send() system call

send(2)                                                               send(2)



NAME
  send - Sends messages on a socket

SYNOPSIS

  #include <sys/types.h>
  #include <sys/socket.h>

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

PARAMETERS

  socket    Specifies the unique name for the socket.

  message   Points to the address of 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 mes-
  sage 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
  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 char-
  acters 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.

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

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

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

  [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), shut-
  down(2), connect(2), socket(2), getsockopt(2), select(2), setsockopt(2)
  delim off