c语言基础:shmget

#include <sys/types.h>
#include <sys/sem.h>
#include <stdio.h>
#include <sys/ipc.h>
#include <sys/shm.h>
#define LOG_SHM_KEY ftok(".", 'c')

int
main (int argc, char **argv)
{
  key_t semkey;
  int shmid;

  semkey = LOG_SHM_KEY;
 

  printf ("key=%d\n", semkey);

  shmid = shmget(semkey, 32000, IPC_CREAT|IPC_EXCL|600); 
  //shmid = shmget (semkey, 0, 0);
  if (shmid == -1)
    {
      shmid = shmget (semkey, 32000, IPC_CREAT);
    
    }

  return 0;
}