system V共享内存程序练习

#include
#include
#include
#include
#include
#include

#define KEY 1234
#define SIZE 1000

void main(int argc,char **argv[])
{
   int shmid;
   char *shmadd;
   struct shmid_ds  buf;
   if(fork()==0){
      shmid = shmget(KEY, SIZE, IPC_CREAT|0600);
      shmadd = (char *) shmat(shmid, NULL, 0);
      strcpy(shmadd, "i am toy");
      shmdt(shmadd);
      return;
   }else {
      sleep(1);
      shmid = shmget(KEY, SIZE, 0);
      shmctl(shmid, IPC_STAT, &buf);
      printf("shm_segsz = %d byte\n",buf.shm_segsz);
      printf("shm_cpid = %d \n",buf.shm_cpid);
      printf("shm_lpid = %d \n",buf.shm_lpid);
      shmadd = (char *) shmat(shmid, NULL, 0);
      printf("get:  %s \n",shmadd);
      shmdt(shmadd);
      shmctl(shmid, IPC_RMID, NULL);
   }
}
编译（makefile）：

all : clean mem
.PHONY : all
clean :
 -rm *.o mem core
mem : mem.o
 cc -g -o mem mem.o
mem.o : mem.c
 cc -g -c mem.c