Non-interactive mode

Use Codex in non-interactive mode to automate common workflows.

codex exec "count the total number of lines of code in this project"

In non-interactive mode, Codex does not ask for command or edit approvals. By default it runs in read-only mode, so it cannot edit files or run commands that require network access.

Use codex exec --full-auto to allow file edits. Use codex exec --sandbox danger-full-access to allow edits and networked commands.

Default output mode

By default, Codex streams its activity to stderr and only writes the final message from the agent to stdout. This makes it easier to pipe codex exec into another tool without extra filtering.

To write the output of codex exec to a file, in addition to using a shell redirect like >, there is also a dedicated flag to specify an output file: -o/--output-last-message.

JSON output mode

codex exec supports a --json mode that streams events to stdout as JSON Lines (JSONL) while the agent runs.

Supported event types:

• thread.started - when a thread is started or resumed.
• turn.started - when a turn starts. A turn encompasses all events between the user message and the assistant response.
• turn.completed - when a turn completes; includes token usage.
• turn.failed - when a turn fails; includes error details.
• item.started/item.updated/item.completed - when a thread item is added/updated/completed.

Supported item types:

• assistant_message - assistant message.
• reasoning - a summary of the assistant's thinking.
• command_execution - assistant executing a command.
• file_change - assistant making file changes.
• mcp_tool_call - assistant calling an MCP tool.
• web_search - assistant performing a web search.

Typically, an assistant_message is added at the end of the turn.

Sample output:

{"type":"thread.started","thread_id":"0199a213-81c0-7800-8aa1-bbab2a035a53"}
{"type":"turn.started"}
{"type":"item.completed","item":{"id":"item_0","item_type":"reasoning","text":"**Searching for README files**"}}
{"type":"item.started","item":{"id":"item_1","item_type":"command_execution","command":"bash -lc ls","aggregated_output":"","status":"in_progress"}}
{"type":"item.completed","item":{"id":"item_1","item_type":"command_execution","command":"bash -lc ls","aggregated_output":"2025-09-11\nAGENTS.md\nCHANGELOG.md\ncliff.toml\ncodex-cli\ncodex-rs\ndocs\nexamples\nflake.lock\nflake.nix\nLICENSE\nnode_modules\nNOTICE\npackage.json\npnpm-lock.yaml\npnpm-workspace.yaml\nPNPM.md\nREADME.md\nscripts\nsdk\ntmp\n","exit_code":0,"status":"completed"}}
{"type":"item.completed","item":{"id":"item_2","item_type":"reasoning","text":"**Checking repository root for README**"}}
{"type":"item.completed","item":{"id":"item_3","item_type":"assistant_message","text":"Yep — there’s a `README.md` in the repository root."}}
{"type":"turn.completed","usage":{"input_tokens":24763,"cached_input_tokens":24448,"output_tokens":122}}

Structured output

By default, the agent responds with natural language. Use --output-schema to provide a JSON Schema that defines the expected JSON output.

The JSON Schema must follow the strict schema rules.

Sample schema:

{
  "type": "object",
  "properties": {
    "project_name": { "type": "string" },
    "programming_languages": { "type": "array", "items": { "type": "string" } }
  },
  "required": ["project_name", "programming_languages"],
  "additionalProperties": false
}

codex exec "Extract details of the project" --output-schema ~/schema.json
...

{"project_name":"Codex CLI","programming_languages":["Rust","TypeScript","Shell"]}

Combine --output-schema with -o to only print the final JSON output. You can also pass a file path to -o to save the JSON output to a file.

Git repository requirement

Codex requires a Git repository to avoid destructive changes. To disable this check, use codex exec --skip-git-repo-check.

Resuming non-interactive sessions

Resume a previous non-interactive session with codex exec resume <SESSION_ID> or codex exec resume --last. This preserves conversation context so you can ask follow-up questions or give new tasks to the agent.

codex exec "Review the change, look for use-after-free issues"
codex exec resume --last "Fix use-after-free issues"

Only the conversation context is preserved; you must still provide flags to customize Codex behavior.

codex exec --model gpt-5-codex --json "Review the change, look for use-after-free issues"
codex exec --model gpt-5 --json resume --last "Fix use-after-free issues"

Authentication

By default, codex exec will use the same authentication method as Codex CLI and VSCode extension. You can override the api key by setting the CODEX_API_KEY environment variable.

CODEX_API_KEY=your-api-key-here codex exec "Fix merge conflict"

NOTE: CODEX_API_KEY is only supported in codex exec.