Ruby script to get TLE from NASA.

tle_iss_nasa.rb

#! /usr/local/bin/ruby
#=直近 TLE データ取得 (from NASA)
# : 過去の直近の TLE データ1件を取得する
#   （過去データが存在しなければ、未来の直近データ）
#
# date          name            version
# 2018.06.11    mk-mode.com     1.00 新規作成
#
# Copyright(C) 2018 mk-mode.com All Rights Reserved.
#---------------------------------------------------------------------------------
# 引数 : [YYYYMMDD[HHMMSS]]
#        （JST を指定。無指定なら現在時刻とみなす）
#---------------------------------------------------------------------------------
#++
require 'time'
require 'open-uri'
require 'timeout'

class TleIssNasa
  URL     = "https://spaceflight.nasa.gov/realdata/sightings/SSapplications/Post/JavaSSOP/orbit/ISS/SVPOST.html"
  UA      = "XXXXXXX Bot (by Ruby/#{RUBY_VERSION}, Administrator: MAIL_ADDRESS)"
  TIMEOUT = 60

  def initialize
    if arg = ARGV.shift
      begin
        @jst = Time.strptime(arg.ljust(14, "0"), "%Y%m%d%H%M%S")
      rescue => e
        $stderr.puts "Invalid date!"
        $stderr.puts "[USAGE] ./tle_iss_nasa.rb [YYYYMMDD[HHMMSS]]"
        exit 1
      end
    else
      @jst = Time.now
    end
  end

  def exec
    tle = ""
    utc_tle = nil

    begin
      puts @jst.strftime("%Y-%m-%d %H:%M:%S.%6N %Z")
      puts @jst.utc.strftime("%Y-%m-%d %H:%M:%S.%6N %Z")
      puts "---"
      get_tle.reverse.each do |new|
        tle = new
        item_utc = tle.split(/\s+/)[3]
        y = 2000 + item_utc[0, 2].to_i
        d = item_utc[2..-1].to_f
        jst = Time.new(y, 1, 1) + d * 24 * 60 * 60 + 9 * 60 * 60
        utc_tle = jst.utc
        break if jst.utc <= @jst.utc
      end
      puts tle
      puts utc_tle.strftime("(%Y-%m-%d %H:%M:%S.%6N %Z)")
    rescue => e
      $stderr.puts "[#{e.class}] #{e.message}"
      e.backtrace.each { |tr| $stderr.puts "\t#{tr}" }
      exit 1
    end
  end

  private

  # 最新 TLE 一覧取得
  def get_tle
    html, charset, status, reason = get_html
    if status != "200" || reason != "OK"
      $stderr.puts "STATUS: #{status} (#{reason})"
      $stderr.puts "[ERROR] Could not retreive html."
      exit 1
    end
    return html.scan(/ISS\n +(1.+?)\n +(2.+?)\n/m).map { |a, b| "#{a}\n#{b}"}
  rescue => e
    raise
  end

  # HTML 取得
  def get_html
    status, reason = nil, nil
    charset = nil
    html    = nil

    begin
      Timeout.timeout(TIMEOUT) do
        html = open(URL, "r:utf-8", {"User-Agent" => UA}) do |f|
          charset = f.charset
          status, reason  = f.status
          f.read
        end
      end
      return [html, charset, status, reason]
    rescue => e
      raise
    end
  end
end

TleIssNasa.new.exec if __FILE__ == $0