GeezerVison

Plenty of Codex CLI cheat sheets still tell you to start with codex --full-auto, a flag the current release rejects with a parse error. This Codex CLI cheat sheet lists the keyboard shortcuts, slash commands, flags and config keys that work today, and it puts the removed ones next to the exact error they print, so you can fix an old script in one pass instead of guessing.

Original content from computingforgeeks.com - post 163001

You get the TUI shortcuts (clear the input, quit, switch to Plan mode, change reasoning effort) and the full slash menu grouped by job. After those come codex exec recipes with real JSON output for scripts and CI, the sandbox and approval presets, the model catalog, and the profile files that replaced [profiles] tables. Codex CLI is OpenAI’s open source terminal agent, and every command, shortcut and error below was run against Codex CLI 0.163.0 on macOS, re-checked against the release notes through 0.166.0 in November 2026.

Codex CLI Keyboard Shortcuts

Press Ctrl+U to clear what you’ve typed in the Codex composer, and Ctrl+C or Ctrl+D on an empty prompt to quit. Both quit on the first press in the current release, with no “press again” confirmation, so a reflex Ctrl+C on an idle session ends it. With text in the composer, Ctrl+C clears the text instead of quitting, which is the other quick way to clear input.

Shift+Tab is not an auto mode shortcut, even though that’s what most people search for. It flips the session between Default and Plan mode, and in our session the toggle also printed Model changed to gpt-6-luna medium for Plan mode, because Plan mode carries its own reasoning effort. If what you want is Codex approving its own commands, open /permissions and pick Approve for me, or launch with codex --approve-for-me. To change the model, type /model. To nudge reasoning effort without opening a menu, use Option+, and Option+. (Alt on Linux and Windows).

Press ? on an empty prompt to open the shortcut overlay. This is what it lists, with the four lab-checked rows (clear, quit) folded in:

Shortcut	What it does
Ctrl+U	Clear the composer (what you typed)
Ctrl+C	Clear the composer; on an empty prompt, quit at once
Ctrl+D	Quit at once on an empty prompt
Shift+Tab	Toggle Default and Plan mode
Option+, / Option+.	Less / more reasoning effort (Alt on Linux and Windows)
Tab	Send the message; queues a slash command while a turn runs
Esc Esc	Edit your last message
Ctrl+J	Insert a new line
Ctrl+V	Paste an image from the clipboard
Ctrl+G	Edit the prompt in your external editor
Ctrl+R	Search prompt history
Ctrl+O	Copy the latest finished output (same as /copy)
/ @ !	Slash menu, attach a file, run a shell command
Left arrow (empty prompt)	Open the agent command center
Option+Left / Option+Right	Switch between subagents
F4	Inspect activity
F8 / F9	Voice input / mute voice
Ctrl+T	Open the transcript
F3	Find in the transcript
PgUp / PgDn	Scroll the transcript
Ctrl+Space	Start a selection
Ctrl+Home / Ctrl+End	Jump to the top / latest
Ctrl+X	Leader key for custom bindings (set in /keymap)

On macOS, the Option shortcuts only work when your terminal sends Option as Meta. If Option+, types ≤ into the prompt instead of lowering the effort, turn on “Use Option as Meta key” in Terminal.app’s keyboard profile (iTerm2 calls it “Esc+” for the Option key). Rebind anything you don’t like with /keymap, which writes the change to config.toml.

Run the Codex Commands You Need Daily

These twenty cover a normal working day: starting and resuming sessions, scripting a one-off task, checking what Codex changed and getting out. The rest of the page is detail behind each row.

Task	Command or key
Start a session in this repo	codex
Start with a prompt	codex "fix the failing auth test"
Resume the last session	codex resume --last
Pick a past session	codex resume
Run one task and exit	codex exec "summarize this repo"
Pipe an error log in	cat err.log | codex exec "explain this"
Let Codex approve safe actions	codex --approve-for-me
Plan before editing	Shift+Tab or /plan
Switch model or effort	/model
Review uncommitted changes	codex review --uncommitted
See the diff Codex made	/diff
Generate AGENTS.md	/init
Free up context	/compact
Fresh chat, same session	/new
Model, policy, context left	/status
Attach a file	@src/app.ts
Run a shell command	!git status
Use a profile file	codex -p quick
Check the install	codex doctor
Quit	Ctrl+C or /exit

Install or update Codex with npm (npm install -g @openai/codex) or Homebrew (brew install --cask codex), then run codex update to stay current. A ChatGPT plan signs in through the browser on first launch. For an API key, pipe it in once so it never lands in your shell history:

printenv OPENAI_API_KEY | codex login --with-api-key

On a server with no browser, codex login --device-auth prints a code to enter on another device, and codex login status tells you which method is active.

Fix Codex Commands That Stopped Working

Most “Codex is broken” reports after an upgrade come from a handful of removed options, one config format change and two argument-order traps. Every error in this table was printed by the current release on our machine, so you can match the message you see and jump straight to the fix:

Old usage	What Codex prints now	Use instead
codex --full-auto	error: unexpected argument '--full-auto' found	codex --approve-for-me
-a untrusted	error: invalid value 'untrusted' for '--ask-for-approval <APPROVAL_POLICY>'	-a on-request; per-project trust_level = "untrusted" still works
-a on-failure	error: invalid value 'on-failure' for '--ask-for-approval <APPROVAL_POLICY>'	-a on-request
codex exec -a never ...	error: unexpected argument '-a' found	codex -a never exec ...
[profiles.fast] in config.toml	Error loading config.toml: --profile `fast` cannot be used while ... contains legacy ... config	~/.codex/fast.config.toml
model_reasoning_effort = "minimal"	Unsupported value: 'minimal' is not supported with the 'gpt-6-luna' model (HTTP 400)	low
codex exec -i shot.png "prompt"	No prompt provided via stdin.	Prompt first, or -i shot.png -- "prompt"
codex mcp-server	Error: stdin is not a terminal	No longer a subcommand; codex app-server serves editor integrations
personality = "pragmatic"	Nothing; the key is accepted and ignored	Delete it; use developer_instructions

The mcp-server row is the sneaky one. Codex does not reject an unknown word. It treats it as the opening prompt for an interactive session, and in a script with no terminal that session dies with “stdin is not a terminal”. The same thing happens to any mistyped subcommand, so when a script prints that error, check the spelling of the first argument before anything else.

Pick a Codex Slash Command by Job

Type / and keep typing to filter the menu. In our session it listed 57 entries, and the exact set depends on your plan and platform (/setup-default-sandbox only appears on Windows, /daybreak only on eligible accounts). While a turn is running, you can type a slash command and press Tab to queue it for the next turn. The commands fall into four groups.

Session and context

Command	What it does
/new	New chat in the same CLI session
/clear	Clear the terminal and start a fresh chat
/compact	Summarize the chat to free tokens
/recap	Summary of the chat without compacting it
/resume	Reopen a saved chat
/fork	Branch the chat into a new one
/side or /btw	Throwaway side chat that leaves the main transcript alone
/rename, /archive, /delete	Name, hide or permanently delete the session
/export	Save the conversation as Markdown
/copy	Copy the latest finished output
/status	Model, approval policy, writable roots, context left
/exit or /quit	Leave Codex

Model, permissions and settings

Command	What it does
/model	Choose the model and its reasoning effort
/fast	Toggle the Fast service tier when the model has one
/permissions	Switch between Ask, Approve for me, Full Access and Read Only
/approve	Retry one action the auto reviewer denied
/config	Search and change settings; shows which need a restart
/keymap	Rebind shortcuts and set the leader key
/vim	Toggle Vim editing in the composer
/experimental	Toggle experimental features
/memories	Turn memory use and generation on or off
/theme, /statusline, /title, /pets	Highlighting theme, footer items, terminal title, terminal pet
/tui, /raw	Fullscreen or scrollback mode, raw copy-friendly scrollback
/logout	Sign out

Code, project and tools

Command	What it does
/init	Write an AGENTS.md scaffold for this directory
/plan	Switch to Plan mode, optionally with a prompt
/goal	Set, pause or clear a goal Codex tracks across a long task
/review	Review the working tree
/diff	Git diff including untracked files
/mention	Attach a file or folder
/worktree	Work in a managed Git worktree
/cd, /pwd	Change or show the working directory
/ps, /stop	Show or stop background terminals
/ide	Pull open files and selection from your editor
/import	Import Claude Code or Cursor setup and chats

Agents, extensions and diagnostics

Command	What it does
/agents, /subagents	Agent command center, switch subagent thread
/mcp	List MCP tools; /mcp verbose for details, /mcp login <name> for OAuth
/skills, /plugins, /hooks	Browse skills, plugins and lifecycle hooks
/voice	Start a voice conversation
/app	Continue this session in the desktop app
/daemon	Background server controls and restart
/warnings	Warnings retained from this session
/feedback	Send logs to the Codex maintainers

If you also run Claude Code, /import is worth trying once: it brings over Claude Code or Cursor setup, projects and chats, which beats rewriting instructions by hand. Our Claude Code cheat sheet covers the slash commands on that side.

Hermes Agent has a similar slash-command set plus /goal, /steer and /bg. The Hermes Agent cheat sheet maps them side by side with its CLI flags.

Script Codex with codex exec

codex exec (alias codex e) runs one task without the TUI and exits, which is what you want in a shell script, a cron job or CI. The examples below use a profile called quick (gpt-6-luna at low effort, shown in the config section) so test runs stay cheap. Every run prints a header to stderr and only the final answer to stdout, so $(codex exec ...) captures the answer alone:

codex -p quick exec "Remember the code word falcon. Reply ok"

The stderr header is the fastest way to confirm what a run actually used. Look at approval: never, which is the exec default even with approval_policy = "on-request" in config.toml, and at the writable roots in brackets after the sandbox mode.

OpenAI Codex v0.163.0
--------
workdir: /Users/josphat/projects/demo
model: gpt-6-luna
provider: openai
approval: never
sandbox: workspace-write [workdir, /tmp, $TMPDIR]
reasoning effort: low
reasoning summaries: none
session id: 01a158fc-7c80-73d0-8251-1c544384fe00
--------
user
Remember the code word falcon. Reply ok
codex
ok
tokens used
13,305

That 13,305 is the real floor for a one-word answer, because nearly all of it is the system prompt and tool definitions Codex sends on every turn, and AGENTS.md, skills and MCP tools only add to it. A cron job that fires every minute sends roughly 19 million input tokens a day before it does any work, so batch small checks into one prompt instead of many tiny runs.

Continue a scripted session

codex exec resume --last picks the previous run back up with its full context, so a two-step job doesn’t need the first answer pasted back in:

codex -p quick exec resume --last "What code word did I give you?"

It answered from the earlier turn. The header also showed the same session id (01a158fc-7c80-...) as the first run, so the id line is how you tell a resume from a fresh session in your logs:

falcon

Use codex exec resume <SESSION_ID> instead of --last when two jobs run in the same directory, because --last simply takes the newest session and a parallel job can slip in between your two steps. codex exec fork <SESSION_ID> branches a run without changing the original, and since it has no --last it always needs the id.

Get JSON events and schema-checked output

Add --json to stream one JSON event per line on stdout instead of the plain answer:

codex -p quick exec --json "Reply with the single word ok"

A one-word run emits four events, and turn.completed carries the token usage you’d feed into a cost dashboard. Our two runs, taken hours apart, both showed cached_input_tokens: 0 with the whole prompt written to cache, so check that field on your own schedule before you count on cached pricing.

{"type":"thread.started","thread_id":"01a15916-c95b-7250-a673-e11706c8bc13"}
{"type":"turn.started"}
{"type":"item.completed","item":{"id":"item_0","type":"agent_message","text":"ok"}}
{"type":"turn.completed","usage":{"input_tokens":13297,"cached_input_tokens":0,"cache_write_input_tokens":13294,"output_tokens":5,"reasoning_output_tokens":0}}

When another program has to parse the answer, give Codex a JSON Schema and it shapes the final message to match. Create schema.json in the project:

vim schema.json

This schema asks for a single integer and nothing else. Codex sends output schemas to the API in strict mode, which requires additionalProperties: false on every object and every property listed in required, so drop either one when you adapt this file and the run fails with an HTTP 400 before any output arrives.

{"type":"object","properties":{"files":{"type":"integer"}},"required":["files"],"additionalProperties":false}

Pass it with --output-schema, and use -o to write the final message to a file as well:

codex -p quick exec --output-schema schema.json -o last.txt "Count the .txt files in this directory"

The model ran find . -maxdepth 1 -type f -name '*.txt' | wc -l on its own, and both stdout and last.txt held only the object, ready for jq:

{"files":2}

The schema only shapes the final message. The agent still decided how to count, so for anything that matters, check the command it ran in the stderr log rather than trusting the number on its own.

Pipe logs and files into a prompt

When stdin is piped and a prompt is also given, Codex appends the piped text to the prompt as a <stdin> block. That makes it a handy log explainer:

printf 'Error: EACCES: permission denied, open /var/log/app.log\n' | codex -p quick exec "In one sentence, what does this error mean?"

The answer came back as one line on stdout.

The app tried to open `/var/log/app.log`, but it lacks permission to access that file.

The flip side is that exec reads stdin whenever it isn’t a terminal, and says so with Reading additional input from stdin... at the top of stderr. In a script where stdin is something you don’t control, end the command with < /dev/null so nothing unexpected gets appended to your prompt.

Review code from a script

Both codex review and codex exec review pick what to review with one of three flags:

• --uncommitted for staged, unstaged and untracked changes
• --base main for everything since a branch
• --commit <SHA> for a single commit

Only the exec form accepts --json and -o, because plain codex review stops with error: unexpected argument '--json' found. Use the exec form in CI so the findings land in a file a later step can parse.

codex exec review --base main --json > review.jsonl

A pre-commit hook is the opposite case. Nobody parses the output there, a human reads it, so codex review --uncommitted is the better fit, and it sees untracked files that git diff alone would miss.

Error: “unexpected argument ‘-a’ found”

Some options belong to the top-level codex command only, so they do not exist after exec, and putting one there fails before any model call is made. The four you are most likely to hit:

• -a, --ask-for-approval
• --search for live web search
• --remote for a remote app server
• --no-alt-screen for the inline TUI

This is what codex exec -a never "Reply ok" prints:

error: unexpected argument '-a' found

  tip: to pass '-a' as a value, use '-- -a'

Usage: codex exec [OPTIONS] [PROMPT]
       codex exec [OPTIONS] <COMMAND> [ARGS]

Move the flag in front of the subcommand and the same run works, as in codex -a never exec "...". The rule of thumb is that anything printed by codex exec --help is safe after exec, because exec parses its own option list and stops at the first one it does not know. The model, sandbox and approve-for-me flags are all in that list, so they work on either side.

Error: “No prompt provided via stdin” with -i

-i accepts several files, so in codex exec -i shot.png "describe this" it swallows your prompt as a second image path. Codex then looks for a prompt on stdin, finds none and stops with No prompt provided via stdin. Put the prompt first, or end the image list with --:

codex exec -i before.png,after.png -- "compare these two screenshots"

Comma-separated paths work as one list: with a red and a blue test image, that command answered Bright red, bright blue. A single image with the prompt placed first (codex exec "describe this" -i shot.png) works too.

A misspelled profile is ignored silently

codex -p nosuch exec "..." exits 0 and runs on your base config, with no warning that the profile file does not exist. If a CI job suddenly costs more or runs a different model, read the model: line in the stderr header before you suspect anything else, because it shows the profile was never applied.

Choose Sandbox and Approval Settings

Two settings decide what Codex may do. The sandbox limits what a command can touch, and the approval policy decides when Codex stops to ask you. /permissions wraps the common combinations into four presets, listed here exactly as the menu shows them:

Preset	What the menu says	Closest launch flag
Ask for approval (default)	Read and edit workspace files and run commands, with approval required for internet access or edits outside the workspace	-s workspace-write -a on-request
Approve for me	Only ask for actions detected as potentially unsafe	--approve-for-me
Full Access	Codex can edit files outside this workspace and access the internet without approval	-s danger-full-access -a never
Read Only	Read workspace files, with approval required for edits or internet access	-s read-only

--approve-for-me (alias --not-so-yolo) routes approval requests to a hidden reviewer model, codex-auto-review, while keeping the workspace-write sandbox. It does not open the network. Our run with it still printed approval: on-request and sandbox: workspace-write, and a curl inside it failed exactly as below. When the reviewer denies something you want, /approve retries that one action. At the far end, --yolo is short for --dangerously-bypass-approvals-and-sandbox and belongs only inside a container or VM that is already isolated.

Error: “curl: (6) Could not resolve host” inside Codex

The workspace-write sandbox has no network, so any curl, npm install or pip install the agent runs fails DNS. This is the command line Codex ran and what came back:

/bin/zsh -lc "curl -sS -o /dev/null -w '%{http_code}' https://example.com" in /Users/josphat/projects/demo
 exited 6 in 0ms:
curl: (6) Could not resolve host: example.com
000

Allow outbound traffic for one run with a config override, without switching to full access:

codex -p quick -c sandbox_workspace_write.network_access=true exec "Run curl -sS -o /dev/null -w '%{http_code}' https://example.com and print only what it outputs"

The same command now reaches the site and gets a 200.

/bin/zsh -lc "curl -sS -o /dev/null -w '%{http_code}' https://example.com" in /Users/josphat/projects/demo
 succeeded in 391ms:
200

To make it permanent for a project that always needs package downloads, set network_access = true under [sandbox_workspace_write] in config.toml. Keep it off by default, because the network is what turns a prompt-injected agent into one that can send your code somewhere.

Pick a Codex Model and Reasoning Effort

Codex loads its model list from your account, so the roster can differ between a ChatGPT plan and an API key. codex debug models prints the raw catalog as JSON. This is what it returned for our API key, sorted by the catalog’s own priority field, and the first visible model in that order is the default.

Model	Catalog description	Default effort	Highest effort
gpt-6.1-sol (default)	Latest workhorse model for coding and everyday work	low	ultra
gpt-6-astra	Frontier intelligence for the most demanding work	low	ultra
gpt-6-sol	Previous generation workhorse model	medium	ultra
gpt-6-luna	Fast and affordable model for easier tasks	medium	max
gpt-5.6-sol	Older generation workhorse; upgrade prompt points to gpt-6-sol	low	ultra
gpt-5.6-terra	Older balanced model; upgrade prompt points to gpt-6-sol	medium	ultra
gpt-5.6-luna	Older fast model; upgrade prompt points to gpt-6-luna	medium	max
gpt-5.5	Legacy coding model	medium	xhigh

Every listed model reports a 272K context window. The catalog also holds hidden entries that /model doesn’t show: codex-auto-review (the approval reviewer) and the Daybreak cybersecurity models, which need an eligible account. Effort levels run low, medium, high, xhigh, max and ultra, and gpt-6-luna stops at max. Our GPT-6 Sol and Luna breakdown covers how the two families compare on benchmarks.

Set the model and effort for one run on the command line when a single task is hard. Pinning gpt-6-astra in config.toml instead makes every small question pay for the frontier model, so most people keep a cheaper default and reach for the flag:

codex -m gpt-6-astra -c model_reasoning_effort="high"

Plan mode has its own key, plan_mode_reasoning_effort, which is why toggling into Plan mode can change the effort shown in the footer. Leave it unset to use the built-in preset, or set it higher than your normal effort if you want Codex to think harder before it touches files.

Configure config.toml, Profiles and AGENTS.md

Codex merges settings from several layers, and the higher layer wins whenever two set the same key. Highest priority first, per the config basics docs:

1. Command-line flags and -c overrides
2. .codex/config.toml in a trusted project (the closest one wins)
3. The profile file picked with -p
4. ~/.codex/config.toml
5. /etc/codex/config.toml

The project layer has one catch. A repo’s .codex/config.toml cannot set profile, model_provider, notify or base URLs, and Codex ignores those keys there, so a teammate’s provider override in the repo does nothing. Put provider and notification settings in your user config instead.

Open your user config. Codex writes to this file too (trusted project entries and TUI flags such as [tui] settings), so edit around those entries rather than pasting a fresh file over them, because deleting the trust entries brings back the trust prompt in every repo.

vim ~/.codex/config.toml

This is the file we loaded with --strict-config, which errors out on any key the installed version doesn’t recognize, so every key below is valid on the current release. The two MCP servers at the bottom are GitHub’s hosted server (it reads a personal access token from GITHUB_PAT) and the Context7 docs server, written by the codex mcp add commands in the MCP section, so swap them for your own:

model = "gpt-6.1-sol"
model_reasoning_effort = "medium"
plan_mode_reasoning_effort = "high"
sandbox_mode = "workspace-write"
approval_policy = "on-request"
web_search = "cached"
developer_instructions = "Run the test suite before you report a task as done."

[sandbox_workspace_write]
network_access = false

[mcp_servers.github]
url = "https://api.githubcopilot.com/mcp/"
bearer_token_env_var = "GITHUB_PAT"

[mcp_servers.context7]
command = "npx"
args = ["-y", "@upstash/context7-mcp"]

Run codex --strict-config after every upgrade. A typo such as model_reasoning_efort is silently ignored without it, while with it Codex stops and points at the line (quick.config.toml:3:1: unknown configuration field `model_reasoning_efort`). The flag works on codex and codex exec but not on codex mcp or codex features, which reject it.

Create a profile file

Profiles are now separate files next to config.toml, named <name>.config.toml, and -p <name> layers one over your base config. Create the quick profile used throughout this page:

vim ~/.codex/quick.config.toml

Two lines are enough, because everything else comes from the base config. Keep profiles that small, so a change to your sandbox or MCP servers in config.toml reaches every profile without editing each file.

model = "gpt-6-luna"
model_reasoning_effort = "low"

With the base config above set to gpt-6.1-sol, a codex -p quick exec run printed model: gpt-6-luna and reasoning effort: low in its header, so the profile wins over the base file. It does not win over a trusted project’s .codex/config.toml, which sits above profiles, so a repo that pins a model overrides -p for that key. Make a second one, such as deep.config.toml with gpt-6-astra and xhigh, for architecture work.

Write AGENTS.md project instructions

AGENTS.md is the Codex counterpart of Claude Code’s CLAUDE.md: plain Markdown loaded at the start of every session in that repo. /init writes a first draft, which you then trim to what the agent can’t work out from the code. Edit it at the repo root:

vim AGENTS.md

Keep it to build commands and rules, because every line is sent with every turn:

# My Project

## Build Commands
- Test: `npm test`
- Build: `npm run build`
- Lint: `npm run lint -- --fix`

## Rules
- Use TypeScript strict mode for all new files
- Write unit tests for every new function
- Never commit directly to main branch

The files Codex keeps under ~/.codex follow the same split: config.toml and profile files, auth.json for stored credentials, rules/ for execution policy, skills/ for the bundled system skills and log/ for debug logs. Point CODEX_HOME somewhere else and Codex uses that directory instead, which is how you keep a throwaway test setup away from your real login.

Use the Codex CLI Subcommands

Most of these appear in codex --help. execpolicy is hidden from that list and debug models sits under debug, and the docs mark both as experimental along with the others flagged below:

Command	What it does
codex exec (codex e)	Run non-interactively; subcommands resume, fork, review
codex review	Code review without the TUI
codex resume / codex fork	Reopen or branch a session; --last skips the picker, --all shows every directory
codex archive / unarchive / delete	Manage saved sessions by id or name
codex queue	Queue a message for an existing session
codex agents	Browse agent sessions on the local background server
codex login / logout	Sign in with ChatGPT, an API key, an access token or a device code
codex mcp	list, get, add, remove, login, logout for MCP servers
codex plugin	Manage plugins
codex doctor	Check install, config, auth, network and the background server
codex update	Update Codex in place
codex features list	Feature flags with stage and current state
codex debug models	Raw model catalog as JSON (experimental)
codex execpolicy check	Test a command against your rules files (experimental)
codex sandbox	Run any command inside the Codex sandbox
codex apply <TASK_ID> (codex a)	Apply a cloud task’s diff with git apply
codex cloud	Codex Cloud tasks (experimental)
codex app / app-server	Desktop app, or the server editors connect to (app-server is experimental)
codex completion zsh	Completion script for bash (default), zsh, fish, elvish or PowerShell

codex doctor --summary is the first thing to run when something feels off. On our Mac it reported 20 checks ok and one failure, TERMINFO unreadable, which only means the terminal capabilities could not be read from a non-interactive shell and did not affect any run on this page.

Set Codex Flags on the Command Line

These apply to codex and, unless the last column says otherwise, to codex exec as well:

Flag	Purpose	Where
-m, --model	Model for this run	both
-p, --profile	Layer $CODEX_HOME/<name>.config.toml	both
-c key=value	Override any config key (value parsed as TOML)	both
-s, --sandbox	read-only, workspace-write, danger-full-access	both
-a, --ask-for-approval	on-request or never	before exec only
--approve-for-me	Auto review of approvals in workspace-write	both
--yolo	No sandbox, no approvals	both
-C, --cd	Working root directory	both
--add-dir	Extra writable directory	both
--worktree	Run in a new managed Git worktree	both
-i, --image	Attach images (end the list with --)	both
--search	Live web search	before exec only
--oss --local-provider ollama	Local model through Ollama or LM Studio	both
--enable / --disable	Turn a feature flag on or off	both
--strict-config	Fail on unknown config keys	both
--json, -o, --output-schema	Machine-readable output	exec only
--ephemeral	Don’t save the session to disk	exec only
--skip-git-repo-check	Run outside a Git repo	exec only
--ignore-user-config, --ignore-rules	Skip config.toml or execpolicy rules for this run	exec only
--no-alt-screen	Inline TUI that keeps terminal scrollback	TUI only

For a fully offline setup, --oss talks to a local server instead of OpenAI. If you already run models locally, our Ollama commands cheat sheet covers pulling and serving them.

Add MCP Servers to Codex

codex mcp add writes the server into config.toml for you, which is less error-prone than editing TOML by hand. Everything after -- is the command for a local stdio server, and --url adds a remote streamable HTTP server:

codex mcp add github --url https://api.githubcopilot.com/mcp/ --bearer-token-env-var GITHUB_PAT
codex mcp add context7 -- npx -y @upstash/context7-mcp

Skip the old @modelcontextprotocol/server-github package that many guides still show, because npm now marks it “Package no longer supported”. codex mcp list then shows stdio and HTTP servers in two separate tables:

Name      Command  Args                      Env  Cwd  Status   Auth
context7  npx      -y @upstash/context7-mcp  -    -    enabled  Unsupported

Name    Url                                 Bearer Token Env Var  Status   Auth
github  https://api.githubcopilot.com/mcp/  GITHUB_PAT            enabled  Bearer token

A server that cannot be reached does not stop the session. When we pointed one at a URL that doesn’t exist, it logged ERROR rmcp::transport::worker: worker quit with fatal: Transport channel closed three times on stderr, and the task still finished. In CI, grep stderr for rmcp if a tool you depend on seems to be missing. HTTP servers that use OAuth sign in with codex mcp login <name>, or /mcp login <name> from inside a session, and --bearer-token-env-var covers token-based ones.

Limit Commands with Skills and Rules

Skills are reusable instructions with optional scripts. Codex scans .agents/skills/ in the project, ~/.agents/skills/ for your personal ones and /etc/codex/skills/ system-wide. Call one with $skill-name in the composer, or browse them with /skills.

Execution policy rules are the harder guardrail: Starlark files in ~/.codex/rules/ that mark a command prefix as allowed, prompt or forbidden. Create one:

vim ~/.codex/rules/default.rules

These two rules block direct pushes and make recursive deletes ask first. A delete gets prompt rather than forbidden because the agent has real reasons to clean a build directory, while a push to a shared remote is never something it should do unattended.

prefix_rule(
    pattern = ["git", "push"],
    decision = "forbidden",
    justification = "No direct pushes, open a pull request instead",
)

prefix_rule(
    pattern = ["rm", "-rf"],
    decision = "prompt",
    justification = "Destructive delete needs a human",
)

Test a command against the file before you rely on it:

codex execpolicy check --rules ~/.codex/rules/default.rules --pretty -- git push origin main

The push matches the first rule and comes back forbidden, with your justification attached.

{
  "matchedRules": [
    {
      "prefixRuleMatch": {
        "matchedPrefix": [
          "git",
          "push"
        ],
        "decision": "forbidden",
        "justification": "No direct pushes, open a pull request instead"
      }
    }
  ],
  "decision": "forbidden"
}

Checking rm -rf build returned "decision":"prompt", and ls -la returned an empty matchedRules list, which means no rule applies and the normal approval policy decides.

Set Codex Environment Variables

Variable	Purpose
CODEX_HOME	Config directory instead of ~/.codex
CODEX_API_KEY	API key for codex exec, without touching the stored login
OPENAI_API_KEY	Key you pipe into codex login --with-api-key
CODEX_CA_CERTIFICATE	Custom CA bundle for corporate TLS proxies
HTTPS_PROXY	Outbound proxy
CODEX_THREAD_ID	Set by Codex inside commands it runs, so scripts know the thread

CODEX_API_KEY earns its place in CI. A stale ChatGPT login makes codex exec cycle through Reconnecting... 1/5 (workspace routing discovery unauthorized (401)) retries, then an HTTPS fallback with more of the same, before it fails, while the variable bypasses the stored login for that one run and leaves it untouched.

Hand Tasks to Codex Cloud

codex cloud sends a task to a disposable container on OpenAI’s side and gives you back a diff. It is still marked experimental, and the CLI cannot look up environments from a script yet, so copy the environment ID from the interactive picker (codex cloud with no arguments) and keep the IDs in variables:

export CODEX_ENV=env_9f2c1a7b
export CODEX_TASK=task_7b3e40d2

Submit, track and apply a task. --attempts asks for best-of-N candidate solutions and --branch sets the Git branch to run on (your current branch by default):

codex cloud exec --env "${CODEX_ENV}" "upgrade all dependencies to their latest minor versions and fix any test breakage"
codex cloud list --env "${CODEX_ENV}" --json
codex cloud status "${CODEX_TASK}"
codex cloud diff "${CODEX_TASK}"
codex cloud apply "${CODEX_TASK}"

Read the diff before you apply it. The container ran with whatever network access and secrets the cloud environment grants, which is a different trust boundary from your local sandbox, so a change that looks harmless can still carry a dependency bump you never asked for. codex cloud diff costs nothing and shows exactly what apply will write.

Compare Codex CLI with Claude Code

The two tools now overlap on most features, so the choice usually comes down to which models you pay for and how much sandboxing you want by default:

Feature	Codex CLI	Claude Code
Models	GPT-6.1 Sol, GPT-6 Astra, Sol and Luna, plus local models	Claude Opus, Sonnet, Haiku and Fable
Sandbox	OS-level (Seatbelt on macOS, Bubblewrap on Linux), on by default	Permission rules; optional sandbox
Project instructions	AGENTS.md	CLAUDE.md
Scripted runs	codex exec	claude -p
Hands-off approvals	--approve-for-me (reviewer model)	auto mode (classifier)
Hard command rules	Starlark execpolicy files	Permission allow and deny rules, hooks
Local models	--oss with Ollama or LM Studio	No built-in local provider flag
Import from the other	/import (Claude Code, Cursor)	claude import codex

If you’d rather not be tied to one vendor, OpenCode talks to most providers, the Gemini CLI brings Google’s models to the same workflow, and Aider commits every change to Git as it goes. Our AI coding agent comparison for DevOps work ranks all of them on infrastructure tasks. If your team already pays for a Copilot seat, our GitHub Copilot CLI cheat sheet covers GitHub’s terminal agent, which switches between GPT and Claude models with /model and reads the same AGENTS.md file Codex does. For an always-on agent that answers from Telegram or Slack instead of a terminal, see the tested OpenClaw cheat sheet (/openclaw-cheat-sheet/).

For the reasoning behind these commands rather than the commands themselves, Agentic Coding with OpenAI Codex CLI (paid link) by Daniel Vaughan (Packt, August 2026, 670 pages) is the one book written for this tool. It covers AGENTS.md, MCP servers, hooks, subagents, CI/CD and security hardening, and it made our list of the best AI coding books.

Upgrade an Old Codex Config

If your ~/.codex predates profile files, the first -p run after an upgrade fails with the legacy-profile error, and the scripts around it fail on removed flags. Work through it in this order, because each step clears the error the next one would otherwise hide:

1. Move each [profiles.NAME] table out of config.toml into ~/.codex/NAME.config.toml, dropping the table header, and delete any top-level profile = "NAME" line.
2. Delete personality and change any model_reasoning_effort = "minimal" to low.
3. Replace approval_policy = "untrusted" or "on-failure" with "on-request"; keep untrusted projects as trust_level = "untrusted" entries.
4. Search your scripts for --full-auto, exec -a and exec -i file "prompt", and apply the fixes from the removed-flags table.
5. Run codex --strict-config -p NAME exec "Reply ok" for each profile and check the model: line in the header.
6. Finish with codex doctor --summary and read every row that isn’t ok.

Step 5 is the one people skip, and it’s the only step that catches a misspelled profile name, because Codex runs on the base config without complaint when the file isn’t there. Once each profile prints the model you expect, the config is safe for the next upgrade too.

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