Displaying information about the signals

• Define the signal handler function for SIGTERM

• Initialize a signal set with only SIGTERM excluded

• Set an event handler for SIGTERM

• Print the process identifier (pid)

• Wait for and output appropriate messages for incoming signals

• If an error occurs, terminate the program

signal-info.c

#include<stdio.h>
#include<stdlib.h>
#include<signal.h>
#include<string.h>
#include<unistd.h>

void signal_handler(int sig)
{
  printf("Signal %i: %s\n", sig, strsignal(sig));
  exit(EXIT_SUCCESS); // 0
}

int main(int argc, char* argv[])
{
  int sig;
  struct sigaction sa;
  sigset_t sset;
  sigfillset(&sset);
  sigdelset(&sset, SIGTERM);
  sigprocmask(SIG_SETMASK, &sset, 0);
  sa.sa_handler = signal_handler;
  sigaction(SIGTERM, &sa, 0);

  printf("My pid is %i\n", getpid());

  while(!sigwait(&sset, &sig))
  {
    printf("Signal %i: %s\n", sig, strsignal(sig));
  }

  return EXIT_FAILURE;
}