Configuration file
The configuration file for Linux is located at: ~/.config/redshift.conf(if the environment variable XDG_CONFIG_HOME is undefined) or ${XDG_CONFIG_HOME}/redshift/redshift.conf (if XDG_CONFIG_HOME is defined). This file does not yet exist but can easily be created with a simple touch (e.g.: touch ~/.config/redshift.conf)
For Windows users create a file named: redshift with the .conf extension in %USERPROFILE%\AppData\Local\ which is also approachable as %localappdata%.
The file always begins with a header for the configparser to read:
[redshift]
To set the day and night screen temperatures you have two keys (temp-day and temp-night respectively) where the value is an integer; by default:
temp-day=5700
temp-night=3500
To disable the smooth fade between temperatures when Redshift starts and stops, you use the fade key with either a 0 or a 1 value; where 0 will cause an immediate change between screen temperatures and 1 will gradually apply the new screen temperature over a couple of seconds. Default:
fade=1
By default, Redshift will use the current elevation of the sun to determine whether it is daytime, night or in transition (dawn/dusk). When the sun is above the degrees specified with the elevation-high key it is considered daytime and below the elevation-low key it is considered night. For example:
elevation-high=3
elevation-low=-6
Instead of using the solar elevation, the time intervals of dawn and dusk can be specified manually. The times must be specified as HH:MM in 24-hour format. E.g.:
dawn-time=6:00-7:45
dusk-time=18:35-20:15
This doesn't change the monitor's brightness settings (nor the gamma's) but manipulates the video output softwarematically to set the screen brightness. Backlight (of the monitor) is not affected either. Default value for brightness is 1.0. Example:
brightness=0.9
It is also possible to use different settings for day and night (version 1.8<)
brightness-day=0.7
brightness-night=0.4
To set the screen gamma:
gamma=0.8
Or for each color channel individually (R:G:B):
gamma=0.8:0.7:0.8
Just as with brightness this can also be set individually for day and night (version 1.10<)
gamma-day=0.8:0.7:0.8
gamma-night=0.6
The location-provider has two options: geoclue2 and manual. Where geoclue2 uses the GeoClue2 library to get your device's location (usually via the internet). With: manual you can set your own longitude and latitude values (see more over at manual). For the sake of completion, we'll take manual for now (this is needed to enable the next header):
location-provider=manual
Different adjustment-method includes: randr and vidmode. randr is the preferred method (X.org), vidmode is an older API; but works in some cases when randr does not. The adjustment method settings are in under the randr header. By default:
adjustment-method=randr
If you set manual for location-provider this header contains the settings for that. Where lat is latitude and lon is longitude. Keep in mind that longitudes west of Greenwich (i.e. the Americas) are negative numbers. Munich - Germany as an example:
[manual]
lat=48.1
lon=11.6
If you set randr for adjustment-method this header contains the settings for that. In this example, randr is configured to adjust only screen 0. Note that the numbering starts from a zero-index, so this is actually the first screen. If this option is not specified, Redshift will try to adjust all screens.
[randr]
screen=0
Not every option is required and you can cherry-pick which options you'd want changed from default, for instance; changing the way Redshift sets it's location:
[redshift]
location-provider=manual
[manual]
lon=60
lat=6