==== Sunwait ====

Run a cron at sunrise/sunset or with some offset.

https://github.com/risacher/sunwait

Examples:

  $ sunwait -p 33.640411N 84.419853W
  Using location:             33.640411N, 84.419853W
  Date:                       20 Sep 2019 
  Local time:                 18:31 
  Day length:                 12:13 hours
  With civil twilight         13:00 hours
  With nautical twilight      13:59 hours
  With astronomical twilight  14:57 hours
  Length of twilight:  civil   0:23 hours
                    nautical   0:52 hours
                astronomical   1:22 hours
  Current specified time zone: EDT (-4 from UTC) 
  Sun transits meridian 1330 EDT
                     Sun rises 0725 EDT, sets 1936 EDT
         Civil twilight starts 0700 EDT, ends 2001 EDT
      Nautical twilight starts 0631 EDT, ends 2030 EDT
  Astronomical twilight starts 0601 EDT, ends 2059 EDT

  $ sunwait -v sun down +1:19:00 33.640411N 84.419853W; /bin/date

RPM is on [[http://rpmfind.net/linux/epel/7/x86_64/Packages/s/sunwait-0.1-0.3.20041208.el7.x86_64.rpm|rpmfind.net]]