Standard C Library (libc, -lc)

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.

• 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.

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.

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

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

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

This manual page was updated by 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.