#!/usr/bin/env ruby

target = ARGV[1].to_i

map = {}

STDIN.each_line do |line|
  chunks = line.split(" ")
  next unless chunks[target]
  map[chunks[target]] ||= []
  map[chunks[target]].push(line)
end

map.each do |identifier, lines|
  File.open("group_#{identifier}.log", 'a+') do |file|
    lines.each do |line|
      file.puts(line)
    end
  end
end