all about shared memory Post: 100500

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LEARN ABOUT SUSE

ipc::sharedmem

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 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
	       nattach
	       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.

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

       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@cpan.org>

COPYRIGHT

       Version 2.x, Copyright (C) 2007, 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 v5.12.1							    2010-04-26						       IPC::SharedMem(3pm)

10 More Discussions You Might Find Interesting

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Discussion started by: joseph_shibu

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help with shared memory

Discussion started by: ddx08