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NetBSD 6.1.5 - man page for sem_post (netbsd section 3)

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SEM_POST(3)			   BSD Library Functions Manual 		      SEM_POST(3)

NAME
     sem_post -- increment (unlock) a semaphore

LIBRARY
     POSIX Real-time Library (librt, -lrt)

SYNOPSIS
     #include <semaphore.h>

     int
     sem_post(sem_t *sem);

DESCRIPTION
     The sem_post() function increments (unlocks) the semaphore pointed to by sem.  If there are
     threads blocked on the semaphore when sem_post() is called, then the highest priority thread
     that has been blocked the longest on the semaphore will be allowed to return from
     sem_wait().

     sem_post() is signal-reentrant and may be called within signal handlers.

RETURN VALUES
     The sem_post() function returns the value 0 if successful; otherwise the value -1 is
     returned and the global variable errno is set to indicate the error.

ERRORS
     sem_post() will fail if:

     [EINVAL]		sem points to an invalid semaphore.

SEE ALSO
     sem_trywait(3), sem_wait(3)

STANDARDS
     sem_post() conforms to ISO/IEC 9945-1:1996 (``POSIX.1'').

BSD					 January 22, 2003				      BSD
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