php man page for shm_attach

SHM_ATTACH(3)								 1							     SHM_ATTACH(3)

shm_attach - Creates or open a shared memory segment

SYNOPSIS
       resource shm_attach (int  $key, [int  $memsize], [int  $perm = 0666])

DESCRIPTION
       shm_attach(3)  returns  an  id that can be used to access the System V shared memory with the given $key, the first call creates the shared
       memory segment with $memsize and the optional perm-bits $perm.

	A second call to shm_attach(3) for the same $key will return a different shared memory identifier, but both identifiers  access  the  same
       underlying shared memory. $memsize and $perm will be ignored.

PARAMETERS
	      o $key
		- A numeric shared memory segment ID

	      o $memsize
		- The memory size. If not provided, default to the sysvshm.init_mem in the php.ini, otherwise 10000 bytes.

	      o $perm
		- The optional permission bits. Default to 0666.

RETURN VALUES
	Returns a shared memory segment identifier.

CHANGELOG
       +--------+---------------------------------------------------+
       |Version |						    |
       |	|						    |
       |	|		     Description		    |
       |	|						    |
       +--------+---------------------------------------------------+
       | 5.3.0	|						    |
       |	|						    |
       |	|  This  function now returns a resource instead of |
       |	| an integer.					    |
       |	|						    |
       +--------+---------------------------------------------------+
NOTES
       Note

	       This function used to return an integer value prior to PHP 5.3.0. To achieve the same value in a portable manner, the return  value
	      can be cast to an integer like:

	      Example #1

		     <?php
		     // Create a temporary file and return its path
		     $tmp = tempnam('/tmp', 'PHP');

		     // Get the file token key
		     $key = ftok($tmp, 'a');

		     // Attach the SHM resource, notice the cast afterwards
		     $id = shm_attach($key);

		     if ($id === false) {
			 die('Unable to create the shared memory segment');
		     }

		     // Cast to integer, since prior to PHP 5.3.0 the resource id
		     // is returned which can be exposed when casting a resource
		     // to an integer
		     $id = (integer) $id;
		     ?>

SEE ALSO
       shm_detach(3), ftok(3).

PHP Documentation Group 													     SHM_ATTACH(3)