send(2)                       4 BSD                       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 specify-
     ing 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 be set to MSG_OOB to send "out-of-
     band" data on sockets which support this notion (e.g.
     SOCK_STREAM).

     See recv(2) for a description of the msghdr structure, of
     sending and receiving file descriptors in Unix domain via
     this msghdr structure, and of receiving out-of-band data.



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send(2)                       4 BSD                       send(2)



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 speci-
                         fied 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.

     [EACCES]            The data transfer failed because of the
                         mandatory access control enforced on a
                         CX/SX system (B1 only).  The security
                         level of the processes using a
                         SOCK_STREAM connection must be the same.
                         The security level of the receiving pro-
                         cess must dominate the sender's for
                         SOCK_DGRAM sockets.  This error is also
                         returned on a CX/SX system when a pro-
                         cess does not have write access to the
                         file associated with a bound UX domain
                         socket.

NOTE
     These functions are defined in the 88open Binary and Object
     Compatibility Standards' Networking Supplements (BCSNS and
     OCSNS) for use in BCSNS/OCSNS compliant applications.
     OCSNS-defined functions may be accessed by passing OCS
     options to cc(1) and ld(1).

SEE ALSO
     recv(2), socket(2). See also bind(2) for address formats in
     different communication domains.

BUGS
     Out-of-band data is only 1 character long.










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