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Creates or open a shared memory segment


shm_attach

(PHP 4, PHP 5)

shm_attachCreates or open a shared memory segment

Description

resource shm_attach ( int $key [, int $memsize [, int $perm ]] )

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 memsize and the optional perm-bits perm.

A second call to shm_attach() for the same key will return a different shared memory identifier, but both identifiers access the same underlying shared memory. memsize and perm will be ignored.

Parameters

key

A numeric shared memory segment ID

memsize

The memory size. If not provided, default to the sysvshm.init_mem in the php.ini, otherwise 10000 bytes.

perm

The optional permission bits. Default to 0666.

Return Values

Returns a shared memory segment identifier.

See Also

  • shm_detach() - Disconnects from shared memory segment
  • ftok() - Convert a pathname and a project identifier to a System V IPC key

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