shm_attach
(PHP 4, PHP 5, PHP 7, PHP 8)
shm_attach — Creates or open a shared memory segment
Description
shm_attach() returns an id that can be used to access
the System V shared memory with the given key, the
first call creates the shared memory segment with
size and the optional perm-bits
permissions.
A second call to shm_attach() for the same
key will return a different SysvSharedMemory
instance, but both instances access the same underlying
shared memory. size and
permissions will be ignored.
Parameters
-
key -
A numeric shared memory segment ID
-
size -
The memory size. If not provided, default to the
sysvshm.init_memin the php.ini, otherwise 10000 bytes. -
permissions -
The optional permission bits. Default to 0666.
Return Values
Returns a SysvSharedMemory instance on success, or false on failure.
Changelog
| Version | Description |
|---|---|
| 8.0.0 | On success, this function returns an SysvSharedMemory instance now; previously, a resource was returned. |
| 8.0.0 |
size is nullable now.
|
See Also
- shm_detach() - Disconnects from shared memory segment
- ftok() - Convert a pathname and a project identifier to a System V IPC key
