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 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 .