Section: User Contributed Perl Documentation (3)
IPC::SharedMem - SysV Shared Memory IPC object class
use IPC::SysV qw(IPC_PRIVATE S_IRUSR S_IWUSR);
$shm = IPC::SharedMem->new(IPC_PRIVATE, 8, S_IRWXU);
$shm->write(pack("S", 4711), 2, 2);
$data = $shm->read(0, 2);
$ds = $shm->stat;
A class providing an object based interface to SysV IPC
- 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.
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 the shared memory segment from the system or mark it as
removed as long as any processes are still attached to it.
Returns true if the shared memory segment has been removed or
marked for removal.
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.
- 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 from the shared memory segment that previously has been attached
to. Returns true if successful, or false on error. See shmdt(2).
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.
Marcus Holland-Moritz <firstname.lastname@example.org
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.