(PHP 4, PHP 5, PHP 7, PHP 8)
shm_attach — Creates or open a shared memory segment
shm_attach(int $key, ?int $size = null, int $permissions = 0666): SysvSharedMemory|false
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.
keyA numeric shared memory segment ID
size The memory size. If not provided, default to the sysvshm.init_mem in the php.ini, otherwise 10000 bytes.
permissionsThe optional permission bits. Default to 0666.
Returns a SysvSharedMemory instance on success, or false on failure.
| 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. |
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https://www.php.net/manual/en/function.shm-attach.php