👋 Welcome, DevOps Learners!

In today’s DevOps world, Linux is king. Whether you're deploying containers, managing servers, or writing automation scripts, chances are you're doing it on a Linux-based system.

So let's explore why Linux matters, what makes it different, and how you can begin your Linux journey as a DevOps engineer.

🔍 Why is Linux So Important in DevOps?

Here’s why you’ll find Linux everywhere in DevOps:

🐳 Docker & Containers run on Linux kernels
☁️ Cloud servers (AWS EC2, Azure VMs, GCP Compute) use Linux
🧱 Infrastructure-as-Code (IaC) tools like Terraform, Ansible, etc., assume Linux environments
🧑‍💻 CI/CD pipelines run shell scripts and build tools on Linux runners
🔐 Security & Networking tasks (SSH, firewall, permissions) are deeply rooted in Linux systems

Simply put: Linux is the backbone of DevOps infrastructure.

🧠 But What is Linux?

Linux is an open-source operating system based on UNIX. It’s like Windows or macOS—but built for power users, developers, and servers.

A Linux OS consists of:

Kernel – the core that talks to hardware
Shell – the command-line interface (CLI)
File system – directories and files arranged in a tree

🗂️ Linux File System Structure

Think of Linux like a house 🏠 with a hierarchy:

/
/bin       → essential binaries (like ls, cp, mv)
/etc       → configuration files
/home      → user directories
/var/log   → system logs
/tmp       → temporary files
/usr       → user-installed programs

Everything starts from / (root). Even devices like USB drives show up as files.

🔐 User & Permission Model

Linux is secure by design:

Every file/folder has a user, group, and permissions.
There’s a root (superuser) account with full control.

Example:

-rw-r--r-- 1 devops devops 1234 Apr 27 myfile.txt

Means:

rw- → owner can read/write
r-- → group can read
r-- → others can read

💻 Working with the Terminal

The terminal (also called the shell) is your best friend as a DevOps engineer.
Instead of clicking buttons, you type commands to interact with the OS.

Example:

pwd         # print current directory
ls          # list files
cd /home    # change directory
mkdir test  # create folder

We’ll explore these in detail in Day 14!

🔧 Getting Started with Linux

Use Ubuntu or CentOS on a VM or via https://replit.com/
Try WSL (Windows Subsystem for Linux)
Use free online labs like Katacoda or LinuxSurvival

✨ Why DevOps Engineers Love Linux

It’s stable, lightweight, and highly customizable
You can automate almost anything
It plays nicely with DevOps tools (Docker, Kubernetes, Jenkins, GitLab CI, etc.)

🎯 Day 13 Task

✅ Set up a Linux terminal using Replit, WSL, or a VM
✅ Navigate the file system using cd, pwd, ls
✅ Identify where key files live (/etc, /home, /var/log)

💬 Coming Up Next (Day 14)

👉 Essential Linux Commands for DevOps – we’ll dive deep into the most-used commands and their use cases. It’s going to be hands-on!

Why Every DevOps Engineer Must Know Linux