AI CLI Tools - Installation

ai cli claude-code codex gemini installation

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Overview

CLI-based AI coding assistants that run in your terminal, providing code generation, explanation, and agentic capabilities.

Tool	Provider	Model	Key Features
Claude Code	Anthropic	Claude	Agentic coding, tool use, background agents
Codex CLI	OpenAI	GPT-4	Code generation, shell integration
Gemini CLI	Google	Gemini	Multimodal, Google ecosystem integration
Aider	Open Source	Multiple	Git integration, pair programming
Continue	Open Source	Multiple	IDE extension with CLI

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Claude Code

Installation

# Install via npm (Node.js 18+ required)
npm install -g @anthropic-ai/claude-code
 
# Or via Homebrew (macOS)
brew install claude-code

Setup

# Authenticate (opens browser)
claude auth login
 
# Or set API key directly
export ANTHROPIC_API_KEY="sk-ant-..."
 
# Verify installation
claude --version

Configuration

Config location: ~/.claude/

# View current config
claude config list
 
# Set default model
claude config set model claude-sonnet-4-20250514
 
# Set default context
claude config set max-tokens 4096

Upgrade

# npm
npm update -g @anthropic-ai/claude-code
 
# Homebrew
brew upgrade claude-code
 
# Check version
claude --version

Basic Usage

# Interactive mode
claude
 
# Single query
claude "explain this error" < error.log
 
# With file context
claude -f src/main.py "add error handling"
 
# In a project directory
cd my-project && claude

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OpenAI Codex CLI

Installation

# Install via npm
npm install -g @openai/codex-cli
 
# Or pip
pip install openai-codex-cli

Setup

# Set API key
export OPENAI_API_KEY="sk-..."
 
# Or configure
codex config set api_key sk-...

Configuration

# Set default model
codex config set model gpt-4
 
# View config
codex config list

Upgrade

# npm
npm update -g @openai/codex-cli
 
# pip
pip install --upgrade openai-codex-cli

Basic Usage

# Interactive mode
codex
 
# Execute with prompt
codex "write a Python script to parse JSON"
 
# Shell mode (generates and runs commands)
codex shell "find all large log files"

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Gemini CLI

Installation

# Install via npm
npm install -g @google/gemini-cli
 
# Or pip
pip install google-gemini-cli

Setup

# Authenticate with Google Cloud
gcloud auth application-default login
 
# Or set API key
export GOOGLE_API_KEY="AI..."
 
# Or Vertex AI
export GOOGLE_CLOUD_PROJECT="your-project"

Configuration

# Set default model
gemini config set model gemini-pro
 
# Enable multimodal
gemini config set multimodal true

Upgrade

# npm
npm update -g @google/gemini-cli
 
# pip
pip install --upgrade google-gemini-cli

Basic Usage

# Interactive mode
gemini
 
# With prompt
gemini "explain this code" < script.py
 
# With image (multimodal)
gemini -i screenshot.png "what's wrong with this UI?"

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Aider (Open Source)

Installation

# pip (recommended)
pip install aider-chat
 
# pipx (isolated)
pipx install aider-chat
 
# Homebrew
brew install aider

Setup

# Works with multiple providers
export ANTHROPIC_API_KEY="sk-ant-..."
# or
export OPENAI_API_KEY="sk-..."
 
# Start in repo
cd my-project
aider

Configuration

Config: ~/.aider.conf.yml or .aider.conf.yml in project

model: claude-3-5-sonnet-20241022
auto-commits: true
git: true

Upgrade

pip install --upgrade aider-chat
# or
pipx upgrade aider-chat

Basic Usage

# Start with specific files
aider src/main.py src/utils.py
 
# With model selection
aider --model claude-3-5-sonnet-20241022
 
# Read-only mode (no edits)
aider --read src/main.py
 
# Show diff before applying
aider --show-diffs

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Environment Variables Summary

# Add to ~/.bashrc, ~/.zshrc, or ~/.profile
 
# Anthropic (Claude)
export ANTHROPIC_API_KEY="sk-ant-..."
 
# OpenAI (Codex, GPT)
export OPENAI_API_KEY="sk-..."
 
# Google (Gemini)
export GOOGLE_API_KEY="AI..."
# Or for Vertex AI
export GOOGLE_CLOUD_PROJECT="project-id"
 
# Optional: Default model preferences
export CLAUDE_MODEL="claude-sonnet-4-20250514"
export OPENAI_MODEL="gpt-4"

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Shell Integration

Bash/Zsh Completion

# Claude Code
claude completion bash >> ~/.bashrc
claude completion zsh >> ~/.zshrc
 
# Aider
aider --install-completion

Aliases

# Add to ~/.bashrc or ~/.zshrc
 
# Quick access
alias cc="claude"
alias ask="claude -q"  # Quick question mode
 
# Project-specific
alias code-review="claude 'review this code for issues'"
alias explain="claude 'explain this code'"

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Troubleshooting

Common Issues

Issue	Solution
command not found	Check PATH, reinstall, restart terminal
401 Unauthorized	Check API key is set correctly
Rate limited	Wait and retry, check usage limits
Node version error	Upgrade Node.js to 18+
SSL certificate error	Check proxy settings, corporate firewall

Proxy Configuration

# For corporate environments
export HTTP_PROXY="http://proxy.company.com:8080"
export HTTPS_PROXY="http://proxy.company.com:8080"
export NO_PROXY="localhost,127.0.0.1"

Debug Mode

# Claude Code
claude --debug
 
# Verbose output
claude -v
 
# Check connectivity
curl -I https://api.anthropic.com
curl -I https://api.openai.com

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Version Management

Check Versions

# All tools
claude --version
codex --version
gemini --version
aider --version
 
# Node.js (required for npm tools)
node --version
npm --version
 
# Python (required for pip tools)
python --version
pip --version

Downgrade if Needed

# npm - specific version
npm install -g @anthropic-ai/claude-code@1.2.3
 
# pip - specific version
pip install aider-chat==0.50.0

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Related

• AI Agents - Background and Orchestration
• VS Code - Personal GitHub + GitHub Enterprise - For API key management