SEND(2)                                                   SEND(2)



     NAME
          send, sendto, sendmsg - send a message from a socket

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

          cc = send(s, msg, len, flags)
          int cc, s;
          char *msg;
          int len, flags;

          cc = sendto(s, msg, len, flags, to, tolen)
          int cc, s;
          char *msg;
          int len, flags;
          struct sockaddr *to;
          int tolen;

          cc = sendmsg(s, msg, flags)
          int cc, s;
          struct msghdr msg[];
          int flags;

     DESCRIPTION
          Send, sendto, and sendmsg are used to transmit a message to
          another socket.  Send may be used only when the socket is in
          a connected state, while sendto and sendmsg may be used at
          any time.

          The address of the target is given by to with tolen
          specifying its size.  The length of the message is given by
          len.  If the message is too long to pass atomically through
          the underlying protocol, then the error EMSGSIZE is
          returned, and the message is not transmitted.

          No indication of failure to deliver is implicit in a send.
          Return values of -1 indicate some locally detected errors.

          If no messages space is available at the socket to hold the
          message to be transmitted, then send normally blocks, unless
          the socket has been placed in non-blocking I/O mode.  The
          select(2) call may be used to determine when it is possible
          to send more data.

          The flags parameter may include one or more of the
          following:

          #define   MSG_OOB        0x1  /* process out-of-band data */
          #define   MSG_DONTROUTE  0x4  /* bypass routing,
                                   use direct interface */




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     SEND(2)                                                   SEND(2)



          The flag MSG_OOB is used to send "out-of-band" data on
          sockets that support this notion (e.g. SOCK_STREAM); the
          underlying protocol must also support "out-of-band" data.
          MSG_DONTROUTE is usually used only by diagnostic or routing
          programs.

          See recv(2) for a description of the msghdr structure.

     RETURN VALUE
          The call returns the number of characters sent, or -1 if an
          error occurred.

     ERRORS
          [EBADF]             An invalid descriptor was specified.

          [ENOTSOCK]          The argument s is not a socket.

          [EFAULT]            An invalid user space address was
                              specified for a parameter.

          [EMSGSIZE]          The socket requires that message be sent
                              atomically, and the size of the message
                              to be sent made this impossible.

          [EWOULDBLOCK]       The socket is marked non-blocking and
                              the requested operation would block.

          [ENOBUFS]           The system was unable to allocate an
                              internal buffer.  The operation may
                              succeed when buffers become available.

          [ENOBUFS]           The output queue for a network interface
                              was full.  This generally indicates that
                              the interface has stopped sending, but
                              may be caused by transient congestion.

     SEE ALSO
          fcntl(2), recv(2), select(2), getsockopt(2), socket(2),
          write(2)

     NOTE
          The primitives documented on this manual page are system
          calls, but unlike most system calls they are not resolved by
          libc.  To compile and link a program that makes these calls,
          follow the procedures for section (3B) routines as described
          in intro(3).

     ORIGIN
          4.3 BSD






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