IPC::SharedMem(3p) Perl Programmers Reference Guide IPC::SharedMem(3p) #
IPC::SharedMem(3p) Perl Programmers Reference Guide IPC::SharedMem(3p)
NNAAMMEE #
IPC::SharedMem - SysV Shared Memory IPC object class
SSYYNNOOPPSSIISS #
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;
DDEESSCCRRIIPPTTIIOONN #
A class providing an object based interface to SysV IPC shared memory.
MMEETTHHOODDSS #
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 "_F_L_A_G_S & 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
sshhmmaatt(2).
detach
Detach from the shared memory segment that previously has been
attached to. Returns true if successful, or false on error. See
sshhmmddtt(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.
SSEEEE AALLSSOO #
IPC::SysV, Class::Struct
AAUUTTHHOORRSS #
Marcus Holland-Moritz <mhx@cpan.org>
CCOOPPYYRRIIGGHHTT #
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 v5.36.3 2023-02-15 IPC::SharedMem(3p)