Codex CLI Cheat Sheet — EdgeSet.dev

⭐ Most Used Commands

Command	Explanation	Typical Usage
codex	Start an interactive session in the current directory	Beginning a coding session. Codex reads your files and waits for instructions
codex "prompt"	Run a one-shot prompt and exit, no interactive session	Quick tasks from the shell: `codex "add error handling to server.py"`
codex -a auto-edit	Auto-apply file edits without asking; still prompts before running shell commands	Faster editing sessions where you trust the changes but still want shell control
codex -a full-auto	Fully autonomous. Applies edits and runs commands without prompting	CI pipelines, sandboxed environments, or tasks you've already reviewed the approach for

⭐ Most Used Slash Commands

Command	Explanation	Typical Usage
/resume	Reload a previously saved session. Picks up context, files, and conversation history	Continuing work from a previous day or after closing the CLI mid-task
/compact	Summarises conversation history to free up context while keeping the working thread	Session is getting long but the task isn't done. Preserve context without starting over
/plan	Enter planning mode. Codex proposes an execution strategy and waits for approval before acting	Before a risky or multi-step task; when you want to review the approach before anything is touched
/status	Display current session config: model, approval mode, and token usage	Quick check on what model you're using or how much context has been consumed
/new	Start a fresh task in the same CLI instance. Clears conversation without restarting the process	Moving to a completely unrelated task without closing and reopening the terminal

💬 Other Slash Commands

/diff Review Git changes in the current repo before committing

/fast Toggle performance optimisation: faster responses on supported models

/fork Branch the current conversation to explore an alternative approach without losing the original thread

/model Switch AI model mid-session without restarting

/permissions Adjust approval requirements on the fly, e.g. switch between auto and read-only mid-session

/personality Change communication style: friendly, pragmatic, or neutral

🛡️ Approval Modes

suggest

Default. Codex proposes changes and explains what it would do. You review and apply manually. Nothing is written or run without your action. Safest mode for getting started.

auto-edit

Middle ground. File edits are applied automatically; shell commands still require approval. Good for iterative coding sessions where you want speed but keep control over what runs.

full-auto

Fully autonomous. All edits and commands are applied without asking. Use inside a sandbox or CI environment. On supported platforms Codex runs network-isolated by default.

🚩 CLI Flags

-a / --approval-mode Set approval mode: suggest, auto-edit, full-auto

-m / --model Model to use, e.g. codex-1, o4-mini, o3

-q / --quiet Suppress interactive UI. Pipe-friendly for scripting

--project-doc <path> Load a specific context file instead of AGENTS.md

--no-project-doc Skip loading AGENTS.md entirely

--dangerously-auto-approve-everything Skip all prompts. For trusted CI environments only

--version Print installed version and exit

--help / -h Show available flags and usage

📄 AGENTS.md

Place an AGENTS.md at your project root to give Codex persistent context: stack, conventions, commands to know, things to avoid.

Codex reads AGENTS.md at the start of every session. It's the Codex equivalent of Claude Code's CLAUDE.md.

What to put in it: tech stack, test commands, code style rules, file layout, anything you'd tell a new engineer on day one.

Use --project-doc <path> to load a different file, or --no-project-doc to skip it entirely.

⚠️ Keep AGENTS.md concise. Focus on non-obvious rules and constraints. Codex can already read your code.

⌨️ Keyboard Shortcuts

Enter Submit message

Ctrl+C Interrupt / cancel the current operation

Ctrl+D Exit Codex

↑ / ↓ Navigate prompt history

h Show inline help during a session

q Quit the session

🧠 Models at a Glance

codex-1 Default. OpenAI's code-optimised agentic model. Best balance of speed, cost, and coding ability

o4-mini Fast, cost-effective reasoning. Good for straightforward tasks and scripting

o3 Most powerful reasoning. Use for complex architecture or hard debugging; slower and pricier

gpt-4.1 Latest GPT-4 generation. Strong general-purpose coding and instruction following

Switch with codex -m o3 "prompt" or set a default in ~/.codex/config.yaml.

⚙️ Setup & Config

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

npm update -g @openai/codex Update to the latest version

API key: set OPENAI_API_KEY as an environment variable, or add it to ~/.codex/config.yaml.

Config file: ~/.codex/config.yaml. Set your default model, approval mode, and other preferences so you don't have to pass flags every time.

Example config.yaml:
model: codex-1
approvalMode: auto-edit

🤖 Scripting & Headless Use

Run one-shot tasks from the shell. Useful for CI, makefiles, and automation pipelines.

codex -q "prompt" Quiet mode: suppresses UI, outputs result only. Pipe-friendly.

Pipe input: cat file.py | codex -q "add docstrings to every function"

Redirect output: codex -q "generate tests for auth.py" > tests/test_auth.py

In CI, combine flags: codex -q -a full-auto --dangerously-auto-approve-everything "fix lint errors"

💡 Tips & Patterns

Start with suggest mode while learning the tool. Switch to auto-edit once you're comfortable, and reserve full-auto for sandboxed CI or pre-reviewed tasks.

AGENTS.md is your first lever. Put project conventions, preferred libraries, and "never do X" rules in it. Codex reads it every session and it shapes every response.

Use --project-doc to switch contexts, e.g. one AGENTS file for backend work, another for frontend. Pass it per-invocation without touching the default file.

Sandbox full-auto. On macOS, full-auto mode runs in a network-isolated sandbox by default. On Linux, use Docker or a VM to get equivalent isolation.

Provide a clear task scope. "Refactor the auth module to use JWTs" works better than "improve the code". The more specific your prompt, the fewer back-and-forth rounds.

Interrupt safely. Ctrl+C cancels the current operation mid-stream. Codex will not apply partial changes. You can redirect or refine your prompt and try again.

Check your version. Codex is actively developed. Run codex --version and npm update -g @openai/codex regularly to pick up new models and fixes.