send - send a message on a socket
cc [ flag ... ] file ... -lxnet [ library ... ]
#include <sys/socket.h>
ssize_t send(int socket, const void *buffer, size_t length, int flags);
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-specific.
MSG_NOSIGNAL
Don't generate the SIGPIPE signal when a
stream-oriented socket is no longer connected.
The length of the message to be sent is specified by the
length argument. If the message is too long to pass through the
underlying protocol, 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
privileges to use the send() function.
The send() function is identical to sendto(3XNET) with a null
pointer dest_len argument, and to write() if no flags are used.
Upon successful completion, send() returns the number of bytes sent.
Otherwise, −1 is returned and errno is set to indicate the
error.
In addition to the errors documented below, an asynchronous error generated by
the underlying socket protocol may be returned. For the full list of errors,
please see the corresponding socket protocol manual page. For example, for a
list of TCP errors, please see tcp(4P).
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
The socket argument refers to a connection
oriented socket and the connection was forcibly closed by the peer and is no
longer valid. I/O can no longer be performed to filedes.
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
transmitted.
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 latter case, and if the
socket is of type SOCK_STREAM, the SIGPIPE signal is generated
to the calling thread unless the MSG_NOSIGNAL flag is set.
The send() function may fail if:
EACCES
The calling process does not have the appropriate
privileges.
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.
See attributes(7) for descriptions of the following attributes:
| ATTRIBUTE
TYPE |
ATTRIBUTE VALUE |
| Interface Stability |
Standard |
| MT-Level |
MT-Safe |
poll(2), select(3C), connect(3XNET),
getsockopt(3XNET), recv(3XNET), recvfrom(3XNET),
recvmsg(3XNET), sendmsg(3XNET), sendto(3XNET),
setsockopt(3XNET), shutdown(3XNET), socket(3XNET),
tcp(4P), attributes(7), standards(7)