HP-UX Reference (11i v2 03/08) - 2 System Calls (vol 5)

s
shutdown(2) shutdown(2)
NAME
shutdown - shut down a socket
SYNOPSIS
#include <sys/socket.h>
int shutdown(int s, int how);
DESCRIPTION
The shutdown() system call is used to shut down a socket. In the case of a full-duplex connection,
shutdown() can be used to either partially or fully shut down the socket, depending upon the value of
how.
how Interpretation
SHUT_RD or 0 Further receives are disallowed
SHUT_WR or 1 Further sends are disallowed
SHUT_RDWR or 2 Further sends and receives are disallowed
The s parameter is a socket descriptor for the socket to be shut down.
Once the socket has been shut down for receives, all further
recv() calls return an end-of-file condi-
tion. A socket that has been shut down for sending causes further
send() calls to return an [EPIPE]
error and send the
SIGPIPE signal. After a socket has been fully shut down, operations other than
recv() and send() return appropriate errors, and the only other thing that can be done to the socket
is a close().
Multiple shutdowns on a connected socket and shutdowns on a socket that is not connected may not
return errors.
A
shutdown() on a connectionless socket, such as
SOCK_DGRAM, only marks the socket as unable to
do further
send() or recv() calls, depending upon the value of how. Once this type of socket has
been disabled for both sending and receiving data, it becomes fully shut down. For SOCK_STREAM
sock-
ets, if how is
1or2, the connection begins to be closed gracefully in addition to the normal actions.
However, the shutdown() call does not wait for the completion of the graceful disconnection. The
disconnection is complete when both sides of the connection have done a
shutdown() with how equal
to
1or2. Once the connection has been completely terminated, the socket becomes fully shut down.
The SO_LINGER option (see socket (2)) does not have any meaning for the shutdown() call, but does
for the close() call. For more information on how the close() call interacts with sockets, see
socket (2).
If a
shutdown() is performed on a SOCK_STREAM socket that has a listen() pending on it, that
socket becomes fully shut down when how =1.
AF_CCITT only:
The how parameter behaves differently if the socket is of the
AF_CCITT address family. If how is set to
0 the specified socket can no longer receive data. The SVC is not cleared and remains intact. However, if
data is subsequently received on the SVC, it is cleared. The connection is not completely down until
either side executes a close() or shutdown() with how set to 1or2.
If how is set to
1 or 2, the SVC can no longer send or receive data and the SVC is cleared. The socket’s
resources are maintained so that data arriving prior to the shutdown() call can still be read.
RETURN VALUE
Upon successful completion,
shutdown() returns 0; otherwise it returns −1 and errno is set to indi-
cate the error.
ERRORS
shutdown() fails if any of the following conditions are encountered:
[EBADF] s is not a valid file descriptor.
[ENOPROTOOPT] The remote system or an intermediate system in the communications path does
not support a protocol option sent by the local system. This option may have been
set using a
getsockopt or setsockopt() call, or set as a system parame-
ter.
[ENOTSOCK] s is a valid file descriptor, but it is not a socket.
HP-UX 11i Version 2: August 2003 − 1 − Hewlett-Packard Company Section 2−−361