SEM_CLOSE(3P)						     POSIX Programmer's Manual						     SEM_CLOSE(3P)

PROLOG

       This  manual page is part of the POSIX Programmer's Manual.  The Linux implementation of this interface may differ (consult the correspond-
       ing Linux manual page for details of Linux behavior), or the interface may not be implemented on Linux.

NAME

       sem_close - close a named semaphore (REALTIME)

SYNOPSIS

       #include <semaphore.h>

       int sem_close(sem_t *sem);

DESCRIPTION

       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 semaphore (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  successfully  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.

RETURN VALUE

       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.

ERRORS

       The sem_close() function shall fail if:

       EINVAL The sem argument is not a valid semaphore descriptor.

       The following sections are informative.

EXAMPLES

       None.

APPLICATION USAGE

       The sem_close() function is part of the Semaphores option and need not be available on all implementations.

RATIONALE

       None.

FUTURE DIRECTIONS

       None.

SEE ALSO

       semctl(), semget(), semop(), sem_init(), sem_open(), sem_unlink(), the Base Definitions volume of IEEE Std 1003.1-2001, <semaphore.h>

COPYRIGHT

       Portions of this text are reprinted and reproduced in electronic form from IEEE Std 1003.1, 2003 Edition, Standard for Information Technol-
       ogy -- 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 original Standard can  be  obtained
       online at http://www.opengroup.org/unix/online.html .

IEEE
/The Open Group						       2003							     SEM_CLOSE(3P)