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send(2)
NAME
  send - Sends messages on a socket

SYNOPSIS
  #include <sys/socket.h>
  ssize_t send (
	  int socket,
	  const void *buffer,
	  size_t length,
	  int flags );

  [Digital]  The following definition of the send() function  does not
  conform to current standards and is supported only for backward
  compatibility (see standards(5)):

  int send (
	  int socket,
	  char *message,
	  int length,
	  int flags );

STANDARDS
  Interfaces documented on this reference page conform to industry standards
  as follows:

  send(): XPG4-UNIX

  Refer to the standards(5) reference page for more information about
  industry standards and associated tags.

PARAMETERS
  socket    Specifies the unique name for the socket.

  buffer    Points to the buffer containing the message to send.

  length    Specifies the length of the message in bytes.

  flags	    Allows the sender to control the transmission of the message.
	    The flags parameter to send a call is formed by logically ORing
	    the values shown in the following list, defined in the
	    sys/socket.h header file:

	    MSG_OOB   Sends out-of-band data on sockets that support out-of-
		      band communication.

	    MSG_DONTROUTE
		      Sends without using routing tables.  (Not recommended,
		      for debugging purposes only.)


DESCRIPTION
  The send() function sends a message only when the socket is connected.  The
  sendto() and sendmsg() functions can be used with unconnected or connected
  sockets.

  Specify the length of the message with the length parameter.	If the
  message is too long to pass through the underlying protocol, the system
  returns an error and does not transmit the message.

  No indication of failure to deliver is implied in a send() function.	A
  return value of -1 indicates only locally detected errors.

  If no space for messages is available at the sending socket to hold the
  message to be transmitted, the send() function blocks unless the socket is
  in a nonblocking I/O mode.  Use the select() function to determine when it
  is possible to send more data.

NOTES
  [Digital] The send() function is identical to the sendto() function with a
  zero-valued dest_len parameter, and to the write() function if no flags are
  used.	 For that reason, the send() function is disabled when 4.4BSD
  behavior is enabled (that is, when the _SOCKADDR_LEN compile-time option is
  defined).

RETURN VALUES
  Upon successful completion, the send() function returns the number of
  characters sent.  Otherwise, a value of -1 is returned and errno is set to
  indicate the error.

ERRORS
  If the send() function fails, errno may be set to one of the following
  values:

  [EBADF]   The socket parameter is not valid.

  [ECONNRESET]
	    A connection was forcibly closed by a peer.

  [EDESTADDRREQ]
	    The socket is not connection-oriented and no peer address is set.

  [EFAULT]  The message parameter is not in a readable or writable part of
	    the user address space.

  [EINTR]   A signal interrupted send before any data was transmitted.

  [EMSGSIZE]
	    The message is too large to be sent all at once, as the socket
	    requires.

  [ENOTCONN]
	    The socket is not connected or otherwise has not had the peer
	    prespecified.

  [ENOTSOCK]
	    The socket parameter refers to a file, not a socket.

  [ENOTSUPP]
	    The socket argument is associated with a socket that does not
	    support

	    one or more of the values set in flags.

  [EPIPE]   The socket is shut down for writing, or the socket is
	    connection-oriented and the peer is closed or shut down for
	    reading. In the latter case, and if the socket is of type
	    SOCK_STREAM, the SIGPIPE signal is generated to the calling
	    process.

  [EWOULDBLOCK]
	    The socket is marked nonblocking, and no space is available for
	    the send() function.

RELATED INFORMATION
  Functions: recv(2), recvfrom(2), recvmsg(2), sendmsg(2), sendto(2),
  shutdown(2), connect(2), socket(2), getsockopt(2), select(2), setsockopt(2)

  Standards: standards(5)