to read the browser files from disk.
Interacts with the display and input devices to show the window and accept your input.
Manages network access for the browser to connect to the internet.

Common Examples of Operating Systems

Windows – Popular for PCs and laptops.
macOS – Apple's OS for Mac computers.
Linux – Open-source OS used in servers, supercomputers, and also desktops.
Android – Based on Linux, used in mobile phones.
iOS – Apple's OS for iPhones and iPads.

What is Linux?
Linux is an open-source Operating System based on Unix. It is known
for its security and flexibility.

Key Features:

Free and open-source.
Highly customizable.
Strong command-line tools.
Large community support.
Preferred for development, DevOps, and servers

Linux Architecture Layers
Linux follows a modular, layered architecture, which provides flexibility, stability, and performance.

Linux File System Hierarchy & Key Directories

Quick Analogy with Windows

Module 2: Virtualization and Linux VMs

What is Virtualization?
Virtualization is the process of creating a virtual (rather than physical) version of something—like a server, storage device, or operating system.

What is a Virtual Machine (VM)?
A Virtual Machine (VM) is an emulation of a physical computer. It behaves like a real computer with:

Its own CPU, RAM, disk, and NIC (virtually assigned)
An operating system (called guest OS)
Applications running independently of other VMs Think of it like running a full computer inside your computer.

What is a Hypervisor?
A hypervisor (also called Virtual Machine Monitor) is software that creates and manages VMs by allocating hardware resources.

Type 1 vs Type 2 Comparison

Module 3: Managing Software on Linux

What is a Package Manager?
A Package Manager is a tool that automates the process of installing, updating, configuring, and removing software packages in a Linux or Unix-like operating system.

Key Functions of a Package Manager:

Popular Package Managers by OS

What are Software Repositories?
Software Repositories (Repos) are online storage locations that contain collections of software packages. Linux distributions or third parties maintain them.

How it Works:

You run a command like apt install curl.
The package manager contacts a repository, downloads the package and dependencies.
It installs and configures the software on your system.