.\" -*- nroff -*- .Dd August 4, 2018 .Os GNU/Linux .Dt LIGHT 1 URM .Sh NAME .Nm light .Nd a program to control backlight controllers .Sh SYNOPSIS .Nm light .Op Ar OPTIONS .Op Ar VALUE .Sh DESCRIPTION .Nm is a program to control backlight display and keyboard controllers under GNU/Linux. .Pp .Bl -bullet -compact .It Operates independently of X (X-Window) .It Can automatically figure out the best controller to use, making full use of the underlying hardware .It Supports a minimum cap on the brightness value, as some controllers set the display to be pitch black at a vaĺue of 0 (or higher) .El .Sh COMMANDS The following unique commands are supported: .Pp .Bl -tag -width Ds .It Fl A Add value .It Fl G Get value, default .It Fl H , Fl h Show help text and exit .It Fl I Restore brightness .It Fl L List controllers .It Fl O Save brightness .It Fl S Set value .It Fl U Subtract value .It Fl V Show program version and exit .El .Sh OPTIONS The behavior of the above commands can be modified using these options: .Pp .Bl -tag -width Ds .It Fl b Set .Fl S , Get .Fl G , Add .Fl A , or Subtract .Fl U active brightness, default .It Fl k Act on keyboard backlight .It Fl l Act on display backlight, default .It Fl m Get .Fl G maximum brightness .It Fl c Set .Fl S or get .Fl G minimum cap for brightness .It Fl a Select controller automatically, default .It Fl p Interpret input and output values in percent, default .It Fl r Interpret input and output values in raw mode .It Fl s Ar ARG Specify controller to use. Use .Fl L to list available controllers .It Fl v Ar ARG Set verbosity level, by default .Nm only outputs read values: .Pp .Bl -tag -width 0: -compact .It 0: Read values .It 1: Read values, Errors .It 2: Read values, Errors, Warnings .It 3: Read values, Errors, Warnings, Notices .El .El .Sh FILES When run in its classic SUID root mode .Nm caches settings and current brightness in .Pa /etc/light . In its non-priviliged mode of operation the .Pa ~/.cache/light directory is used instead. .Sh AUTHORS Copyright \(co 2014-2018 Fredrik Haikarainen .Pp This is free software, see the source for copying conditions. There is NO warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE