perldoc > IPC::SharedMem

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📛 NAME

IPC::SharedMem - SysV Shared Memory IPC object class

🚀 Quick Reference

Use Case	Command	Description
🆕 Create segment	$shm = IPC::SharedMem->new(IPC_PRIVATE, 1024, S_IRWXU);	Create a new shared memory segment
✍️ Write data	$shm->write($data, 0, 4);	Write bytes at a position
📖 Read data	$data = $shm->read(0, 4);	Read bytes from a position
📊 Get stats	$ds = $shm->stat;	Retrieve segment metadata
🔗 Attach	$shm->attach;	Permanently attach for memread/memwrite
🔌 Detach	$shm->detach;	Detach previously attached segment
🗑️ Remove	$shm->remove;	Remove the segment from the system

📄 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 your 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.

📛 NAME 🚀 Quick Reference 📄 SYNOPSIS 📖 DESCRIPTION 🛠️ METHODS 🔗 SEE ALSO 👥 AUTHORS ©️ COPYRIGHT