.\" Copyright (c) 1983, 1991 The Regents of the University of California.
.\" All rights reserved.
.\"
.\" SPDX-License-Identifier: BSD-4-Clause-UC
.\"
.\"     $Id: shutdown.2,v 1.1.1.1 1999/03/21 22:52:23 freitag Exp $
.\"
.\" Modified Sat Jul 24 09:57:55 1993 by Rik Faith <faith@cs.unc.edu>
.\" Modified Tue Oct 22 22:04:51 1996 by Eric S. Raymond <esr@thyrsus.com>
.\" Modified 1998 by Andi Kleen
.\"
.TH shutdown 2 2023-03-30 "Linux man-pages 6.05.01"
.SH NAME
shutdown \- shut down part of a full-duplex connection
.SH LIBRARY
Standard C library
.RI ( libc ", " \-lc )
.SH SYNOPSIS
.nf
.B #include <sys/socket.h>
.PP
.BI "int shutdown(int " sockfd ", int " how );
.fi
.SH DESCRIPTION
The
.BR shutdown ()
call causes all or part of a full-duplex connection on the socket
associated with
.I sockfd
to be shut down.
If
.I how
is
.BR SHUT_RD ,
further receptions will be disallowed.
If
.I how
is
.BR SHUT_WR ,
further transmissions will be disallowed.
If
.I how
is
.BR SHUT_RDWR ,
further receptions and transmissions will be disallowed.
.SH RETURN VALUE
On success, zero is returned.
On error, \-1 is returned, and
.I errno
is set to indicate the error.
.SH ERRORS
.TP
.B EBADF
.I sockfd
is not a valid file descriptor.
.TP
.B EINVAL
An invalid value was specified in
.I how
(but see BUGS).
.TP
.B ENOTCONN
The specified socket is not connected.
.TP
.B ENOTSOCK
The file descriptor
.I sockfd
does not refer to a socket.
.SH STANDARDS
POSIX.1-2008.
.SH HISTORY
POSIX.1-2001, 4.4BSD
(first appeared in 4.2BSD).
.SH NOTES
The constants
.BR SHUT_RD ,
.BR SHUT_WR ,
.B SHUT_RDWR
have the value 0, 1, 2,
respectively, and are defined in
.I <sys/socket.h>
since glibc-2.1.91.
.SH BUGS
Checks for the validity of
.I how
are done in domain-specific code,
and before Linux 3.7 not all domains performed these checks.
.\" https://bugzilla.kernel.org/show_bug.cgi?id=47111
Most notably, UNIX domain sockets simply ignored invalid values.
This problem was fixed for UNIX domain sockets
.\" commit fc61b928dc4d72176cf4bd4d30bf1d22e599aefc
.\" and for DECnet sockets in commit 46b66d7077b89fb4917ceef19b3f7dd86055c94a
in Linux 3.7.
.SH SEE ALSO
.BR close (2),
.BR connect (2),
.BR socket (2),
.BR socket (7)