ybacklight
Manage screen backlight brightness. See also `xbacklight`.
TLDR
Print current brightness and maximal brightness, shortened and separated by a slash
$ ybacklight Sc/Sm
Set the brightness to 420
$ ybacklight s[420]
Increase the brightness by 42 big steps (4200 by default)
$ ybacklight Si[42]
Decrease the brightness by 300
$ ybacklight d[300]
