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REDSHIFT(1)		     General Commands Manual		     REDSHIFT(1)

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

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

DESCRIPTION
     redshift  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 redshift, the GUI redshift-gtk pro-
     vides 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 redshift.conf can optionally  be  placed
     in  ~/.config/.  The  file has standard INI format. General program options
     are placed under the redshift 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  when	Redshift
	    starts or stops

     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:

	    $ redshift -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:

	    [redshift]
	    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/redshift/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  when	Redshift
     starts  up  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 "Redshift" "Period changed to $3"
	    esac

AUTHOR
     redshift was written by Jon Lund Steffensen <jonlst@gmail.com>.

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

BUGS
     Please report bugs to <https://github.com/jonls/redshift/issues>

KNOWN ISSUES
     redshift 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)

Want to link to this manual page? Use this URL:
<https://man.freebsd.org/cgi/man.cgi?query=redshift&sektion=1&manpath=FreeBSD+Ports+15.1.quarterly>

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