How to Run Codex from the Command Line

You can run Codex from the command line without opening the chat screen. The codex exec command runs Codex in non-interactive mode: it takes one prompt, runs the task, prints the answer and exits. Use it in scripts, cron jobs or for a quick question.

Install Codex CLI

On macOS or Linux, run the installer:

curl -fsSL https://chatgpt.com/codex/install.sh | sh

On Windows, run this in PowerShell:

powershell -ExecutionPolicy ByPass -c "irm https://chatgpt.com/codex/install.ps1 | iex"

You can also install it with npm:

npm install -g @openai/codex

Or with Homebrew:

brew install --cask codex

Then start the Codex command line once and choose Sign in with ChatGPT. You can also use an OpenAI API key.

codex

Run a prompt with codex exec

Put the prompt in quotes after codex exec:

codex exec "what is the purpose of life? answer one word"

Here is what the Codex CLI output looks like:

Codex prints:

• a header with the version, working folder, model, sandbox, approval mode and session id;
• your prompt under user;
• the answer under codex;
• the number of tokens used.

Then it exits and returns you to the shell.

Interactive session or one-shot run:

Useful codex exec options for scripts

Send a file or command output to Codex. Piped text is added to your prompt:

cat error.log | codex exec "explain this error in two sentences"

Read the whole prompt from a file:

cat prompt.txt | codex exec -

Save the final answer to a file. Codex still prints it in the terminal:

codex exec "summarize README.md in three bullets" -o answer.txt

How input and output flow:

Get JSON for a script. Each event comes as one JSON line:

codex exec --json "summarize the repo structure"

Let Codex change files. By default codex exec runs read-only, unless ~/.codex/config.toml sets another sandbox (as in the screenshot). To allow edits in the current folder:

codex exec --sandbox workspace-write "add a .gitignore for a Node.js project"

Run outside a Git repository. Codex stops outside a Git repo. Skip the check if you trust the folder:

codex exec --skip-git-repo-check "what is the purpose of life? answer one word"

Continue the last run with a follow-up prompt:

codex exec resume --last "now explain it in one sentence"

For all flags, run codex exec --help or see the Codex non-interactive mode docs.

Related guides

• How to Run Claude Code from the Command Line, the same task with claude -p.
• Codex YOLO Mode: Run Without Approvals Safely, before you turn off approval prompts.