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IPC::SharedMem(3pm)    Perl Programmers Reference Guide    IPC::SharedMem(3pm)




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

           o   "KEY" is equal to "IPC_PRIVATE"

           o   "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(3), Class::Struct(3)


AUTHORS

       Marcus Holland-Moritz <mhx@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.



perl v5.24.0                      2016-03-19               IPC::SharedMem(3pm)

perl 5.24 - Generated Mon Nov 14 18:59:55 CST 2016
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