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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] [OP-
       TIONS...]

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  delayed  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
       different  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 temper-
       ature  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-indi-
       cator 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 num-
	      bers, 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
	      available	methods).

       -o     One-shot	mode  (do  not continuously adjust color temperature).
	      Use this with the	-P option to clear the	existing  gamma	 ramps
	      before applying 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
       undefined) or ${XDG_CONFIG_HOME}/gammastep/ (if XDG_CONFIG_HOME is  de-
       fined).	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 op-
	      tion 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 op-
	      tion 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 indicates	the event and further parameters may indicate more de-
       tails  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 sig-
       naled 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
       Public License, version 3.

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

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

								   REDSHIFT(1)

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