pthread_once_t; /* one-time initialization control context */
typedef struct
{
      int __detachstate; /* JOINABLE or not */
      int __schedpolicy; /* SCHED_FIFO or SCHED_RR or SCHED_OTHER */
      struct sched_param __schedparam; /* pthread PRIORITY in RR or FIFO schedule */
      int __inheritsched; /* INHERIT or not */
      int __scope; /* in SYSTEM or PROCESS */
      size_t __guardsize; /* protection size */
      int __stackaddr_set; /* USER STACK or not */
      void *__stackaddr; /* stack address */
      unsigned long int __stacksize; /* stack size */
}pthread_attr_t; /* thread attributes object */
pthread_mutex_t ; /* mutex */
pthread_mutexattr_t; /* mutex attributes object */
pthread_cond_t; /* condition variable */
pthread_condattr_t; /* conditin variable attributes object */
pthread_key_t; /* key for thread-specific data */
pthread_t; /* thread identifer */
pthread_rwlock_t; /* read-write lock */
pthread_rwlockattr_t; /* read-write lock attributes object */


sem_t; /* Posix semaphores */
...

//reference: TLPI(the linux programming interface 3rd)