listup the lacking files with date from and date to

check_date.rb

#!/usr/bin/ruby
require 'date'

_date_from = ARGV[0]
_date_to   = ARGV[1]
target_dir = ARGV[2]

if _date_from.nil? or _date_to.nil?
  STDERR.puts "please specify the date_from and date_to."
  exit 1
end

date_from = date_to = nil
begin
  date_from = Date.parse(_date_from)
  date_to   = Date.parse(_date_to)
rescue
  STDERR.puts "failed. #{$!}"
  exit 1
end

the_day = date_from
while (the_day <= date_to)
  str_ptn = the_day.strftime("%Y%m%d")
  glob_ptn = "#{target_dir}/*#{str_ptn}*"
  if Dir.glob(glob_ptn).empty?
    puts str_ptn
  end
  the_day = the_day.succ
end