sync 的使用

FILE *fp;
 if ((fp = fopen(write_filename, "wb")) == NULL) {
    fprintf("can't open %s\n", write_filename);
    exit(1);
 }
 ...
 fflush(fp);
 int fd = fileno(fp);
 fdatasync(fd);
 //fsync(fd);
 fclose(fp);