gistfile1.builder

# to install the gems:
# gem install icalendar
# or
# Add devel:languages:ruby:extensions 
# zypper in rubygem-icalendar
require 'rubygems'
require 'icalendar'
require 'open-uri'
require 'date'

CALENDAR_URI = "http://www.schulferien.org/iCal/Ferien/icals/Ferien_Bayern_2010.ics"

cal_file = open(CALENDAR_URI)
cals = Icalendar.parse(cal_file)

now = DateTime.now

# for every calendar in the file
cals.each do |calendar|
  # and each event
  calendar.events.each do |event|
    # ignore past events
    next if event.dtstart < now

    # execute command if     
    puts event.summary
    # (event.dtstart - now) is a rational
    # measuring days

    hours_to_event = ((event.dtstart - now) * 24).to_i
    if hours_to_event <= 1
      # execute some command        
      puts `ls -la`
    end

  end
end