yml_to_tsv.rb

require 'yaml'

def generate_line(items)
  line = ''
  items.each_with_index do |item, index|
    line += item
    line += "\t" if index < items.length - 1
  end
  line += "\n"
  line
end

yaml_file = File.read(ARGV[0])
hashes = YAML::load(yaml_file)
header = hashes[0].keys

result = generate_line(header)
hashes.each { |item| result += generate_line(item.values) }

File.write(ARGV[1], result, mode: 'w')