进程间通信常用技术及函数

（1）消息队列
#include
int msgget(key_t key, int flag);
int msgctl(int msqid, int cmd, struct msqid_ds *buf);
int msgsnd(int msqid, const void *ptr, size_t nbytes, int flag);
int msgrcv(int msqid, void *ptr, size_t nbytes, long type, int flag);

（2）信号量
#include
int semget(key_t key, int nsems, int flag);
int semctl(int semid, int semnum, int cmd, ... /* union semun arg */);
int semop(int semid, struct sembuf semoparray[], size_t nops);

（3）共享存储
#include
int shmget(key_t key, size_t size, int flag);
int shmctl(int shmid, int cmd, struct shmid_ds *buf);
int shmat(int shmid, const void *addr, int flag);
int shmdt(void *addr);