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REDSHIFT(1)		     General Commands Manual		     REDSHIFT(1)

NAME
     gammastep - set color temperature of display according to time of day

SYNOPSIS
     gammastep [-l LAT:LON | -l PROVIDER:OPTIONS] [-t DAY:NIGHT] [OPTIONS...]

DESCRIPTION
     gammastep	adjusts  the  color temperature of your screen according to your
     surroundings. This may help your eyes hurt less or reduce the risk for  de-
     layed  sleep  phase  syndrome  if you are working in front of the screen at
     night.

     The color temperature is set according to the position of the sun.  A  dif-
     ferent  color  temperature is set during night and daytime. During twilight
     and early morning, the color temperature transitions smoothly from night to
     daytime temperature to allow your eyes to slowly adapt  over  a  period  of
     about  an	hour.  At night the color temperature should be set to match the
     lamps in  your  room.  This  is  typically  a  low  temperature  at  around
     3000K-4000K  (default  is	4500K).  During  the  day, the color temperature
     should match the light from outside, typically around 5500K-6500K	(default
     is 6500K). The light has a higher temperature on an overcast day.

     In addition to the command-line tool gammastep, the GUI gammastep-indicator
     provides  an  alternative interface that shows up as a notification icon in
     the desktop environment.

OPTIONS
     -h     Display help message.

     -v     Enable verbose output.

     -V     Show program version.

     -b DAY:NIGHT
	    Screen brightness to apply (between 0.1 and 1.0).

     -c FILE
	    Load settings from specified configuration file.

     -g R:G:B
	    Additional gamma correction to apply.

     -l LAT:LON
	    Your current location, in degrees, given as floating point	numbers,
	    towards north and east, with negative numbers representing south and
	    west, respectively.

     -l PROVIDER[:OPTIONS]
	    Select provider for automatic location updates (Use "-l list" to see
	    available providers).

     -m METHOD[:OPTIONS]
	    Method  to use to set color temperature (Use "-m list" to see avail-
	    able methods).

     -o     One-shot mode (do not continuously adjust  color  temperature).  Use
	    this with the -P option to clear the existing gamma ramps before ap-
	    plying the new color temperature.

     -O TEMP
	    One-shot  manual mode (set color temperature).  Use this with the -P
	    option to clear the existing gamma ramps  before  applying	the  new
	    color temperature.

     -p     Print mode (only print parameters and exit).

     -P     Reset existing gamma ramps before applying new color effect.

     -x     Reset mode (remove adjustment from screen).

     -r     Disable fading between color temperatures.

     -t DAY:NIGHT
	    Color temperature to set at daytime/night.

     The  neutral  temperature	is  6500K.  Using this value will not change the
     color temperature of the display. Setting the color temperature to a  value
     higher than this results in more blue light, and setting a lower value will
     result in more red light.

     Default temperature values:

	    Daytime: 6500K, night: 4500K

CONFIGURATION FILE
     A	configuration  file with the name config.ini can optionally be placed in
     ~/.config/gammastep/ (if the environment variable XDG_CONFIG_HOME is  unde-
     fined)  or  ${XDG_CONFIG_HOME}/gammastep/	(if XDG_CONFIG_HOME is defined).
     The file has standard INI format. General program options are placed  under
     the  general  header,  while  options for location providers and adjustment
     methods are placed under a header with the name of that provider or method.
     General options are:

     temp-day = integer
	    Daytime temperature

     temp-night = integer
	    Night temperature

     fade = 0 or 1
	    Disable or enable fading between color temperatures.

     brightness-day = 0.1-1.0
	    Screen brightness at daytime

     brightness-night = 0.1-1.0
	    Screen brightness at night

     elevation-high = decimal
	    The solar elevation in degrees for the transition to daytime

     elevation-low = decimal
	    The solar elevation in degrees for the transition to night

     dawn-time = HH:MM[-HH:MM]
	    The custom time interval for the transition from night to day in the
	    morning.  When specified, the solar elevation will not  be	used  to
	    determine  the  current daytime/night period. If this option is set,
	    dusk-time must also be specified.

     dusk-time = HH:MM[-HH:MM]
	    The custom time interval for the transition from day to night in the
	    evening.  When specified, the solar elevation will not  be	used  to
	    determine  the  current daytime/night period. If this option is set,
	    dawn-time must also be specified.

     gamma = R:G:B
	    Gamma adjustment to apply (day and night)

     gamma-day = R:G:B
	    Gamma adjustment to apply at daytime

     gamma-night = R:G:B
	    Gamma adjustment to apply at night

     adjustment-method = name
	    Select adjustment method. Options for the adjustment method  can  be
	    given under the configuration file heading of the same name.

     location-provider = name
	    Select  location  provider. Options for the location provider can be
	    given under the configuration file heading of the same name.

     Options for location providers and adjustment methods can be found  in  the
     help output of the providers and methods.

EXAMPLE
     Example for Copenhagen, Denmark:

	    $ gammastep -l 55.7:12.6 -t 5700:3600 -g 0.8 -m randr -v

     An  example  configuration  file  with the same effect as the above command
     line:

	    [general]
	    temp-day=5700
	    temp-night=3600
	    gamma=0.8
	    adjustment-method=randr
	    location-provider=manual

	    [manual]
	    lat=55.7
	    lon=12.6

HOOKS
     Executables (e.g. scripts) placed in folder ~/.config/gammastep/hooks  will
     be  run when a certain event happens. The first parameter to the script in-
     dicates the event and further parameters may indicate  more  details  about
     the  event.  The  event period-changed is indicated when the period changes
     (night, daytime, transition). The second parameter is the	old  period  and
     the third is the new period. The event is also signaled at startup with the
     old period set to none.  Any dotfiles in the folder are skipped.

     A simple script to handle these events can be written like this:

	    #!/bin/sh
	    case $1 in
		period-changed)
		    exec notify-send "Gammastep" "Period changed to $3"
	    esac

AUTHOR
     gammastep was written by Jon Lund Steffensen <jonlst@gmail.com>, and is now
     maintained by Cameron Nemo <cam@nohom.org>.

     Both gammastep and this manual page are released under the GNU General Pub-
     lic License, version 3.

BUGS
     Please  report  bugs to <https://gitlab.freedesktop.org/CameronNemo/gammas-
     tep/issues>

KNOWN ISSUES
     gammastep will not affect the color of your cursor when your graphics  dri-
     ver  is  configured  to use hardware cursors. Some graphics drivers have an
     option to disable hardware cursors.

								     REDSHIFT(1)

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