shutdown function in socket

socket shutdown (2) function

The following shows the function synopsis of the shutdown(2) function:

#include <sys/socket.h>

int shutdown(int s, int how);

The function shutdown(2) requires two arguments. They are

• Socket descriptor s specifies the socket to be partially shut down. 
• Argument how indicates how this socket should be shut down.

The returned value is zero if the function call succeeded. A failure is indicated by returning a value of -1, and the reason for the failure is posted to errno.

The permissible values for how are shown in Table 1.1.

Value	Macros	Description
0	SHUT_RD	No further reads will be allowed on the specified socket.
1	SHUT_WR	No further writes will be allowed on the specified socket.
2	SHUT_RDWR	No further reads or writes will be allowed on the specified socket.

Table 1.1: Permissible Values of the shutdown(2) how Argument

Value Macro Description

Notice that when the how value is supplied as 2, this function call becomes almost equivalent to a close(2) call.