1. touch ~/.irbrc
2. Edit the .irbrc and add the following code:
require 'pp'
require 'rubygems'
class Object
def ls
%x{ls}.split("\n")
end
def pwd
Dir.pwd
end
def cd(dir)
Dir.chdir(dir)
pwd
end
end
alias p pp
3. Now whenever you open an irb session you can now list the directory contents by doing ls, print working directory by pwd and change directory by doing cd "directory-name".