SEND(3XNET)SEND(3XNET)NAMEsend - send a message on a socket
SYNOPSIS
cc [ flag ... ] file ... -lxnet [ library ... ]
#include <sys/socket.h>
ssize_t send(int socket, const void *buffer, size_t length, int flags);
PARAMETERS
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 OR'ing zero or more of the
following flags:
MSG_EOR
Terminates a record (if supported by the protocol)
MSG_OOB
Sends out-of-band data on sockets that support
out-of-band communications. The significance and
semantics of out-of-band data are protocol-spe‐
cific.
DESCRIPTION
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 (including when the peer of a connectionless
socket has been set via connect(3XNET)).
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 O_NONBLOCK
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 O_NONBLOCK set, send() will fail. The
select(3C) and poll(2) functions can be used to determine when it is
possible to send more data.
The socket in use may require the process to have appropriate privi‐
leges to use the send() function.
USAGE
The send() function is identical to sendto(3XNET) with a null pointer
dest_len argument, and to write() if no flags are used.
RETURN VALUES
Upon successful completion, send() returns the number of bytes sent.
Otherwise, −1 is returned and errno is set to indicate the error.
ERRORS
The send() function will fail if:
EAGAIN
EWOULDBLOCK
The socket's file descriptor is marked O_NONBLOCK and
the requested operation would block.
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-mode and no peer address
is set.
EFAULT
The buffer parameter can not be accessed.
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-mode and is no longer connected. In the lat‐
ter case, and if the socket is of type SOCK_STREAM, the
SIGPIPE signal is generated to the calling thread.
The send() function may fail if:
EACCES
The calling process does not have the appropriate privi‐
leges.
EIO
An I/O error occurred while reading from or writing to
the file system.
ENETDOWN
The local interface used to reach the destination is
down.
ENETUNREACH
No route to the network is present.
ENOBUFS
Insufficient resources were available in the system to
perform the operation.
ENOSR
There were insufficient STREAMS resources available for
the operation to complete.
ATTRIBUTES
See attributes(5) for descriptions of the following attributes:
┌────────────────────┬─────────────────┐
│ ATTRIBUTE TYPE │ ATTRIBUTE VALUE │
├────────────────────┼─────────────────┤
│Interface Stability │ Standard │
├────────────────────┼─────────────────┤
│MT-Level │ MT-Safe │
└────────────────────┴─────────────────┘
SEE ALSOconnect(3XNET), getsockopt(3XNET), poll(2), recv(3XNET),
recvfrom(3XNET), recvmsg(3XNET), select(3C), sendmsg(3XNET),
sendto(3XNET), setsockopt(3XNET), shutdown(3XNET), socket(3XNET),
attributes(5), standards(5)
Nov 1, 2003 SEND(3XNET)
