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 .

IEEE/The Open Group                                   2003                                         SHM_UNLINK(P)