🐧 Linux Engine

Linux notes organized by topic — covering everything from the basics to shell scripting, built for DevOps and cloud work.

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📁 Structure

Content is grouped by topic — so it's easy to find exactly what you need without hunting through numbered folders.

linux-engine/
│
├── 01-Basics/
│   ├── introduction-to-linux.md
│   └── virtual-machines-hypervisors.md
│
├── 02-Navigation-and-Files/
│   ├── linux-navigation-commands.md
│   ├── file-and-directory-management.md
│   └── file-copy-move-sort.md
│
├── 03-System-Utilities/
│   ├── search-compare-utilities.md
│   └── archives-downloads-text-processing.md
│
├── 04-Users-and-Permissions/
│   └── users-permissions-ssh.md
│
├── 05-System-Administration/
│   ├── system-monitoring-processes.md
│   └── file-transfer-windows-linux.md
│
├── 06-Networking/
│   ├── ssh-server-management-systemctl.md
│   └── linux-networking-commands.md
│
├── 07-Scripting/
│   └── shell-scripting-basics.md
│
└── README.md

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📋 Course Index

🟦 Module 1 — Basics

Topic	What's Covered
Introduction to Linux	Linux kernel, distributions (Ubuntu, Debian, RHEL, Kali), OS responsibilities (CPU/RAM/Storage/Users), Linux vs Unix, why Linux runs the internet and cloud
Virtual Machines & Hypervisors	What a VM is, how a hypervisor allocates CPU/RAM/Disk to VMs, Type 1 (ESXi, Hyper-V, Xen) vs Type 2 (VirtualBox, VMware Workstation), tools to connect: PuTTY, MobaXterm, WinSCP, SSH

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🟩 Module 2 — Navigation & Files

Topic	What's Covered
Linux Navigation	pwd, ls with all flags (-l, -a, -la, -lh, -lt, -R), cd (absolute, relative, ~, /, -)
File & Directory Management	cat, less, more, head, tail, tail -f, touch, echo, mkdir -p, rm -rf, cp, mv, editing with nano / vi / vim
Copy, Move & Sort	cp (single, multiple, folder, from parent), mv (move + rename), sort (alpha, numeric, reverse), uniq, piping sort | uniq -c, absolute vs relative paths

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🟨 Module 3 — System Utilities

Topic	What's Covered
Search, Compare & Utilities	grep (-i, -n, -c, -r), wildcards (*, ?, []), wc -l, diff, cmp, find (by name, type, extension), locate, which, whereis, history, man, cal, script
Archives, Downloads & Text Processing	zip/unzip, gzip/gunzip, tar (-cf, -xf, -czf, -xzf), wget, curl (GET, POST, headers), export env vars, ~/.bashrc, cut, tr, sed -n, fold, column, alias

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🟥 Module 4 — Users & Permissions

Topic	What's Covered
Users, Permissions & Remote Access	apt/yum/dnf package install, useradd, passwd, userdel, usermod, whoami, who, su, sudo, visudo, SSH connect + key-based login (ssh-keygen, ssh-copy-id), scp (file + folder), chmod (symbolic + numeric: 755, 644), chown, chgrp, umask, SUID/SGID/sticky bit

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🟧 Module 5 — System Administration

Topic	What's Covered
System Monitoring & Processes	free -h, top, htop, df -h, du -sh, uname -a, lscpu, lsblk, cat /etc/os-release, ps aux, pidof, kill -9, systemctl (start/stop/restart), background jobs (&, jobs, fg, bg), reboot, shutdown, crontab -e, user & group management (groupadd, groupdel, usermod, id)
File Transfer Windows ↔ Linux	WinSCP setup (SFTP, port 22), drag-drop transfer, scp (local→remote, remote→local, remote→remote), scp -i with key, scp -p preserve permissions, scp -C compression, sftp interactive session (put, get), rsync -avz, common errors and fixes

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🟪 Module 6 — Networking

Topic	What's Covered
SSH & Server Management	SSH protocol, default port 22, /etc/ssh/sshd_config, rpm -qa | grep ssh, install openssh, systemctl full service lifecycle (start/stop/restart/enable/disable/mask/unmask/is-enabled), systemctl list-sockets, poweroff, reboot -i, passwordless SSH (keygen → copy-id → login)
Linux Networking Commands	ping (flags: -c, -i, -s, -t), traceroute (flags: -n, -I, -T, -p, -m), netstat vs ss (-tuln, -tulnp, -s), ip a / ip route / ip neigh / ip link set, DNS tools (nslookup, dig, host), curl (GET/POST/headers), wget, lsof -i, nc, tcpdump, mtr, firewall (ufw, firewall-cmd), real-world troubleshoot flow

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🔶 Module 7 — Scripting

Topic	What's Covered
Shell Scripting	Shebang (#!/bin/bash), variables, read, special vars ($0, $1, $#, $?), arithmetic ($(( ))), if/elif/else, for/while/until loops, case, functions, file tests (-f, -d, -r, -x), string ops, command substitution $(), output redirection, bash -x debugging, cron scheduling

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📊 Progress Tracker

#	Topic	Status
1	Introduction to Linux	✅
2	Virtual Machines & Hypervisors	✅
3	Linux Navigation Commands	✅
4	File & Directory Management	✅
5	Copy, Move & Sort	✅
6	Search, Compare & Utilities	✅
7	Archives, Downloads & Text Processing	✅
8	Users, Permissions & Remote Access	✅
9	System Monitoring & Processes	✅
10	File Transfer Windows ↔ Linux	✅
11	SSH, Server Management & systemctl	✅
12	Linux Networking Commands	✅
13	Shell Scripting Complete Guide	✅

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🛠️ How to Use This Repo

Clone it and open any .md file directly — each file is self-contained with commands, examples, and explanations.

git clone https://github.com/Shubhamx18/linux-engine.git
cd linux-engine

Each topic builds on the previous one, so going in order is recommended for beginners.
If you already know the basics, jump directly to any module using the index above.

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⚙️ Environment

All commands are tested on:

• Ubuntu 22.04 / 24.04 LTS
• CentOS / RHEL 8+
• Works on any Debian or RPM-based distro

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If this repo helped you — drop a ⭐ !!!