int shmget (key_t key, size_t size, int shmflg);
IPC_PRIVATE - private key value
IPC_CREAT - object with key can be created
IPC_EXCL - object with key must not exist
void *shmat (int shmid, const void *shmaddr, int shmflg); int shmdt (const void *shmaddr);
key_t ftok (const char *pathname, int proj_id);