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<h3 class="section">8.220 <code>SIGNAL</code> — Signal handling subroutine (or function)</h3>
<p><a name="index-SIGNAL-1000"></a><a name="index-system_002c-signal-handling-1001"></a>
<dl>
<dt><em>Description</em>:<dd><code>SIGNAL(NUMBER, HANDLER [, STATUS])</code> causes external subroutine
<var>HANDLER</var> to be executed with a single integer argument when signal
<var>NUMBER</var> occurs. If <var>HANDLER</var> is an integer, it can be used to
turn off handling of signal <var>NUMBER</var> or revert to its default
action. See <code>signal(2)</code>.
<p>If <code>SIGNAL</code> is called as a subroutine and the <var>STATUS</var> argument
is supplied, it is set to the value returned by <code>signal(2)</code>.
<br><dt><em>Standard</em>:<dd>GNU extension
<br><dt><em>Class</em>:<dd>Subroutine, function
<br><dt><em>Syntax</em>:<dd>
<p><table summary=""><tr align="left"><td valign="top" width="80%"><code>CALL SIGNAL(NUMBER, HANDLER [, STATUS])</code>
<br></td></tr><tr align="left"><td valign="top" width="80%"><code>STATUS = SIGNAL(NUMBER, HANDLER)</code>
<br></td></tr></table>
<br><dt><em>Arguments</em>:<dd>
<p><table summary=""><tr align="left"><td valign="top" width="15%"><var>NUMBER</var> </td><td valign="top" width="70%">Shall be a scalar integer, with <code>INTENT(IN)</code>
<br></td></tr><tr align="left"><td valign="top" width="15%"><var>HANDLER</var></td><td valign="top" width="70%">Signal handler (<code>INTEGER FUNCTION</code> or
<code>SUBROUTINE</code>) or dummy/global <code>INTEGER</code> scalar.
<code>INTEGER</code>. It is <code>INTENT(IN)</code>.
<br></td></tr><tr align="left"><td valign="top" width="15%"><var>STATUS</var> </td><td valign="top" width="70%">(Optional) <var>STATUS</var> shall be a scalar
integer. It has <code>INTENT(OUT)</code>.
<br></td></tr></table>
<!-- TODO: What should the interface of the handler be? Does it take arguments? -->
<br><dt><em>Return value</em>:<dd>The <code>SIGNAL</code> function returns the value returned by <code>signal(2)</code>.
<br><dt><em>Example</em>:<dd>
<pre class="smallexample"> program test_signal
intrinsic signal
external handler_print
call signal (12, handler_print)
call signal (10, 1)
call sleep (30)
end program test_signal
</pre>
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