Robby He
f3989f6092
# Unified Exec Shell Selection on Windows ## Problem reference issue #7466 The `unified_exec` handler currently deserializes model-provided tool calls into the `ExecCommandArgs` struct: ```rust #[derive(Debug, Deserialize)] struct ExecCommandArgs { cmd: String, #[serde(default)] workdir: Option<String>, #[serde(default = "default_shell")] shell: String, #[serde(default = "default_login")] login: bool, #[serde(default = "default_exec_yield_time_ms")] yield_time_ms: u64, #[serde(default)] max_output_tokens: Option<usize>, #[serde(default)] with_escalated_permissions: Option<bool>, #[serde(default)] justification: Option<String>, } ``` The `shell` field uses a hard-coded default: ```rust fn default_shell() -> String { "/bin/bash".to_string() } ``` When the model returns a tool call JSON that only contains `cmd` (which is the common case), Serde fills in `shell` with this default value. Later, `get_command` uses that value as if it were a model-provided shell path: ```rust fn get_command(args: &ExecCommandArgs) -> Vec<String> { let shell = get_shell_by_model_provided_path(&PathBuf::from(args.shell.clone())); shell.derive_exec_args(&args.cmd, args.login) } ``` On Unix, this usually resolves to `/bin/bash` and works as expected. However, on Windows this behavior is problematic: - The hard-coded `"/bin/bash"` is not a valid Windows path. - `get_shell_by_model_provided_path` treats this as a model-specified shell, and tries to resolve it (e.g. via `which::which("bash")`), which may or may not exist and may not behave as intended. - In practice, this leads to commands being executed under a non-default or non-existent shell on Windows (for example, WSL bash), instead of the expected Windows PowerShell or `cmd.exe`. The core of the issue is that **"model did not specify `shell`" is currently interpreted as "the model explicitly requested `/bin/bash`"**, which is both Unix-specific and wrong on Windows. ## Proposed Solution Instead of hard-coding `"/bin/bash"` into `ExecCommandArgs`, we should distinguish between: 1. **The model explicitly specifying a shell**, e.g.: ```json { "cmd": "echo hello", "shell": "pwsh" } ``` In this case, we *do* want to respect the model’s choice and use `get_shell_by_model_provided_path`. 2. **The model omitting the `shell` field entirely**, e.g.: ```json { "cmd": "echo hello" } ``` In this case, we should *not* assume `/bin/bash`. Instead, we should use `default_user_shell()` and let the platform decide. To express this distinction, we can: 1. Change `shell` to be optional in `ExecCommandArgs`: ```rust #[derive(Debug, Deserialize)] struct ExecCommandArgs { cmd: String, #[serde(default)] workdir: Option<String>, #[serde(default)] shell: Option<String>, #[serde(default = "default_login")] login: bool, #[serde(default = "default_exec_yield_time_ms")] yield_time_ms: u64, #[serde(default)] max_output_tokens: Option<usize>, #[serde(default)] with_escalated_permissions: Option<bool>, #[serde(default)] justification: Option<String>, } ``` Here, the absence of `shell` in the JSON is represented as `shell: None`, rather than a hard-coded string value.
npm i -g @openai/codex
or brew install --cask codex
Codex CLI is a coding agent from OpenAI that runs locally on your computer.
If you want Codex in your code editor (VS Code, Cursor, Windsurf), install in your IDE
If you are looking for the cloud-based agent from OpenAI, Codex Web, go to chatgpt.com/codex
Quickstart
Installing and running Codex CLI
Install globally with your preferred package manager. If you use npm:
npm install -g @openai/codex
Alternatively, if you use Homebrew:
brew install --cask codex
Then simply run codex to get started:
codex
If you're running into upgrade issues with Homebrew, see the FAQ entry on brew upgrade codex.
You can also go to the latest GitHub Release and download the appropriate binary for your platform.
Each GitHub Release contains many executables, but in practice, you likely want one of these:
- macOS
- Apple Silicon/arm64:
codex-aarch64-apple-darwin.tar.gz - x86_64 (older Mac hardware):
codex-x86_64-apple-darwin.tar.gz
- Apple Silicon/arm64:
- Linux
- x86_64:
codex-x86_64-unknown-linux-musl.tar.gz - arm64:
codex-aarch64-unknown-linux-musl.tar.gz
- x86_64:
Each archive contains a single entry with the platform baked into the name (e.g., codex-x86_64-unknown-linux-musl), so you likely want to rename it to codex after extracting it.
Using Codex with your ChatGPT plan
Run codex and select Sign in with ChatGPT. We recommend signing into your ChatGPT account to use Codex as part of your Plus, Pro, Team, Edu, or Enterprise plan. Learn more about what's included in your ChatGPT plan.
You can also use Codex with an API key, but this requires additional setup. If you previously used an API key for usage-based billing, see the migration steps. If you're having trouble with login, please comment on this issue.
Model Context Protocol (MCP)
Codex can access MCP servers. To configure them, refer to the config docs.
Configuration
Codex CLI supports a rich set of configuration options, with preferences stored in ~/.codex/config.toml. For full configuration options, see Configuration.
Execpolicy
See the Execpolicy quickstart to set up rules that govern what commands Codex can execute.
Docs & FAQ
- Getting started
- Configuration
- Sandbox & approvals
- Execpolicy quickstart
- Authentication
- Automating Codex
- Advanced
- Zero data retention (ZDR)
- Contributing
- Install & build
- FAQ
- Open source fund
License
This repository is licensed under the Apache-2.0 License.