Php/docs/function.shm-attach
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shm_attach
(PHP 4, PHP 5, PHP 7)
shm_attach — Creates or open a shared memory segment
说明
shm_attach
( int $key
[, int|null $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.
参数
key- A numeric shared memory segment ID
size- The memory size. If not provided, default to the
sysvshm.init_memin thephp.ini, otherwise 10000 bytes. permissions- The optional permission bits. Default to 0666.
返回值
Returns a SysvSharedMemory instance on success, 或者在失败时返回 false.
更新日志
| 版本 | 说明 |
|---|---|
| 8.0.0 | On success, this function returns an SysvSharedMemory instance now;
previously, a resource was returned. |
| 8.0.0 | size is nullable now.
|
参见
- shm_detach() - Disconnects from shared memory segment
- ftok() - Convert a pathname and a project identifier to a System V IPC key
