How to Install Codex CLI on Linux: A 15-Minute Tutorial

OpenAI released Codex CLI in 2026 — a terminal-based coding agent like Claude Code. Here’s the full install on Linux, plus 5 real workflows.

Install (Ubuntu/Debian, 15 min)

# 1. Install Node.js 20+
curl -fsSL https://deb.nodesource.com/setup_20.x | sudo -E bash -
sudo apt install -y nodejs

# 2. Install Codex CLI globally
npm install -g @openai/codex

# 3. Authenticate
codex login

# 4. Verify
codex --version
# Should print: 1.x.x

That’s it. Total time: 10-15 min including download.

5 Real Workflows I Tested (1 month)

1. Single-file refactor

codex "Refactor src/auth.js to use async/await"

2. Multi-file feature

codex "Add rate limiting to /api endpoints using express-rate-limit"

3. Test generation

codex "Write Jest tests for src/utils.js"

4. Bug fix

codex "Fix the race condition in src/sync.js"

5. Documentation

codex "Generate JSDoc comments for all functions in src/api/"

Comparison vs Claude Code

Feature	Codex CLI	Claude Code
Model	GPT-4o / GPT-5	Claude 3.5/4 Sonnet
Setup time	15 min	10 min
Cost	Pay-per-token	Pay-per-token
Best for	OpenAI ecosystem	Long autonomous tasks
Tool ecosystem	Newer, smaller	Mature, larger

My Verdict

Codex CLI is solid for OpenAI users who want a terminal coding agent. If you’re already paying for OpenAI API, this is the natural choice.

Use Claude Code if: you want the most mature agent with the best tool ecosystem. Use Codex CLI if: you’re on the OpenAI stack and want terminal coding.

FAQ

Q: Does Codex CLI work on macOS? A: Yes, same npm install -g works.

Q: Can I use GPT-4o with it? A: Yes, default is GPT-4o. You can switch to GPT-5 with codex config.

Q: Is it free? A: No, pay-per-token like OpenAI API.

Q: Can I use it offline? A: No, requires OpenAI API.

Recommended

If you’re on OpenAI stack: Codex CLI is the natural choice. If you’re on Anthropic stack: Use Claude Code. If you want local + free: Use Aider + MiMo (see other articles).