Claude Code CLI Setup

What is Claude Code CLI?

Claude Code CLI is a terminal-based AI coding assistant from Anthropic. You type natural language prompts directly in your terminal and Claude reads, writes, and modifies files on your machine. It is the recommended tool for following the CoEngineers guides.

Before You Start

All the steps below happen inside a terminal. If you have never used a terminal before, follow the Using the Terminal guide first, then come back here.

Step 1: Install Node.js

Claude Code CLI requires Node.js 18 or later. You may already have it installed. Open your terminal and run:

node --version

If you see a version number like v18.x.x or higher, skip ahead to Step 2. If you see “command not found” or a version below 18, follow the instructions below.

Install Node.js

macOS

Visit nodejs.org and download the LTS installer for macOS. Run the .pkg file and follow the prompts.

Alternatively, if you have Homebrew installed:

brew install node

Windows

Visit nodejs.org and download the LTS installer for Windows. Run the .msi file and follow the prompts. Make sure “Add to PATH” is ticked during installation.

After installing, verify by running:

node --version

You should see a version number like v20.x.x or higher.

Step 2: Install Claude Code CLI

Open your terminal and run:

npm install -g @anthropic-ai/claude-code

Verify the installation:

claude --version

Step 3: Authenticate

Run Claude Code for the first time:

claude

This will open your browser and prompt you to sign in with your Anthropic account. Follow the on-screen instructions to complete authentication. Once authenticated, the CLI will confirm you are signed in and you will see the Claude Code prompt in your terminal.

Step 4: Basic Usage

Navigate to your project folder and start Claude Code:

cd ~/my-project
claude

You are now in an interactive session. Try your first prompt:

List all the files in this directory and describe what each one does

Here's what I found in this directory:

1. meeting-notes.docx: A Word document containing meeting notes
2. budget.xlsx: A spreadsheet with budget figures
3. photos/: A folder containing image files

The directory has 2 files and 1 folder.

LLM outputs are non-deterministic and may vary from this example.

Claude will read your files and respond directly in the terminal.

Useful Commands

Command	Description
`claude`	Start an interactive session in the current directory
`claude "your prompt"`	Run a single prompt without entering interactive mode
`claude --help`	Show all available options
`/help`	Show help within an interactive session
`Ctrl+C`	Cancel the current response
`Ctrl+D` or `/exit`	Exit the interactive session

Next Steps

Return to the Prerequisites page and continue with the guides. When you see an LLM Prompt Box, copy the prompt and paste it into your Claude Code CLI session.