ask_and_execute.rb

#!/usr/bin/env ruby

def ask(message)
  print "#{message} [Y/n] "
  case gets.strip
  when /n/i
  else
    yield
  end
end

def ask_and_execute(command)
  ask("`#{command}`") do
    system command
  end
end

# Example
ask_and_execute 'cd ~'
ask_and_execute 'mkdir bar'