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 | Action |
| PF_INET | SOCK_DGRAM | IPPROTO_SCTP | |
| PF_INET | SOCK_DGRAM | IPPROTO_UDP | |
| PF_INET | SOCK_STREAM | IPPROTO_SCTP | |
| PF_INET | SOCK_STREAM | IPPROTO_TCP | |
| PF_INET6 | SOCK_DGRAM | IPPROTO_SCTP | |
| PF_INET6 | SOCK_DGRAM | IPPROTO_UDP | |
| PF_INET6 | SOCK_STREAM | IPPROTO_SCTP | |
| PF_INET6 | SOCK_STREAM | IPPROTO_TCP |
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 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 socket which is not connected.
- [ENOTSOCK]
-
The s argument does not refer to a socket.
SEE ALSO
STANDARDS
The shutdown() system call is expected to comply with IEEE Std 1003.1g-2000 (“POSIX.1g”), 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.1g”).
AUTHORS
This manual page was updated by Bruce M. Simpson ⟨[email protected]⟩ 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.