if (!$read(listing $+ $replace($date,/,-) $+ .txt, w, $+(*,%x,*))) {
^ That would find any occurance of %x's contents in the file, however as hixxy said, if your actually looking for %x being on the end of the string with other words then a space before it its.
if (!$read(listing $+ $replace($date,/,-) $+ .txt, w, * %x)) {

Quote:
these are for "book packs" that we offer our customers.

Interesting reading these books are they?