Linux Interview Questions and Answers on Signal Handling for Freshers

1. If a signal is received by a process, when will it be processed?

a) It is processed immediately
b) It is processed when process is switching to kernel mode
c) It is processsed in the next timeslice given to the process
d) None of the mentioned

Answer: b

2. Which signal is generated when we press control-C?

a) SIGINT
b) SIGTERM
c) SIGKILL
d) SIGSEGV

Answer: a

3. Which signal is generated when we press ctrl-Z?

a) SIGKILL
b) SIGSTOP
c) SIGABRT
d) SIGINT

Answer: b

4. Which signal is sent when the Child process terminates?

a) SIGINIT
b) SIGKILL
c) SIGSTOP
d) SIGCHLD

Answer: d

5. Which of the following signal cannot be handled or ignored?

a) SIGINT
b) SIGCHLD
c) SIGKILL
d) SIGALRM

Answer: c

6. Another signal that cannot be caught is:

a) SIGPIPE
b) SIGHUP
c) SIGSTOP
d) SIGUSR1

Answer: c

7. When real interval timer expires which signal is generated?

a) SIGINT
b) SIGCHLD
c) SIGKILL
d) SIGALRM

Answer: d

8. Signals are handled using which system call?

a) kill
b) signal
c) both
d) none

Answer: b

9. Default action of SIGSEGV is

a) Terminate
b) Core dump + Terminate
c) Stop
d) Cont

Answer: b

10. The kill system call is used to

a) Send shutdown messages to all by superuser
b) Send a signal to a process
c) Kill processes
d) Stop the processes

Answer: b

11. What is the output of the below code?

    void sig_handler ( int signum) {
        printf(“Handled the signal\n”);
    }
 
    int main() {
        int pid;
        signal (SIGKILL, sig_handler);
        pid = fork();
        if (pid==0) {
            kill(getppid(), SIGKILL);
            exit(0);
        } else {
            sleep(20);
        }
        return 0;
    }

a) Error child cannot send a SIGKILL signal to parent
b) Parent goes to the signal handler, prints handled the signal and goes back to sleep
c) Parent goes to the signal handler, prints handled the signal and exits
d) Parent exits without going to the signal handler

Answer: d