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



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

NAME
       sem_close -- close a named semaphore

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 any threads
       in the calling process are currently blocked on the semaphore, the
       behavior 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 may fail if:

       EINVAL The sem argument is not a valid semaphore descriptor.

       The following sections are informative.

EXAMPLES
       None.

APPLICATION USAGE
       None.

RATIONALE
       None.

FUTURE DIRECTIONS
       None.

SEE ALSO
       semctl(), semget(), semop(), sem__init(), sem__open(), sem__unlink()

       The Base Definitions volume of POSIX.1-2017, <semaphore.h>

COPYRIGHT
       Portions of this text are reprinted and reproduced in electronic form
       from IEEE Std 1003.1-2017, Standard for Information Technology --
       Portable Operating System Interface (POSIX), The Open Group Base
       Specifications Issue 7, 2018 Edition, Copyright (C) 2018 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 .

       Any typographical or formatting errors that appear in this page are
       most likely to have been introduced during the conversion of the source
       files to man page format. To report such errors, see
       https://www.kernel.org/doc/man-pages/reporting_bugs.html .



IEEE/The Open Group                  2017                         SEM_CLOSE(3)
