Signal Handling Question:

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

Answer:

b) "Alarm clock"
Explanation:After 5 seconds of the execution of this program, the signal SIGALRM hits the process and handler executes.
Output:
[root@localhost google]# gcc -o san san.c
[root@localhost google]# ./san
Alarm clock
[root@localhost google]#

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What happnes as the signal SIGINT hits the current process in the program?

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

void response (int);
void response (int sig_no)
{
printf("Linuxn");
}
int main()
{
struct sigaction act;
act.sa_handler = response;
act.sa_flags = 0;
sigemptyset(&act.sa_mask);
sigaction(SIGINT,&act,0);
while(1){
printf("googlen");
sleep(1);
}
return 0;
}
a) the process terminates
b) the string "Linux" prints
c) the string "Linux" prints and then process terminates
d) none of the mentioned

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