backlight-dbus.1

.TH backlight-dbus 1 "NOVEMBER 2020" Linux "User Manuals"

.SH NAME
backlight-dbus \- a backlight controller using DBus

.SH SYNOPSIS
.B backlight-dbus
.RB [\-h ]
.RB [\-v ]
.RB [\-d
.IR device_name ]
.RB [\-t
.IR countdown ]
.RB [\fIbrightness\fP]

.SH DESCRIPTION
\fIbacklight-dbus\fP is a small utility to adjust the backlight brightness of a
monitor using the DBus interface of systemd-logind. When called with no arguments,
the current and maximum brightness levels are printed.

.SH OPTIONS
.TP
.B \-h
Show help message.
.TP
.B \-v
Enable verbose output (debug messages).
.TP
.BI \-d\ \fIdevice_name\fP
The device name to control. This is a folder (usually a symlink) in
\fI/sys/class/backlight/\fP. If not specified, the first folder found
will be used.
.TP
.BI \-t\ \fIcountdown\fP
The number of seconds over which the brightness should fade. This can
be a floating point number.
.TP
.BI \fIbrightness\fP
This can be one of:
.RS 4
.IP \[bu] 3
An absolute number, like the value in \fI/sys/class/backlight/<device_name>/brightness\fP.
.IP \[bu]
A plus (+) or minus (-) sign followed by an absolute number. The number will be
added/subtracted from the current brightness value.
.IP \[bu]
A number followed by a percent sign (%). The brightness will be set to this
percentage of the maximum value.

The +/- signs and the % sign may be combined together.
.RE

.SH ENVIRONMENT VARIABLES
If the environment variable XDG_SESSION_ID is set, then it will be used to
obtain the DBus session object path. Otherwise, the auto session path will
be used instead.

.SH EXAMPLES
$ backlight-dbus -d acpi_video0 15

$ backlight-dbus -200

$ backlight-dbus -t 3.5 75%

$ backlight-dbus -10%

.SH NOTES
Currently, the program will run for longer than the specified countdown
because the time it takes to wait for a DBus method call to return is
not accounted for.

.SH SEE ALSO
.IR xbacklight(1)
\- adjust backlight brightness using RandR extension

.SH AUTHOR
Max Erenberg