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PROLOG | NAME | SYNOPSIS | DESCRIPTION | RETURN VALUE | ERRORS | EXAMPLES | APPLICATION USAGE | RATIONALE | FUTURE DIRECTIONS | SEE ALSO | COPYRIGHT |
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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.1‐2017, sys_mman.h(0p)
Portions of this text are reprinted and reproduced in electronic
form from IEEE Std 1003.1-2017, Standard for Information
Technology -- Portable Operating System Interface (POSIX), The
Open Group Base Specifications Issue 7, 2018 Edition, Copyright
(C) 2018 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 .
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 2017 SHM_UNLINK(3P)
Pages that refer to this page: sys_mman.h(0p), shmat(3p), shmctl(3p), shmdt(3p), shmget(3p), shm_open(3p)
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HTML rendering created 2024-06-26 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. |
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