SEM_UNLINK(3)              POSIX Programmer's Manual             SEM_UNLINK(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_unlink -- remove a named semaphore

SYNOPSIS
       #include <semaphore.h>

       int sem_unlink(const char *name);

DESCRIPTION
       The sem__unlink() function shall remove the semaphore named by the
       string name.  If the semaphore named by name is currently referenced by
       other processes, then sem__unlink() shall have no effect on the state of
       the semaphore. If one or more processes have the semaphore open when
       sem__unlink() is called, destruction of the semaphore is postponed until
       all references to the semaphore have been destroyed by calls to
       sem__close(), __exit(), or exec.  Calls to sem__open() to recreate or
       reconnect to the semaphore refer to a new semaphore after sem__unlink()
       is called. The sem__unlink() call shall not block until all references
       have been destroyed; it shall return immediately.

RETURN VALUE
       Upon successful completion, the sem__unlink() function shall return a
       value of 0. Otherwise, the semaphore shall not be changed and the
       function shall return a value of -1 and set errno to indicate the
       error.

ERRORS
       The sem__unlink() function shall fail if:

       EACCES Permission is denied to unlink the named semaphore.

       ENOENT The named semaphore does not exist.

       The sem__unlink() function may fail if:

       ENAMETOOLONG
              The length of the name argument exceeds {_POSIX_PATH_MAX} on
              systems that do not support the XSI option or exceeds
              {_XOPEN_PATH_MAX} on XSI systems, or has a pathname component
              that is longer than {_POSIX_NAME_MAX} on systems that do not
              support the XSI option or longer than {_XOPEN_NAME_MAX} on XSI
              systems.  A call to sem__unlink() with a name argument that
              contains the same semaphore name as was previously used in a
              successful sem__open() call shall not give an [ENAMETOOLONG]
              error.

       The following sections are informative.

EXAMPLES
       None.

APPLICATION USAGE
       None.

RATIONALE
       None.

FUTURE DIRECTIONS
       A future version might require the sem__open() and sem__unlink()
       functions to have semantics similar to normal file system operations.

SEE ALSO
       semctl(), semget(), semop(), sem__close(), sem__open()

       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_UNLINK(3)
