( int shmid, int start, int count )
shmop_read() will read a string from shared memory block.
shmop_read() takes 3 parameters: shmid, which is the shared
memory block identifier created by shmop_open(), offset from
which to start reading and count on the number of bytes to read.
Example 1. Reading shared memory block
$shm_data = shmop_read($shm_id, 0, 50);
This example will read 50 bytes from shared memory block and place the data