Here are the two programs:
#!/use/bin/perl -w

open(EXT,"< LDB_EXTID.lst") || die "something";
while (<EXT>) {
   push (@externaluids, $_) || die "dead again";
}

close (EXT)

foreach $externaluid (@externaluids) {
    my $output = `ldbtest.pl -e $externaluid -t 123`;

    #for my testing purposes
    $counter++;
    exit if $counter > 10;
}

exit

#program ldbtest is simply...
#!/use/bin/perl -w
use Getopt::Std;
getopt ('et');

print $opt_e
print $opt_t

exit