BACKLIGHT(1) - General Commands Manual

NAME

backlight - adjust screen brightness

SYNOPSIS

backlight decrease [amount]
backlight get
backlight increase [amount]
backlight set percentage

DESCRIPTION

The backlight tool adjust the brightness on your screen using direct access to ACPI video extension.

The following commands are available:

decrease

Decrease the specific amount percentage value (default: 10).

get

Get the current level scaled to a percentage range.

increase

Increase the specific amount percentage value (default: 10).

set

Set brightness to the percentage value.

SYSTEM SUPPORT

Linux

On Linux, you need to have ACPI Video support either as module or built-in the kernel.

You may use backlight as non-root user if you create appropriate udev rules to make files under /sys/class/backlight writable by a group or per user.

The source package comes with an example of udev rule that can be installed in /usr/lib/udev/rules.d.

FreeBSD

Access to brightness under FreeBSD requires super-user, you may need to run backlight as root or use setuid permission for non-root users.

You also need to load acpi_video(4) module at boot by adding acpi_video_load=“YES” in /boot/loader.conf.

OpenBSD

On OpenBSD, the device /dev/ttyC0 must be writable in your user but this is normally the case when you login. Otherwise you may simply run the program as root.

Note: you may need to specify a bigger amount with the increase, decrease commands if your system use small percentages.

AUTHORS

backlight was written by David Demelier <markand@malikania.fr>

Mac OS X 10.15 - September 16, 2019