Manual Pages  — SHUTDOWN

shutdown – disable sends and/or receives on a socket

LIBRARY SYNOPSIS DESCRIPTION IMPLEMENTATION NOTES RETURN VALUES ERRORS SEE ALSO STANDARDS HISTORY AUTHORS BUGS

Standard C Library (libc, -lc)

#include <sys/types.h>

#include <sys/socket.h>

int
shutdown(int s, int how)

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.

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. Return -1. The global variable Return 0. ICMP messages will Return 0. Send queued data and tear down association. Return 0. Send queued data, wait for ACK, then send FIN. Return -1. The global variable Return 0. ICMP messages will Return 0. Send queued data and tear down association. Return 0. Send queued data, wait for ACK, then send FIN.

Domain	Type	Protocol	Return value and action
PF_INET	SOCK_DGRAM	IPPROTO_SCTP
errno will be set to
EOPNOTSUPP.
PF_INET	SOCK_DGRAM	IPPROTO_UDP
not be generated.
PF_INET	SOCK_STREAM	IPPROTO_SCTP
PF_INET	SOCK_STREAM	IPPROTO_TCP
PF_INET6	SOCK_DGRAM	IPPROTO_SCTP
errno will be set to
EOPNOTSUPP.
PF_INET6	SOCK_DGRAM	IPPROTO_UDP
not be generated.
PF_INET6	SOCK_STREAM	IPPROTO_SCTP
PF_INET6	SOCK_STREAM	IPPROTO_TCP

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.

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.

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

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

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

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.