Week-2 : Fundamentals of Linux OS for DevOps

What is Operating System?

An Operating System (OS) is system software that manages computer hardware and software resources. It provides a user interface and enables applications to run.

There are basically two types of OS we use,

🔹 Client OS

A Client Operating System is designed for personal computers, laptops, or mobile devices. It provides a user-friendly interface and supports applications for day-to-day tasks.

Examples of Client OS:

✅ Windows (Windows 10, Windows 11)
✅ Linux (Ubuntu, Fedora)
✅ macOS

🔹Server OS

A Server Operating System is designed to manage network resources and serve multiple clients. It runs on servers that host websites, applications, and databases.

Generally, used in the industrial purposes as it is a multi-user and multi-tasking.

Examples of Server OS:

✅ Windows Server (Windows Server 2019, 2022)
✅ Linux Server (Ubuntu Server, CentOS, Red Hat Enterprise Linux)
✅ macOS Server

Linux Basics

Linux is established by Linus Torvalds.

It is open source
multi-user & multi-tasking

Flavors of Linux : Ubuntu, CentOS, RedHat, Fedora

Architecture of Linux

Architecture

1. Hardware Layer 🖥️

The physical components of the system (CPU, RAM, Hard Disk, Network Card, etc.).
Linux interacts with hardware via device drivers.

2. Kernel 🛠️ (Core of Linux)

The heart of the OS, directly communicating with hardware.
Manages system resources like CPU, memory, and devices.
Provides an interface for applications to interact with hardware.
Types of kernels in Linux: Monolithic (Linux Kernel), Microkernel, Hybrid.

3. Shell (Command Line Interface) 💻

Acts as a bridge between the user and the kernel.
Users give commands using the shell (e.g., Bash, Zsh), which the kernel executes.

4. Application Layer 🏗️

Where user programs and applications run (e.g., browsers, text editors, media players).
Users interact with applications via CLI (Command Line Interface) or GUI (Graphical User Interface).

In Linux, “Everything is Directory or a File.”
- / - Root Directory
Root level linux directories

1) Var (Variables) : Backup, cache, logs,…..etx

2) tmp (temporary) : Everyone can access

3) mnt (mount) : for stoarage adding

4) home

5) sbin : System level binary files

6) Root : root user (handles the system

7) etc : contains the configuration files

8) bin : contains the all linux commands

Some important linux commands,

man : used to display the details of the commands
cp : copy files
mkdir : To make a new directory
rm : remove files only
rmdir : removes the directory
rm -r : removes directory having files inside
rm -v : remove files and show the message that “removed file_name”
vim : used for creating a files and opening file in in write mode for writing a text, message into it.

Package manager : apt for ubuntu

update : used to download the package. ( sudo apt-get update )
upgrade : used to install the package. ( sudo apt-get upgrade )

sudo (super user do) : It is a group that has a super user / root user permissions.

How to Install nginx server on Linux.

nginx :

reverse proxy server
generally used to host the web pages
files of nginx are stored in the : /var

To install nginx on linux ,

sudo apt-get install nginx

To check , nginx is installed or check status of nginx

systemctl status nginx

systemctl : tool that control the services that installed on the system

To stop the nginx server.

sudo systemctl stop nginx

To start the nginx server.

sudo systemctl start ngnix

Conclusion

Linux is a powerful, open-source OS widely used for both personal and server environments. Its architecture includes Hardware, Kernel, Shell, and Application Layers, making it secure, multi-user, and multi-tasking. Mastering Linux commands, directories, and package management is essential for system administration. Additionally, setting up Nginx for web hosting showcases its flexibility in managing servers. Linux skills are crucial for DevOps, cloud computing, and automation! 🚀