PROLOG

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

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 .