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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)