Increment all serial numbers at once in a named/bind dns zone file.
Just run the script in the current directory /etc/bind/namedb and all serial numbers will be incremented by one.

#!/usr/bin/ruby

Dir.glob("*.db") do |file_name|
  new_zone = []
  File.open(file_name) do |file|
    while (line = file.gets)
        line.chomp!
        if line =~ /Serial/
          line =~ /(\s*?)(\d+)(\s*?)(;.*)/
          serial = $2.to_i
          serial += 1
          puts "#{file_name} serial line:  #{$1} #{$2} #{$3} #{$4} -> #{$1}#{serial}#{$3}#{$4}"
          line = "#{$1}#{serial}#{$3}#{$4}"
        end
        new_zone << line
    end
  end
  new_zone << "\n"

  File.open(file_name, "w") do |new_file|
    new_file.write(new_zone.join("\n"));
  end
end