has 'cmd_logfile' 	=> ( is => 'ro', isa => 'Str', required => 0, lazy => 1, builder => '_build_cmd_logfile' );

sub _build_cmd_logfile
{
	my $self = shift;
	my $inner = $self->dl_inner_dir; defined $inner or die "Error: DL_INNER_DIR not set.";

	my $b4_ext = "$inner/transfer"; my $ext = "log";
	my $filename = "$b4_ext.$ext";
	my $i = 2;

	while (-s $filename)
	{
		$filename = "$b4_ext-$i.$ext";
		$i++;
	}

	return $filename;
}