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SHM_UNLINK(3P) POSIX Programmer's Manual SHM_UNLINK(3P)
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.
shm_unlink — remove a shared memory object (REALTIME)
#include <sys/mman.h>
int shm_unlink(const char *name);
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).
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.
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
contains 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.
None.
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.
None.
A future version might require the shm_open() and shm_unlink()
functions to have semantics similar to normal file system operations.
close(3p), mmap(3p), munmap(3p), shmat(3p), shmctl(3p), shmdt(3p),
shm_open(3p)
The Base Definitions volume of POSIX.1‐2008, sys_mman.h(0p)
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 Electrical 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.kernel.org/doc/man-pages/reporting_bugs.html .
IEEE/The Open Group 2013 SHM_UNLINK(3P)
Pages that refer to this page: sys_mman.h(0p), shmat(3p), shmctl(3p), shmdt(3p), shmget(3p), shm_open(3p)