last update Jan 2, 2002 (hackie@prohost.org/ilia@prohost.org) Shared Memory Operations Extension to PHP	While developing a search deamon we needed a php based front end	to communicate the deamon via SHM. PHP already had a shared memory	extension (sysvshm) written by Christian Cartus <cartus@atrior.de>,	unfortunately this extension was designed with PHP only in mind and	offers high level features which are extremly bothersome for basic SHM	we had in mind. After spending a day trying to reverse engineer and figure	out the format of sysvshm we decided that it would be much easier to	add our own extension to php for simple SHM operations, we were right :)). the functions are: int shmop_open(int key, string flags, int mode, int size)	key	- the key of/for the shared memory block	flags	- 4 flags are avalible	a for read only access (sets SHM_RDONLY)	w for read & write access	c create or open an existing segment (sets IPC_CREATE)	n create a new segment and fail if one already exists under same name (sets IPC_CREATE|IPC_EXCL)	(the n flag is mostly useful for security perpouses, so that you don't end up opening a faked segment	if someone guesses your key)	mode	- acsess mode same as for a file (0644) for example	size	- size of the block in bytes	returns an indentifier char shmop_read(int shmid, int start, int count)	shmid	- shmid from which to read	start	- offset from which to start reading	count	- how many bytes to read	returns the data read int shmop_write(int shmid, string data, int offset)	shmid	- shmid from which to read	data	- string to put into shared memory	offset	- offset in shm to write from	returns bytes written int shmop_size(int shmid)	shmid	- shmid for which to return the size	returns the size in bytes of the shm segment int shmop_delete(int shmid)	marks the segment for deletion, the segment will be deleted when all processes mapping it will detach	shmid	- shmid which to mark for deletion	returns 1 if all ok, zero on failure int shmop_close(int shmid)	shmid	- shmid which to close	returns zero