Handle SIGCHLD in C to be notified when a child process has exited. via http://www.linuxquestions.org/questions/programming-9/how-a-father-process-know-which-child-process-send-the-signal-sigchld-266290/

wait.c

// Via http://www.linuxquestions.org/questions/programming-9/how-a-father-process-know-which-child-process-send-the-signal
#include <stdio.h>
#include <signal.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/wait.h>

void handler(int sig)
{
  pid_t pid;

  pid = wait(NULL);

  printf("Pid %d exited.\n", pid);
}

int main(void)
{
  signal(SIGCHLD, handler);

  if(!fork())
  {
    printf("Child pid is %d\n", getpid());
    exit(0);
  }
  printf("Parent pid is %d\n", getpid());

  getchar();
  return 0;
}

In order the script to work you must inlucde also "#include <stdlib.h>"

very nice... simplistic mechanism to make handleres

fork() will return -1 when it fails, may be worth adding a comment or updating your code

Even better if you change the exit(0) to return 0 you can exit the program more cleanly and you no longer have a dependency on stdlib.h.

Even better if you change the exit(0) to return 0 you can exit the program more cleanly and you no longer have a dependency on stdlib.h.

True, it also saves about 100b and a compiler warning.