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PROLOG | NAME | SYNOPSIS | DESCRIPTION | RETURN VALUE | ERRORS | EXAMPLES | APPLICATION USAGE | RATIONALE | FUTURE DIRECTIONS | SEE ALSO | COPYRIGHT |
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SHMDT(3P) POSIX Programmer's Manual SHMDT(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.
shmdt — XSI shared memory detach operation
#include <sys/shm.h>
int shmdt(const void *shmaddr);
The shmdt() function operates on XSI shared memory (see the Base
Definitions volume of POSIX.1‐2017, Section 3.346, 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.
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.
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.
None.
The POSIX Realtime Extension defines alternative interfaces for
interprocess 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.
None.
None.
Section 2.7, XSI Interprocess Communication, Section 2.8,
Realtime, exec(1p), exit(3p), fork(3p), shmat(3p), shmctl(3p),
shmget(3p), shm_open(3p), shm_unlink(3p)
The Base Definitions volume of POSIX.1‐2017, Section 3.346, Shared
Memory Object, sys_shm.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 SHMDT(3P)
Pages that refer to this page: sys_shm.h(0p), ipcs(1p), shmat(3p), shmctl(3p), shmget(3p), shm_open(3p), shm_unlink(3p)
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HTML rendering created 2025-09-06 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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