NAME

       shutdown — disable sends and/or receives on a socket

LIBRARY

       Standard C Library (libc, -lc)

SYNOPSIS

       #include <sys/types.h>
       #include <sys/socket.h>

       int
       shutdown(int s, int how);

DESCRIPTION

       The  shutdown()  system call disables sends or receives on a socket.  The how argument specifies the type
       of shutdown.  Possible values are:

       SHUT_RD    Further receives will be disallowed.

       SHUT_WR    Further sends will be disallowed.  This may cause actions specific to the protocol  family  of
                  the socket s to happen; see “IMPLEMENTATION NOTES”.

       SHUT_RDWR  Further sends and receives will be disallowed.  Implies SHUT_WR.

       If  the  file  descriptor  s  is  associated  with  a  SOCK_STREAM socket, all or part of the full-duplex
       connection will be shut down.

IMPLEMENTATION NOTES

       The following protocol specific actions apply to the use of SHUT_WR  (and  potentially  also  SHUT_RDWR),
       based on the properties of the socket associated with the file descriptor s.

       Domain      Type           Protocol        Action
       PF_INET     SOCK_DGRAM     IPPROTO_SCTP    Failure, as socket is not connected.
       PF_INET     SOCK_DGRAM     IPPROTO_UDP     Failure, as socket is not connected.
       PF_INET     SOCK_STREAM    IPPROTO_SCTP    Send queued data and tear down association.
       PF_INET     SOCK_STREAM    IPPROTO_TCP     Send queued data, wait for ACK, then send FIN.
       PF_INET6    SOCK_DGRAM     IPPROTO_SCTP    Failure, as socket is not connected.
       PF_INET6    SOCK_DGRAM     IPPROTO_UDP     Failure, as socket is not connected.
       PF_INET6    SOCK_STREAM    IPPROTO_SCTP    Send queued data and tear down association.
       PF_INET6    SOCK_STREAM    IPPROTO_TCP     Send queued data, wait for ACK, then send FIN.

RETURN VALUES

       The  shutdown()  function  returns  the value 0 if successful; otherwise the value -1 is returned and the
       global variable errno is set to indicate the error.

ERRORS

       The shutdown() system call fails if:

       [EBADF]            The s argument is not a valid file descriptor.

       [EINVAL]           The how argument is invalid.

       [ENOTCONN]         The s argument specifies a socket which is not connected.

       [ENOTSOCK]         The s argument does not refer to a socket.

SEE ALSO

       connect(2), socket(2), inet(4), inet6(4)

STANDARDS

       The shutdown() system call is expected to comply with IEEE Std 1003.1g-2000 (“POSIX.1”), when finalized.

HISTORY

       The shutdown() system call appeared in 4.2BSD.  The SHUT_RD, SHUT_WR, and SHUT_RDWR constants appeared in
       IEEE Std 1003.1g-2000 (“POSIX.1”).

AUTHORS

       This manual page was updated by Bruce M. Simpson <bms@FreeBSD.org> to reflect how shutdown() behaves with
       PF_INET and PF_INET6 sockets.

BUGS

       The ICMP “port unreachable” message should be generated in response to datagrams received on a local port
       to which s is bound after shutdown() is called.

Debian                                            July 27, 2015                                      SHUTDOWN(2)