not run shell

i want run php shell on server
server is redhat 7.2 run php 4.2.3

script content
#!/usr/bin/php
<?
...........
if (($sock = socket_create AF_INET, SOCK_STREAM, 0)) < 0) {
echo "socket_create() failed: reason: " . socket_strerror ($sock) . "n";
}
..............
?>
ans tell me not call socket_create
can't not found.
but' /usr/bin/php can run other unctin.
who can help me
thank's

You'll need to recompile PHP with

--enable-sockets