Prerequisites and Initial Setup

This lesson covers the prerequisites and the quick start for using Claude Code — the developer CLI that helps you generate, inspect, and run code in your project. Claude Code is available as an npm package (@anthropic-ai/claude-code). If you already use npm, installation is straightforward; otherwise, you only need a recent Node.js runtime (Node 18+) and an active Claude or Anthropic Console account.

Ensure Node.js 18 or newer is installed and that you have an active Claude (or Anthropic Console) account before continuing.

What you’ll need

Item	Purpose	Notes / Example
Node.js 18+	Runtime for the CLI	Install via package manager, nvm, or the official installer: https://nodejs.org/
npm	Installs the Claude Code package	Bundled with Node.js
Claude account or Anthropic Console	Authentication for the CLI	Use subscription-based login or API-key via console
Terminal / shell	Run the `claude` command	macOS, Linux, Windows PowerShell, WSL, or VS Code integrated terminal

Install Node.js

On macOS (Homebrew):

# macOS (Homebrew)
brew install node

Typical output when Node is already installed:

jeremy@MACSTUDIO Demos % brew install node
Warning: node 24.4.1 is already installed and up-to-date.
To reinstall 24.4.1, run:
    brew reinstall node
jeremy@MACSTUDIO Demos %

On Debian/Ubuntu, the distribution repos may contain older Node versions. Use NodeSource for Node 18:

# Debian/Ubuntu (NodeSource installer for Node 18)
curl -fsSL https://deb.nodesource.com/setup_18.x | sudo -E bash -
sudo apt-get install -y nodejs

Or use nvm to manage multiple Node versions:

# Install nvm (follow printed instructions to add to your shell)
curl -o- https://raw.githubusercontent.com/nvm-sh/nvm/v0.39.3/install.sh | bash

# Then restart your shell and install Node 18
nvm install 18
nvm use 18

On Windows, download and run the installer from the official site: https://nodejs.org/. The important requirement is Node.js 18+.

Install Claude Code (global)

Install the CLI globally so you can run claude from any project folder:

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

Example output after installation:

jeremy@MACSTUDIO demos % npm install -g @anthropic-ai/claude-code

added 12 packages in 1s

11 packages are looking for funding
run `npm fund` for details
jeremy@MACSTUDIO demos %

Note: the -g flag installs the package globally. Without -g the package installs into the current project only. On some systems you may need sudo for global installs or to configure npm to use a user-writable global directory.

If you see permission errors installing globally, avoid using sudo as a first choice — instead configure npm to use a user-owned global directory or use a version manager (nvm) to install Node and npm without elevated privileges.

First run and authentication

Start the CLI:

claude

On first run the CLI will prompt for initial preferences (for example, text/ANSI color settings) and then guide you through authentication. The CLI supports two login flows:

The CLI attempts to open a browser for OAuth. If a browser cannot be opened (for example, when using WSL, SSH, or a headless environment), the CLI prints a URL that you can copy into any browser to complete sign-in. Example output when the CLI prints an authorization URL (wraps across lines):

Browser didn't open? Use the url below to sign in:

https://claude.ai/oauth/authorize?code=true&client_id=9d1c250a-...&response_type=code&redirect_uri=https%3A%2F%2Fconsole.anthropic.com%2Foauth%2Fcode%2Fcallback&scope=org%3Acreate_api_key+user%3Aprofile+user%3Ainference&code_challenge=...&code_challenge_method=S256&state=...

Paste code here if prompted >

After authorizing in the browser you’ll receive a short code to paste back into the CLI. A successful login looks like:

Login successful.
Press Enter to continue.

A dark-themed browser window showing an OAuth authorization prompt where "Claude Code" is requesting to connect to a Claude chat account, with prominent "Authorize" and "Decline" buttons. The dialog lists the account permissions against a black background.

The browser prompt asks you to allow Claude Code to access your account (profile info, usage contribution, etc.). Authorize to proceed.

Quick demo — generate a Python script that reads a CSV

This quick example shows Claude Code generating a small Python script to read members.csv and print first and last names. I created a members.csv file using Mockaroo and placed it into a project folder.

A screenshot of the Mockaroo web interface showing a mock data schema with fields like id, first_name, last_name, email, gender, and ip_address. The page includes options to generate, preview, and export the dataset (CSV format) and other schema settings.

At the Claude Code prompt I asked it to create a Python file that reads members.csv and displays first and last names. Claude Code inspected the current directory and generated this robust script using Python’s csv module. Generated file: read_members.py

import csv

def read_members():
    try:
        with open('members.csv', 'r', newline='') as file:
            reader = csv.DictReader(file)
            for row in reader:
                # Support different possible header capitalizations
                first_name = row.get('first_name', row.get('First Name', ''))
                last_name = row.get('last_name', row.get('Last Name', ''))
                print(f"{first_name} {last_name}")
    except FileNotFoundError:
        print("Error: members.csv file not found")
    except Exception as e:
        print(f"Error reading file: {e}")

if __name__ == "__main__":
    read_members()

Why this script is practical:

Uses csv.DictReader to work with named columns.
Handles header capitalization differences (first_name vs First Name).
Catches FileNotFoundError and general exceptions for clearer error messages.

Run the generated script

From the same project folder you can run the script directly. Optionally create and activate a virtual environment first:

python -m venv venv
# macOS / Linux
source venv/bin/activate
# Windows (PowerShell)
venv\Scripts\Activate.ps1

Then execute:

python read_members.py

Example output (first and last names from the CSV):

Marleah Danes
Jenica Jansie
Shepperd Kemmett
Floris Bolsover
Archie St. Queintain
Ansel Wandrey
Ola Puncher
Driren Vanner
Gusella Nairne
Concettina Khotler
Fidelity Clemens
Danita Excell
Ilyse Pusey
Hurlee Devereu
Katharine Vasyukhin
Jammie Grisedale
Lucila Portingale
Peria Buffin

Keep Claude Code running in any terminal (for example, the integrated terminal in VS Code) and continue issuing requests, generating or editing files, and iterating interactively.

Troubleshooting tips

If claude is not found after global install, ensure your npm global binaries directory is on your PATH. For many systems that directory is ~/.npm-global/bin or the location printed by npm bin -g.
If OAuth browser flow doesn’t open, copy the printed URL into a browser and follow the instructions. Paste the verification code back into the CLI when prompted.
Use nvm to avoid permission issues and to switch Node versions without sudo.

Summary and next steps

Install Node.js 18+ and verify npm is available.
Install Claude Code globally: npm install -g @anthropic-ai/claude-code.
Authenticate the CLI via browser OAuth or Anthropic Console.
Use Claude Code to generate code (like a Python CSV reader), inspect, and run it — then iterate.

Further lessons will cover advanced workflows, integrations (editors and CI), and project-specific customization.

Links and references

Claude Code npm package: https://www.npmjs.com/package/@anthropic-ai/claude-code
Node.js: https://nodejs.org/
Mockaroo (sample data generation): https://mockaroo.com/
nvm (Node Version Manager): https://github.com/nvm-sh/nvm
Visual Studio Code: https://code.visualstudio.com/

Introduction

Getting Started with Claude Code

Working with Claude Code

Code Review with Claude Code

Security Auditing with Claude Code

Advanced Features

Prerequisites and Initial Setup

What you’ll need

Install Node.js

Install Claude Code (global)

First run and authentication

Quick demo — generate a Python script that reads a CSV

Run the generated script

Troubleshooting tips

Summary and next steps

Links and references

Watch Video

​What you’ll need

​Install Node.js

​Install Claude Code (global)

​First run and authentication

​Quick demo — generate a Python script that reads a CSV

​Run the generated script

​Troubleshooting tips

​Summary and next steps

​Links and references

Watch Video

What you’ll need

Install Node.js

Install Claude Code (global)

First run and authentication

Quick demo — generate a Python script that reads a CSV

Run the generated script

Troubleshooting tips

Summary and next steps

Links and references