Comparing Two Arrays in Ruby

compare.rb

list1 = Array.new
list2 = Array.new

exist = File.open("exist.txt").each_line {|line| list1 << line.gsub(/\s+/, "")}
tocheck = File.open("tocheck.txt").each_line {|line| list2 << line.gsub(/\s+/, "")}

list2.each do |line|
	if list1.include?(line) 
		File.open("output.txt", 'w') {|f| f.write(line) }
	end
end