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SHMDT(3P) POSIX Programmer's Manual SHMDT(3P)
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.
NAME
shmdt — XSI shared memory detach operation
SYNOPSIS
#include <sys/shm.h>
int shmdt(const void *shmaddr);
DESCRIPTION
The shmdt() function operates on XSI shared memory (see the Base Defi‐
nitions volume of POSIX.1‐2008, Section 3.342, Shared Memory Object).
It is unspecified whether this function interoperates with the realtime
interprocess communication facilities defined in Section 2.8, Realtime.
The shmdt() function detaches the shared memory segment located at the
address specified by shmaddr from the address space of the calling
process.
RETURN VALUE
Upon successful completion, shmdt() shall decrement the value of
shm_nattch in the data structure associated with the shared memory ID
of the attached shared memory segment and return 0. Also, the shm_dtime
timestamp shall be set to the current time, as described in Section
2.7.1, IPC General Description.
Otherwise, the shared memory segment shall not be detached, shmdt()
shall return −1, and errno shall be set to indicate the error.
ERRORS
The shmdt() function shall fail if:
EINVAL The value of shmaddr is not the data segment start address of a
shared memory segment.
The following sections are informative.
EXAMPLES
None.
APPLICATION USAGE
The POSIX Realtime Extension defines alternative interfaces for inter‐
process communication. Application developers who need to use IPC
should design their applications so that modules using the IPC routines
described in Section 2.7, XSI Interprocess Communication can be easily
modified to use the alternative interfaces.
RATIONALE
None.
FUTURE DIRECTIONS
None.
SEE ALSO
Section 2.7, XSI Interprocess Communication, Section 2.8, Realtime,
exec, exit(), fork(), shmat(), shmctl(), shmget(), shm_open(),
shm_unlink()
The Base Definitions volume of POSIX.1‐2008, Section 3.342, Shared Mem‐
ory Object, <sys_shm.h>
COPYRIGHT
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 Electri‐
cal 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.ker‐
nel.org/doc/man-pages/reporting_bugs.html .
IEEE/The Open Group 2013 SHMDT(3P)
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