1REDSHIFT(1) General Commands Manual REDSHIFT(1)
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6 gammastep - set color temperature of display according to time of day
7
9 gammastep [-l LAT:LON | -l PROVIDER:OPTIONS] [-t DAY:NIGHT] [OP‐
10 TIONS...]
11
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 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 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.
32
34 -h Display help message.
35 -v Enable verbose output.
37 -V Show program version.
39 -b DAY:NIGHT
41 Screen brightness to apply (between 0.1 and 1.0).
42 -c FILE
44 Load settings from specified configuration file.
45 -g R:G:B
47 Additional gamma correction to apply.
48 -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 -l PROVIDER[:OPTIONS]
55 Select provider for automatic location updates (Use "-l list" to
56 see available providers).
57 -m METHOD[:OPTIONS]
59 Method to use to set color temperature (Use "-m list" to see
60 available methods).
61 -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 -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 -p Print mode (only print parameters and exit).
72 -P Reset existing gamma ramps before applying new color effect.
74 -x Reset mode (remove adjustment from screen).
76 -r Disable fading between color temperatures.
78 -t DAY:NIGHT
80 Color temperature to set at daytime/night.
81 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 Default temperature values:
88 Daytime: 6500K, night: 4500K
90
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 de‐
95 fined). 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:
99 temp-day = integer
101 Daytime temperature
102 temp-night = integer
104 Night temperature
105 fade = 0 or 1
107 Disable or enable fading between color temperatures.
108 brightness-day = 0.1-1.0
110 Screen brightness at daytime
111 brightness-night = 0.1-1.0
113 Screen brightness at night
114 elevation-high = decimal
116 The solar elevation in degrees for the transition to daytime
117 elevation-low = decimal
119 The solar elevation in degrees for the transition to night
120 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 op‐
125 tion is set, dusk-time must also be specified.
126 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 op‐
131 tion is set, dawn-time must also be specified.
132 gamma = R:G:B
134 Gamma adjustment to apply (day and night)
135 gamma-day = R:G:B
137 Gamma adjustment to apply at daytime
138 gamma-night = R:G:B
140 Gamma adjustment to apply at night
141 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 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.
149 Options for location providers and adjustment methods can be found in
151 the help output of the providers and methods.
152
154 Example for Copenhagen, Denmark:
155 $ gammastep -l 55.7:12.6 -t 5700:3600 -g 0.8 -m randr -v
157 An example configuration file with the same effect as the above command
159 line:
160 [general]
162 temp-day=5700
163 temp-night=3600
164 gamma=0.8
165 adjustment-method=randr
166 location-provider=manual
167 [manual]
169 lat=55.7
170 lon=12.6
171
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 de‐
176 tails 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 A simple script to handle these events can be written like this:
183 #!/bin/sh
185 case $1 in
186 period-changed)
187 exec notify-send "Gammastep" "Period changed to $3"
188 esac
189
191 gammastep was written by Jon Lund Steffensen <jonlst@gmail.com>, and is
192 now maintained by Cameron Nemo <cam@nohom.org>.
193 Both gammastep and this manual page are released under the GNU General
195 Public License, version 3.
196
198 Please report bugs to <https://gitlab.freedesktop.org/CameronNemo/gam‐
199 mastep/issues>
200
202 gammastep will not affect the color of your cursor when your graphics
203 driver is configured to use hardware cursors. Some graphics drivers
204 have an option to disable hardware cursors.
205 REDSHIFT(1)