freebsd man page for shutdown

SHUTDOWN(2)						      BSD 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	Return value and action
     PF_INET	 SOCK_DGRAM	IPPROTO_SCTP	Return -1.  The global variable errno will be set to EOPNOTSUPP.
     PF_INET	 SOCK_DGRAM	IPPROTO_UDP	Return 0.  ICMP messages will not be generated.
     PF_INET	 SOCK_STREAM	IPPROTO_SCTP	Return 0.  Send queued data and tear down association.
     PF_INET	 SOCK_STREAM	IPPROTO_TCP	Return 0.  Send queued data, wait for ACK, then send FIN.
     PF_INET6	 SOCK_DGRAM	IPPROTO_SCTP	Return -1.  The global variable errno will be set to EOPNOTSUPP.
     PF_INET6	 SOCK_DGRAM	IPPROTO_UDP	Return 0.  ICMP messages will not be generated.
     PF_INET6	 SOCK_STREAM	IPPROTO_SCTP	Return 0.  Send queued data and tear down association.
     PF_INET6	 SOCK_STREAM	IPPROTO_TCP	Return 0.  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 indi-
     cate 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.

     [EOPNOTSUPP]	The socket associated with the file descriptor s does not support this operation.

     [ENOTCONN] 	The s argument specifies a SOCK_STREAM 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.

BSD
								   March 5, 2007							       BSD