A Python script to change screen brightness via the ACPI method on Linux. Written because other methods either failed (xbacklight) or required heavy dependencies (gnome).

In order to use this script, you must have read and write permissions on the relevant files in /sys/class/backlight/{KERNEL}. From the above wiki page:

/etc/udev/rules.d/backlight.rules

ACTION=="add", SUBSYSTEM=="backlight", KERNEL=="intel_backlight", RUN+="/bin/chgrp video /sys/class/backlight/%k/brightness"
ACTION=="add", SUBSYSTEM=="backlight", KERNEL=="intel_backlight", RUN+="/bin/chmod g+w /sys/class/backlight/%k/brightness"

The current version requires setting the files within the script. A future version will have a small configuration file for separation of code and data. The code should be simple enough to work on all Python versions without dependencies.

Input is taken as the first argument on the command line, which is an integer from MIN to MAX. Current version will perform limiting on the input, i.e. if the input is higher or lower than MAX or MIN respectively, the value used will be the relevant limit. Future versions may complain about invalid input for input enforcement.

Released to the public domain.