$dirName = "/blahdeblah/source";
open (FIELDS, "fields.dat") or die $!;
open (FOUND, ">found.dat") or die $!;

while (<FIELDS>) {
       $field = $_;
        while (defined($nextfile = <$dirName/*cm*.4gl>)) {
                $rc = system ("grep $field $nextfile 1>/dev/null");

                if (!$rc) {
                      print FOUND "$field $nextfile\n";
                      last;
                }
        }
}