sem_get

(PHP 4, PHP 5, PHP 7)

sem_get ¡ª Get a semaphore id

Description

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.

Return Values

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

Notes

Warning

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

¡û sem_acquire

sem_release ¡ú

Licensed under the Creative Commons Attribution License v3.0 or later.

https://secure.php.net/manual/en/function.sem-get.php