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Description
$key
[, int $max_acquire = 1
[, int $perm = 0666
[, int $auto_release = 1
]]] ) : resource
sem_get() returns an id that can be used to
access the System V semaphore with the given key.
A second call to sem_get() for the same key will return a different semaphore identifier, but both identifiers access the same underlying semaphore.
Parameters
-
key -
-
max_acquire -
The number of processes that can acquire the semaphore simultaneously is set to
max_acquire. -
perm -
The semaphore permissions. Actually this value is set only if the process finds it is the only process currently attached to the semaphore.
-
auto_release -
Specifies if the semaphore should be automatically released on request shutdown.
Notes
When using sem_get() to access a semaphore created outside PHP, note that the semaphore must have been created as a set of 3 semaphores (for example, by specifying 3 as the nsems parameter when calling the C semget() function), otherwise PHP will be unable to access the semaphore.
See Also
- sem_acquire() - Acquire a semaphore
- sem_release() - Release a semaphore
- ftok() - Convert a pathname and a project identifier to a System V IPC key
English translation
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Document created the 30/01/2003, last modified the 26/10/2018
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References
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