use warnings;
use strict;
use File::Find;
# $data_dir is determined.
$SIG{__WARN__} = sub {
  print "Skipping...\n";
  # skip the rest of the loop for the file.
}
sub find_process {
  # open each file that meets the naming criteria.
  # begin looping through the file.
  # attempt to access the substr.
  # skip this file if there was a substr warning and report it.
}
find(\&find_process, $data_dir);