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 postponed 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(), reuse 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. Otherwise, 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.

       ENAMETOOLONG
              The length of the name argument exceeds  {PATH_MAX}  or  a  pathname  component  is
              longer than {NAME_MAX}.

       ENOENT The named shared memory object does not exist.

       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

       None.

SEE ALSO

       close() , mmap() , munmap() , shmat() ,  shmctl()  ,  shmdt()  ,  shm_open()  ,  the  Base
       Definitions volume of IEEE Std 1003.1-2001, <sys/mman.h>

COPYRIGHT

       Portions  of  this  text  are  reprinted  and  reproduced in electronic form from IEEE Std
       1003.1, 2003 Edition, Standard for Information Technology  --  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 .