1REDSHIFT(1)                 General Commands Manual                REDSHIFT(1)
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NAME

6       gammastep - set color temperature of display according to time of day
7

SYNOPSIS

9       gammastep   [-l   LAT:LON   |   -l   PROVIDER:OPTIONS]  [-t  DAY:NIGHT]
10       [OPTIONS...]
11

DESCRIPTION

13       gammastep adjusts the color temperature of  your  screen  according  to
14       your surroundings. This may help your eyes hurt less or reduce the risk
15       for delayed sleep phase syndrome if you are working  in  front  of  the
16       screen at night.
17
18       The  color  temperature  is set according to the position of the sun. A
19       different color temperature is set during  night  and  daytime.  During
20       twilight  and early morning, the color temperature transitions smoothly
21       from night to daytime temperature to allow your eyes  to  slowly  adapt
22       over  a  period of about an hour. At night the color temperature should
23       be set to match the lamps in your room. This is typically a low temper‐
24       ature  at  around  3000K-4000K  (default is 4500K). During the day, the
25       color temperature should match the light from outside, typically around
26       5500K-6500K  (default  is 6500K). The light has a higher temperature on
27       an overcast day.
28
29       In addition to the command-line tool gammastep, the GUI gammastep-indi‐
30       cator provides an alternative interface that shows up as a notification
31       icon in the desktop environment.
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OPTIONS

34       -h     Display help message.
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36       -v     Enable verbose output.
37
38       -V     Show program version.
39
40       -b DAY:NIGHT
41              Screen brightness to apply (between 0.1 and 1.0).
42
43       -c FILE
44              Load settings from specified configuration file.
45
46       -g R:G:B
47              Additional gamma correction to apply.
48
49       -l LAT:LON
50              Your current location, in degrees, given as floating point  num‐
51              bers, towards north and east, with negative numbers representing
52              south and west, respectively.
53
54       -l PROVIDER[:OPTIONS]
55              Select provider for automatic location updates (Use "-l list" to
56              see available providers).
57
58       -m METHOD[:OPTIONS]
59              Method  to  use  to  set color temperature (Use "-m list" to see
60              available methods).
61
62       -o     One-shot mode (do not continuously  adjust  color  temperature).
63              Use  this  with  the -P option to clear the existing gamma ramps
64              before applying the new color temperature.
65
66       -O TEMP
67              One-shot manual mode (set color temperature).  Use this with the
68              -P  option to clear the existing gamma ramps before applying the
69              new color temperature.
70
71       -p     Print mode (only print parameters and exit).
72
73       -P     Reset existing gamma ramps before applying new color effect.
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75       -x     Reset mode (remove adjustment from screen).
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77       -r     Disable fading between color temperatures.
78
79       -t DAY:NIGHT
80              Color temperature to set at daytime/night.
81
82       The neutral temperature is 6500K. Using this value will not change  the
83       color  temperature  of  the display. Setting the color temperature to a
84       value higher than this results in more blue light, and setting a  lower
85       value will result in more red light.
86
87       Default temperature values:
88
89              Daytime: 6500K, night: 4500K
90

CONFIGURATION FILE

92       A  configuration file with the name config.ini can optionally be placed
93       in ~/.config/gammastep/ (if the environment variable XDG_CONFIG_HOME is
94       undefined)  or  ${XDG_CONFIG_HOME}/gammastep/  (if  XDG_CONFIG_HOME  is
95       defined). The file has standard INI format. General program options are
96       placed  under  the general header, while options for location providers
97       and adjustment methods are placed under a header with the name of  that
98       provider or method. General options are:
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100       temp-day = integer
101              Daytime temperature
102
103       temp-night = integer
104              Night temperature
105
106       fade = 0 or 1
107              Disable or enable fading between color temperatures.
108
109       brightness-day = 0.1-1.0
110              Screen brightness at daytime
111
112       brightness-night = 0.1-1.0
113              Screen brightness at night
114
115       elevation-high = decimal
116              The solar elevation in degrees for the transition to daytime
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118       elevation-low = decimal
119              The solar elevation in degrees for the transition to night
120
121       dawn-time = HH:MM[-HH:MM]
122              The custom time interval for the transition from night to day in
123              the morning.  When specified, the solar elevation  will  not  be
124              used  to  determine  the  current  daytime/night period. If this
125              option is set, dusk-time must also be specified.
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127       dusk-time = HH:MM[-HH:MM]
128              The custom time interval for the transition from day to night in
129              the  evening.   When  specified, the solar elevation will not be
130              used to determine the  current  daytime/night  period.  If  this
131              option is set, dawn-time must also be specified.
132
133       gamma = R:G:B
134              Gamma adjustment to apply (day and night)
135
136       gamma-day = R:G:B
137              Gamma adjustment to apply at daytime
138
139       gamma-night = R:G:B
140              Gamma adjustment to apply at night
141
142       adjustment-method = name
143              Select  adjustment method. Options for the adjustment method can
144              be given under the configuration file heading of the same name.
145
146       location-provider = name
147              Select location provider. Options for the location provider  can
148              be given under the configuration file heading of the same name.
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150       Options  for  location providers and adjustment methods can be found in
151       the help output of the providers and methods.
152

EXAMPLE

154       Example for Copenhagen, Denmark:
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156              $ gammastep -l 55.7:12.6 -t 5700:3600 -g 0.8 -m randr -v
157
158       An example configuration file with the same effect as the above command
159       line:
160
161              [general]
162              temp-day=5700
163              temp-night=3600
164              gamma=0.8
165              adjustment-method=randr
166              location-provider=manual
167
168              [manual]
169              lat=55.7
170              lon=12.6
171

HOOKS

173       Executables  (e.g.  scripts) placed in folder ~/.config/gammastep/hooks
174       will be run when a certain event happens. The first  parameter  to  the
175       script  indicates  the  event  and further parameters may indicate more
176       details about the event. The event period-changed is indicated when the
177       period  changes  (night,  daytime, transition). The second parameter is
178       the old period and the third is the new period. The event is also  sig‐
179       naled  at startup with the old period set to none.  Any dotfiles in the
180       folder are skipped.
181
182       A simple script to handle these events can be written like this:
183
184              #!/bin/sh
185              case $1 in
186                  period-changed)
187                      exec notify-send "Gammastep" "Period changed to $3"
188              esac
189

AUTHOR

191       gammastep was written by Jon Lund Steffensen <jonlst@gmail.com>, and is
192       now maintained by Cameron Nemo <cnemo@tutanota.com>.
193
194       Both  gammastep and this manual page are released under the GNU General
195       Public License, version 3.
196

BUGS

198       Please report bugs to <https://gitlab.com/chinstrap/gammastep/issues>
199

KNOWN ISSUES

201       gammastep will not affect the color of your cursor when  your  graphics
202       driver  is  configured  to  use hardware cursors. Some graphics drivers
203       have an option to disable hardware cursors.
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207                                                                   REDSHIFT(1)
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