send(3N-xs) (X/OPEN SOCKETS) send(3N-xs)
NAME
send - send a message on a socket
SYNOPSIS
cc [flag ...] file ... -lxnet [library ...]
#include <sys/socket.h>
ssizet send(int socket, const void *buffer, sizet length,
int flags);
DESCRIPTION
socket Specifies the socket file descriptor.
buffer Points to the buffer containing the message to send.
length Specifies the length of the message in bytes.
flags Specifies the type of message transmission. Values of
this argument are formed by logically ORing zero or more
of the following flags:
MSGEOR Terminates a record (if supported by the pro-
tocol)
MSGOOB Sends out-of-band data on sockets that support
out-of-band communications. The significance
and semantics of out-of-band data are
protocol-specific.
The send function initiates transmission of a message from the speci-
fied socket to its peer. The send function sends a message only when
the socket is connected.
The length of the message to be sent is specified by the length argu-
ment. If the message is too long to pass through the underlying proto-
col, send fails and no data is transmitted.
Successful completion of a call to send does not guarantee delivery of
the message. A return value of -1 indicates only locally-detected
errors.
If space is not available at the sending socket to hold the message to
be transmitted and the socket file descriptor does not have ONONBLOCK
set, send blocks until space is available. If space is not available
at the sending socket to hold the message to be transmitted and the
socket file descriptor does have ONONBLOCK set, send will fail. The
select and poll functions can be used to determine when it is possible
to send more data.
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send(3N-xs) (X/OPEN SOCKETS) send(3N-xs)
RETURN VALUE
Upon successful completion, send returns the number of bytes sent.
Otherwise, -1 is returned and errno is set to indicate the error.
APPLICATION USAGE
The send function is identical to sendto with a null pointer destlen
argument, and to write if no flags are used.
ERRORS
The send function will fail if:
EBADF The socket argument is not a valid file descriptor.
ECONNRESET A connection was forcibly closed by a peer.
EDESTADDRREQ The socket is not connection-oriented and no peer
address is set.
EINTR A signal interrupted send before any data was trans-
mitted.
EMSGSIZE The message is too large 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 argument does not refer to 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 SOCKSTREAM, the SIGPIPE signal is
generated to the calling process.
EWOULDBLOCK or EAGAIN
The socket's file descriptor is marked ONONBLOCK and
the requested operation would block.
The send function may fail if:
ENETDOWN The local interface used to reach the destination is
down.
ENETUNREACH No route to the network is present.
ENOBUFS The resources available in the system were not suffi-
cient to perform the operation.
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send(3N-xs) (X/OPEN SOCKETS) send(3N-xs)
ENOSR The STREAMS resources available were not sufficient to
complete the operation.
EIO An I/O error occurred while reading from or writing to
the file system.
SEE ALSO
poll(2), select(3C), connect(3N-xs), getsockopt(3N-xs), recv(3N-xs),
recvfrom(3N-xs), recvmsg(3N-xs), sendmsg(3N-xs), sendto(3N-xs),
setsockopt(3N-xs), shutdown(3N-xs), socket(3N-xs).
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