Sends data to a connected socket - Справочник: PHP5.4

int socket_send ( resource $socket , string $buf , int $len , int $flags )

The function socket_send() sends len bytes to the socket socket from buf.

socket

A valid socket resource created with socket_create() or socket_accept().

buf

A buffer containing the data that will be sent to the remote host.

len

The number of bytes that will be sent to the remote host from buf.

flags

The value of flags can be any combination of the following flags, joined with the binary OR (|) operator.

Possible values for *`flags`*
`MSG_OOB`	Send OOB (out-of-band) data.
`MSG_EOR`	Indicate a record mark. The sent data completes the record.
`MSG_EOF`	Close the sender side of the socket and include an appropriate notification of this at the end of the sent data. The sent data completes the transaction.
`MSG_DONTROUTE`	Bypass routing, use direct interface.

socket_send() returns the number of bytes sent, or FALSE on error.