Some collected recipes to make irb and script/console a bit nicer to use:

• pretty printing (pp whatever)
• enhanced tab completion
• rails logging to console
• saves command history between sessions
• use readline extensions module

Tips were collected from posts by Dr. Nic, Toolman Tim and Dzone Snippets.

~/.irbrc

require 'pp'
require 'irb/completion'
ARGV.concat [ "--readline", "--prompt-mode", "simple" ]
IRB.conf[:AUTO_INDENT]=true

# load console_with_helpers if possible
script_console_running = ENV.include?('RAILS_ENV') && IRB.conf[:LOAD_MODULES] && IRB.conf[:LOAD_MODULES].include?('console_with_helpers')
rails_running = ENV.include?('RAILS_ENV') && !(IRB.conf[:LOAD_MODULES] && IRB.conf[:LOAD_MODULES].include?('console_with_helpers'))
irb_standalone_running = !script_console_running && !rails_running

# log Rails stuff to STDOUT
if script_console_running
  require 'logger'
  Object.const_set(:RAILS_DEFAULT_LOGGER, Logger.new(STDOUT))
end

# Keep command-line history between startups
require 'irb/ext/save-history'
IRB.conf[:SAVE_HISTORY] = 100
IRB.conf[:HISTORY_FILE] = "#{ENV['HOME']}/.irb-save-history" 

Update: my friend Joannou pointed out Utility Belt which looks pretty nice also.

Update 2 (a month later): Been using Utility Belt for a while and noticed some problems… it has a tendency to conflict with ActiveRecord validations and trigger bogus errors during callbacks. Also seems to destroy some of the init process with certain plugins like ActiveScaffold. Perhaps it’s too clever. I ended up rolling back to my old .irbc – YMMV.