who.rb

# Ever forget the hostname of that server you logged into last week? 
# Quickly get a chronological listing of hosts you've come to know...

require 'rubygems'
require 'net/ssh'

def who_do_i_know?
  who = []
  known_host_files = Net::SSH::KnownHosts.hostfiles({})
  scanner = StringScanner.new("")
  known_host_files.each do |host_file|
    begin
      File.open(File.expand_path(host_file)) do |file|
        file.each_line do |line|
          scanner.string = line
          scanner.skip(/\s*/)
          next if scanner.match?(/$|#/)
          host_list = scanner.scan(/\S+/).split(/,/)
          who << host_list[0]
        end
      end
    rescue
    end
  end
  who
end

puts who_do_i_know?