Redshift is a small utility that gradually – as day turns into night – shifts the colour composition of the light from your monitor. The later it gets, the ‘warmer’ (i.e. redder) the colour becomes. This may sound odd but the effect is really pleasant and (literally) easy on the eyes. Once you’ve grown used to it, looking at a screen late at night you’ll really notice how harsh and cold the light will appear without it. I owe this discovery to Graham Morrison from Linux Voice. You can read more about it in Graham’s piece on page 78 in the now free issue 14 of Linux Voice (you should also subscribe to LV as it’s a really good magazine).
Redshift is the sort of thing you want to have running as soon as you log into your desktop but occasionally, you want it to turn it off. I occasionally play Spelunky into the wee hours of the night and running redshift while playing the game makes dark levels, well dark. Pitch black, more like. So a classic Gnome autostart file is not ideal as we can’t interact with it (apart from killing the resulting process). Redshift does come with a small tray utility that should allow for turning on and off but I really dislike tray litter and anyway Gnome’s trying to do away with this sort of thing. So systemd to the rescue.
Sadly the redshift package in Ubuntu 16.04 comes without a systemd .service file so I put together one myself.