Mon, 12 Apr 2021 20:22:57 +0200

David Demelier <>
Mon, 12 Apr 2021 20:22:57 +0200
changeset 27
parent 23

misc: update copyright years

backlight INSTALL

Supported systems

- Linux: requires video ACPI module,
- FreeBSD: requires the `acpi_video(4)` loaded,
- OpenBSD.

Installation on Linux

First, build the program:


On Linux, adjusting the brightness can be done as normal user if you have write
access to the appropriate files which are usually under */sys*.

The recommandation is to install the udev rule which change the ownership of the
brightness file to `video` group and writable by users in this group. Use the
`install-udev` for that purpose. Then don't forget to check if you are part of
the video group.

	make install
	make install-udev

Otherwise, as alternative you can simply install the binary as setuid if you
don't run udev.

	make install-setuid

Installation on FreeBSD

In FreeBSD, it's required to have the tool in setuid as there is no way to
change sysctl values from a regular user.

Also, you will need the ACPI video module, add the following to your


Alternatively, you can compile this module into the kernel.

Then install using:

	make install-setuid