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@@ -0,0 +1,126 @@ +NAME + blue - Creates table of when the blue hour etc. occurs + +SYNPOSIS + blue [-d delev]* [-D delev]* [-e elev]* [-m elev]* [-h [-L] | -u | -L] + [-l lat:lon | -l loc] [-s year-month-day | -s -] [-r num[h|m|s]] + [-bBgGnN] + +DESCRIPTION + blue prints a list of time point when the select event occurs. + +OPTIONS + -b + List the time when the blue hour begins. (default) + + -B + List the time when the blue hour ends. + + -d DELEV + List the time when the first derivative of the Sun's elevation + is DELEV and the Sun's elevation is non-negative (daytime). + + -D DELEV + List the time when the first derivative of the Sun's elevation + is DELEV and the Sun's elevation is non-positive (nighttime). + + -e ELEV + List the time when the Sun's elevation is ELEV and the first + derivative of the Sun's elevation is non-positive (evening). + + -g + List the time when the golden hour begins. (default) + + -G + List the time when the golden hour ends. + + -h + Print times in human readable format. + + -l LATITUDE:LONGITUDE + Tell blue where you are. The values are measured in degrees + and in the GPS (you probably do not have too care about that, + the differences between the systems should not be significant + another), and must be in decimal. + + Reminder for Americans (particularly US Americans), you are + an the western hemisphere, not the eastern, thus your longtiude + is negative. If you experience weird time listings, 100 % of + the times it is because you forgot the minus sign. But no need + to feel stupid, it is a really common mistake. + + No complicated stuff please, only latitudes within ±90° and + longitudes within ±180°. No unit thought. + + -l LOCATION + Use a named location. In particular, the one stored in the + file ~/.config/geolocation.d/LOCATION, or the file LOCATION, + if it begins with either ./ (dot slash), ../ (dot dot slash), + or / (slash). By default ~/.config/geolocation, or + /etc/geolocation as a fallback, is used. + + -L + Print times in local time. + + -e ELEV + List the time when the Sun's elevation is ELEV and the first + derivative of the Sun's elevation is non-negative (morning). + + -n + List the time of solar noon. + + -N + List the time of solar midnight. + + -r RES + Print the in RES resultion. RES must be an integer followed + by on the the suffixes: + + h hours + m minutes (min is not a valid suffix) + s seconds + + For example: -r 15m prints the nearest quarters of the times. + + -s DATE + The last date (local time) to include in the last. + A dash (-) for an infinite list. Default limit is one month. + + -u + Print times in UNIX-time format. + +FILES + ~/.config/geolocation + Used to get your location if -l is not used. This file contains + your geographical location using the Global Positioning System + in decimal format. This will never change. Other programs are + encouraged to use this file too. + + If the file contains more than one line, only the first line, + even if it is empty, is used. + + /etc/geolocation + Fallback file use if ~/.config/geolocation is missing. Other + programs are encouraged to use this file too. + + ~/.config/geolocation.d/ + Directory used for named locations. The files are formatted + in the same way as ~/.config/geolocation. Other programs are + encouraged to use this directory too. + + /etc/geolocation.d/ + Directory used for named locations, used when the named + location is not listed in ~/.config/geolocation.d/. The files + are formatted in the same way as ~/.config/geolocation. Other + programs are encouraged to use this directory too. + +RATIONALE + This is useful if you plan to take nice photographies, for example + during the blue hours, or the golden hour. + +NOTES + US Americans, remember, you are on the Western Hemisphere. Therefore, + you should specify a negative longitude. + +SEE ALSO + locateme(1) |