static void do_set_cgroup(const char *fname, pid_t pid) {
	FILE *fp = fopen(fname, "ae");
	if (!fp) {
		fwarning("cannot open %s for writing: %s\n", fname, strerror(errno));
		return;
	}

	int rv = fprintf(fp, "%d\n", pid);
	(void) rv;
	fclose(fp);
}
static void do_set_cgroup(const char *fname, pid_t pid) {
	FILE *fp = fopen(fname, "ae");
	if (!fp) {
		fwarning("cannot open %s for writing: %s\n", fname, strerror(errno));
		return;
	}

	int rv = fprintf(fp, "%d\n", pid);
	(void) rv;
	fclose(fp);
}