Usage

cron = CrontabParser.new(`crontab -l`)
now = Time.now
cron.find_all{|row|
  row.should_run?(now)
}.each{|row|
  puts "#{row.cmd} goes run just now"
}

cron = CrontabParser.new(<<-CRON)
* * * * * monitor-process
@daily mailme
@monthly full-backup
CRON

now = Time.now
cron.find_all{|row|
  row.should_run?(now)
}.each{|row|
  puts "#{row.cmd} goes run just now"
}