Semaphores with key of 0

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LEARN ABOUT PHP

sem_get

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)

UNIX for Advanced & Expert Users