CLI Environment Setup — Install Claude Code, Codex & Gemini CLI

How to set up your environment for AI CLI tools. Install Node.js and globally install Claude Code CLI, OpenAI Codex CLI, and Gemini CLI on Windows and macOS before configuring an API key.

Environment check

Works on Windows, macOS, and Linux (adjust paths if needed).

(1) Node.js

npm list -g --depth=0

OK: output or empty list.
Fail: “command not found” → install Node.js LTS (18+), reopen the terminal, retry.

node -v
npm -v

(2) Install CLIs

npm i -g @anthropic-ai/claude-code@latest
npm i -g @openai/codex@latest
npm i -g @google/gemini-cli@latest

Install only the tools you need.

(3) First run (creates config dirs)

Run each command once so ~/.claude, ~/.codex, and ~/.gemini are created.

claude

codex

gemini

Exit with Ctrl+C or the on-screen prompt when you see a UI or wizard.

(4) Next

With an API key:

Install issues

Issue	Fix
`EACCES`	Avoid `sudo npm -g`; use nvm or fix npm prefix
Corporate proxy	Set `HTTPS_PROXY` / npm proxy
Old version	`npm i -g package@latest`