# BT.envs

## Function

 returns the currently valid environment variable object.

## Syntax

```bt
BT.envs()
```

## Parameters

| Parameters | Type | Required | Default value | Description |
| ------ | ------ | ------ | ------ | ------ |
| None | - | No | None | No parameters required. |

## Return Value

| Type | Description |
| ------ | ------ |
| Object | Returns the dynamic key-value object that combines OS environment variables and BT runtime overlay. See below for field rules. |

## Return object field

`BT.envs()` returns a dynamic object, not a fixed structure object. Object fields come from current OS environment variables and BT runtime overlay.

| Field | Type | Must exist | Description |
| ------ | ------ | ------ | ------ |
| Any environment variable name | String | No | A valid environment variable value. The field name is the environment variable name, such as `PATH`, `BT_MODE`. When the variable does not exist or is obscured by `BT.remove_env(name)`, this field does not exist and the read result is `empty`. |

## Examples

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

// Output: dev
print result
```

## Notes

 - BT.envs() will traverse OS environment variables as needed, which may result in more string allocations.
 - Variables that have been obscured by the remove_env removal flag will not appear in the returned object.
- The overlay written by `BT.set_env(name, value)` will overwrite the OS environment variable with the same name.