File Systems

Question 1

⭐️ Give the definition:
Array of persistent bytes that can be created/read/written/deleted

Answer 1

File

Question 2

⭐️ Give the definition:
Refers to collection of files. Describes how files are mapped onto physical devices. Also refers to parts of the OS that manages these files

Answer 2

File System (FS)

Question 3

⭐️ Give the definition:
Low-level names for files, index node

Answer 3

Inode

Question 4

⭐️ What do we call the type of files that are human readable?

Answer 4

Path

Question 5

⭐️ What do we call the file type that describes a files runtime state?

Answer 5

File descriptor

Question 6

⭐️ What are inodes unique within?

Answer 6

A FS

Question 7

⭐️ How many inode numbers does a file have?

Answer 7

1

Question 8

What does this command do?
$ stat -x <file></file>

Answer 8

Shows inodes

Question 9

Give the definition:
Reads for getting final inode

Answer 9

Traversal

Question 10

Give the definition:
Unique ID for a file

Answer 10

Inode

Question 11

How does the FS interact with inode numbers?

Answer 11

By using path-to-inode mappings

Question 12

Where are path-to-inode mappings stored?

Answer 12

In a directory

Question 13

Give the definition:
Placing directories within other directories

Answer 13

Directory tree/hierarchy

Question 14

Directories and files can have the same name as long as they’re in…

Answer 14

Different locations of the file system tree

Question 15

Give the definition:
Runtime name to read & write files

Answer 15

File descriptor

Question 16

What table contains pointers to open file descriptors?

Answer 16

File descriptor table

Question 17

Integers used for file I/O are indexes into what table?

Answer 17

File descriptor table

Question 18

Give the definition:
An API used for manipulation of files

Answer 18

File API

Question 19

⭐️ What command in the file API is this?
Returns a file descriptor

Answer 19

open()

Question 20

⭐️ What command in the file API is this?
Allows a process to create a new file descriptor that refers to the same underlying open file as an existing descriptor

Answer 20

dup()

Question 21

⭐️ What commands in the file API is this?
Calls return the processed bytes

Answer 21

read() & write()

Question 22

⭐️ What command in the file API is this?
Deletes a descriptor. Returns 0 for success & -1 for failure.

Answer 22

close()

Question 23

⭐️ What command in the file API is this?
read & write non-sequentially

Answer 23

lseek()

Question 24

⭐️ What is whence in lseek() set to if offset is set to offset bytes?

Answer 24

SEEK_SET

Question 25

⭐️ What is whence in lseek() set to if offset is set to its current location + offset bytes?

Answer 25

SEEK_CUR

Question 26

⭐️ What is whence in lseek() set to if offset is set to the size of the file & offset bytes?

Answer 26

SEEK_END

Question 27

⭐️ Give the definition: Writing immediately. Forces buffers to flush to disk, tells disk to flush its write cache.

Answer 27

fsync()

Question 28

⭐️ Does a write buffer improve or lower performance?

Answer 28

Improve

Question 29

Which function for deleting a file is this: Deletes paths when called

Answer 29

unlink()

Question 30

What function for deleting a file is this: function descriptors are deleted

Answer 30

close() / process quitting

Question 31

What function for renaming files is this? - Deletes an old link to a file - Creates a new link to a file

Answer 31

rename(char* old, char* new)

Question 32

Does the rename() function both change the name of a file, and move data?

Answer 32

No, it only changes the name of the file

Question 33

What sort of call is the rename() function implemented as?

Answer 33

Atomic - only old/new contents can be seen if crash

Question 34

⭐️ What are the three key factors that contribute to the latency of reading a file on a computer with a HDD?

Answer 34

Seek, rotation & transfer