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shm_get_var	shm_put_var

Semaphore Functions	Last updated: Mon, 26 Oct 2026

shm_has_var

(PHP 5 >= 5.3.0, PHP 7, PHP 8)

shm_has_var — Check whether a specific entry exists

Description

function shm_has_var(SysvSharedMemory $shm, int $key): bool

Checks whether a specific key exists inside a shared memory segment.

Parameters

shm: A shared memory segment obtained from shm_attach().
key: The variable key.

Return Values

Returns true if the entry exists, otherwise false

Errors/Exceptions

Throws an Error if shm has already been detached with shm_detach().

Changelog

Version	Description
8.0.0	`shm` expects a SysvSharedMemory instance now; previously, a resource was expected.

See Also

shm_get_var() - Returns a variable from shared memory
shm_put_var() - Inserts or updates a variable in shared memory

shm_get_var	shm_put_var

Semaphore Functions	Last updated: Mon, 26 Oct 2026