.irbrc

.irbrc

# This irb script enables:
# - irb completion. (Ex: "".[tab] show available methods)
# - commands history. Up and Down arrows to navigate at commands.
# - requires pretty print.
# - if "awesome print" gem is available, replace pp command for ap.
# - if RAILS_ENV exists, set irb console as logger. (I can see queries from ActiveRecord)

require 'irb/completion'
ARGV.concat [ "--readline", "--prompt-mode", "simple" ]

module Readline
  module History
    LOG = "#{ENV['HOME']}/.irb-history"

    def self.write_log(line)
      File.open(LOG, 'ab') {|f| f << "#{line}\n"}
    end

    def self.load_history
      lines = File.read(LOG)
      lines.to_a.each do |line|
        line.strip!
        HISTORY << line unless (line.empty? or line.start_with?("#"))
      end
    end

    def self.start_session_log
      load_history

      write_log("\n# session start: #{Time.now}\n#\n")

      at_exit do
        write_log("\n# session stop: #{Time.now}\n")
      end
    end
  end

  alias :old_readline :readline
  def readline(*args)
    ln = old_readline(*args)
    begin
      History.write_log(ln)
    rescue
    end
    ln
  end

end

Readline::History.start_session_log

require "pp"  #pretty print

begin
  require "rubygems"
  require "ap"
  puts "Loaded awesome print!"

  alias old_pp pp
  alias pp ap

rescue LoadError => ex
  puts "#{ex.message}\n"
  puts "you can do \"gem install awesome_print\" if want! ;)"
end

#show Rails log
require "logger"
if ENV.include?('RAILS_ENV')&& !Object.const_defined?('RAILS_DEFAULT_LOGGER')
  Object.const_set('RAILS_DEFAULT_LOGGER', Logger.new(STDOUT))
end

def ansi_values
  ansi = {}
  ansi[:RESET]     = "\e[0m"
  ansi[:BOLD]      = "\e[1m"
  ansi[:UNDERLINE] = "\e[4m"
  ansi[:LGRAY]     = "\e[0;37m"
  ansi[:GRAY]      = "\e[1;30m"
  ansi[:RED]       = "\e[31m"
  ansi[:GREEN]     = "\e[32m"
  ansi[:YELLOW]    = "\e[33m"
  ansi[:BLUE]      = "\e[34m"
  ansi[:MAGENTA]   = "\e[35m"
  ansi[:CYAN]      = "\e[36m"
  ansi[:WHITE]     = "\e[37m"
  ansi 
end

# When you're using Rails 3 console, show queries in the console
# Thanks Iain Hecker! http://gist.github.com/368237
if defined?(ActiveSupport::Notifications)
  ansi = ansi_values
  $odd_or_even_queries = false
  ActiveSupport::Notifications.subscribe('active_record.sql') do |*args|
    $odd_or_even_queries = !$odd_or_even_queries
    color = $odd_or_even_queries ? ansi[:CYAN] : ansi[:MAGENTA]
    time  = "%.1fms" % ((args[2] - args[1]) * 1000)
    name  = args.last[:name]
    sql   = args.last[:sql].gsub("\n", " ").squeeze(" ")
    puts "  #{ansi[:UNDERLINE]}#{color}#{name} (#{time})#{ansi[:RESET]}  #{sql}"
  end
end

You forgot to define the colors (the ANSI constant)

Thanks again!
I didn't have time to test Rails 3! :X