sigchi.c

#include <sys/wait.h>
#include <stdio.h>
#include <unistd.h>


int main(int argc, char **argv)
{
  pid_t chpid = fork();

  if (! chpid) {
    for(;;) usleep(5000);
    return 0;
  }

  pid_t pid=getpid();
  printf("parent pid: %d\n", pid);

//#define FPID ("/home/box/pid")
#define PPID ("./pid_parent")
#define CPID ("./pid_child")
  FILE *f1=fopen(PPID, "w");
  FILE *f2=fopen(CPID, "w");
  if (NULL == f1 || NULL == f2) {
	perror("fopen");
	return(1);
  }
  int rc = fprintf(f1, "%d\0", pid);
  fprintf(f2, "%d\0", chpid);
  fflush(f1); fflush(f2);
  printf("%d\n", rc);

  waitpid(chpid, &rc, 0);
  printf("child process killed: %d\n", rc);
  for(;;) usleep(5000);

  fclose(f1); fclose(f2);
  return 0;
}