my $id = '2009-02-12-1234';
my $filename = "file-$id.dat";
my $local_file = "$src_dir/$filename";

# upload 'real' file
$ftp->put ( $local_file, $filename ) || die "can't upload: $!";

# it completed ok - upload the completion marker
$ftp->put ( $dummy_file, "$filename.complete" );