shmdt(3p) — Linux manual page

SHMDT(3P)               POSIX Programmer's Manual              SHMDT(3P)

PROLOG         top

       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         top

       shmdt — XSI shared memory detach operation

SYNOPSIS         top

       #include <sys/shm.h>

       int shmdt(const void *shmaddr);

DESCRIPTION         top

       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.

RETURN VALUE         top

       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         top

       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         top

       None.

APPLICATION USAGE         top

       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.

RATIONALE         top

       None.

FUTURE DIRECTIONS         top

       None.

SEE ALSO         top

       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)

COPYRIGHT         top

       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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