# exec

The `exec` command performs an action on a module within the system. It is a remote procedure call.

```javascript
{
    "id": 3,                 // tracking id
    "cmd": "exec",           // request type
    "sys": "sys-YNQ8ucvndO", // system id
    "mod": "Display",        // module name
    "index": 2,              // module index in the system
    "name": "switch_to",     // the driver function to call
    "args": ["hdmi"]         // The function arguments (if required)
}
```

The return value of the function is returned in the response, assuming it can be serialised into JSON.

```javascript
{
    "id": 3,
    "type": "success",
    "value": ["hdmi"]
}
```

If an error was raised, the error message is returned.

```javascript
{
    "id": 3,
    "type": "error",
    "code": 3,
    "msg": "ZeroDivisionError: divided by 0"
}
```


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