Cygwin and irb
If you had tried to start irb in Windows that has cygwin installed, you might have got the following exception trace: C:/Ruby192/lib/ruby/site_ruby/1.9.1/rbreadline.rb:2095:in `expand_path': non-absolute home (ArgumentError) from C:/Ruby192/lib/ruby/site_ruby/1.9.1/rbreadline.rb:2095:in `_rl_read_init_file' from C:/Ruby192/lib/ruby/site_ruby/1.9.1/rbreadline.rb:2078:in `rl_read_init_file' from C:/Ruby192/lib/ruby/site_ruby/1.9.1/rbreadline.rb:2499:in `readline_initialize_everything' from C:/Ruby192/lib/ruby/site_ruby/1.9.1/rbreadline.rb:3730:in `rl_initialize' from C:/Ruby192/lib/ruby/site_ruby/1.9.1/rbreadline.rb:4737:in `readline' from C:/Ruby192/lib/ruby/site_ruby/1.9.1/readline.rb:40:in `readline' from C:/Ruby192/lib/ruby/1.9.1/irb/input-method.rb:115:in `gets' from C:/Ruby192/lib/ruby/1.9.1/irb.rb:139:in `block (2 levels) in eval_input' from C:/Ruby192/lib/ruby/1.9.1/irb.r...