remote_file_exits.rb

def remote_file_exits?(url, limit=10)
  raise ArgumentError, 'too many HTTP redirects' if limit == 0
  
  uri = URI(url)

  response = Net::HTTP.get_response(uri)

  case response
    when Net::HTTPNotFound then
      false
    when Net::HTTPSuccess then
      true
    when Net::HTTPRedirection then
      location = response['location']
      warn "redirected to #{location}"
      file_exists?(location, limit - 1)
    else
      raise response.value
    end
end