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).