Linux：实时信号

Question

I am testing different scenarios with real-time signals and unable to found the meaning of every signal such as SIGRTMIN+1 and SIGRTMIN+13.

I am able to send and receive the signals but trying to understand the meaning of all the SIGRTMIN+n signals. For example, I send number of Signals based on my program and one of them is killing a process:

/* The child process executes this function. */
void
child_function (void)
{
  /* Perform initialization. */
  printf ("I'm here!!!  My pid is %d.\n", (int) getpid ());

  /* Let parent know you’re done. */
  kill (getppid (), SIGUSR1);

  /* Continue with execution. */
  puts ("Bye, now....");
  exit (0);
}

I want to understand these SIGRTMIN+13, how does it work if I pass this to pass to kill a process forcefully.

Answer 1

real-time signals are designed to be used for application-defined purposes(it's up to you to give them a meaning),they have the advantage to be queued and accompanied with data which is not possible with standard signals, to use them effectively they are sent using sigqueue() "not kill()", and handled by sigaction() "not signal()".