#!/usr/bin/ruby

filename = "test.txt"

def mkrandom length, max, array
  if length > 0
    r = rand(max)
    unless array.include? r
      array << r
      length -= 1
    end
    mkrandom length, max, array
  else
    array
  end
end

lines = File.readlines(filename)

ra = mkrandom 2, lines.size, []

i = 0
lines.each do |line|
  if ra.include? i
    puts line
  end
  i += 1
end