SHUTDOWN(2) | System Calls Manual | SHUTDOWN(2)

# NAME

`shutdown` — disable sends or receives on a socket

# SYNOPSIS

`#include <sys/socket.h>`

int
`shutdown`(int s, int how);

# DESCRIPTION

The `shutdown`() system call disables sends or receives on a socket.

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 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.
`SHUT_RDWR`
  Further sends and receives will be disallowed.

The following protocol specific actions apply to the use of `SHUT_WR` based on the properties of the socket associated with the file descriptor s:

DOMAIN | TYPE | PROTOCOL | RETURN VALUE AND ACTION
`AF_INET` | `SOCK_DGRAM` | `IPPROTO_UDP` | Return 0. ICMP messages will not be generated.
`AF_INET` | `SOCK_STREAM` | `IPPROTO_TCP` | Return 0. Send queued data, wait for ACK, then send FIN.
`AF_INET6` | `SOCK_DGRAM` | `IPPROTO_UDP` | Return 0. ICMP messages will not be generated.
`AF_INET6` | `SOCK_STREAM` | `IPPROTO_TCP` | Return 0. Send queued data, wait for ACK, then send FIN.

# RETURN VALUES

Upon successful completion, the value 0 is returned; 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 `SOCK_STREAM` socket which is not connected.
[`ENOTSOCK`]
  The s argument does not refer to a socket.
[`EOPNOTSUPP`]
  The socket associated with the file descriptor s does not support this operation.

# SEE ALSO

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

# STANDARDS

The `shutdown`() function conforms to IEEE Std 1003.1-2008 (“POSIX.1”).

# HISTORY

The `shutdown`() system call first appeared in 4.1cBSD. The `SHUT_RD`, `SHUT_WR`, and `SHUT_RDWR` constants appeared in IEEE Std 1003.1g-2000 (“POSIX.1g”).

# 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.

September 9, 2014 | Debian