Signal Handling Question:

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What is the output of this program?

#include<stdio.h>
#include<signal.h>
#include<stdlib.h>

void response (int);
void response (int sig_no)
{
printf("%sn",sys_siglist[sig_no]);
printf("This is singal handlern");
}
int main()
{
pid_t child;
int status;
child = fork();
switch (child){
case -1 :
perror("fork");
exit (1);
case 0 :
kill(getppid(),SIGKILL);
printf("I am an orphan process because my parent has been killed by men");
printf("Handler failedn");
break;
default :
signal(SIGKILL,response);
wait(&status);
printf("The parent process is still aliven");
break;
}
return 0;
}
a) the child process kills the parent process
b) the parent process kills the child process
c) handler function executes as the signal arrives to the parent process
d) none of the mentioned

Linux Signal Handling Interview Question

Answer:

a) the child process kills the parent process
Explanation:
The SIGKILL signal can not be handled by singal handler function.
Output:
[root@localhost google]# gcc -o san san.c
[root@localhost google]# ./san
Killed
[root@localhost google]# I am an orphan process because my parent has been killed by me
Handler failed
[root@localhost google]#

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This program will print:

#include<stdio.h>
#include<signal.h>
#include<unistd.h>

void response (int);
void response (int sig_no)
{
printf("%s is workingn",sys_siglist[sig_no]);
}
int main()
{
alarm(5);
sleep(50);
printf("googlen");
signal(SIGALRM,response);
return 0;
}
a) "google"
b) "Alarm clock"
c) nothing
d) none of the mentioned

Which one of the following is not true about this program?

#include<stdio.h>
#include<signal.h>

void response (int);
void response (int signo)
{
printf("%sn",sys_siglist[signo]);
signal(SIGSEGV,SIG_IGN);
}
int main()
{
signal (SIGSEGV,response);
char *str;
*str = 10;
return 0;
}
a) kernel sends SIGSEGV signal to a process as segmentation fault occurs
b) in this process signal handler will execute only one time of recieving the signal SIGSEGV
c) both (a) and (b)
d) none of the mentioned