OpenAI Codex CLI

OpenAI Codex CLI is a cross-platform local coding agent that runs in your terminal. It combines a large language model with direct access to your filesystem, shell commands, and development tools to produce software changes while you observe and guide the process.

The mental model

Codex CLI functions as an interactive pair programmer that can read, write, and execute. Unlike a chat interface that only discusses code, Codex operates on your actual project files and can run tests, linters, and build tools.

your prompt
  -> Codex reads relevant files
  -> proposes changes and commands
  -> you approve or reject
  -> Codex applies changes
  -> iterate until done

The agent maintains context across a session. It remembers earlier decisions, file contents it has examined, and the current state of your request. This allows multi-step work where each turn builds on previous actions.

Installation and setup

Install Codex CLI using the official installer script, package manager, or Homebrew:

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

# npm
npm install -g @openai/codex

# Homebrew
brew install --cask codex

After installation, run codex with no arguments to start an interactive session. The first launch prompts you to authenticate with your OpenAI account.