# BT.env

## Function

 reads the currently valid environment variables.

## Syntax

```bt
BT.env(name)
```

## Parameters

| Parameters | Type | Required | Default value | Description |
| ------ | ------ | ------ | ------ | ------ |
| name | String | Yes | None | Environment variable name. |

## Return Value

| Type | Description |
| ------ | ------ |
| String/Empty | Returns a string if the variable exists; returns empty if it does not exist or is obscured by a BT overlay delete mark. |

## Examples

```bt
BT.set_env('BT_MODE', 'dev')
result = BT.env('BT_MODE')

// Output: dev
print result
```

## Notes

- When reading, first check the BT runtime environment variable overlay, and then fall back to the OS environment variable.
- An error will be reported when the environment variable name is empty.