In an era of graphical interfaces, the command line may seem like a relic. But for those who know how to use it, the terminal remains the most direct, efficient, and powerful way to control a computer, automate complex workflows, and operate at scale. It is an indispensable tool for developers, system administrators, and researchers alike.

Mastering Terminal in the Age of AI: A Guide to Command Line is your structured, accessible pathway into the world of the terminal. This book is designed to bridge the gap for everyone, from beginners who have never opened a terminal to experienced developers seeking to refine their productivity. It provides a clear understanding of core concepts across Windows, macOS, and Linux, focusing on the three major shells: Bash, Zsh, and PowerShell. A central theme of this guide is the emerging role of Artificial Intelligence within the terminal. Far from making command-line skills obsolete, AI-powered tools amplify them, creating a paradigm shift in how we interact with our computers. This book will show you how to integrate intelligent agents like Claude Code, Codex CLI, and Gemini CLI into your workflows, moving from issuing step-by-step instructions to describing high-level goals.