Chapter VII document management

Catalog

One . Single topic selection （ common 41 topic ,94.3 branch ）

1. ( Single topic selection ) The following are not file attributes （ ）.

2. ( Single topic selection ) The following are not file system managed objects （ ）.

3. ( Single topic selection ) The smallest data unit that can be named in a file system is （ ）.

4. ( Single topic selection ) Index file consists of logical file and （ ） form .

5. ( Single topic selection ) File control block FCB Usually stored in （ ） in .

6. ( Single topic selection ) stay UNIX The directory entries in the system are （ ）.

7. ( Single topic selection ) To allow files of different users to use the same file name , Usually, the file system uses （ ）.

8. ( Single topic selection ) In a file system ,FCB Occupy 64B, The size of a disk block is 1KB, Adopt the first level directory , Assume that there is... In the file directory 3200 Catalog items , The average time to retrieve a file is （ ） Access to disk .

9. ( Single topic selection ) In the tree , The first time a user accesses a file, they usually use （ ）.

10. ( Single topic selection ) The mistake in the following description is （ ）.

11. ( Single topic selection ) Suppose the size of the disk block is 1KB, about 1.2MB Floppy disk of ,FAT12 Need to occupy （ ） Storage space .

12. ( Single topic selection ) In the following discussion about sequential files and linked files , The correct argument is （ ）.

13. ( Single topic selection ) In the following discussion on index files , The correct argument is （ ）.

14. ( Single topic selection ) In the following physical files ,（ ） Least suitable for random access to files .

15. ( Single topic selection ) The main purpose of setting the current working directory is （ ）.

16. ( Single topic selection ) File system , The reasonable location for storing file access control information is （ ）.

17. ( Single topic selection ) Set file F1 The current reference count value of is 1, First create a file F1 The symbolic link （ Soft link ） file F2, Then create a file F1 Hard link file for F3, Then delete the file F1. here , file F2 And documents F3 The reference count values of are （ ）.

18. ( Single topic selection ) From the user's point of view , The purpose of introducing the file system into the operating system is （ ）.

19. ( Single topic selection ) When the file system creates a file , Build a... For it （ ）.

20. ( Single topic selection ) The main work of opening a file is （ ）.

21. ( Single topic selection )UNIX Operating system , Input / The output device is regarded as （ ）.

22. ( Single topic selection ) Among the following files, the files with logical structure are （ ）.

23. ( Single topic selection ) The organization form of logical files is determined by （ ） decision .

24. ( Single topic selection ) In the logical structure of the file , What does not belong to structured files is （ ）.

25. ( Single topic selection ) Index file consists of logical file and （ ） form .

26. ( Single topic selection ) There is a sequential file containing 10 000 A record , The average number of records searched is 5 000 individual , Adopt index sequential file structure , In the best case, you only need to find （ ） Time record .

27. ( Single topic selection ) The relative pathname of a file is from （ ） Start , Gradually trace back along subdirectories at all levels , Finally, a string of all subdirectory names on the whole path to the specified file .

28. ( Single topic selection )FAT32 The file directory entry for does not include （ ）.

29. ( Single topic selection ) The purpose of using multi-level directory structure in file system is （ ）.

30. ( Single topic selection ) If two files in the file system have the same name , Should not be used （ ）.

31. ( Single topic selection ) The operating system is to ensure that it is not authorized by the file owner , This file cannot be used by any other user , The solution offered is （ ）.

32. ( Single topic selection ) In the file system , The following methods that do not belong to file protection are （ ）.

33. ( Single topic selection ) Access to a file , Often by （ ） Common restrictions .

34. ( Single topic selection ) Compared with encryption protection and access control （ ）.

35. ( Single topic selection ) In order to safely manage the files in the file system , Any user must register when entering the system , This level of safety management is （ ）.

36. ( Single topic selection ) In the physical structure of the following files , What is not conducive to the dynamic growth of file length is （ ）.

37. ( Single topic selection ) In the file system, if the physical structure of the file adopts continuous structure , be FCB The physical location of relevant documents in the shall include ( ).I. First block address II． file length III． Index table address

38. ( Single topic selection ) On disk , The physical file structure most likely to cause storage fragmentation is （ ）.

39. ( Single topic selection ) Some operating systems separate file description information from directory entries , The advantage of this is （ ）.

40. ( Single topic selection ) Physical files are organized by （ ） affirmatory .

41. ( Single topic selection ) If the document is random （ direct ） Access method use , And the file size is not fixed , Then （ ） Physical structure .

Two . Calculation questions （ common 1 topic ,5.7 branch ）

42. ( Calculation questions ) A file has 100 Disk blocks , Assume that the file control block of the file is in memory . In the following cases , Calculate and explain respectively under the continuous organization mode and the display link organization mode , How many times do you need to execute disk I/O operation ？（ Suppose that every read or write to a disk block is a disk operation ; Suppose that under the continuous organization , There is no free disk block in the file header , But there are free disk blocks at the end of the file ）（ Assume that the disk block number is from 0~99, The first 50 A block refers to a block numbered 49 My disk ）（1） Add a disk block at the beginning of the file （ You need to write data to the added disk block ）;（2） In Document No 50 Add a disk block before the block （ There is no need to write data to the added disk block ）;（3） Delete file No 50 Block disk block ;（4） Delete a disk block at the end of the file .

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One . Single topic selection （ common 41 topic ,94.3 branch ）

1. ( Single topic selection ) The following are not file attributes （ ）.

• A. file name

• B. file type

• C. file length

• D. The physical location of the file

My answer : A right key : A

2. ( Single topic selection ) The following are not file system managed objects （ ）.

• A. file

• B. Catalog

• C. Memory

• D. disk

My answer : C right key : C

3. ( Single topic selection ) The smallest data unit that can be named in a file system is （ ）.

• A. character string

• B. Data item

• C. Record

• D. file

My answer : B right key : B

Analysis of the answer ：

The allocation of file storage space is based on files , Users access files in units of records 、 Search, etc , The smallest data unit that can be named is the data item .

4. ( Single topic selection ) Index file consists of logical file and （ ） form .

• A. The symbol table

• B. Index table

• C. Cross access table

• D. Link table

My answer : B right key : B

5. ( Single topic selection ) File control block FCB Usually stored in （ ） in .

• A. Memory

• B. Data disk block of the file

• C. The data disk block of the parent directory of the file

• D. The index disk block of the file

My answer : C right key : C

6. ( Single topic selection ) stay UNIX The directory entries in the system are （ ）.

• A. FCB

• B. File table pointer

• C. Index node

• D. File name and index node pointer

My answer : D right key : D

7. ( Single topic selection ) To allow files of different users to use the same file name , Usually, the file system uses （ ）.

• A. Duplicate name translation

• B. Multi level directory

• C. File name to file physical address mapping table

• D. Index table

My answer : B right key : B

8. ( Single topic selection ) In a file system ,FCB Occupy 64B, The size of a disk block is 1KB, Adopt the first level directory , Assume that there is... In the file directory 3200 Catalog items , The average time to retrieve a file is （ ） Access to disk .

• A. 50

• B. 54

• C. 100

• D. 200

My answer : C right key : C

Analysis of the answer ：

Each disk block can store 1KB/64B=16 Catalog items , The file directory occupies... In total 3200/16=200 A plate

link ： In a file system ,FCB Occupy 64B, The size of a disk block is 1KB, use __ Cattle from source ： Cattle from

A file directory entry corresponds to a file control block , Let's find out whether a file has a directory entry , On average, it takes to search the catalog table in order 1600 Time (n The average number of searches in the sequence table of elements is (n+1)/2), The size of a disk block is 1KB, The size of a file control block is 64B, There are... In a disk block 1KB/64B=16 A file control block , It is equivalent to finding 1600/16=100 A disk

9. ( Single topic selection ) In the tree , The first time a user accesses a file, they usually use （ ）.

• A. File symbol name

• B. File pathname

• C. Pointer to memory index node

• D. User file descriptor

My answer : B right key : B

10. ( Single topic selection ) The mistake in the following description is （ ）.

• A. One file in the same system , Copies on different storage media , The same physical structure should be used .

• B. The physical structure of the file is not only related to the allocation of external memory , It is also related to the characteristics of the storage medium , Generally, only sequential structure is suitable for tape .

• C. Files with sequential structure are suitable for sequential access , It is also suitable for random access .

• D. Although the disk is a random access device , But the files can also use the sequential structure .

My answer : A right key : A

11. ( Single topic selection ) Suppose the size of the disk block is 1KB, about 1.2MB Floppy disk of ,FAT12 Need to occupy （ ） Storage space .

• A. 1KB

• B. 1.5KB

• C. 1.8KB

• D. 2.4KB

My answer : C right key : C

Analysis of the answer ：

The floppy disk contains 1.2MB/1KB=1.2K A plate , namely FAT common 1.2K Table items , be FAT12 The length of the table item is taken as 12bit=1.5B, therefore FAT12 Need to occupy 1.2K*1.5B=1.8KB

2.4KB

Hello , Suppose that the size of the disk block should be 1K. Then I'll talk about the idea of calculation ： floppy disk （ Or hard disk ） Capacity / Disk size = Number of disks . Number of disks Disk size = Required storage capacity of disk block . （1）1.22^20/(12^10)=1.2k, So the floppy disk needs 1.22^10 Table items . Because there is no explanation in the title FAT yes FAT12 still FAT16, We use FAT12 For example .（FAT12 Middle table items account for 12 position ,1.5 Bytes ） 1.22^101.5=1.8K; The second idea is exactly the same , You can do it yourself ~

floppy disk （ Or hard disk ） Capacity / Disk size = Number of disks . Number of disks * Disk size = Required storage capacity of disk block .

 

12. ( Single topic selection ) In the following discussion about sequential files and linked files , The correct argument is （ ）.

• A. Sequential files are suitable for building on sequential storage devices , Not for disk .

• B. In the display link file, a link pointer is set in each disk block , Used to link all blocks of a file .

• C. Sequential files must be distributed continuously , Link files and index files can be distributed in a discrete way .

• D. stay MS-DOS The implicit link file structure is used in .

My answer : C right key : C

13. ( Single topic selection ) In the following discussion on index files , The correct argument is （ ）.

• A. In the index file , Each entry of the index table contains the key of the corresponding record and the logical address of the record .

• B. When retrieving sequential files , First of all, from the FCB Read the first block number of the file in ; When retrieving index files , We should start with FCB Read the starting address of the file index table in .

• C. For a file with a three-level index table , Accessing a record usually requires three disk accesses .

• D. When the file is large , Whether sequential access or random access , Usually, the index file is the fastest .

My answer : B right key : B

14. ( Single topic selection ) In the following physical files ,（ ） Least suitable for random access to files .

• A. Sequence file

• B. Implicitly linked files

• C. Explicitly link files

• D. Index file

My answer : B right key : B

15. ( Single topic selection ) The main purpose of setting the current working directory is （ ）.

• A. External memory space

• B. Save memory space

• C. Speed up file retrieval

• D. Speed up file reading / Write speed

My answer : C right key : C

Analysis of the answer ：

16. ( Single topic selection ) File system , The reasonable location for storing file access control information is （ ）.

• A. File control block

• B. File allocation table

• C. Password table

• D. System registry

My answer : A right key : A

17. ( Single topic selection ) Set file F1 The current reference count value of is 1, First create a file F1 The symbolic link （ Soft link ） file F2, Then create a file F1 Hard link file for F3, Then delete the file F1. here , file F2 And documents F3 The reference count values of are （ ）.

• A. 0、1

• B. 1、1

• C. 1、2

• D. 2、1

My answer : B right key : B

Analysis of the answer ：

F2 Itself is a file , When created, the reference count is 1.

18. ( Single topic selection ) From the user's point of view , The purpose of introducing the file system into the operating system is （ ）.

• A. Protect user data

• B. Realize file name access

• C. Implement virtual storage

• D. Save user and system documents and data

My answer : B right key : B

19. ( Single topic selection ) When the file system creates a file , Build a... For it （ ）.

• A. File directory entry

• B. Directory file

• C. Logical structure

• D. Logical space

My answer : A right key : A

20. ( Single topic selection ) The main work of opening a file is （ ）.

• A. Copy the directory of the specified file to the specified area of memory

• B. Copy the specified file to the specified area of memory

• C. Find the directory of the specified file on the storage medium where the specified file is located

• D. Find the specified file in memory

My answer : A right key : A

Analysis of the answer ：

The system will specify the attributes of the named file （ Include the physical location of the file in external storage ）, Copy from external memory to the table entry of the memory open file table , And number the table （ Or index number ） Return to the user .

A The operation of opening a file is to FCB Active file directory table stored in memory , Instead of copying the contents of the file to main memory , Finding the specified file directory is the operation before opening the file .

21. ( Single topic selection )UNIX Operating system , Input / The output device is regarded as （ ）.

• A. Ordinary documents

• B. Directory file

• C. Index file

• D. Special documents

My answer : D right key : D

22. ( Single topic selection ) Among the following files, the files with logical structure are （ ）.

• A. Sequential files

• B. System files

• C. Link to the file

• D. Streaming files

My answer : D right key : D

23. ( Single topic selection ) The organization form of logical files is determined by （ ） decision .

• A. Storage media characteristics

• B. Management mode of operating system

• C. Main memory capacity

• D. user

My answer : D right key : D

24. ( Single topic selection ) In the logical structure of the file , What does not belong to structured files is （ ）.

• A. Index file

• B. Partition file

• C. Sequence file

• D. Index sequential files

My answer : B right key : B

Analysis of the answer ：

25. ( Single topic selection ) Index file consists of logical file and （ ） form .

• A. The symbol table

• B. Index table

• C. Cross access table

• D. Link table

My answer : B right key : B

26. ( Single topic selection ) There is a sequential file containing 10 000 A record , The average number of records searched is 5 000 individual , Adopt index sequential file structure , In the best case, you only need to find （ ） Time record .

• A. 1 000

• B. 10 000

• C. 100

• D. 500

My answer : C right key : C

Analysis of the answer ：

27. ( Single topic selection ) The relative pathname of a file is from （ ） Start , Gradually trace back along subdirectories at all levels , Finally, a string of all subdirectory names on the whole path to the specified file .

• A. Current directory

• B. root directory

• C. Multi level directory

• D. Two level directory

My answer : A right key : A

28. ( Single topic selection )FAT32 The file directory entry for does not include （ ）.

• A. file name

• B. File access permission description

• C. The physical location of the file control block

• D. The physical location of the file

My answer : C right key : C

29. ( Single topic selection ) The purpose of using multi-level directory structure in file system is （ ）.

• A. Reduce system overhead

• B. Save storage space

• C. Resolve naming conflicts

• D. Reduce transmission time

My answer : C right key : C

30. ( Single topic selection ) If two files in the file system have the same name , Should not be used （ ）.

• A. Single level directory structure

• B. Two level directory structure

• C. Tree directory structure

• D. Multi level directory structure

My answer : A right key : A

31. ( Single topic selection ) The operating system is to ensure that it is not authorized by the file owner , This file cannot be used by any other user , The solution offered is （ ）.

• A. File protection

• B. Document confidentiality

• C. File dump

• D. File sharing

My answer : A right key : A

32. ( Single topic selection ) In the file system , The following methods that do not belong to file protection are （ ）.

• A. password

• B. Access control

• C. User authority table

• D. Use the close command after reading and writing

My answer : C right key : D

33. ( Single topic selection ) Access to a file , Often by （ ） Common restrictions .

• A. User access rights and file attributes

• B. User access rights and user priorities

• C. Priority and file attributes

• D. File properties and password

My answer : A right key : A

34. ( Single topic selection ) Compared with encryption protection and access control （ ）.

• A. The encryption protection mechanism is more flexible

• B. The security of access control mechanism is higher

• C. The encryption protection mechanism must be implemented by the system

• D. The access control mechanism must be implemented by the system

My answer : D right key : D

35. ( Single topic selection ) In order to safely manage the files in the file system , Any user must register when entering the system , This level of safety management is （ ）.

• A. The system level

• B. Catalog level

• C. User level

• D. File level

My answer : A right key : A

36. ( Single topic selection ) In the physical structure of the following files , What is not conducive to the dynamic growth of file length is （ ）.

• A. Continuous structure

• B. Link structure

• C. Index structure

• D. Hash structure

My answer : A right key : A

37. ( Single topic selection ) In the file system, if the physical structure of the file adopts continuous structure , be FCB The physical location of relevant documents in the shall include ( ).I. First block address II． file length III． Index table address

• A. Only I

• B. I、II

• C. II、III

• D. I、III

My answer : B right key : B

Analysis of the answer ：

38. ( Single topic selection ) On disk , The physical file structure most likely to cause storage fragmentation is （ ）.

• A. Implicit linking

• B. Store in sequence

• C. Index storage

• D. Explicit links

My answer : B right key : B

39. ( Single topic selection ) Some operating systems separate file description information from directory entries , The advantage of this is （ ）.

• A. Reduce the of reading files I/O The amount of information

• B. Reduce the of writing files I/O The amount of information

• C. Reduce the of searching for files I/O The amount of information

• D. Reduce the of copying files I/O The amount of information

My answer : C right key : C

40. ( Single topic selection ) Physical files are organized by （ ） affirmatory .

• A. Applications

• B. Main memory capacity

• C. External memory capacity

• D. operating system

My answer : D right key : D

41. ( Single topic selection ) If the document is random （ direct ） Access method use , And the file size is not fixed , Then （ ） Physical structure .

• A. direct ;

• B. Indexes ;

• C. Random ;

• D. The order

My answer : B right key : B

Two . Calculation questions （ common 1 topic ,5.7 branch ）

42. ( Calculation questions ) A file has 100 Disk blocks , Assume that the file control block of the file is in memory . In the following cases , Calculate and explain respectively under the continuous organization mode and the display link organization mode , How many times do you need to execute disk I/O operation ？（ Suppose that every read or write to a disk block is a disk operation ; Suppose that under the continuous organization , There is no free disk block in the file header , But there are free disk blocks at the end of the file ）（ Assume that the disk block number is from 0~99, The first 50 A block refers to a block numbered 49 My disk ）（1） Add a disk block at the beginning of the file （ You need to write data to the added disk block ）;（2） In Document No 50 Add a disk block before the block （ There is no need to write data to the added disk block ）;（3） Delete file No 50 Block disk block ;（4） Delete a disk block at the end of the file .

• My answer ：

  （1）201,1（2）102,0（3）100,0（4）0,0

• right key ：

  （1） Continuous organization ,201 Time I/O; Show how links are organized ,1 Time I/O（2） Continuous organization ,102 Time I/O; Show how links are organized ,0 Time I/O（3） Continuous organization ,100 Time I/O; Show how links are organized ,0 Time I/O（4） Continuous organization ,0 Time I/O; Show how links are organized ,0 Time I/O The display link assignment focuses on the modification of the file assignment table .

Analysis of the answer ：

Analysis of the answer ： Continuous organization , Because there is no free disk block in the file header , So when you add a disk block at the beginning of a file , You need to read out all the disk contents of the file （100 Time ） And write （100 Time ）, And the writing of new block contents （1 Time ）, So we have 201 Time . In the 50 Add a disk block before the block , Need to 51 A disk block reads （51 Time ） And write （51 Time ）, common 102 Time ;

Delete the first 50 block , Read it out 50 block , Write this 50 Piece of data . Delete the end , Just modify the file control block information in memory .

Show how connections are organized ,FAT Has been called into memory , Whether you insert or delete a disk block , Are focused on FAT Modification of , There is no need to start I/O, So for 0 Time . But writing data to the newly added data block needs to start I/O1 Time .