1   
    2   void handler(int sig)
    3   {
    4     int status;
    5     pid_t pid;
    6   
    7     pid = waitpid(-1, &status, 0);
    8   
    9     if ( pid < 0 ) {
   10       printf("waitpid error: %s\n", strerror(errno));
   11     } else {
   12       printf("child %d terminated\n", pid);
   13       if (WIFEXITED(status)) {
   14         printf("child exit value: %d\n", WEXITSTATUS(status));
   15       } else {
   16         printf("(did not terminate normally)\n");
   17       }
   18     }
   19   }
   20   
   21   int main()
   22   {
   23     int i;
   24     pid_t pid;
   25   
   26     Signal(SIGCHLD, handler);
   27     for(i = 0; i < 5; i++) {
   28       if ( (pid = fork()) == 0 ) {
   29         sleep(1);
   30         printf("child %d exiting\n", getpid());
   31         exit(10+i);
   32       }
   33     }
   34   
   35     printf("parent waits in infinite loop: (ctrl-c to end)\n");
   36     while(1) {
   37     }
   38     return 0;
   39   }