dns.rb

#!/usr/bin/ruby

# save in ~/bin/dns and chmod 755

unless ARGV[0]
  print `networksetup -getdnsservers Wi-Fi`
  exit
end

servers = case ARGV[0]
when 'adblock'
  '176.103.130.130 2a00:5a60::ad1:0ff'
when 'fast'
  '1.1.1.1 2606:4700:4700::1111'
when 'default'
  'empty'
else
  raise ArgumentError, <<~DOCS
  usage:
    dns [adblock|fast|default] # change dns of Wi-Fi
    dns                         # show current Wi-Fi dns settings
  DOCS
end

print `networksetup -setdnsservers Wi-Fi #{servers}`