Enables Natural Scrolling at Ubuntu like OS X has. Simple script to run on X start.

natural_scroll.rb

#!env ruby

# This script enables 'Natural scrolling' as in OS X.
#
# Usage:
#   1. Find your touchpad name by running xinput list
#   2. Run ./natural_scroll.rb 'touchpad name'
#
# Limitations:
#   - Tested only on Ubuntu 13.04
#   - Assuming scroll up is 4, scroll down is 5
# 
# License: MIT
# Author: Denis Yagofarov <[email protected]>

def touchpad_name
  @touchpad_name ||= ARGV[0].to_s
end

def input_id
  `xinput list | grep "#{touchpad_name}"`.
    strip.
    match(/id=(\d+)/)[1].
    to_i
rescue
  0
end

raise 'You must set name of touchpad device. Find one in `xinput list`' if touchpad_name.size == 0

error_command = "notify-send -u critical 'Natural scroll' 'Unable to determine touchpad devise, named \"#{touchpad_name}\"' -i input-tablet"
swap_command  = "xinput set-button-map #{input_id} 1 2 3 5 4"

if input_id > 0
  `#{swap_command}`
else
  `#{error_command}`
  exit 1
end