Keep in mind, that at the time of writing (08 January 2023), the upstream project seems dead. The alternative is the gammastep project. The package for it is x11-misc/gammastep.
Redshift is an automatic color temperature adjustment to help reduce monitor eye strain induced by working in low-light conditions. Depending on the location (longitude and latitude) of the user's computer system, Redshift will change the color of the screen from the default bluish color to a orange/reddish color during evening hours, and then back again to bluish tint during daylight hours.
USE flags for x11-misc/redshift A screen color temperature adjusting software
After setting necessary USE flags, install Redshift:
emerge --ask x11-misc/redshift
A configuration file can be created in each users home directory at ~/.config/redshift.conf
In order for Redshift to start, it will require longitude and latitude information inside the configuration file.
redshift -l manual:help
Redshift can be quickly established in working order by adding correct location information into the configuration file. Lat/Lon values can be found searching for the closest city or region at Wikipedia or with a map service such as OpenStreetMap.
When using OpenStreetMap, simply search for the location. When it appears on the map tiles click the Export button (should be near the top left). The center of the displayed tiles will be the exact Lat/Lon location. The Lat value is the second number from the end displayed in the URL. The Lon value is the last number on the end.
A finished .conf file will look something like this:
[redshift] location-provider=manual [manual] lat=47.6587803 lon=-117.4260466
Redshift does not currently include an OpenRC init script.
systemctl --user enable redshift.service
systemctl --user start redshift.service
Usage: redshift -l LAT:LON -t DAY:NIGHT [OPTIONS...] Set color temperature of display according to time of day. -h Display this help message -v 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 -l PROVIDER Select provider for automatic location updates (Type `list' to see available providers) -m METHOD Method to use to set color temperature (Type `list' to see available methods) -o One shot mode (do not continuously adjust color temperature) -O TEMP One shot manual mode (set color temperature) -p Print mode (only print parameters and exit) -x Reset mode (remove adjustment from screen) -r Disable temperature transitions -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 values: Daytime temperature: 6500K Night temperature: 4500K Please report bugs to <https://github.com/jonls/redshift/issues>
No display manager
When not using a Display manager, users may encounter a similar error in the output of systemctl --user status redshift
systemctl --user status redshift
Jan 04 17:55:16 systemd: Started Redshift display colour temperature adjustment. Jan 04 17:55:16 redshift: `RANDR Query Version' returned error -1 Jan 04 17:55:16 redshift: Initialization of randr failed. Jan 04 17:55:16 redshift: Trying next method... Jan 04 17:55:16 redshift: X request failed: XOpenDisplay Jan 04 17:55:16 redshift: Initialization of vidmode failed. Jan 04 17:55:16 redshift: Trying next method... Jan 04 17:55:16 redshift: No more methods to try. Jan 04 17:55:16 systemd: redshift.service: Main process exited, code=exited, status=1/FAILURE
To verify this, simply issue redshift in a terminal. If redshift starts up correctly, then this is likely the issue.
There are a couple simple solutions to this problem:
- Install and use a Display manager
- Add redshift & to the user ~/.xinitrc file