SEM_GET(3) 1 SEM_GET(3)
sem_get - Get a semaphore id
SYNOPSIS
resource sem_get (int $key, [int $max_acquire = 1], [int $perm = 0666], [int $auto_release = 1])
DESCRIPTION
sem_get(3) returns an id that can be used to access the System V semaphore with the given $key.
A second call to sem_get(3) for the same key will return a different semaphore identifier, but both identifiers access the same underlying
semaphore.
PARAMETERS
o $key
-
o $max_acquire
- The number of processes that can acquire the semaphore simultaneously is set to $max_acquire.
o $perm
- The semaphore permissions. Actually this value is set only if the process finds it is the only process currently attached to the
semaphore.
o $auto_release
- Specifies if the semaphore should be automatically released on request shutdown.
RETURN VALUES
Returns a positive semaphore identifier on success, or FALSE on error.
CHANGELOG
+--------+-----------------------------------------+
|Version | |
| | |
| | Description |
| | |
+--------+-----------------------------------------+
| 4.3.0 | |
| | |
| | The $auto_release parameter was added. |
| | |
+--------+-----------------------------------------+
NOTES
Warning
When using sem_get(3) to access a semaphore created outside PHP, note that the semaphore must have been created as a set of 3 sema-
phores (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(3), sem_release(3), ftok(3).
PHP Documentation Group SEM_GET(3)
