Linux Interview Questions and Answers – Signal Handling

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
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2. Which signal is generated when we press control-C?
a) SIGINT
b) SIGTERM
c) SIGKILL
d) SIGSEGV
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3. Which signal is generated when we press ctrl-Z?
a) SIGKILL
b) SIGSTOP
c) SIGABRT
d) SIGINT
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4. Which signal is sent when the Child process terminates?
a) SIGINIT
b) SIGKILL
c) SIGSTOP
d) SIGCHLD
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5. Which of the following signal cannot be handled or ignored?
a) SIGINT
b) SIGCHLD
c) SIGKILL
d) SIGALRM
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6. Another signal that cannot be caught is:
a) SIGPIPE
b) SIGHUP
c) SIGSTOP
d) SIGUSR1
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7. When real interval timer expires which signal is generated?
a) SIGINT
b) SIGCHLD
c) SIGKILL
d) SIGALRM
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8. Signals are handled using which system call?
a) kill
b) signal
c) both
d) none
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9. Default action of SIGSEGV is
a) Terminate
b) Core dump + Terminate
c) Stop
d) Cont
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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
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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
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