Before windows and icons, every computer was used through a command line. Graphical interfaces made software easier for most people, but the CLI never went away, because typed commands are fast, precise and easy to repeat or automate. Today almost every developer tool ships with a CLI, and AI coding agents rely on it heavily.
How Does a CLI Work?
You open a terminal app, type a command and press Enter. A command usually has three parts: the program name, an action, and options. For example, git status asks Git to show what has changed in a project, and vercel --prod tells the Vercel CLI to deploy to production. The program runs, prints its result, and waits for the next command.
CLI vs GUI
- GUI (graphical user interface): menus, buttons and forms. Easier to learn and better for visual work.
- CLI: typed commands. Faster for repeated tasks, easy to script, and works well over remote connections and inside automations.
Many tools offer both. You might create a Vercel project in the dashboard and deploy it from the CLI.
Common CLI Tools
- git and gh: version control and GitHub.
- npm and pnpm: installing JavaScript packages and running project scripts.
- vercel, aws and gcloud: deploying and managing cloud services.
- AI coding agents such as Claude Code, which run in the terminal and use other CLIs to do their work.
CLI and AI Agents
AI agents that work on code or files usually have a shell tool that lets them run CLI commands. That gives them access to thousands of existing tools without a custom integration for each one. The alternative is connecting tools through MCP, which offers typed, documented tools but adds definitions to every request. Our post on MCP vs CLI explains the trade-off, including why a stable CLI based setup is often cheaper in tokens.
Why Should Marketers Care About the CLI?
You do not need to become a developer, but basic comfort with the command line helps. It lets you run an AI coding agent on your own website, deploy a site, pull data from tools like Google Search Console through scripts, and follow technical guides without getting stuck. Many CLIs ask for an API key or a login the first time you use them, so knowing how to store those safely matters too.
Frequently asked questions
What is a CLI?+
A CLI, or command-line interface, is a text based way to control software by typing commands into a terminal and reading the text output, instead of clicking through a graphical interface.
What is the difference between a CLI and a terminal?+
The terminal is the app where you type commands. A CLI is the command-line interface of a specific program, such as the Git CLI or the Vercel CLI, that you use inside the terminal.
Why do AI agents use the CLI?+
Running CLI commands gives an agent access to thousands of existing tools through one shell tool, without building a custom integration for each, which keeps setups simple and token costs predictable.