9.22. shutdown()

Stop further sends and receives on a socket

Prototypes
#include <sys/socket.h>

int shutdown(int s, int how);
Description
That's it! I've had it! No more send()s are allowed on this socket, but I still want to recv() data on it! Or vice-versa! How can I do this?

When you close() a socket descriptor, it closes both sides of the socket for reading and writing, and frees the socket descriptor. If you just want to close one side or the other, you can use this shutdown() call.

As for parameters, s is obviously the socket you want to perform this action on, and what action that is can be specified with the how parameter. How can be SHUT_RD to prevent further recv()s, SHUT_WR to prohibit further send()s, or SHUT_RDWR to do both.

Note that shutdown() doesn't free up the socket descriptor, so you still have to eventually close() the socket even if it has been fully shut down.

This is a rarely used system call.

Return Value
Returns zero on success, or -1 on error (and errno will be set accordingly.)

Example
int s = socket(PF_INET, SOCK_STREAM, 0);

// ...do some send()s and stuff in here...

// and now that we're done, don't allow any more sends()s:
shutdown(s, SHUT_WR);
See Also
close()