gistfile1.rb

require 'optparse'

OptionParser.new do |o|
  o.on("-r") {puts 'read mode'}
  o.on("-w") {puts 'write mode'}
  o.on("-e") {puts 'edit mode'}                                                                                                                                                     
  o.on("-d") {puts 'delete mode'}
end.parse! ARGV