SHM_UNLINK(P) POSIX Programmer's Manual SHM_UNLINK(P)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.
NAMEshm_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.
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 ALSOclose() , 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)
