mirror of https://github.com/mkerrisk/man-pages
179 lines
5.4 KiB
Plaintext
179 lines
5.4 KiB
Plaintext
.\" Copyright (c) 2001-2003 The Open Group, All Rights Reserved
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.TH "SEND" 3P 2003 "IEEE/The Open Group" "POSIX Programmer's Manual"
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.\" send
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.SH PROLOG
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This manual page is part of the POSIX Programmer's Manual.
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The Linux implementation of this interface may differ (consult
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the corresponding Linux manual page for details of Linux behavior),
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or the interface may not be implemented on Linux.
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.SH NAME
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send \- send a message on a socket
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.SH SYNOPSIS
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.LP
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\fB#include <sys/socket.h>
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.br
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.sp
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ssize_t send(int\fP \fIsocket\fP\fB, const void *\fP\fIbuffer\fP\fB,
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size_t\fP \fIlength\fP\fB, int\fP
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\fIflags\fP\fB);
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.br
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\fP
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.SH DESCRIPTION
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.LP
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The \fIsend\fP() function shall initiate transmission of a message
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from the specified socket to its peer. The \fIsend\fP()
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function shall send a message only when the socket is connected (including
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when the peer of a connectionless socket has been set
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via \fIconnect\fP()).
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.LP
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The \fIsend\fP() function takes the following arguments:
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.TP 7
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\fIsocket\fP
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Specifies the socket file descriptor.
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.TP 7
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\fIbuffer\fP
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Points to the buffer containing the message to send.
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.TP 7
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\fIlength\fP
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Specifies the length of the message in bytes.
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.TP 7
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\fIflags\fP
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Specifies the type of message transmission. Values of this argument
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are formed by logically OR'ing zero or more of the
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following flags:
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.TP 7
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MSG_EOR
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.RS
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Terminates a record (if supported by the protocol).
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.RE
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.TP 7
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MSG_OOB
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.RS
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Sends out-of-band data on sockets that support out-of-band communications.
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The significance and semantics of out-of-band data
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are protocol-specific.
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.RE
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.sp
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.sp
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.LP
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The length of the message to be sent is specified by the \fIlength\fP
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argument. If the message is too long to pass through the
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underlying protocol, \fIsend\fP() shall fail and no data shall be
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transmitted.
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.LP
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Successful completion of a call to \fIsend\fP() does not guarantee
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delivery of the message. A return value of -1 indicates only
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locally-detected errors.
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.LP
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If space is not available at the sending socket to hold the message
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to be transmitted, and the socket file descriptor does not
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have O_NONBLOCK set, \fIsend\fP() shall block until space is available.
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If space is not available at the sending socket to hold
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the message to be transmitted, and the socket file descriptor does
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have O_NONBLOCK set, \fIsend\fP() shall fail. The \fIselect\fP() and
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\fIpoll\fP() functions can be used to
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determine when it is possible to send more data.
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.LP
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The socket in use may require the process to have appropriate privileges
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to use the \fIsend\fP() function.
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.SH RETURN VALUE
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.LP
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Upon successful completion, \fIsend\fP() shall return the number of
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bytes sent. Otherwise, -1 shall be returned and
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\fIerrno\fP set to indicate the error.
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.SH ERRORS
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.LP
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The \fIsend\fP() function shall fail if:
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.TP 7
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.B EAGAIN \fRor\fP EWOULDBLOCK
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.sp
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The socket's file descriptor is marked O_NONBLOCK and the requested
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operation would block.
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.TP 7
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.B EBADF
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The \fIsocket\fP argument is not a valid file descriptor.
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.TP 7
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.B ECONNRESET
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A connection was forcibly closed by a peer.
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.TP 7
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.B EDESTADDRREQ
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.sp
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The socket is not connection-mode and no peer address is set.
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.TP 7
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.B EINTR
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A signal interrupted \fIsend\fP() before any data was transmitted.
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.TP 7
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.B EMSGSIZE
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The message is too large to be sent all at once, as the socket requires.
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.TP 7
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.B ENOTCONN
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The socket is not connected or otherwise has not had the peer pre-specified.
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.TP 7
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.B ENOTSOCK
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The \fIsocket\fP argument does not refer to a socket.
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.TP 7
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.B EOPNOTSUPP
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The \fIsocket\fP argument is associated with a socket that does not
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support one or more of the values set in
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\fIflags\fP.
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.TP 7
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.B EPIPE
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The socket is shut down for writing, or the socket is connection-mode
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and is no longer connected. In the latter case, and if
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the socket is of type SOCK_STREAM, the SIGPIPE signal is generated
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to the calling thread.
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.sp
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.LP
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The \fIsend\fP() function may fail if:
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.TP 7
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.B EACCES
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The calling process does not have the appropriate privileges.
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.TP 7
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.B EIO
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An I/O error occurred while reading from or writing to the file system.
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.TP 7
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.B ENETDOWN
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The local network interface used to reach the destination is down.
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.TP 7
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.B ENETUNREACH
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.sp
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No route to the network is present.
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.TP 7
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.B ENOBUFS
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Insufficient resources were available in the system to perform the
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operation.
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.sp
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.LP
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\fIThe following sections are informative.\fP
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.SH EXAMPLES
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.LP
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None.
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.SH APPLICATION USAGE
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.LP
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The \fIsend\fP() function is equivalent to \fIsendto\fP() with a null
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pointer
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\fIdest_len\fP argument, and to \fIwrite\fP() if no flags are used.
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.SH RATIONALE
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.LP
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None.
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.SH FUTURE DIRECTIONS
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.LP
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None.
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.SH SEE ALSO
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.LP
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\fIconnect\fP(), \fIgetsockopt\fP(), \fIpoll\fP(), \fIrecv\fP(),
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\fIrecvfrom\fP(), \fIrecvmsg\fP(), \fIselect\fP(), \fIsendmsg\fP(),
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\fIsendto\fP(), \fIsetsockopt\fP(), \fIshutdown\fP(), \fIsocket\fP(),
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the Base Definitions volume of
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IEEE\ Std\ 1003.1-2001, \fI<sys/socket.h>\fP
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.SH COPYRIGHT
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Portions of this text are reprinted and reproduced in electronic form
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from IEEE Std 1003.1, 2003 Edition, Standard for Information Technology
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-- Portable Operating System Interface (POSIX), The Open Group Base
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Specifications Issue 6, Copyright (C) 2001-2003 by the Institute of
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Electrical and Electronics Engineers, Inc and The Open Group. In the
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event of any discrepancy between this version and the original IEEE and
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The Open Group Standard, the original IEEE and The Open Group Standard
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is the referee document. The original Standard can be obtained online at
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http://www.opengroup.org/unix/online.html .
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