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   sem_post    ( 3 )

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Имя (Name)

sem_post - unlock a semaphore

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Синопсис (Synopsis)

#include <semaphore.h>

       int sem_post(sem_t *sem);

       Link with -pthread.

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Описание (Description)

sem_post() increments (unlocks) the semaphore pointed to by sem.
       If the semaphore's value consequently becomes greater than zero,
       then another process or thread blocked in a sem_wait(3) call will
       be woken up and proceed to lock the semaphore.

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Возвращаемое значение (Return value)

sem_post() returns 0 on success; on error, the value of the
       semaphore is left unchanged, -1 is returned, and errno is set to
       indicate the error.

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Ошибки (Error)

EINVAL sem is not a valid semaphore.

       EOVERFLOW
              The maximum allowable value for a semaphore would be
              exceeded.

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Атрибуты (Attributes)

For an explanation of the terms used in this section, see
       attributes(7).

       ┌──────────────────────────────────────┬───────────────┬─────────┐
       │Interface                             │ Attribute     │ Value   │
       ├──────────────────────────────────────┼───────────────┼─────────┤
       │sem_post()                            │ Thread safety │ MT-Safe │
       └──────────────────────────────────────┴───────────────┴─────────┘

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Стандарты (Conforming to)

POSIX.1-2001.

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Примечание (Note)

sem_post() is async-signal-safe: it may be safely called within a
       signal handler.

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Примеры (Examples)

See sem_wait(3) and shm_open(3).

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Смотри также (See also)

sem_getvalue(3), sem_wait(3), sem_overview(7), signal-safety(7)

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