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UC Jung
UC Jung

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Chapter 1. Claude Code CLI Installation Guide

#ai #cli #tooling #tutorial

1.1 What is Claude Code CLI?

A command-line tool that lets you direct an AI to write code using natural language, right from your terminal.
It is a separate program from Claude.ai in the web browser, and is launched with the claude command after installation.

1.2 Prerequisites

Item Requirement
Operating System Windows 10+, Ubuntu 20.04+, macOS 10.15+
Account Claude Pro / Max / Teams / Enterprise (free plan not supported)
Internet Required for installation and use
RAM / Disk 4GB+ / 500MB+

Installation Method Comparison

Method Node.js Auto-update Notes
① Native Not required ✅ ⭐ Officially recommended
② WinGet (Windows only) Not required ❌ Manual
③ npm 18+ required ❌ Manual ⛔ Deprecated

1.3 Windows PowerShell

① Native Installation (Recommended)

Prerequisites — Install Git for Windows

Claude Code uses Git Bash internally, so this is required.

  1. Download from https://git-scm.com → install with default settings
  2. Verify: 
   git --version
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Installation

irm https://claude.ai/install.ps1 | iex
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irm (downloads the script from the web) → iex (executes it)

Verify — Close PowerShell, open a new window, then run

claude --version
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If you see a "claude is not recognized" error

[Environment]::SetEnvironmentVariable("PATH", "$env:PATH;$env:USERPROFILE\.local\bin", [EnvironmentVariableTarget]::User)
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→ Restart PowerShell and verify again

② WinGet Installation 

winget install Anthropic.ClaudeCode
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Auto-update is not supported. To update manually: winget upgrade Anthropic.ClaudeCode

③ npm Installation (⛔ Deprecated)

🚨 Deprecation notice. Do not use for new installations.

# Node.js 18+ must be installed beforehand (https://nodejs.org LTS version)
npm install -g @anthropic-ai/claude-code
claude --version
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Migrating from npm to Native

irm https://claude.ai/install.ps1 | iex          # Install native
npm uninstall -g @anthropic-ai/claude-code        # Remove npm package
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Your settings (~/.claude/) are preserved during migration.

1.4 Ubuntu Terminal

① Native Installation (Recommended)

Installation

curl -fsSL https://claude.ai/install.sh | bash
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curl (downloads the script from the web) → bash (executes it)

Verify — Restart the terminal or run source ~/.bashrc, then run

claude --version
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If you see a "command not found" error

echo 'export PATH="$HOME/.local/bin:$PATH"' >> ~/.bashrc
source ~/.bashrc
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② npm Installation (⛔ Deprecated)

🚨 Deprecation notice. Do not use for new installations.

# Install Node.js
sudo apt update && sudo apt install -y nodejs npm

# Configure global installs without sudo
mkdir ~/.npm-global
npm config set prefix '~/.npm-global'
echo 'export PATH=~/.npm-global/bin:$PATH' >> ~/.bashrc
source ~/.bashrc

# Install Claude Code
npm install -g @anthropic-ai/claude-code
claude --version
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Migrating from npm to Native

curl -fsSL https://claude.ai/install.sh | bash    # Install native
npm uninstall -g @anthropic-ai/claude-code         # Remove npm package
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1.5 First Launch and Authentication (All Platforms) 

cd ~/my-project    # Navigate to your project folder
claude             # Launch
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  1. A browser window opens automatically → sign in with your Claude.ai account
  2. Authentication complete → automatically reflected in the terminal (no re-authentication needed afterward)

For headless environments (servers, etc.):

export ANTHROPIC_API_KEY=sk-ant-xxxxxxxxxxxxxxxx

1.6 Diagnostics, Updates, and Uninstallation

Diagnostics

claude doctor
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Updates

Method Command
Native Automatic (no action needed)
WinGet winget upgrade Anthropic.ClaudeCode
npm npm update -g @anthropic-ai/claude-code

Uninstallation

claude uninstall                                   # Native
winget uninstall Anthropic.ClaudeCode              # WinGet (Windows)
npm uninstall -g @anthropic-ai/claude-code         # npm
rm -rf ~/.claude                                   # Remove settings files (optional)
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1.7 Quick Command Reference

Windows PowerShell 

# Native (recommended)
irm https://claude.ai/install.ps1 | iex

# WinGet
winget install Anthropic.ClaudeCode

# npm (⛔ Deprecated)
npm install -g @anthropic-ai/claude-code

# Common
claude --version    # Check version
claude              # Launch
claude doctor       # Diagnostics
claude uninstall    # Uninstall
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Ubuntu Terminal 

# Native (recommended)
curl -fsSL https://claude.ai/install.sh | bash

# npm (⛔ Deprecated)
npm install -g @anthropic-ai/claude-code

# Common
claude --version    # Check version
claude              # Launch
claude doctor       # Diagnostics
claude uninstall    # Uninstall
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1.8 Glossary

Term Definition
CLI A method of controlling a computer using keyboard commands
Terminal A program used to enter CLI commands (e.g., PowerShell, Terminal)
PATH The list of directories the OS searches when looking for programs
npm The Node.js package manager
WinGet The official Windows package manager
Deprecated Scheduled for removal; currently functional but may be dropped in a future release
OAuth An authentication method that works through a browser
API Key A credential used to authenticate with a service

Reference: https://code.claude.com/docs/en/setup | https://github.com/anthropics/claude-code

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