针对操作系统进行二级目录文件系统的模拟 用disk.txt模拟硬盘，设定硬盘容量分为100个物理块，每个物理块的大小512字节，盘块之间用(‘\n’)分割。

因此一个盘块：512字节数据＋1字节(‘\n’)分割符＝513字节，则disk.txt 长度＝51300（ 100×513 ）＋1字节（文件结束符）＝51301字节 。

-Secondary directory for the operating system file system simulation using simulation disk.txt hard drive, hard drive capacity set is divided into 100 physical blocks, each physical block size of 512 bytes, between the disk block (　) partition. Thus, a disk block: 512 bytes of data　 1 byte (　) partition Fu = 513 bytes, then disk.txt length = 51300 (100 × 513)　1 bytes (at end-of-file) = 51,301 bytes.