How to Install and Use Redshift on Ubuntu 20.04

Redshift can be used to change your monitor's color temperature,

in the night or in a dark room or we need reading the document on screen, sometimes we need our screen color temperature during 3000K-4000K, or 6500K, or 5500K-6500K. then you can be using this tool to do it.

in Ubuntu 20.04, you can use this command:

$ sudo apt update
$ sudo apt install redshift redshift-gtk

then you can find "redshift" in your program list, and can work, but is the default setting, for more settings, you need a config file to save a new file to ~/.config/redshift.conf.

setting config-sample:  https://raw.githubusercontent.com/jonls/redshift/master/redshift.conf.sample