Linux Command Line Essentials for Penetration Testing

This course involves the use of artificial intelligence tools.

Your operating system is your first weapon. Learn to wield it.

Most servers on the internet run Linux. Most penetration testing tools run on Linux. And most people who try to break into cybersecurity get stuck at the same wall: they can't move confidently around a terminal.

This course removes that wall.

Instead of dumping a hundred commands on you, we start with how Linux thinks — the philosophy of small tools, chained together, with everything stored as a file. Once that clicks, the commands stop feeling like memorization and start feeling like logic.

You'll learn the architecture of a Linux system from hardware up through the kernel, shell and utility layers. You'll map the entire file system hierarchy and learn which directories actually matter during an assessment. You'll read your prompt like a pro to know instantly whether you're an unprivileged user or root.

Then we get practical. You'll run reconnaissance on a live box — who am I, where am I, what's running here. You'll create and manage files, decode every column of ls -la, and hunt down configuration files, backups and flags using find, locate and which. You'll finish with user and group management, and see exactly why /etc/shadow is the file every attacker wants.

Every section is demonstrated live in Kali Linux, so you're watching real output on a real terminal — not slides.

The course closes with three hands-on lab tasks covering user creation, hidden files and system enumeration, and file discovery. Do them. Terminal skill is muscle memory, and muscle memory only comes from typing.

No prior Linux experience required. Just a free virtual machine and a willingness to break things.

Course Curriculum

Course Introduction

• Welcome & what this course covers

• Why Linux is non-negotiable in cybersecurity

• How to follow along (setting up your environment)

The Linux Philosophy

• Principle 1: Everything is a file

• Principle 2: Small, single-purpose programs

• Principle 3: Chaining programs for complex tasks

• Principle 4: Avoid captive user interfaces

• Principle 5: Configuration stored in text files

Linux Architecture & Components

• The bootloader (GRUB) and the boot process

• The kernel: managing hardware and resources

• Daemons: background services explained

• The shell: Bash, Zsh and Fish

• Graphics server, window managers (GNOME, KDE) and utilities

• The four layers: hardware → kernel → shell → system utility

The Linux File System Hierarchy

• Why Linux has no "C: drive" — the single root explained

• Directory cheat sheet: /bin, /boot, /dev, /etc, /home, /lib

• Directory cheat sheet: /media, /mnt, /opt, /root, /sbin, /tmp, /usr, /var

• Demo: Exploring the root filesystem via terminal and GUI

Reading the Shell Prompt

• Anatomy of the prompt: user, host and path

• The tilde ~ and your home directory

• $ vs #: knowing your privilege level at a glance

• Demo: Switching to root with sudo su

Getting Help in the Terminal

• Why nobody memorizes every command

• Quick reference with --help

• Deep documentation with man

• Demo: Comparing wget --help and man wget

System Information & Reconnaissance

• Who am I? — whoami and id

• Where am I? — pwd and hostname

• What is this box? — uname

• Network recon — ifconfig, ip, netstat, ss

• Process and session info — ps, who, env

• Hardware enumeration — lsblk, lsusb, lsof, lspci

• Demo: Running your first recon sequence on a live machine

Navigating the File System

• The cd command and absolute vs relative paths

• Moving backwards with cd ..

• Navigation shortcuts worth knowing

Working with Files & Directories

• Creating empty files with touch

• Creating directories with mkdir

• Moving and renaming with mv

• Listing files with ls and the -la flag

• Decoding ls -la: permissions, links, owner, group, size, timestamp, name

• Demo: Create, list and rename files from scratch

Finding Files Like a Pentester

• Checking if a tool is installed with which

• Fast database searches with locate and sudo updatedb

• The find command: the gold standard

• find filters: -type, -name, -user, -size, -newermt

• Suppressing permission errors with 2>/dev/null

• Demo: Hunting backup files across the entire filesystem

User & Group Management

• Privilege escalation: from unprivileged user to root

• /etc/passwd — universally readable, no hashes

• /etc/shadow — where the password hashes live

• Running commands as another user: sudo and su

• Account management: useradd, userdel, usermod

• Group management: addgroup, delgroup

• Changing passwords with passwd

• Demo: Reading /etc/shadow with root privileges

Hands-On Lab Tasks

• Lab overview and how to approach the tasks

• Task 1: Create a user, add it to the root group, switch to it

• Task 2: Create a hidden readme file, reveal it, and run system info commands

• Task 3: Locate the files john.list and sudo using multiple methods

• Lab walkthrough and solutions