Linux Fundamentals

By bamr87

Basic Linux concepts including navigation, scripting, security, and networking

Estimated reading time: 3 minutes

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Table of Contents

Linux Fundamentals

Welcome to the Penguin’s Domain, brave adventurer! Linux is the backbone of modern servers, cloud infrastructure, and countless development environments. Mastering its fundamentals is like learning the ancient language of the digital realm — it unlocks power and flexibility that no other platform can match.

🎯 Quest Objectives

Primary Objectives (Required for Quest Completion)

• Master File Navigation — Navigate the Linux file system with ls, cd, pwd, and find
• Learn File Operations — Copy, move, rename, and delete files and directories
• Understand Bash Scripting Basics — Write scripts with variables, loops, and functions
• Grasp File Permissions — Use chmod, chown, and understand rwx notation

Secondary Objectives (Bonus Achievements)

• Set Up SSH — Generate SSH keys and connect to a remote server
• Configure a Cron Job — Schedule an automated task
• Explore Networking Tools — Use ping, traceroute, netstat, and curl
• Harden Your System — Configure a basic firewall with ufw

Mastery Indicators

• Can navigate any directory structure without a GUI
• Can write a Bash script that automates a multi-step task
• Can manage Linux users and permissions
• Can diagnose basic network connectivity issues

🗺️ Quest Prerequisites

📋 Knowledge Requirements

• Basic understanding of operating systems and file systems
• Familiarity with typing commands into a terminal

🛠️ System Requirements

• Linux distribution installed (Ubuntu recommended) or WSL on Windows
• Terminal access
• Internet connection for package installations

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Introduction

This guide covers essential Linux concepts that every IT professional should know. Whether you’re just starting your journey or need a refresher, these fundamentals will help you navigate the Linux ecosystem effectively.

Navigation - File Exploration

Basic Commands

• ls - List directory contents
• cd - Change directory
• pwd - Print working directory
• find - Search for files and directories
• locate - Find files using a database
• which - Locate a command

File Operations

• cp - Copy files and directories
• mv - Move/rename files and directories
• rm - Remove files and directories
• mkdir - Create directories
• rmdir - Remove empty directories

Scripting

Bash Scripting Basics

• Variables and environment setup
• Control structures (if/else, loops)
• Functions and parameter handling
• Input/output redirection
• Error handling and debugging

Shell Automation

• Cron jobs for scheduling
• Service management with systemctl
• Log analysis and monitoring
• Backup and maintenance scripts

Security

File Permissions

• Understanding rwx permissions
• chmod and chown commands
• User and group management
• sudo configuration

System Security

• SSH key management
• Firewall configuration (iptables/ufw)
• User authentication and authorization
• Security updates and patching

Networking

Network Basics

• TCP/IP fundamentals
• Network configuration
• DNS and hostname resolution
• Port management and services

Network Tools

• ping - Test connectivity
• traceroute - Trace network path
• netstat - Display network connections
• ss - Modern socket statistics
• curl and wget - Download and test HTTP endpoints

Resources

🏆 Quest Completion Validation

Skills Demonstrated

• File System Navigation — Confident use of ls, cd, pwd, find, locate
• File Operations — Copying, moving, renaming, and deleting files
• Scripting — Writing Bash scripts with variables and control structures
• Security — Managing permissions and understanding sudo
• Networking — Basic connectivity diagnostics and HTTP testing

📚 References & Resources

• Linux Command Line Basics
• Advanced Bash Scripting Guide
• Linux Security Best Practices