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int semget(
key_t key, //±êʶÐźÅÁ¿µÄ¹Ø¼ü×Ö£¬ÓÐÈýÖÖ·½·¨£º1¡¢Ê¹ÓÃIPC——PRIVATEÈÃϵͳ²úÉú£¬ 2¡¢Ìôѡһ¸öËæ»úÊý£¬3¡¢Ê¹ÓÃftok´ÓÎļþ·¾¶ÃûÖвúÉú
int nSemes, //ÐźÅÁ¿¼¯ÖÐÔªËØ¸öÊý
int flag //IPC_CREAT£»IPC_EXCL Ö»ÓÐÔÚÐźÅÁ¿¼¯²»´æÔÚʱ´´½¨
)
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1.2 ʹÓÃftokº¯Êý¸ù¾ÝÎļþ·¾¶Ãû²úÉúÒ»¸ö¹Ø¼ü×Ö
key_t ftok(const char *pathname,int proj_id);
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1.3 ¿ØÖÆÐźÅÁ¿
int semctl(
int semid, //ÐźÅÁ¿¼¯µÄ¾ä±ú
int semnum, //ÐźÅÁ¿¼¯µÄÔªËØÊý
int cmd, //ÃüÁî
/*union senum arg */... //
)
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cmd: IPC_RMID ɾ³ýÒ»¸öÐźÅÁ¿
IPC_EXCL Ö»ÓÐÔÚÐźÅÁ¿¼¯²»´æÔÚʱ´´½¨
IPC_SET ÉèÖÃÐźÅÁ¿µÄÐí¿ÉȨ
SETVAL ÉèÖÃÖ¸¶¨ÐźÅÁ¿µÄÔªËØµÄֵΪ agc.val
GETVAL »ñµÃÒ»¸öÖ¸¶¨ÐźÅÁ¿µÄÖµ
GETPID »ñµÃ×îºó²Ù×Ý´ËÔªËØµÄ×îºó½ø³ÌID
GETNCNT »ñµÃµÈ´ýÔªËØ±äΪ1µÄ½ø³ÌÊý
GETZCNT »ñµÃµÈ´ýÔªËØ±äΪ0µÄ½ø³ÌÊý
union senum ¶¨ÒåÈçÏ£º
union senum{
int val;
struct semid_ds *buf;
unsigned short * array;
}agc;
ÆäÖÐ semid_ds ¶¨ÒåÈçÏ£º
struct semid_ds{
struct ipc_pem sem_pem; /
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