Install Codex and understand its surfaces

What you will learn

• Install and verify Codex CLI.
• Choose between the CLI, IDE extension, app, and cloud tasks.
• Open a first session inside a repository.

Minimal setup

Codex CLI works with the files and tools on your machine. OpenAI recommends the standalone installer on macOS and Linux; npm remains a cross-platform alternative. Check the version before signing in.

# Recommended on macOS and Linux
curl -fsSL https://chatgpt.com/codex/install.sh | sh

# npm alternative
npm install -g @openai/codex

codex --version
cd ~/code/my-project
codex

On first launch, follow the sign-in flow shown by Codex. Inside a session, /status summarizes the active directory, model, and permissions.

/status
/permissions
/model

Choose a surface

• CLI for fast local work, scripts, Git, and terminal-native workflows.
• IDE for changes closely tied to the file or selection in view.
• App for longer tasks, visual review, and coordinating parallel work.
• Cloud for delegated work in a prepared, isolated environment.

Codex alongside Cursor, Windsurf, or your IDE

You do not need to choose a single tool. Use Cursor, Windsurf, or your IDE for localized edits, visual navigation, and small refactors. Use Codex when you need to traverse a repository, run commands, review Git, automate checks, or complete a whole task with evidence.

Practical rule: if the context fits on one screen, the IDE works well; if the context lives across files, commands, logs, and commits, Codex usually gives you more operational control.

First check

Start with a read-only request: “Summarize the architecture, tell me how tests run, and do not edit files.” Confirm that Codex identifies the language, package manager, and Git state correctly.