[UPDATE: Now works for multiple connected outputs] I woke up around midnight with an urge to do some late night hacking, but I didn't want a bright monitor screwing up my body's circadian rhythm. I've heard that at night blue (short wavelength) lights are particularly bad for your diurnal clock. That may be a bunch of hooey, but it is true that redder (longer wavelength) colors are easier on my eyes at night. This command makes the screen dimmer and adjusts the gamma curves to improve contrast, particularly darkening blues and greens (Rɣ=2, Gɣ=3, Bɣ=4). To reset your screen to normal, you can run this command: xrandr | sed -n 's/ connected.*//p' | xargs -n1 -tri xrandr --output {} --brightness 1 --gamma 1:1:1 or, more briefly, xgamma -g 1 Note: The sed part is fragile and wrong. I'm doing it this way because of a misfeature in xrandr(1), which requires an output be specified but has no programmatic way of querying available outputs. Someone needs to patch up xrandr to be shell script friendly or at least add virtual outputs named "PRIMARY" and "ALL". . Todo: Screen should dim (gradually) at sunset and brighten at sunrise. I think this could be done with a self-resubmitting at job, but I'm running into the commandlinefu 127 character limit just getting the sunrise time: wget http://aa.usno.navy.mil/cgi-bin/aa_pap.pl --post-data=$(date "+xxy=%Y&xxm=%m&xxd=%d")"&st=WA&place=Seattle" -q -O- | sed -rn 's/\W*Sunrise\W*(.*)/\1/p' I hope some clever hacker comes up with a command line interface to Google's "OneBox", since the correct time shows up as the first hit when googling for "sunrise:cityname". . [Thank you to @flatcap for the sed improvement, which is much better than the head|tail|cut silliness I had before. And thank you to @braunmagrin for pointing out that the "connected" output may not be on the second line.] Show Sample Output

Uses Google's "OneBox" to look up the sunrise in any city by name. If no city is specified, it defaults to Seattle. For the sunset time, you change the search query to "sunset", like so, . sunset() { city=${1-Seattle}; w3m "google.com/search?q=sunset:$city" | sed -r '1,/^\s*1\./d; /^\s*2\./,$d; /^$/d' ;} . "OneBox" is Google's term for that box that appears before the organic search results that has useful information that Google thinks you might be looking for (mathematical calculations, weather, currency conversions, and such). I'm not actually using OneBox correctly, but that's because I'm not sure that there is a "correctly". I looked for a command line API, but couldn't find one, so I settled on parsing stdout from the fantastic w3m web browser. I use the sed script to show only the first hit by deleting everything from the beginning of the file until it sees " 1." and then deleting everything from " 2." to the end of the file. Ugly and fragile, yes, but it works fine. . BUG1: w3m represents the picture of the sun rising, "weather_sunset-40.gif" as "[weat]" which is slightly confusing and probably should be removed. . BUG2: The output is more easily readable by a human, which means it's less useful for scripting. Show Sample Output