COMP1521 - Week 9 Comprehensive Quiz

Question 1

Which system call is used to open a file in Unix and returns a file descriptor?

A) read()

B) write()

C) open()

D) close()

Question 2

What is the purpose of the file descriptor 0 in Unix systems?

A) Standard output (stdout)

B) Standard input (stdin)

C) Standard error (stderr)

D) First opened file

Question 3

Which system call is used to change the current read/write position in a file?

A) fflush()

B) fseek()

C) lseek()

D) rewind()

Question 4

What is the difference between a hard link and a symbolic link?

A) Hard links work across filesystems, symbolic links don't

B) Symbolic links point to inode numbers, hard links point to filenames

C) Hard links point to the same inode, symbolic links point to a pathname

D) There is no difference in functionality

Question 5

Which system call is used to create a new directory?

A) create()

B) mkdir()

C) mknode()

D) opendir()

Question 6

What does the `stat` system call return about a file?

A) Only the file size

B) File contents

C) File metadata (inode information)

D) File descriptor

Question 7

Which of the following is NOT a standard file descriptor automatically opened by Unix?

A) 0 (stdin)

B) 1 (stdout)

C) 2 (stderr)

D) 3 (first user file)

Question 8

What is the purpose of the `O_APPEND` flag when opening a file?

A) Create the file if it doesn't exist

B) Truncate the file to zero length

C) Always write to the end of the file

D) Open in read-only mode

Question 9

Which system call is used to read directory entries?

A) read()

B) readdir()

C) scandir()

D) getdents()

Question 10

What happens when you delete a file that has multiple hard links?

A) The file is immediately deleted from disk

B) The link count is decremented, file space is freed when count reaches 0

C) All hard links become invalid

D) The file system becomes corrupted

Question 11

Which flag would you use with `open()` to ensure exclusive creation of a file?

A) O_CREAT

B) O_EXCL

C) O_TRUNC

D) O_WRONLY

Question 12

What is the purpose of the `umask` value in Unix file creation?

A) Sets the maximum file size

B) Masks out permission bits from newly created files

C) Determines file ownership

D) Sets the default file type

Question 13

Which system call would you use to duplicate a file descriptor?

A) fork()

B) dup()

C) clone()

D) copy()

Question 14

What is the difference between `read()` and `pread()`?

A) `pread()` can read from multiple files simultaneously

B) `pread()` reads from a specified offset without changing file position

C) `pread()` is always faster than `read()`

D) There is no difference

Question 15

Which of the following best describes what an inode contains?

A) File name and directory path

B) File metadata and data block pointers

C) File contents only

D) Directory structure information

Question 16

What is the purpose of the `fsync()` system call?

A) Synchronize file access between multiple processes

B) Force writes of file data and metadata to disk

C) Flush the file system cache

D) Check file system integrity

Question 17

Which system call is used to change file permissions?

A) chmod()

B) chown()

C) chgrp()

D) access()

Question 18

What does the `fcntl()` system call primarily do?

A) Create new files

B) Perform file control operations (e.g., duplicating descriptors, setting flags)

C) Read file contents

D) Write file contents

Question 19

Which of the following is true about FIFO (named pipe) files?

A) They persist after the creating process terminates

B) They can only be used by related processes

C) They work like regular files for random access

D) They require special kernel modules

Question 20

What is the typical return value of `write()` when it successfully writes all requested bytes?

A) 0

B) -1

C) The number of bytes written

D) The file descriptor

Question 21

Which system call is used to remove a directory?

A) delete()

B) rmdir()

C) remove()

D) unlink()

Question 22

What is the purpose of the `O_NONBLOCK` flag?

A) Prevents the file from being blocked by other processes

B) Makes I/O operations non-blocking (return immediately if no data available)

B) Locks the file for exclusive access

D) Enables buffered I/O

Question 23

Which system call would you use to get the current working directory?

A) getpath()

B) getcwd()

C) pwd()

D) getdir()

Question 24

What happens when you call `close()` on a file descriptor?

A) The file is deleted from disk

B) The file descriptor is deallocated and can be reused

C) All data is immediately written to disk

D) The file system is synchronized

Question 25

Which of the following best describes what a symbolic link contains?

A) File data directly

B) An inode number

C) A path name string

D) File metadata

Question 26

What is the purpose of the `access()` system call?

A) Open a file with specific permissions

B) Check real user's permissions for a file

C) Change file permissions

D) List directory contents

Question 27

Which system call is used to create a hard link?

A) link()

B) symlink()

C) ln()

D) create()

Question 28

What is the purpose of the `dirent` structure?

A) Store file metadata

B) Represent directory entries (filename and inode number)

C) Handle file permissions

D) Manage file descriptors

Question 29

Which of the following is NOT typically stored in a file's inode?

A) File size

B) File name

C) Modification time

D) Owner user ID

Question 30

What is the primary purpose of the `select()` system call?

A) Select files for backup

B) Monitor multiple file descriptors for I/O readiness

C) Choose between different system calls

D) Select a file by name

Question 31

Which system call would you use to truncate a file to a specific length?

A) truncate()

B) ftruncate()

C) Both A and B

D) resize()

Question 32

What is the difference between `O_RDONLY` and `O_WRONLY` flags?

A) O_RDONLY creates the file, O_WRONLY doesn't

B) O_RDONLY opens for reading only, O_WRONLY for writing only

C) O_RDONLY is for text files, O_WRONLY for binary files

D) No difference

Question 33

Which system call is used to change the ownership of a file?

A) chown()

B) chmod()

C) chgrp()

D) owner()

Question 34

What is the purpose of the `DIR` structure in directory operations?

A) Store directory permissions

B) Represent an open directory stream

C) Contain directory metadata

D) Handle file locking

Question 35

Which of the following best describes what happens when you reach EOF during a `read()` operation?

A) Returns -1 and sets errno to EOF

B) Returns 0

C) Blocks until more data is available

D) Returns the file descriptor

Question 36

What is the purpose of the `pathconf()` and `fpathconf()` functions?

A) Configure file paths

B) Get configurable pathname limits

C) Compare two file paths

D) Validate file path syntax

Question 37

Which system call is used to create a new named pipe (FIFO)?

A) pipe()

B) mkfifo()

C) mknod()

D) Both B and C

Question 38

What is the purpose of the `mmap()` system call in the context of file I/O?

A) Map a file into memory for direct access

B) Copy file contents to a new location

C) Move files between directories

D) Compress file data

Question 39

Which of the following is true about the `writev()` system call?

A) Writes to multiple files simultaneously

B) Writes data from multiple buffers in a single call

C) Writes data in a specific vector format

D) Writes data with verification

Question 40

What is the primary difference between `lstat()` and `stat()`?

A) `lstat()` is faster than `stat()`

B) `lstat()` returns information about the link itself, not the file it points to

C) `lstat()` works only on local files, `stat()` works on remote files