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

SYNOPSIS
  #include <sys/socket.h>

  ssize_t send(
		  int socket,
	  const void *buffer,
	  size_t length,
	  int flags );

  [Tru64 UNIX]	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(): XNS4.0, XNS5.0

  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 (this
  includes when the peer of a connectionless socket has been set with a
  connect() call). 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.

  The socket in use may also require that the calling process have
  appropriate privileges.

NOTES
  [Tru64 UNIX]	 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:

  [EACCES]
      The calling proces does not have the appropriate privileges.

  [EACCES]
      The message cannot be delivered because of information label float
      restrictions.

  [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 buffer parameter cannot be accessed.

      [Tru64 UNIX]  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.

  [EIO]
      An I/O error occurred while reading from or writing to the file system.

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

  [ENETDOWN]
      The local network connection is not operational.

  [ENETUNREACH]
      The destination network is unreachable.

  [ENOBUFS]
      Insufficient resources were available in the system to complete the
      call.

  [ENOSR]
      The available STREAMS resources were insufficient for the operation to
      complete.

  [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.

  [EOPNOTSUPP]
      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.

SEE ALSO
  Functions: connect(2), getsockopt(2), poll(2), recv(2), recvfrom(2),
  recvmsg(2), select(2), sendmsg(2), sendto(2), setsockopt(2), shutdown(2),
  socket(2),

  Standards: standards(5)

  Network Programmer's Guide

Index for Section 2

Alphabetical listing for S

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