Process management

Question 1

What is a process in an operating system?

Answer 1

A process is a program in execution, consisting of program code, data, and system resources.

Question 2

What are the different states of a process?

Answer 2

New, Ready, Running, Waiting, Terminated.

Question 3

What is the difference between a process and a thread?

Answer 3

A process is an independent execution unit with its own memory, whereas a thread is a lightweight execution unit sharing memory within a process.

Question 4

What is process creation?

Answer 4

It is the initiation of a new process using system calls like fork(), exec(), or CreateProcess().

Question 5

Which system calls are used for process creation in UNIX?

Answer 5

fork(), exec(), wait(), exit().

Question 6

What does the fork() system call do?

Answer 6

It creates a new child process by duplicating the parent process.

Question 7

What is the difference between fork() and exec()?

Answer 7

fork() creates a new process, while exec() replaces the current process image with a new one.

Question 8

What happens if fork() is called multiple times?

Answer 8

Multiple child processes are created, leading to exponential growth in processes.

Question 9

What is the return value of fork()?

Answer 9

0 for the child process, child’s PID for the parent process, and -1 if the fork fails.

Question 10

What is the use of the wait() system call?

Answer 10

It makes a parent process wait until its child process terminates.

Question 11

What is the difference between wait() and waitpid()?

Answer 11

wait() waits for any child process, while waitpid() can wait for a specific child.

Question 12

What is an orphan process?

Answer 12

A child process whose parent has terminated.

Question 13

What is an init process?

Answer 13

The first process in UNIX/Linux (PID 1) that adopts orphan processes.

Question 14

What is a zombie process?

Answer 14

A process that has completed execution but still has an entry in the process table.

Question 15

How do you prevent a zombie process?

Answer 15

By calling wait() or waitpid() in the parent process.

Question 16

What is the difference between a zombie and an orphan process?

Answer 16

A zombie has terminated but is still in the process table; an orphan is running without a parent.

Question 17

What is the exec() system call?

Answer 17

It replaces the current process image with a new one.

Question 18

What are the variants of exec() in UNIX?

Answer 18

execl(), execle(), execlp(), execv(), execve(), execvp().

Question 19

What happens to process ID (PID) after exec()?

Answer 19

It remains the same as exec() does not create a new process.

Question 20

What is inter-process communication (IPC)?

Answer 20

It is a mechanism for processes to communicate, using pipes, message queues, shared memory, etc.

Question 21

What is the difference between IPC using pipes and shared memory?

Answer 21

Pipes provide unidirectional or bidirectional communication, whereas shared memory allows direct access to data.

Question 22

What is the parent-child relationship in processes?

Answer 22

A parent creates a child process using fork(), and both share some resources.

Question 23

What is a daemon process?

Answer 23

A background process that runs without user interaction.

Question 24

How do you create a daemon process?

Answer 24

By detaching it from the terminal using fork(), setsid(), and changing the working directory.

Question 25

What is the difference between user mode and kernel mode?

Answer 25

User mode runs application code with limited privileges, while kernel mode has full system access.

Question 26

What is context switching?

Answer 26

The process of saving and restoring the state of a CPU when switching between processes.

Question 27

What is a Process Control Block (PCB)?

Answer 27

A data structure that stores process information like PID, state, registers, and scheduling information.

Question 28

What is a process table?

Answer 28

A system structure that maintains information about active processes.

Question 29

What is process scheduling?

Answer 29

The method by which the OS decides which process to execute next.

Question 30

What are the different types of schedulers?

Answer 30

Long-term, short-term, and medium-term schedulers.

Question 31

What is the difference between preemptive and non-preemptive scheduling?

Answer 31

Preemptive scheduling allows the OS to interrupt and switch processes, whereas non-preemptive does not.

Question 32

What is a time slice in scheduling?

Answer 32

The fixed time a process gets to run before being preempted.

Question 33

What is a system call?

Answer 33

A request from a user program to the OS for a service, such as process creation.

Question 34

What are some examples of system calls related to processes?

Answer 34

fork(), exec(), wait(), exit(), getpid().

Question 35

What is the difference between exit() and _exit()?

Answer 35

exit() performs cleanup before terminating, while _exit() terminates immediately.

Question 36

What is signal handling in process management?

Answer 36

A mechanism to send and handle signals for process control (e.g., SIGKILL, SIGSTOP).

Question 37

What happens when SIGKILL is sent to a process?

Answer 37

It terminates the process immediately without cleanup.

Question 38

What is the difference between SIGTERM and SIGKILL?

Answer 38

SIGTERM allows cleanup before termination, SIGKILL does not.

Question 39

What is the role of the process scheduler?

Answer 39

It manages process execution, deciding which process runs next.

Question 40

What is the purpose of nice values in scheduling?

Answer 40

They determine process priority, with lower values having higher priority.

Question 41

What is the difference between a foreground and background process?

Answer 41

A foreground process runs interactively, while a background process runs without user intervention.