Linux Interview Questions and Answers on File Management for Freshers

1. Each process has unique

a) fd table
b) file table
c) inode table
d) data block table

Answer: a

2. File descriptor table indexes which kernel structure?

a) struct file
b) strruct fs_struct
c) files_struct
d) struct inode

Answer: a

3. What is the default number of files open per user process?

a) 0
b) 1
c) 2
d) 3

Answer: d

4. The file system information is stored in

a) Boot block
b) Super Block
c) Inode Table
d) Data Block

Answer: b

5. Switch table is used by

a) device special file
b) directory file
c) fifo
d) link file

Answer: a

6. What is the use of fcntl function?

a) locking a file
b) reading the file descriptor flag
c) changing the file status flag
d) all of the mentioned

Answer: d

7. Which function can be used instead of the dup2 to duplicate the file descriptor?

a) read()
b) open()
c) stat()
d) fcntl()

Answer: d

8. printf() uses which system call

a) open
b) read
c) write
d) close

Answer: c

9. read() system call on success returns

a) 0
b) -1
c) number of character
d) none

Answer: c

10. Which system call is used to create a hard link?

a) hardlink
b) link
c) symlink
d) ln

Answer: b

11. namei() is

a) ANSI C library function
b) C library function
c) System call
d) kernel routine

Answer: d

12. dup2(1,0)

a) closes the stdout and copies the stdin descriptor to stdout
b) closes the stdin and copies the stdout descriptor to stdin
c) will produce compilation error
d) None of the mentioned

Answer: b

13. Given a code snippet below?

    #define PERMS  (S_IRUSR | S_IWUSR | S_IRGRP | S_IWGRP | S_IROTH | S_IWOTH)
    int main() 
    {
        int fd1, fd2;
        umask(0);
        fd1 = open(“file1”, O_CREAT | O_RDWR, PERMS)
        umask(S_IRGRP | S_IWGRP | S_IROTH | S_IWOTH);
        fd2 = open(“file2”, O_CREAT | O_RDWR, PERMS)
        return 0;
    }

The newly created files file1 and file2 will have the permissions respectively

a) rw-rw-rw- r——–
b) r——– rw-rw-rw-
c) rw-rw-rw- rw——-
d) None of the mentioned

Answer: c

14. Below is the code

    int main() 
   {
        int fd1, fd2;
        struct stat buff1, buff2;
        fd1 = open(“1.txt”, O_RDWR);
        fd2 = open(“2.txt”, O_RDWR | O_APPEND);
        lseek(fd1, 10000, SEEK_SET);
        write(fd1, “abcdefghij”, 10);
        write(fd2, “abcdefghij”, 10);
        fstat(fd1, &buff1);
        fstat(fd2, &buff2);
        printf(“ %d %d”, buff1.st_size, buff2.st_size);
        return 0;
    }

Before running the program, the file 1.txt and 2.txt size is 20 each. What is the output?

a) 30 30
b) 100020 20
c) 100030 30
d) 100010 30

Answer: d

15. What is stored in logfile as per below mentioned code if we execute ./a.out > logfile?

    int main() 
    {
        int fd;
        close(1);
        fd = open(“logfile”,O_RDWR, 0744);
        write(fd, “Hello”, 5);
        printf(“World\n”);
        return 0;
    }

a) Hello
b) HelloWorld
c) World
d) None

Answer: b

16. For the below mentioned code,

   int main() 
   {
        int fd;
        fd = open(“logfile”, O_CREAT|O_RDWR, 0600);
        lseek(fd, 5, SEEK_CUR);
        write(fd, “Hello”, 5);
        return 0;
    }

What is the logfile size now if it’s initially was 1024 bytes?
a) 5
b) 1024
c) 1029
d) 1034

Answer: b

17. Code snippets

    str1=”45678\n”
    str2=”123\n”
    f1 = fopen(file1,RDWR,RWX)
    f2 = fopen(file1,RDWR,RWX)
    write(f1,str1,len_str1)
    write(f2,str2,len_str2)
 
    o/p:

a) 12378
b) 123(newline)8(newline)
c) 123(newline)78(newline)
d) 45678(newline)123(newline)

Answer: b

18. Code snippets

    str1=”45678\n”
    str2=”123\n”
    f1 = fopen(file1,RDWR,RWX)
    f2 = dup(f1)
    write(f1,str1,len_str1)
    write(f2,str2,len_str2)
 
    o/p:

a) 12378
b) 123(newline)8(newline)
c) 123(newline)78(newline)
d) 45678(newline)123(newline)

Answer: d

19. Code snippet (file1 size is 2024)

    f1 = fopen (file1, RDWR, RWX)
    lseek(f1,1024,SEEK_SET)
    write(f1,buf,10) 
    What is offset now.

a) 1024
b) 1034
c) 2034
d) 2054

Answer: b