my $args =
            defined $c->config->{binary_cache_public_key_file}
            ? "--option binary-cache-public-keys " . read_file($c->config->{binary_cache_public_key_file}) . "\n"
            : "";

        my $args = "";
        if (defined $c->config->{binary_cache_public_key_file}
            && -r $c->config->{binary_cache_public_key_file})
        {
            $args = "--option binary-cache-public-keys " . read_file($c->config->{binary_cache_public_key_file});
        }