I recently got a request to resolve the domains bound to our company's service to their corresponding storage spaces. It mostly involved string processing, so I wrote a script with the little Ruby I'd learned.

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# /usr/bin/ruby -w
# coding:utf-8
# dig the domain and bucket
# https://github.com/bluemonk/net-dns
require 'net/dns'
require 'json'
# Run dig on the given URL and take the first record in the answer section
def dig_dns(url)
  packet = Net::DNS::Resolver.start("#{url}")
  r = packet.answer[0].to_s.split(" ")
  print "#{r[0].to_s.chop}  " "#{r[4].to_s.split(".")[0]}\n"
end
# Replace * in wildcard domains with test so they follow DNS naming rules
def subt(str)
	if str.include? '*'
		str.sub('*','upyun')
	else
		str
	end
end
# Pass in a file containing domains as an argument
# filename = ARGV[0]
filename = 'yuming.txt'
def afile(filename)
	File.open(filename,'r') do |f|
		f.each do |line|
			line.split(' ').each {|s|
				dig_dns(subt(s))
			}
		end
	end
end
afile(filename)