SHUTDOWN(2)               FreeBSD System Calls Manual              SHUTDOWN(2)

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.1g"), 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.1g").

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.

FreeBSD 13.1-RELEASE-p6          July 27, 2015         FreeBSD 13.1-RELEASE-p6