download.rb

require 'zlib'
require 'open-uri'

file_name = "hello.tar.gz"
download_url = "https://cache.ruby-lang.org/pub/ruby/2.1/ruby-2.1.8.tar.gz"

File.open(file_name, "wb") do |f|
  f.write(Zlib::GzipReader.new(open(download_url)).read)
end


File.open(file_name, "r") do |f|
  g = Zlib::GzipReader.open(f)
  puts g.read
  g.close
end