shutdown — disable sends and/or receives on a socket
Standard C Library (libc, −lc)
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:
Further receives will be disallowed.
Further sends will be disallowed. This may cause actions specific to the protocol family of the socket s to happen; see IMPLEMENTATION NOTES.
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.
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.
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:
The s argument is not a valid file descriptor.
The how argument is invalid.
The s argument specifies a socket which is not connected.
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 4.2BSD. The SHUT_RD, SHUT_WR, and SHUT_RDWR constants appeared in IEEE Std 1003.1g-2000 (’’POSIX.1’’).
This manual page was updated by Bruce M. Simpson <bms [AT] 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.
BSD July 27, 2015 BSD