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 Definitions volume of
       IEEE Std 1003.1-2001, Section 3.340, Shared Memory Object). It is unspecified whether this
       function  interoperates with the realtime interprocess communication facilities defined in
       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.

       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  interprocess
       communication. Application developers who need to use IPC should design their applications
       so  that modules using the IPC routines described in XSI Interprocess Communication can be
       easily modified to use the alternative interfaces.

RATIONALE

       None.

FUTURE DIRECTIONS

       None.

SEE ALSO

       XSI Interprocess Communication , Realtime , exec() , exit() , fork() , shmat() ,  shmctl()
       ,   shmget()   ,   shm_open()   ,   shm_unlink()   ,   the   Base  Definitions  volume  of
       IEEE Std 1003.1-2001, <sys/shm.h>

COPYRIGHT

       Portions of this text are reprinted and  reproduced  in  electronic  form  from  IEEE  Std
       1003.1,  2003  Edition,  Standard  for Information Technology -- Portable Operating System
       Interface (POSIX), The Open Group Base Specifications Issue 6, Copyright (C) 2001-2003  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 .