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

# otter-nightlight

> Color-temperature daemon using wlr-gamma-control. Bar widget and CLI talk to it.

`otter-nightlight` applies a warm gamma table through `wlr-gamma-control-unstable-v1`. That works on Hyprland, Sway, and other wlroots compositors. One binary: no arguments starts the daemon. Any other argument is a client command.

Only one client can own gamma per output. Stop `wlsunset` or `hyprsunset` while this runs.

## Usage

Start the daemon (autostart at login):

```bash theme={null}
otter-nightlight
```

Add it to compositor autostart. On Niri: `spawn-at-startup "otter-nightlight"`. On Hyprland, use `exec-once`. See [Session setup](/desktop/session-setup) for the same pattern.

Client commands:

```bash theme={null}
otter-nightlight toggle
otter-nightlight temp 4000
otter-nightlight schedule-on
otter-nightlight start 20 0
otter-nightlight end 6 0
otter-nightlight suspend 60
otter-nightlight resume
```

| Command                           | Meaning                              |
| --------------------------------- | ------------------------------------ |
| `toggle`                          | Enable or disable night light        |
| `enable` / `disable`              | Set the state directly               |
| `temp KELVIN`                     | Night temperature (1000 to 10000)    |
| `schedule-on` / `schedule-off`    | Follow or ignore the schedule window |
| `start HOUR MIN` / `end HOUR MIN` | Schedule bounds, local 24-hour clock |
| `suspend MINUTES`                 | Pause until then                     |
| `resume`                          | Clear a suspend                      |

A start later than end wraps midnight.

## Bar widget

Add `nightlight` to an [otter-bar](/desktop/otter-bar) layout. Left-click enables or disables. Right-click opens temperature presets, the schedule window, and a one-hour suspend.

The widget is a client. It does nothing if the daemon is not running.

## Configuration

Config: `~/.config/otter-shell/otter-nightlight.conf`

<Tip>
  The **Night Light** tab in [otter-settings](/desktop/otter-settings) writes the same file.
</Tip>

```conf theme={null}
enabled = true
schedule = true
temperature = 4000
day_temperature = 6500
start_hour = 20
start_minute = 0
end_hour = 6
end_minute = 0
```

Times are local 24-hour clock.

## Dependencies

* Wayland compositor with `wlr-gamma-control-unstable-v1`