SEM_POST(3) Linux Programmer's Manual SEM_POST(3)NAMEsem_post - unlock a semaphore
SYNOPSIS
#include <semaphore.h>
int sem_post(sem_t *sem);
DESCRIPTIONsem_post() increments (unlocks) the semaphore pointed to by sem. If
the semaphore's value consequently becomes greater than zero, then
another process or thread blocked in a sem_wait(3) call will be woken
up and proceed to lock the semaphore.
RETURN VALUEsem_post() returns 0 on success; on error, the value of the semaphore
is left unchanged, -1 is returned, and errno is set to indicate the
error.
ERRORS
EINVAL sem is not a valid semaphore.
CONFORMING TO
POSIX.1-2001.
NOTESsem_post() is async-signal-safe: it may be safely called within a sig‐
nal handler.
SEE ALSOsem_getvalue(3), sem_wait(3), sem_overview(7)Linux 2.6.16 2006-03-25 SEM_POST(3)