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