shmget
int shmget(key_t, size_t, int);
struct shmget_args shmget;
if ((shmid = shmget(shmkey, 10 * pgsize, IPC_CREAT | IPC_EXCL | 0640)) == -1) {
if ((sender_shmid = shmget(shmkey, pgsize, IPC_CREAT | 0640)) == -1)
if ((shmid = shmget(shmkey, pgsize, 0)) == -1)
id = shmget(key, 0, 0);