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| <h4 class="subsection">16.8.2 Closing a Socket</h4> |
| |
| <p><a name="index-socket_002c-closing-1777"></a><a name="index-closing-a-socket-1778"></a><a name="index-shutting-down-a-socket-1779"></a><a name="index-socket-shutdown-1780"></a> |
| When you have finished using a socket, you can simply close its |
| file descriptor with <code>close</code>; see <a href="Opening-and-Closing-Files.html#Opening-and-Closing-Files">Opening and Closing Files</a>. |
| If there is still data waiting to be transmitted over the connection, |
| normally <code>close</code> tries to complete this transmission. You |
| can control this behavior using the <code>SO_LINGER</code> socket option to |
| specify a timeout period; see <a href="Socket-Options.html#Socket-Options">Socket Options</a>. |
| |
| <p><a name="index-sys_002fsocket_002eh-1781"></a>You can also shut down only reception or transmission on a |
| connection by calling <code>shutdown</code>, which is declared in |
| <samp><span class="file">sys/socket.h</span></samp>. |
| |
| <!-- sys/socket.h --> |
| <!-- BSD --> |
| <div class="defun"> |
| — Function: int <b>shutdown</b> (<var>int socket, int how</var>)<var><a name="index-shutdown-1782"></a></var><br> |
| <blockquote><p>The <code>shutdown</code> function shuts down the connection of socket |
| <var>socket</var>. The argument <var>how</var> specifies what action to |
| perform: |
| |
| <dl> |
| <dt><code>0</code><dd>Stop receiving data for this socket. If further data arrives, |
| reject it. |
| |
| <br><dt><code>1</code><dd>Stop trying to transmit data from this socket. Discard any data |
| waiting to be sent. Stop looking for acknowledgement of data already |
| sent; don't retransmit it if it is lost. |
| |
| <br><dt><code>2</code><dd>Stop both reception and transmission. |
| </dl> |
| |
| <p>The return value is <code>0</code> on success and <code>-1</code> on failure. The |
| following <code>errno</code> error conditions are defined for this function: |
| |
| <dl> |
| <dt><code>EBADF</code><dd><var>socket</var> is not a valid file descriptor. |
| |
| <br><dt><code>ENOTSOCK</code><dd><var>socket</var> is not a socket. |
| |
| <br><dt><code>ENOTCONN</code><dd><var>socket</var> is not connected. |
| </dl> |
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