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SHM_UNLINK(3P)             POSIX Programmer's Manual            SHM_UNLINK(3P)
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
       shm_unlink -- remove a shared memory object (REALTIME)
SYNOPSIS
       #include <sys/mman.h>
       int shm_unlink(const char *name);
DESCRIPTION
       The shm_unlink() function shall remove the name of  the  shared  memory
       object named by the string pointed to by name.
       If  one  or  more references to the shared memory object exist when the
       object is unlinked, the  name  shall  be  removed  before  shm_unlink()
       returns,  but  the removal of the memory object contents shall be post-
       poned until all open and map references to  the  shared  memory  object
       have been removed.
       Even  if the object continues to exist after the last shm_unlink(), re-
       use of the name shall subsequently cause shm_open() to behave as if  no
       shared memory object of this name exists (that is, shm_open() will fail
       if O_CREAT is not set, or will create a new  shared  memory  object  if
       O_CREAT is set).
RETURN VALUE
       Upon  successful completion, a value of zero shall be returned.  Other-
       wise, a value of -1 shall be returned and errno  set  to  indicate  the
       error.  If  -1 is returned, the named shared memory object shall not be
       changed by this function call.
ERRORS
       The shm_unlink() function shall fail if:
       EACCES Permission is denied to unlink the named shared memory object.
       ENOENT The named shared memory object does not exist.
       The shm_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 shm_unlink() with a name argument that con-
              tains the same shared memory object name as was previously  used
              in a successful shm_open() call shall not give an [ENAMETOOLONG]
              error.
       The following sections are informative.
EXAMPLES
       None.
APPLICATION USAGE
       Names of memory objects that were allocated  with  open()  are  deleted
       with  unlink()  in the usual fashion. Names of memory objects that were
       allocated with shm_open() are deleted with shm_unlink().  Note that the
       actual memory object is not destroyed until the last close and unmap on
       it have occurred if it was already in use.
RATIONALE
       None.
FUTURE DIRECTIONS
       A future version might require the shm_open()  and  shm_unlink()  func-
       tions to have semantics similar to normal file system operations.
SEE ALSO
       close(), mmap(), munmap(), shmat(), shmctl(), shmdt(), shm_open()
       The Base Definitions volume of POSIX.1-2008, <sys_mman.h>
COPYRIGHT
       Portions  of  this text are reprinted and reproduced in electronic form
       from IEEE Std 1003.1, 2013 Edition, Standard for Information Technology
       --  Portable  Operating  System  Interface (POSIX), The Open Group Base
       Specifications Issue 7, Copyright (C) 2013 by the Institute of Electri-
       cal  and  Electronics  Engineers,  Inc  and  The  Open Group.  (This is
       POSIX.1-2008 with the 2013 Technical Corrigendum  1  applied.)  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.unix.org/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.ker-
       nel.org/doc/man-pages/reporting_bugs.html .
IEEE/The Open Group                  2013                       SHM_UNLINK(3P)