We have listed here some multiple choice questions with answer on UNIX Operating System, Which has asked by multiple companies like ABB, Aditi, BSNL, Integra, Lifetree, L & T Infotech etc.

You can prepare your job written and interview by using these sets of question fro here.

1. Which of the following is not a system defined variable?
a) $PATH
b) $HOME
c) $SHELL
d) $cd

Answer: d

2. Command substitution requires the command to use ________
a) standard input
b) standard output
c) standard error
d) all of the above

Answer: b

3. A process is said to be ____ when it starts its execution.
a) born
b) die
c) waiting
d) terminated

Answer: a

4. Some attributes of every process are maintained by the kernel in memory in a separate structure called the ______
a) pcb
b) task control block
c) process table
d) task table

Answer: c

5. The parent id of a child is called ______
a) PID
b) PPID
c) TID
d) PTID

Answer: b

6. The PID of our login shell doesn’t change.
a) True
b) False

Answer: b

7. Which of the following command doesn’t create a process?
a) pwd
b) fork
c) cd
d) pwd and cd

Answer: d

8. What will the output of the following command?

$ ps -t dev/console
a) processes running on terminal named console
b) undefined output
c) erroneous
d) processes running on the current terminal

Answer: a

9. A system call is a programmatic way in which the program requests for the service from the kernel of an operating system.
a) True
b) False

Answer: a

10. Which system call is used to run a new program?
a) fork
b) wait
c) exec
d) exit

Answer: c

11. It is necessary to terminate the command line with &, even when we are using nohup command.
a) True
b) False

Answer: a

12. nohup command doesn’t send the standard output of a command to any file.
a) True
b) False

Answer: b

13. nice command is a ______ command in C shell.
a) internal
b) external
c) built-in
d) directory

Answer: c

14. Which signal is used with kill command to terminate the process when they ignore the SIGTERM signal (15)?
a) SIGTERM (16)
b) SIGTERM(0)
c) SIGKILL(9)
d) -d

Answer: c

15. What is a job?
a) group of tasks
b) group of commands
c) group of processes
d) group of signals

Answer: c

16. What does the following command do?

$ kill %2
a) kills job number 2
b) kills the second background job
c) invalid command
d) kill all foreground & background jobs

Answer: b

17. Which of the following keyword is not supported by at command?
a) now
b) noon
c) tomorrow
d) evening

Answer: d

18. We cannot find out the name of the program scheduled using at command.
a) True
b) False

Answer: a

19. What is a daemon?
a) process whose parent has died
b) process who has completed its execution but still has an entry in the process table
c) process which is running infinitely
d) process which runs automatically without any user interaction.

Answer: d

20. What is cron?
a) a simple process
b) an orphan process
c) a daemon
d) a zombie process

Answer: c

21. Which of the following command will remove the current crontab?
a) crontab -p
b) crontab -l
c) crontab -e
d) crontab -r

Answer: d

22. The UNIX shell is both _______ and _______ language.
a) interactive, responsive
b) interpreter, executing
c) scripting, interpreter
d) high level, low level

Answer: c

23. Shell variables are of ____ types.
a) 1
b) 3
c) 2
d) 4

Answer: c

24. ____ command displays all the variables available in the current shell.
a) env
b) set
c) var
d) sh

Answer: b

25. Which command is used in bash and Korn shells to display the previously used commands?
a) his
b) history
c) sh
d) ps

Answer: b

Explanation: Bash and Korn support a versatile history feature that treats a previous command as an event and associates it with an event number. The history command displays the history list showing the event number of every previously executed command.