shmget


>>-shmget--key--+-----------------+--permissions---------------><
                '-size--+-------+-'                
                        '-flags-'

Function

shmget locates or creates a shared memory segment.

Parameters

key

The memory segment key. The value must be 4 bytes.

size

The size of the shared memory segment. The default is 0.

flags

The type of connection. The default is either 0, which obtains the existing queue, or a sum of any of the following flags:

IPC_CREAT

Creates an entry if the key does not exist.

IPC_EXCL

Fails if the key exists.

IPC_MEGA

Allocates in megabytes.

IPC_SHAREAS

Shares within an address space.

permissions

Permission settings in octal (the default is 600). It is dependent on the flags being specified.

Example

'shmget WJSM 4096 (ipc_creat)'

Usage notes

Upon return, RETVAL contains -1 if the service failed. Otherwise, the segment ID is returned.