Child process can't send signal to itself.

Hi!

When I am trying to execute the following program the child process simply waits for the signal.

Code:

#include <stdio.h>
#include <unistd.h>
#include <signal.h>
#include <stdlib.h>
#include <sys/types.h>

static int alarm_fired = 0;

void ding(int sig)
{
     alarm_fired = 1;
}

int main()
{
     pid_t pid;
     (void)signal(SIGALRM, ding);
    
     printf("alarm application starting.\n");
    
     pid = fork();
    
     switch(pid){
     case -1:
               /* failure */
               perror("Fork failed");
               exit(1);
              
     case 0:
               /* child */
               sleep(1);
               kill(getpid(), SIGALRM);
               break;
         
     default:
               exit(0);
              
}
     printf("waiting for alarm to go off\n");
    
     pause();
     if(alarm_fired)
          printf("Ding!\n");
     exit(0);
}

Output:

linux:~/prog # ./thread
alarm application starting.
linux:~/prog # waiting for alarm to go off
...waits here...

Why can't the child process send the signal to itself?

Regards,

Arun

Hi!

It is workig if I remove the pause() call.
Why is this happening?

Regards,

Arun

Hi!

I traced it out. pause() is called after the signal is sent.

Regards,

Arun