backlight(8)

backlight8

Configure backlight hardware

Usage

backlight [-q] [-f device]

backlight [-q] [-f device] -i

backlight [-f device] value

backlight {[-f device] incr | + [value]}

backlight {[-f device] decr | - [value]}

Overview

The backlight utility can be used to configure brightness levels for registered backlights.

Called without any arguments it will print the current brightness level of the first registered backlight.

The options are as follows:

-f device

Device to operate on. If not specified, /dev/backlight/backlight0 is used. If an unqualified name is provided, /dev/backlight/ is automatically prepended.

-i

Query information about the backlight (name, type).

-q

When querying the brightness level only print the value.

value

Set the brightness level to this value, must be between 0 and 100. A trailing “%” is valid.

incr|+ [value]

Increment the backlight level. If no value is specified a default of 10 percent is used.

decr|- [value]

Decrement the backlight level. If no value is specified a default of 10 percent is used.

Brightness levels may not be preserved across a reboot unless backlight_enable is set to “YES” in rc.conf(5). This is disabled by default to avoid intefering with desktop environments that do their own backlight management.

Examples

Show the current brightness level:

$ backlight -f /dev/backlight/backlight0
brightness: 98

Releases

15 releases since FreeBSD 13.0-RELEASE; the text changed 4 times.

  1. 13.0–13.1
  2. 13.2
  3. 13.3–13.5
  4. 14.0–15.1
  5. 16.0

History

The backlight utility appeared in FreeBSD 13.0.

Authors

The backlight utility and this manual page were written by Emmanuel Vadot ⟨[email protected]⟩.

From base 16.0-CURRENT-20261027-61c70dc16a79 in FreeBSD 16.0-CURRENT (2026-10-27). Parsed by carta from the page's mdoc source.