уничтожить безымянный семафор  (destroy an unnamed semaphore)
  
Имя (Name)
sem_destroy - destroy an unnamed semaphore
Синопсис (Synopsis)
#include <semaphore.h>
       int sem_destroy(sem_t *sem);
       Link with -pthread.
Описание (Description)
sem_destroy() destroys the unnamed semaphore at the address
       pointed to by sem.
       Only a semaphore that has been initialized by sem_init(3) should
       be destroyed using sem_destroy().
       Destroying a semaphore that other processes or threads are
       currently blocked on (in sem_wait(3)) produces undefined
       behavior.
       Using a semaphore that has been destroyed produces undefined
       results, until the semaphore has been reinitialized using
       sem_init(3).
Возвращаемое значение (Return value)
sem_destroy() returns 0 on success; on error, -1 is returned, and
       errno is set to indicate the error.
Ошибки (Error)
EINVAL sem is not a valid semaphore.
Атрибуты (Attributes)
For an explanation of the terms used in this section, see
       attributes(7).
       ┌──────────────────────────────────────┬───────────────┬─────────┐
       │Interface                             │ Attribute     │ Value   │
       ├──────────────────────────────────────┼───────────────┼─────────┤
       │sem_destroy()                         │ Thread safety │ MT-Safe │
       └──────────────────────────────────────┴───────────────┴─────────┘
Стандарты (Conforming to)
POSIX.1-2001, POSIX.1-2008.
Примечание (Note)
An unnamed semaphore should be destroyed with sem_destroy()
       before the memory in which it is located is deallocated.  Failure
       to do this can result in resource leaks on some implementations.
Смотри также (See also)
sem_init(3), sem_post(3), sem_wait(3), sem_overview(7)