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| <h4 class="subsection">24.2.4 Asynchronous I/O Signals</h4> |
| |
| <p>The signals listed in this section are used in conjunction with |
| asynchronous I/O facilities. You have to take explicit action by |
| calling <code>fcntl</code> to enable a particular file descriptor to generate |
| these signals (see <a href="Interrupt-Input.html#Interrupt-Input">Interrupt Input</a>). The default action for these |
| signals is to ignore them. |
| |
| <!-- signal.h --> |
| <!-- BSD --> |
| <div class="defun"> |
| — Macro: int <b>SIGIO</b><var><a name="index-SIGIO-2867"></a></var><br> |
| <blockquote><p><a name="index-input-available-signal-2868"></a><a name="index-output-possible-signal-2869"></a>This signal is sent when a file descriptor is ready to perform input |
| or output. |
| |
| <p>On most operating systems, terminals and sockets are the only kinds of |
| files that can generate <code>SIGIO</code>; other kinds, including ordinary |
| files, never generate <code>SIGIO</code> even if you ask them to. |
| |
| <p>In the GNU system <code>SIGIO</code> will always be generated properly |
| if you successfully set asynchronous mode with <code>fcntl</code>. |
| </p></blockquote></div> |
| |
| <!-- signal.h --> |
| <!-- BSD --> |
| <div class="defun"> |
| — Macro: int <b>SIGURG</b><var><a name="index-SIGURG-2870"></a></var><br> |
| <blockquote><p><a name="index-urgent-data-signal-2871"></a>This signal is sent when “urgent” or out-of-band data arrives on a |
| socket. See <a href="Out_002dof_002dBand-Data.html#Out_002dof_002dBand-Data">Out-of-Band Data</a>. |
| </p></blockquote></div> |
| |
| <!-- signal.h --> |
| <!-- SVID --> |
| <div class="defun"> |
| — Macro: int <b>SIGPOLL</b><var><a name="index-SIGPOLL-2872"></a></var><br> |
| <blockquote><p>This is a System V signal name, more or less similar to <code>SIGIO</code>. |
| It is defined only for compatibility. |
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