NAME

sem_close − Deallocates the specified named semaphore (P1003.1b)

SYNOPSIS

#include <semaphore.h>
 
int sem_close (
sem_t ∗sem) ;

LIBRARY

Realtime Library (librt.so, librt.a)

PARAMETERS

semReferences the semaphore to be closed.  Use the sem argument returned by the previous call to sem_open. 

DESCRIPTION

The sem_close function makes a semaphore available for reuse by deallocating any system resources allocated for use by the current process for the named semaphore indicated by sem. 

If the semaphore has not been removed with a call to sem_unlink, sem_close does not change the current state of the semaphore. 

If the semaphore has been removed with a call to sem_unlink after the most recent call to sem_open with O_CREAT, the semaphore is no longer available after all processes that opened the semaphore close it. 

RETURN VALUES

On a successful call, a value of 0 (zero) is returned. Otherwise, a value of −1 is returned and errno is set to indicate that an error occurred. 

ERRORS

The sem_close function fails under the following condition:

[EINVAL]
The sem argument is not a valid semaphore descriptor. 

SEE ALSO

Functions: sem_init(3), sem_open(3), sem_unlink(3)

Guide to Realtime Programming