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.\" Copyright (c) 2001-2003 The Open Group, All Rights Reserved 
.TH "SEND" P 2003 "IEEE/The Open Group" "POSIX Programmer's Manual"
.\" send 
.SH NAME
send \- send a message on a socket
.SH SYNOPSIS
.LP
\fB#include <sys/socket.h>
.br
.sp
ssize_t send(int\fP \fIsocket\fP\fB, const void *\fP\fIbuffer\fP\fB,
size_t\fP \fIlength\fP\fB, int\fP
\fIflags\fP\fB);
.br
\fP
.SH DESCRIPTION
.LP
The \fIsend\fP() function shall initiate transmission of a message
from the specified socket to its peer. The \fIsend\fP()
function shall send a message only when the socket is connected (including
when the peer of a connectionless socket has been set
via \fIconnect\fP()).
.LP
The \fIsend\fP() function takes the following arguments:
.TP 7
\fIsocket\fP
Specifies the socket file descriptor.
.TP 7
\fIbuffer\fP
Points to the buffer containing the message to send.
.TP 7
\fIlength\fP
Specifies the length of the message in bytes.
.TP 7
\fIflags\fP
Specifies the type of message transmission. Values of this argument
are formed by logically OR'ing zero or more of the
following flags: 
.TP 7
MSG_EOR
.RS
Terminates a record (if supported by the protocol).
.RE
.TP 7
MSG_OOB
.RS
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.
.RE
.sp
.sp
.LP
The length of the message to be sent is specified by the \fIlength\fP
argument. If the message is too long to pass through the
underlying protocol, \fIsend\fP() shall fail and no data shall be
transmitted.
.LP
Successful completion of a call to \fIsend\fP() does not guarantee
delivery of the message. A return value of -1 indicates only
locally-detected errors.
.LP
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, \fIsend\fP() shall block 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, \fIsend\fP() shall fail. The \fIselect\fP() and
\fIpoll\fP() functions can be used to
determine when it is possible to send more data.
.LP
The socket in use may require the process to have appropriate privileges
to use the \fIsend\fP() function.
.SH RETURN VALUE
.LP
Upon successful completion, \fIsend\fP() shall return the number of
bytes sent. Otherwise, -1 shall be returned and
\fIerrno\fP set to indicate the error.
.SH ERRORS
.LP
The \fIsend\fP() function shall fail if:
.TP 7
.B EAGAIN \fRor\fP EWOULDBLOCK
.sp
The socket's file descriptor is marked O_NONBLOCK and the requested
operation would block.
.TP 7
.B EBADF
The \fIsocket\fP argument is not a valid file descriptor.
.TP 7
.B ECONNRESET
A connection was forcibly closed by a peer.
.TP 7
.B EDESTADDRREQ
.sp
The socket is not connection-mode and no peer address is set.
.TP 7
.B EINTR
A signal interrupted \fIsend\fP() before any data was transmitted.
.TP 7
.B EMSGSIZE
The message is too large to be sent all at once, as the socket requires.
.TP 7
.B ENOTCONN
The socket is not connected or otherwise has not had the peer pre-specified.
.TP 7
.B ENOTSOCK
The \fIsocket\fP argument does not refer to a socket.
.TP 7
.B EOPNOTSUPP
The \fIsocket\fP argument is associated with a socket that does not
support one or more of the values set in
\fIflags\fP.
.TP 7
.B 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.
.sp
.LP
The \fIsend\fP() function may fail if:
.TP 7
.B EACCES
The calling process does not have the appropriate privileges.
.TP 7
.B EIO
An I/O error occurred while reading from or writing to the file system.
.TP 7
.B ENETDOWN
The local network interface used to reach the destination is down.
.TP 7
.B ENETUNREACH
.sp
No route to the network is present.
.TP 7
.B ENOBUFS
Insufficient resources were available in the system to perform the
operation.
.sp
.LP
\fIThe following sections are informative.\fP
.SH EXAMPLES
.LP
None.
.SH APPLICATION USAGE
.LP
The \fIsend\fP() function is equivalent to \fIsendto\fP() with a null
pointer
\fIdest_len\fP argument, and to \fIwrite\fP() if no flags are used.
.SH RATIONALE
.LP
None.
.SH FUTURE DIRECTIONS
.LP
None.
.SH SEE ALSO
.LP
\fIconnect\fP() , \fIgetsockopt\fP() , \fIpoll\fP() , \fIrecv\fP()
, \fIrecvfrom\fP() , \fIrecvmsg\fP() , \fIselect\fP() , \fIsendmsg\fP()
, \fIsendto\fP() , \fIsetsockopt\fP() , \fIshutdown\fP() , \fIsocket\fP()
, the Base Definitions volume of
IEEE\ Std\ 1003.1-2001, \fI<sys/socket.h>\fP
.SH COPYRIGHT
Portions of this text are reprinted and reproduced in electronic form
from IEEE Std 1003.1, 2003 Edition, Standard for Information Technology
-- Portable Operating System Interface (POSIX), The Open Group Base
Specifications Issue 6, Copyright (C) 2001-2003 by the Institute of
Electrical and Electronics Engineers, Inc and The Open Group. In the
event of any discrepancy between this version and the original IEEE and
The Open Group Standard, the original IEEE and The Open Group Standard
is the referee document. The original Standard can be obtained online at
http://www.opengroup.org/unix/online.html .

1 by Francesco Paolo Lovergine rules: linking manpages-posix not manpages.	1	.\" Copyright (c) 2001-2003 The Open Group, All Rights Reserved
2 by Francesco Paolo Lovergine * Alligned to linux main manpages edition.	2	.TH "SEND" P 2003 "IEEE/The Open Group" "POSIX Programmer's Manual"
1 by Francesco Paolo Lovergine rules: linking manpages-posix not manpages.	3	.\" send
	4	.SH NAME
	5	send \- send a message on a socket
	6	.SH SYNOPSIS
	7	.LP
	8	\fB#include <sys/socket.h>
	9	.br
	10	.sp
	11	ssize_t send(int\fP \fIsocket\fP\fB, const void *\fP\fIbuffer\fP\fB,
	12	size_t\fP \fIlength\fP\fB, int\fP
	13	\fIflags\fP\fB);
	14	.br
	15	\fP
	16	.SH DESCRIPTION
	17	.LP
	18	The \fIsend\fP() function shall initiate transmission of a message
	19	from the specified socket to its peer. The \fIsend\fP()
	20	function shall send a message only when the socket is connected (including
	21	when the peer of a connectionless socket has been set
	22	via \fIconnect\fP()).
	23	.LP
	24	The \fIsend\fP() function takes the following arguments:
	25	.TP 7
	26	\fIsocket\fP
	27	Specifies the socket file descriptor.
	28	.TP 7
	29	\fIbuffer\fP
	30	Points to the buffer containing the message to send.
	31	.TP 7
	32	\fIlength\fP
	33	Specifies the length of the message in bytes.
	34	.TP 7
	35	\fIflags\fP
	36	Specifies the type of message transmission. Values of this argument
	37	are formed by logically OR'ing zero or more of the
	38	following flags:
	39	.TP 7
	40	MSG_EOR
	41	.RS
	42	Terminates a record (if supported by the protocol).
	43	.RE
	44	.TP 7
	45	MSG_OOB
	46	.RS
	47	Sends out-of-band data on sockets that support out-of-band communications.
	48	The significance and semantics of out-of-band data
	49	are protocol-specific.
	50	.RE
	51	.sp
	52	.sp
	53	.LP
	54	The length of the message to be sent is specified by the \fIlength\fP
	55	argument. If the message is too long to pass through the
	56	underlying protocol, \fIsend\fP() shall fail and no data shall be
	57	transmitted.
	58	.LP
	59	Successful completion of a call to \fIsend\fP() does not guarantee
	60	delivery of the message. A return value of -1 indicates only
	61	locally-detected errors.
	62	.LP
	63	If space is not available at the sending socket to hold the message
	64	to be transmitted, and the socket file descriptor does not
	65	have O_NONBLOCK set, \fIsend\fP() shall block until space is available.
	66	If space is not available at the sending socket to hold
67	the message to be transmitted, and the socket file descriptor does
68	have O_NONBLOCK set, \fIsend\fP() shall fail. The \fIselect\fP() and
69	\fIpoll\fP() functions can be used to
70	determine when it is possible to send more data.
71	.LP
72	The socket in use may require the process to have appropriate privileges
73	to use the \fIsend\fP() function.
74	.SH RETURN VALUE
75	.LP
76	Upon successful completion, \fIsend\fP() shall return the number of
77	bytes sent. Otherwise, -1 shall be returned and
78	\fIerrno\fP set to indicate the error.
79	.SH ERRORS
80	.LP
81	The \fIsend\fP() function shall fail if:
82	.TP 7
2 by Francesco Paolo Lovergine * Alligned to linux main manpages edition.	83	.B EAGAIN \fRor\fP EWOULDBLOCK
1 by Francesco Paolo Lovergine rules: linking manpages-posix not manpages.	84	.sp
	85	The socket's file descriptor is marked O_NONBLOCK and the requested
	86	operation would block.
	87	.TP 7
	88	.B EBADF
	89	The \fIsocket\fP argument is not a valid file descriptor.
	90	.TP 7
	91	.B ECONNRESET
	92	A connection was forcibly closed by a peer.
	93	.TP 7
	94	.B EDESTADDRREQ
	95	.sp
	96	The socket is not connection-mode and no peer address is set.
	97	.TP 7
	98	.B EINTR
	99	A signal interrupted \fIsend\fP() before any data was transmitted.
	100	.TP 7
	101	.B EMSGSIZE
	102	The message is too large to be sent all at once, as the socket requires.
	103	.TP 7
	104	.B ENOTCONN
	105	The socket is not connected or otherwise has not had the peer pre-specified.
	106	.TP 7
	107	.B ENOTSOCK
	108	The \fIsocket\fP argument does not refer to a socket.
	109	.TP 7
	110	.B EOPNOTSUPP
	111	The \fIsocket\fP argument is associated with a socket that does not
	112	support one or more of the values set in
	113	\fIflags\fP.
	114	.TP 7
	115	.B EPIPE
	116	The socket is shut down for writing, or the socket is connection-mode
	117	and is no longer connected. In the latter case, and if
	118	the socket is of type SOCK_STREAM, the SIGPIPE signal is generated
	119	to the calling thread.
	120	.sp
	121	.LP
	122	The \fIsend\fP() function may fail if:
	123	.TP 7
	124	.B EACCES
	125	The calling process does not have the appropriate privileges.
	126	.TP 7
	127	.B EIO
	128	An I/O error occurred while reading from or writing to the file system.
	129	.TP 7
	130	.B ENETDOWN
	131	The local network interface used to reach the destination is down.
	132	.TP 7
	133	.B ENETUNREACH
	134	.sp
	135	No route to the network is present.
	136	.TP 7
	137	.B ENOBUFS
	138	Insufficient resources were available in the system to perform the
	139	operation.
	140	.sp
	141	.LP
	142	\fIThe following sections are informative.\fP
	143	.SH EXAMPLES
	144	.LP
	145	None.
	146	.SH APPLICATION USAGE
	147	.LP
148	The \fIsend\fP() function is equivalent to \fIsendto\fP() with a null
149	pointer
150	\fIdest_len\fP argument, and to \fIwrite\fP() if no flags are used.
151	.SH RATIONALE
152	.LP
153	None.
154	.SH FUTURE DIRECTIONS
155	.LP
156	None.
157	.SH SEE ALSO
158	.LP
159	\fIconnect\fP() , \fIgetsockopt\fP() , \fIpoll\fP() , \fIrecv\fP()
160	, \fIrecvfrom\fP() , \fIrecvmsg\fP() , \fIselect\fP() , \fIsendmsg\fP()
161	, \fIsendto\fP() , \fIsetsockopt\fP() , \fIshutdown\fP() , \fIsocket\fP()
162	, the Base Definitions volume of
163	IEEE\ Std\ 1003.1-2001, \fI<sys/socket.h>\fP
164	.SH COPYRIGHT
165	Portions of this text are reprinted and reproduced in electronic form
166	from IEEE Std 1003.1, 2003 Edition, Standard for Information Technology
167	-- Portable Operating System Interface (POSIX), The Open Group Base
168	Specifications Issue 6, Copyright (C) 2001-2003 by the Institute of
169	Electrical and Electronics Engineers, Inc and The Open Group. In the
170	event of any discrepancy between this version and the original IEEE and
171	The Open Group Standard, the original IEEE and The Open Group Standard
172	is the referee document. The original Standard can be obtained online at
173	http://www.opengroup.org/unix/online.html .