Programming Interfaces Guide

Closing Sockets

A SOCK_STREAM socket can be discarded by a close(2) interface call. If data is queued to a socket that promises reliable delivery after a close(2), the protocol continues to try to transfer the data. The data is discarded if it remains undelivered after an arbitrary period.

A shutdown(3SOCKET) closes SOCK_STREAM sockets gracefully. Both processes can acknowledge that they are no longer sending. This call has the form:

shutdown(s, how);

where how is defined as


Disallows further data reception


Disallows further data transmission


Disallows further transmission and further reception