NAME

sem_post - increment (unlock) a semaphore

LIBRARY

POSIX Real-time Library (librt, -lrt)

SYNOPSIS



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

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'') .