redshift 

pacman -S redshift
  • add location to configuration file ~/.config/redshift/redshift.conf 
[redshift]
location-provider=manual

[manual]
lat=33.78
lon=-84.39
  • can get coordinates with geonames.org
  • note: to convert xxo yy' zz" to decimal find xx + yy/60 + zz/3600 (hours minutes seconds)
  • note: north and east are positive, south and west are negative
  • can also use google maps, right-click location
  • start system service
systemctl --user status redshift.service