shmop_open() can create or open a shared memory block.
System's id for the shared memory block. Can be passed as a decimal or hex.
The flags that you can use:
The permissions that you wish to assign to your memory segment, those
are the same as permission for a file. Permissions need to be passed
in octal form, like for example
The size of the shared memory block you wish to create in bytes
Note: the 3rd and 4th should be entered as 0 if you are opening an existing memory segment.
On success shmop_open() will return an id that you can
use to access the shared memory segment you've created.
returned on failure.
$shm_key = ftok(__FILE__, 't');
$shm_id = shmop_open($shm_key, "c", 0644, 100);
This example opened a shared memory block with a system id returned by ftok().