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28 .\" $FreeBSD: src/lib/libc_r/man/sem_wait.3,v 1.1.2.7 2001/12/17 10:08:26 ru Exp $
29 .\" $DragonFly: src/lib/libc_r/man/sem_wait.3,v 1.2 2003/06/17 04:26:48 dillon Exp $
36 .Nd decrement (lock) a semaphore
42 .Fn sem_wait "sem_t *sem"
44 .Fn sem_trywait "sem_t *sem"
48 function decrements (locks) the semaphore pointed to by
50 but blocks if the value of
52 is zero, until the value is non-zero and the value can be decremented.
56 function decrements (locks) the semaphore pointed to by
58 only if the value is non-zero. Otherwise, the semaphore is not decremented and
70 points to an invalid semaphore.
78 The semaphore value was zero, and thus could not be decremented.