top10.rb

# Outputs the top 10 most used commands.
# Usage:
# history | ruby top10.rb

require 'Set'
excluded_commands = Set.new ["ls", "cd ..", "irb", "exit"]
distribution = Hash.new(0)
ARGF.each do |line|
  command = line.match(/[\s\d]*(\D.*)/)[1].strip
  distribution[command] += 1 unless excluded_commands.include? command
end
sorted = Hash[distribution.sort_by{|k, v| v}.reverse]
sorted.first(10).each do |key, value|
  puts "#{value}: #{key}"
end