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SEM_POST(2)                 BSD System Calls Manual                SEM_POST(2)

NAME
     sem_post -- unlock a semaphore

SYNOPSIS
     #include <semaphore.h>

     int
     sem_post(sem_t *sem);

DESCRIPTION
     The semaphore referenced by sem is unlocked, the value of the semaphore
     is incremented, and all threads which are waiting on the semaphore are
     awakened.

     sem_post() is reentrant with respect to signals and may be called from
     within a signal hanlder.

     If successful, sem_post() will return 0.  Otherwise, -1 is returned and
     errno is set.

ERRORS
     sem_post() succeeds unless:

     [EINVAL]           sem is not a valid semaphore descriptor.

SEE ALSO
     sem_open(2), sem_trywait(2), sem_wait(2), semctl(2), semget(2), semop(2)

HISTORY
     sem_post() is specified in the POSIX Realtime Extension
     (1003.1b-1993/1003.1i-1995).

Darwin                           June 8, 2000                           Darwin