sprintf(url, "http:/v%s/containers/%s/exec", getenv("DOCKER_ENGINE_VERSION"), device_id);
curl_easy_setopt(curl, CURLOPT_URL, url);
sprintf(url, "http:/v%s/containers/%s/exec", getenv("DOCKER_ENGINE_VERSION"), device_id);
curl_easy_setopt(curl, CURLOPT_URL, url);