foreach my $line (@data) {
  my ($linecount, $filename) = split(/\s+/, $line);

  $filename =~ s/^$in_prefix//; # strip base directory from filename

  my ($campaign, $month, $fname) = split('/', $filename); # info is stored in the directory nesting

  push @files, { campaign => $campaign,
                 month => $month,
                 file => $fname,
                 count => $count,
                 sort => "$campaign:$month:$file" };
}