.\"  -*- 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 H , Fl h
Show help text and exit
.It Fl V
Show program version and exit
.It Fl L
List available devices
.It Fl A
Increase brightness by value
.It Fl U
Decrease brightness by value
.It Fl T
Multiply brightness by value (can be non-integer)
.It Fl S
Set brightness to value
.It Fl G
Get brightness, default
.It Fl N
Set minimum brightness to value
.It Fl P
Get minimum brightness
.It Fl O
Save current brightness
.It Fl I
Restore previously saved brightness
.El
.Sh OPTIONS
The behavior of the above commands can be modified using these options:
.Pp
.Bl -tag -width Ds
.It Fl r
Interpret input and output values in raw mode
.It Fl s Ar PATH
Specify device target path.  Use
.Fl L
to list available devices
.It Fl v Ar LEVEL
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-privileged mode of operation the
.Pa ~/.cache/light
directory is used instead.
.Sh AUTHORS
Copyright \(co 2012-2018 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