> ## Documentation Index
> Fetch the complete documentation index at: https://jncpkg.org/llms.txt
> Use this file to discover all available pages before exploring further.

# jnc exec

> Run a command in a temporary environment.

# jnc exec

Runs a command in a temporary, isolated environment. The required packages are automatically installed into a cached environment and the command is executed within it. This is useful for one-off commands without creating a full workspace.

Temporary environments are cached for reuse. Clear them with `jnc clean cache --exec`.

## Usage

```bash theme={null}
jnc exec [OPTIONS] <COMMAND> [ARGS]...
```

**Alias:** `x`

## Arguments

| Argument              | Description                                                                                                                  |
| --------------------- | ---------------------------------------------------------------------------------------------------------------------------- |
| `<COMMAND> [ARGS]...` | The executable to run, followed by any arguments. If `--spec` is not provided, the package is guessed from the command name. |

## Options

| Option                  | Short | Description                                                                                                             |
| ----------------------- | ----- | ----------------------------------------------------------------------------------------------------------------------- |
| `--spec <SPEC>`         | `-s`  | Matchspecs of packages to install. Can be specified multiple times. When provided, disables automatic package guessing. |
| `--with <SPEC>`         | `-w`  | Additional matchspecs to install alongside the guessed package. Cannot be combined with `--spec`.                       |
| `--channel <CHANNEL>`   | `-c`  | The channel to search for packages. Can be specified multiple times. Defaults to `conda-forge`.                         |
| `--platform <PLATFORM>` | `-p`  | The platform to create the environment for. Defaults to the current platform.                                           |
| `--force-reinstall`     |       | Always create a new environment, even if a cached one exists.                                                           |
| `--list[=REGEX]`        |       | List packages in the environment before executing the command. Optionally filter by regex.                              |
| `--no-modify-ps1`       |       | Disable modification of the PS1 prompt to indicate the temporary environment.                                           |

## Examples

Run Python in a temporary environment:

```bash theme={null}
jnc exec python
```

Run Python with a specific version:

```bash theme={null}
jnc exec --spec "python=3.12" python -- -c "print('hello')"
```

Run a command with additional packages:

```bash theme={null}
jnc exec --with numpy python -- -c "import numpy; print(numpy.__version__)"
```

Use a specific channel:

```bash theme={null}
jnc exec --channel conda-forge --spec "nodejs=20" node -- --version
```

Force a fresh environment:

```bash theme={null}
jnc exec --force-reinstall python
```

List packages in the temporary environment before running:

```bash theme={null}
jnc exec --list python
```