phpMan > man > IPC::SharedMem

NAME
    IPC::SharedMem - SysV Shared Memory IPC object class

SYNOPSIS
        use IPC::SysV qw(IPC_PRIVATE S_IRUSR S_IWUSR);
        use IPC::SharedMem;

        $shm = IPC::SharedMem->new(IPC_PRIVATE, 8, S_IRWXU);

        $shm->write(pack("S", 4711), 2, 2);

        $data = $shm->read(0, 2);

        $ds = $shm->stat;

        $shm->remove;

DESCRIPTION
    A class providing an object based interface to SysV IPC shared memory.

METHODS
    new ( KEY , SIZE , FLAGS )
        Creates a new shared memory segment of "SIZE" bytes size associated with "KEY". A new
        segment is created if

        *   "KEY" is equal to "IPC_PRIVATE"

        *   "KEY" does not already have a shared memory segment associated with it, and "*FLAGS* &
            IPC_CREAT" is true.

        On creation of a new shared memory segment "FLAGS" is used to set the permissions. Be
        careful not to set any flags that the Sys V IPC implementation does not allow: in some
        systems setting execute bits makes the operations fail.

    id  Returns the shared memory identifier.

    read ( POS, SIZE )
        Read "SIZE" bytes from the shared memory segment at "POS". Returns the string read, or
        "undef" if there was an error. The return value becomes tainted. See shmread.

    write ( STRING, POS, SIZE )
        Write "SIZE" bytes to the shared memory segment at "POS". Returns true if successful, or
        false if there is an error. See shmwrite.

    remove
        Remove the shared memory segment from the system or mark it as removed as long as any
        processes are still attached to it.

    is_removed
        Returns true if the shared memory segment has been removed or marked for removal.

    stat
        Returns an object of type "IPC::SharedMem::stat" which is a sub-class of "Class::Struct". It
        provides the following fields. For a description of these fields see you system
        documentation.

            uid
            gid
            cuid
            cgid
            mode
            segsz
            lpid
            cpid
            nattch
            atime
            dtime
            ctime

    attach ( [FLAG] )
        Permanently attach to the shared memory segment. When a "IPC::SharedMem" object is attached,
        it will use memread and memwrite instead of shmread and shmwrite for accessing the shared
        memory segment. Returns true if successful, or false on error. See shmat(2).

    detach
        Detach from the shared memory segment that previously has been attached to. Returns true if
        successful, or false on error. See shmdt(2).

    addr
        Returns the address of the shared memory that has been attached to in a format suitable for
        use with "pack('P')". Returns "undef" if the shared memory has not been attached.

SEE ALSO
    IPC::SysV, Class::Struct

AUTHORS
    Marcus Holland-Moritz <mhx AT cpan.org>

COPYRIGHT
    Version 2.x, Copyright (C) 2007-2013, Marcus Holland-Moritz.

    Version 1.x, Copyright (c) 1997, Graham Barr.

    This program is free software; you can redistribute it and/or modify it under the same terms as
    Perl itself.