Redshift Configuration and use
It is a program which adjusts the color temperature of your screen with GTK+ integration. Think about daylight and night light difference. From the developer's page: http://jonls.dk/redshift/
“Redshift adjusts the color temperature of your screen according to your surroundings.”
It has been in the repositories since Precise Pangolin 12.04, and you can install redshift-gtk along with it.
Redshift-gtk is a simple user interface. Once installed you will find it in the accessories menus. It is not installed as a dependency and isn't even a recommended package, for the time being.
What it does
It is used to start redshift, and once started, it sits in the tray to allow enabling and disabling redshift, suspend it for a while, or quit. This is all it does, and it does not provide a configuration of any kind. The man and help commands are not very helpful either, especially on the syntax needed for the latitude and longitude.
So here is an example of a working configuration, which you can adapt to your needs. Name it redshift.conf and place it in your $HOME/.config directory, then ajust it to your needs.
[redshift] ; Set the day and night screen temperatures temp-day=5800 temp-night=4800 ; Enable/Disable a smooth transition between day and night ; 0 will cause a direct change from day to night screen temperature. ; 1 will gradually increase or decrease the screen temperature transition=1 ; Set the screen brightness. Default is 1.0 ;brightness=0.9 ; It is also possible to use different settings for day and night since version 1.8. ;brightness-day=0.7 ;brightness-night=0.4 ; Set the screen gamma (for all colors, or each color channel individually) gamma=0.9 ;gamma=0.8:0.7:0.8 ; Set the location-provider: 'geoclue', 'gnome-clock', 'manual' ; type 'redshift -l list' to see possible values ; The location provider settings are in a different section. location-provider=manual ; Set the adjustment-method: 'randr', 'vidmode' ; type 'redshift -m list' to see all possible values ; 'randr' is the preferred method, 'vidmode' is an older API ; but works in some cases when 'randr' does not. ; The adjustment method settings are in a different section. adjustment-method=randr ; Configuration of the location-provider: ; type 'redshift -l PROVIDER:help' to see the settings ; e.g. 'redshift -l manual:help' [manual] lat=43 lon=1 ; Configuration of the adjustment-method ; type 'redshift -m METHOD:help' to see the settings ; ex: 'redshift -m randr:help' ; In this example, randr is configured to adjust screen 1. ; Note that the numbering starts from 0, so this is actually the second screen. [randr] screen=0
Of course, you can play with the temp-day and temp-night values the gamma, and you will have to provide the correct values for "lat" and "lon" according to your geographical position.