=begin
$ ls -l
-rw-r--r-- 1 ireul users  15747 ago 12 12:02 20130812-idnlog.sql
-rw-r--r-- 1 ireul users 381459 ago 13 18:20 20130813-wordpress.sql
-rw-r--r-- 1 ireul users 379758 ago 20 16:45 20130820-wordpress.sql
-rw-r--r-- 1 ireul users 390494 ago 23 16:55 20130823-wordpress.sql
-rw-r--r-- 1 ireul users     95 sep  9 15:11 a.rb

$ ruby a.rb
20130823-wordpress.sq

=end

newest_file = Dir["*"].sort_by{|e|
 e.scan(/\d{8}\-wordpress\.sql/)
}.last

print newest_file