Getting Started with Claude Code

Welcome to Claude Code, Anthropic's official CLI tool that brings the power of Claude AI directly into your development workflow. This comprehensive guide will walk you through everything you need to get started, from installation to your first AI-powered coding session.

Table of Contents

1. What is Claude Code?
2. System Requirements
3. Installation Guide
4. Initial Setup
5. Your First Claude Code Session
6. Basic Commands and Usage
7. Hands-On Exercise
8. Troubleshooting
9. Next Steps

What is Claude Code?

Claude Code is a powerful command-line interface (CLI) tool that integrates Claude AI into your local development environment. It allows you to:

• Get AI assistance for coding tasks directly in your terminal
• Generate, review, and refactor code with natural language commands
• Debug issues with intelligent error analysis
• Create documentation and tests automatically
• Work with multiple programming languages seamlessly

Key Benefits

• Context-Aware: Claude Code understands your project structure and codebase
• Multi-Language Support: Works with Python, JavaScript, TypeScript, Java, Go, and more
• Privacy-First: Your code stays on your machine; only queries are sent to Claude
• Integrated Workflow: Seamlessly fits into your existing development process

System Requirements

Before installing Claude Code, ensure your system meets these requirements:

Minimum Requirements

• Operating System:
  • macOS 10.15 (Catalina) or later
  • Windows 10 version 1903 or later
  • Ubuntu 20.04 LTS or later (or equivalent Linux distribution)
• Memory: 4GB RAM (8GB recommended)
• Storage: 500MB free disk space
• Internet: Stable connection for API calls

Prerequisites

• Node.js: Version 16.0 or higher
• npm or yarn: Latest stable version
• Git: Version 2.0 or higher (optional but recommended)

Installation Guide

Step 1: Install Node.js (if not already installed)

First, check if Node.js is installed:

node --version

If not installed, download from nodejs.org or use a package manager:

macOS (using Homebrew):

brew install node

Windows (using Chocolatey):

choco install nodejs

Linux (using apt):

sudo apt update
sudo apt install nodejs npm

Step 2: Install Claude Code

Once Node.js is installed, install Claude Code globally using npm:

npm install -g claude-code

Or using yarn:

yarn global add claude-code

Step 3: Verify Installation

Confirm Claude Code is installed correctly:

claude-code --version

You should see output like:

Claude Code v1.0.0

Initial Setup

Step 1: Authentication

First, you'll need to authenticate with your Anthropic API key:

claude-code auth

This will prompt you to:

1. Enter your API key (get one at console.anthropic.com)
2. Choose your preferred model (Claude 3 Opus, Sonnet, or Haiku)
3. Set your default preferences

Step 2: Configuration

Configure Claude Code for your environment:

claude-code config

You'll be asked about:

• Default project directory
• Preferred code style (tabs vs spaces, line endings)
• Language preferences
• Output verbosity

Step 3: Test Connection

Verify everything is working:

claude-code test

You should see:

✓ API connection successful
✓ Authentication valid
✓ Configuration loaded
Ready to start coding with Claude!

Your First Claude Code Session

Let's create a simple Python script with Claude's help:

Step 1: Start a New Session

Navigate to your project directory and start Claude Code:

cd ~/my-projects
claude-code start

You'll see:

Claude Code v1.0.0
Connected to Claude 3 Opus
Type 'help' for available commands or start chatting!

>

Step 2: Create Your First File

Ask Claude to create a simple Python script:

> Create a Python script that fetches weather data from an API and displays it nicely

Claude will:

1. Generate the code
2. Explain what it does
3. Ask if you want to save it

Step 3: Review and Save

Claude will show you the generated code:

import requests
import json
from datetime import datetime

def get_weather(city, api_key):
    """
    Fetch weather data for a given city using OpenWeatherMap API
    """
    base_url = "http://api.openweathermap.org/data/2.5/weather"
    params = {
        "q": city,
        "appid": api_key,
        "units": "metric"
    }
    
    try:
        response = requests.get(base_url, params=params)
        response.raise_for_status()
        return response.json()
    except requests.exceptions.RequestException as e:
        print(f"Error fetching weather data: {e}")
        return None

def display_weather(weather_data):
    """
    Display weather information in a formatted way
    """
    if not weather_data:
        return
    
    city = weather_data['name']
    country = weather_data['sys']['country']
    temp = weather_data['main']['temp']
    feels_like = weather_data['main']['feels_like']
    description = weather_data['weather'][0]['description']
    humidity = weather_data['main']['humidity']
    
    print(f"\n🌤️  Weather in {city}, {country}")
    print(f"{'='*30}")
    print(f"Temperature: {temp}°C (feels like {feels_like}°C)")
    print(f"Condition: {description.capitalize()}")
    print(f"Humidity: {humidity}%")
    print(f"{'='*30}\n")

if __name__ == "__main__":
    # You'll need to get an API key from OpenWeatherMap
    API_KEY = "your_api_key_here"
    city = input("Enter city name: ")
    
    weather_data = get_weather(city, API_KEY)
    display_weather(weather_data)

Save it with:

> save weather.py

Basic Commands and Usage

Essential Commands

Command	Description	Example
help	Show all available commands	> help
create [filename]	Create a new file	> create app.js
edit [filename]	Edit an existing file	> edit weather.py
review [filename]	Get code review	> review weather.py
explain [filename]	Get explanation of code	> explain weather.py
test [filename]	Generate tests	> test weather.py
docs [filename]	Generate documentation	> docs weather.py
refactor [filename]	Suggest improvements	> refactor weather.py
debug	Help debug errors	> debug TypeError in line 15
exit	Exit Claude Code	> exit

Natural Language Commands

You can also use natural language:

> Add error handling to the weather function
> Make this code more pythonic
> Add type hints to all functions
> Create a README for this project

Working with Context

Claude Code maintains context throughout your session:

> Look at weather.py
> Add a function to save weather data to a CSV file
> Now create a function to plot temperature trends

Hands-On Exercise

Let's build a simple task manager application step by step:

Exercise: Create a CLI Task Manager

1. Start Claude Code:

   claude-code start
   

2. Create the initial structure:

   > Create a Python CLI task manager with the following features:
   > - Add tasks
   > - List tasks
   > - Mark tasks as complete
   > - Delete tasks
   > - Save tasks to a JSON file
   

3. Add features incrementally:

   > Add a priority system (high, medium, low) to tasks
   > Add due dates to tasks
   > Add a function to show overdue tasks
   

4. Improve the code:

   > Review the task manager code and suggest improvements
   > Add proper error handling
   > Create unit tests for the task manager
   

5. Generate documentation:

   > Create a README.md with usage examples
   > Add docstrings to all functions
   

Expected Outcome

By the end of this exercise, you'll have:

• A functional CLI task manager
• Comprehensive error handling
• Unit tests
• Complete documentation
• Experience with Claude Code's workflow

Troubleshooting

Common Issues and Solutions

API Key Issues

Problem: "Invalid API key" error Solution:

claude-code auth --reset

Then re-enter your API key.

Connection Problems

Problem: "Cannot connect to Claude API" Solution:

1. Check internet connection
2. Verify firewall settings
3. Try using a different network
4. Check API status at status.anthropic.com

Installation Issues

Problem: "command not found: claude-code" Solution:

1. Ensure npm/yarn global bin is in PATH
2. Reinstall with admin privileges:

   sudo npm install -g claude-code
   

Performance Issues

Problem: Slow responses Solution:

1. Check internet speed
2. Consider using a faster model (Haiku for simple tasks)
3. Clear cache: claude-code cache clear

Getting Help

• Documentation: Run claude-code docs
• Community Forum: Visit community.anthropic.com
• GitHub Issues: Report bugs at github.com/anthropics/claude-code
• Email Support: support@anthropic.com

Next Steps

Congratulations! You've successfully installed and started using Claude Code. Here's what to explore next:

Recommended Tutorials

1. Claude Code Advanced Features - Learn about advanced capabilities
2. Building a Web App with Claude Code - Create a full-stack application
3. Claude Code for Data Science - Use Claude for data analysis

Tips for Success

1. Be Specific: The more detailed your requests, the better Claude's responses
2. Iterate: Don't hesitate to ask for modifications or improvements
3. Learn Shortcuts: Use claude-code shortcuts to see time-saving commands
4. Provide Context: Share relevant files and explain your goals
5. Experiment: Try different approaches and learn what works best

Join the Community

• Follow @AnthropicAI for updates
• Join our Discord server for real-time help
• Share your projects with #ClaudeCode on social media

---

Summary

You've learned how to:

• ✅ Install and configure Claude Code
• ✅ Authenticate with your API key
• ✅ Create your first AI-assisted program
• ✅ Use basic commands and natural language
• ✅ Complete a hands-on project
• ✅ Troubleshoot common issues

Claude Code is now ready to accelerate your development workflow. Happy coding!

---

Last updated: January 2025 | Report an issue | Suggest improvements