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# sem_get

(PHP 3 >= 3.0.6, PHP 4, PHP 5)

sem_get -- Get a semaphore id

## Description

resource sem_get ( int key [, int max_acquire [, int perm [, int auto_release]]] )

sem_get() returns an id that can be used to access the System V semaphore with the given `key`. The semaphore is created if necessary using the permission bits specified in `perm` (defaults to 0666). The number of processes that can acquire the semaphore simultaneously is set to `max_acquire` (defaults to 1). Actually this value is set only if the process finds it is the only process currently attached to the semaphore.

Optional parameter `auto_release` specifies if the semaphore should be automatically released on request shutdown. It is available since PHP 4.3.0.

Returns a positive semaphore identifier on success, or `FALSE` on error.

A second call to sem_get() for the same key will return a different semaphore identifier, but both identifiers access the same underlying semaphore.

See also sem_acquire(), sem_release(), and ftok().

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