apod.rb

require 'httparty'
require 'fileutils'
require 'open-uri'

base_url = "https://apod.nasa.gov/apod/"
page = "astropix.html"
regex = /<img SRC="(.+)"/i

output_dir = Dir.home+'/.apod/'
FileUtils.mkdir_p output_dir

response = HTTParty.get(base_url+page)
if response.code == 200
  url = regex.match response.body
  url = url[1]
  filename = url.split('/').last
  File.open(output_dir + filename, "wb" ) do |file|
    open(base_url + url, "rb") do |img|
      file.write(img.read)
    end
  end
  system("hsetroot -fill #{output_dir + filename}")
end