And for completeness, a Ruby implementation: puts STDIN.read .split(/[^A-Za-z]+/) .group_by(&:downcase).transform_values(&:size) .sort_by(&:last)

And for completeness, a Ruby implementation: puts STDIN.read .split(/[^A-Za-z]+/) .group_by(&:downcase).transform_values(&:size) .sort_by(&:last).reverse .take(ARGV[0].to_i) .map{ |l| l.join("\t") }.join("\n") Wordier than the bash script, but still pretty short and fairly trivial. Anyone could make this in five minutes.