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.\" $OpenBSD: shutdown.2,v 1.15 2014/09/09 09:00:17 guenther Exp $
.\" $NetBSD: shutdown.2,v 1.5 1995/02/27 12:37:11 cgd Exp $
.\"
.\" Copyright (c) 1983, 1991, 1993
.\" The Regents of the University of California. All rights reserved.
.\"
.\" Redistribution and use in source and binary forms, with or without
.\" modification, are permitted provided that the following conditions
.\" are met:
.\" 1. Redistributions of source code must retain the above copyright
.\" notice, this list of conditions and the following disclaimer.
.\" 2. Redistributions in binary form must reproduce the above copyright
.\" notice, this list of conditions and the following disclaimer in the
.\" documentation and/or other materials provided with the distribution.
.\" 3. Neither the name of the University nor the names of its contributors
.\" may be used to endorse or promote products derived from this software
.\" without specific prior written permission.
.\"
.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
.\" SUCH DAMAGE.
.\"
.\" @(#)shutdown.2 8.1 (Berkeley) 6/4/93
.\"
.Dd $Mdocdate: September 9 2014 $
.Dt SHUTDOWN 2
.Os
.Sh NAME
.Nm shutdown
.Nd disable sends or receives on a socket
.Sh SYNOPSIS
.In sys/socket.h
.Ft int
.Fn shutdown "int s" "int how"
.Sh DESCRIPTION
The
.Fn shutdown
system call disables sends or receives on a socket.
.Pp
If the file descriptor
.Fa s
is associated with a
.Dv SOCK_STREAM
socket, all or part of the full-duplex connection will be shut down.
.Pp
The
.Fa how
argument specifies the type of shutdown.
Possible values are:
.Bl -tag -width "SHUT_RDWRXXX" -offset indent
.It Dv SHUT_RD
Further receives will be disallowed.
.It Dv SHUT_WR
Further sends will be disallowed.
This may cause actions specific to the protocol family of the socket
.Fa s
to happen.
.It Dv SHUT_RDWR
Further sends and receives will be disallowed.
.El
.Pp
The following protocol specific actions apply to the use of
.Dv SHUT_WR
based on the properties of the socket associated with the file descriptor
.Fa s :
.Bl -column "AF_INET6" "SOCK_STREAM" "IPPROTO_UDP" -offset indent
.It DOMAIN Ta TYPE Ta PROTOCOL Ta "RETURN VALUE AND ACTION"
.Pp
.It Dv AF_INET Ta Dv SOCK_DGRAM Ta Dv IPPROTO_UDP Ta
Return 0.
ICMP messages will
.Em not
be generated.
.It Dv AF_INET Ta Dv SOCK_STREAM Ta Dv IPPROTO_TCP Ta
Return 0.
Send queued data, wait for ACK, then send FIN.
.It Dv AF_INET6 Ta Dv SOCK_DGRAM Ta Dv IPPROTO_UDP Ta
Return 0.
ICMP messages will
.Em not
be generated.
.It Dv AF_INET6 Ta Dv SOCK_STREAM Ta Dv IPPROTO_TCP Ta
Return 0.
Send queued data, wait for ACK, then send FIN.
.El
.Sh RETURN VALUES
.Rv -std
.Sh ERRORS
The
.Fn shutdown
system call fails if:
.Bl -tag -width Er
.It Bq Er EBADF
The
.Fa s
argument is not a valid file descriptor.
.It Bq Er EINVAL
The
.Fa how
argument is invalid.
.It Bq Er ENOTCONN
The
.Fa s
argument specifies a
.Dv SOCK_STREAM
socket which is not connected.
.It Bq Er ENOTSOCK
The
.Fa s
argument does not refer to a socket.
.It Bq Er EOPNOTSUPP
The socket associated with the file descriptor
.Fa s
does not support this operation.
.El
.Sh SEE ALSO
.Xr connect 2 ,
.Xr socket 2 ,
.Xr inet 4 ,
.Xr inet6 4
.Sh STANDARDS
The
.Fn shutdown
function conforms to
.St -p1003.1-2008 .
.Sh HISTORY
The
.Fn shutdown
system call first appeared in
.Bx 4.1c .
The
.Dv SHUT_RD , SHUT_WR ,
and
.Dv SHUT_RDWR
constants appeared in
.St -p1003.1g-2000 .
.Sh BUGS
The ICMP
.Dq port unreachable
message should be generated in response to
datagrams received on a local port to which
.Fa s
is bound
after
.Fn shutdown
is called.
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