SEM_CLOSE(P) POSIX Programmer's Manual SEM_CLOSE(P)
sem_close - close a named semaphore (REALTIME)
int sem_close(sem_t *sem);
The sem_close() function shall indicate that the calling process is finished using the
named semaphore indicated by sem. The effects of calling sem_close() for an unnamed sema-
phore (one created by sem_init()) are undefined. The sem_close() function shall deallocate
(that is, make available for reuse by a subsequent sem_open() by this process) any system
resources allocated by the system for use by this process for this semaphore. The effect
of subsequent use of the semaphore indicated by sem by this process is undefined. If the
semaphore has not been removed with a successful call to sem_unlink(), then sem_close()
has no effect on the state of the semaphore. If the sem_unlink() function has been suc-
cessfully invoked for name after the most recent call to sem_open() with O_CREAT for this
semaphore, then when all processes that have opened the semaphore close it, the semaphore
is no longer accessible.
Upon successful completion, a value of zero shall be returned. Otherwise, a value of -1
shall be returned and errno set to indicate the error.
The sem_close() function shall fail if:
EINVAL The sem argument is not a valid semaphore descriptor.
The following sections are informative.
The sem_close() function is part of the Semaphores option and need not be available on all
semctl() , semget() , semop() , sem_init() , sem_open() , sem_unlink() , the Base Defini-
tions volume of IEEE Std 1003.1-2001, <semaphore.h>
Portions of this text are reprinted and reproduced in electronic form from IEEE Std
1003.1, 2003 Edition, Standard for Information Technology -- Portable Operating System
Interface (POSIX), The Open Group Base Specifications Issue 6, Copyright (C) 2001-2003 by
the Institute of Electrical and Electronics Engineers, Inc and The Open Group. In the
event of any discrepancy between this version and the original IEEE and The Open Group
Standard, the original IEEE and The Open Group Standard is the referee document. The orig-
inal Standard can be obtained online at http://www.opengroup.org/unix/online.html .
IEEE/The Open Group 2003 SEM_CLOSE(P)