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<h1>sigtrap</h1>
<!-- -->
<ul><li><a href="#NAME">NAME</a><li><a href="#SYNOPSIS">SYNOPSIS</a><li><a href="#DESCRIPTION">DESCRIPTION</a><li><a href="#OPTIONS">OPTIONS</a><ul><li><a href="#SIGNAL-HANDLERS">SIGNAL HANDLERS</a><li><a href="#SIGNAL-LISTS">SIGNAL LISTS</a><li><a href="#OTHER">OTHER</a></ul><li><a href="#EXAMPLES">EXAMPLES</a></ul><a name="NAME"></a><h1>NAME</h1>
<p>sigtrap - Perl pragma to enable simple signal handling</p>
<a name="SYNOPSIS"></a><h1>SYNOPSIS</h1>
<pre class="verbatim"><ol><li> <a class="l_k" href="functions/use.html">use</a> <span class="w">sigtrap</span><span class="sc">;</span></li><li> <a class="l_k" href="functions/use.html">use</a> <span class="w">sigtrap</span> <span class="q">qw(stack-trace old-interface-signals)</span><span class="sc">;</span> <span class="c"># equivalent</span></li><li> <a class="l_k" href="functions/use.html">use</a> <span class="w">sigtrap</span> <span class="q">qw(BUS SEGV PIPE ABRT)</span><span class="sc">;</span></li><li> <a class="l_k" href="functions/use.html">use</a> <span class="w">sigtrap</span> <span class="q">qw(die INT QUIT)</span><span class="sc">;</span></li><li> <a class="l_k" href="functions/use.html">use</a> <span class="w">sigtrap</span> <span class="q">qw(die normal-signals)</span><span class="sc">;</span></li><li> <a class="l_k" href="functions/use.html">use</a> <span class="w">sigtrap</span> <span class="q">qw(die untrapped normal-signals)</span><span class="sc">;</span></li><li> <a class="l_k" href="functions/use.html">use</a> <span class="w">sigtrap</span> <span class="q">qw(die untrapped normal-signals</span></li><li> <span class="q">stack-trace any error-signals)</span><span class="sc">;</span></li><li> <a class="l_k" href="functions/use.html">use</a> <span class="w">sigtrap</span> <span class="q">'handler'</span> <span class="cm">=></span> \<span class="i">&my_handler</span><span class="cm">,</span> <span class="q">'normal-signals'</span><span class="sc">;</span></li><li> <a class="l_k" href="functions/use.html">use</a> <span class="w">sigtrap</span> <span class="q">qw(handler my_handler normal-signals</span></li><li> <span class="q">stack-trace error-signals)</span><span class="sc">;</span></li></ol></pre><a name="DESCRIPTION"></a><h1>DESCRIPTION</h1>
<p>The <b>sigtrap</b> pragma is a simple interface to installing signal
handlers. You can have it install one of two handlers supplied by
<b>sigtrap</b> itself (one which provides a Perl stack trace and one which
simply <code class="inline"><a class="l_k" href="functions/die.html">die()</a></code>s), or alternately you can supply your own handler for it
to install. It can be told only to install a handler for signals which
are either untrapped or ignored. It has a couple of lists of signals to
trap, plus you can supply your own list of signals.</p>
<p>The arguments passed to the <code class="inline"><a class="l_k" href="functions/use.html">use</a></code> statement which invokes <b>sigtrap</b>
are processed in order. When a signal name or the name of one of
<b>sigtrap</b>'s signal lists is encountered a handler is immediately
installed, when an option is encountered it affects subsequently
installed handlers.</p>
<a name="OPTIONS"></a><h1>OPTIONS</h1>
<a name="SIGNAL-HANDLERS"></a><h2>SIGNAL HANDLERS</h2>
<p>These options affect which handler will be used for subsequently
installed signals.</p>
<ul>
<li><a name="*stack-trace*"></a><b><b>stack-trace</b></b>
<p>The handler used for subsequently installed signals outputs a Perl stack
trace to STDERR and then tries to dump core. This is the default signal
handler.</p>
</li>
<li><a name="*die*"></a><b><b>die</b></b>
<p>The handler used for subsequently installed signals calls <code class="inline"><a class="l_k" href="functions/die.html">die</a></code>
(actually <code class="inline"><span class="w">croak</span></code>
) with a message indicating which signal was caught.</p>
</li>
<li><a name="*handler*-_your-handler_"></a><b><b>handler</b> <i>your-handler</i></b>
<p><i>your-handler</i> will be used as the handler for subsequently installed
signals. <i>your-handler</i> can be any value which is valid as an
assignment to an element of <code class="inline"><span class="i">%SIG</span></code>
. See <a href="perlvar.html">perlvar</a> for examples of
handler functions.</p>
</li>
</ul>
<a name="SIGNAL-LISTS"></a><h2>SIGNAL LISTS</h2>
<p><b>sigtrap</b> has a few built-in lists of signals to trap. They are:</p>
<ul>
<li><a name="*normal-signals*"></a><b><b>normal-signals</b></b>
<p>These are the signals which a program might normally expect to encounter
and which by default cause it to terminate. They are HUP, INT, PIPE and
TERM.</p>
</li>
<li><a name="*error-signals*"></a><b><b>error-signals</b></b>
<p>These signals usually indicate a serious problem with the Perl
interpreter or with your script. They are ABRT, BUS, EMT, FPE, ILL,
QUIT, SEGV, SYS and TRAP.</p>
</li>
<li><a name="*old-interface-signals*"></a><b><b>old-interface-signals</b></b>
<p>These are the signals which were trapped by default by the old
<b>sigtrap</b> interface, they are ABRT, BUS, EMT, FPE, ILL, PIPE, QUIT,
SEGV, SYS, TERM, and TRAP. If no signals or signals lists are passed to
<b>sigtrap</b>, this list is used.</p>
</li>
</ul>
<p>For each of these three lists, the collection of signals set to be
trapped is checked before trapping; if your architecture does not
implement a particular signal, it will not be trapped but rather
silently ignored.</p>
<a name="OTHER"></a><h2>OTHER</h2>
<ul>
<li><a name="*untrapped*"></a><b><b>untrapped</b></b>
<p>This token tells <b>sigtrap</b> to install handlers only for subsequently
listed signals which aren't already trapped or ignored.</p>
</li>
<li><a name="*any*"></a><b><b>any</b></b>
<p>This token tells <b>sigtrap</b> to install handlers for all subsequently
listed signals. This is the default behavior.</p>
</li>
<li><a name="_signal_"></a><b><i>signal</i></b>
<p>Any argument which looks like a signal name (that is,
<code class="inline"><span class="q">/^[A-Z][A-Z0-9]*$/</span></code>
) indicates that <b>sigtrap</b> should install a
handler for that name.</p>
</li>
<li><a name="_number_"></a><b><i>number</i></b>
<p>Require that at least version <i>number</i> of <b>sigtrap</b> is being used.</p>
</li>
</ul>
<a name="EXAMPLES"></a><h1>EXAMPLES</h1>
<p>Provide a stack trace for the old-interface-signals:</p>
<pre class="verbatim"><ol><li> <a class="l_k" href="functions/use.html">use</a> <span class="w">sigtrap</span><span class="sc">;</span></li></ol></pre><p>Ditto:</p>
<pre class="verbatim"><ol><li> <a class="l_k" href="functions/use.html">use</a> <span class="w">sigtrap</span> <span class="q">qw(stack-trace old-interface-signals)</span><span class="sc">;</span></li></ol></pre><p>Provide a stack trace on the 4 listed signals only:</p>
<pre class="verbatim"><ol><li> <a class="l_k" href="functions/use.html">use</a> <span class="w">sigtrap</span> <span class="q">qw(BUS SEGV PIPE ABRT)</span><span class="sc">;</span></li></ol></pre><p>Die on INT or QUIT:</p>
<pre class="verbatim"><ol><li> <a class="l_k" href="functions/use.html">use</a> <span class="w">sigtrap</span> <span class="q">qw(die INT QUIT)</span><span class="sc">;</span></li></ol></pre><p>Die on HUP, INT, PIPE or TERM:</p>
<pre class="verbatim"><ol><li> <a class="l_k" href="functions/use.html">use</a> <span class="w">sigtrap</span> <span class="q">qw(die normal-signals)</span><span class="sc">;</span></li></ol></pre><p>Die on HUP, INT, PIPE or TERM, except don't change the behavior for
signals which are already trapped or ignored:</p>
<pre class="verbatim"><ol><li> <a class="l_k" href="functions/use.html">use</a> <span class="w">sigtrap</span> <span class="q">qw(die untrapped normal-signals)</span><span class="sc">;</span></li></ol></pre><p>Die on receipt one of an of the <b>normal-signals</b> which is currently
<b>untrapped</b>, provide a stack trace on receipt of <b>any</b> of the
<b>error-signals</b>:</p>
<pre class="verbatim"><ol><li> <a class="l_k" href="functions/use.html">use</a> <span class="w">sigtrap</span> <span class="q">qw(die untrapped normal-signals</span></li><li> <span class="q">stack-trace any error-signals)</span><span class="sc">;</span></li></ol></pre><p>Install my_handler() as the handler for the <b>normal-signals</b>:</p>
<pre class="verbatim"><ol><li> <a class="l_k" href="functions/use.html">use</a> <span class="w">sigtrap</span> <span class="q">'handler'</span><span class="cm">,</span> \<span class="i">&my_handler</span><span class="cm">,</span> <span class="q">'normal-signals'</span><span class="sc">;</span></li></ol></pre><p>Install my_handler() as the handler for the normal-signals, provide a
Perl stack trace on receipt of one of the error-signals:</p>
<pre class="verbatim"><ol><li> <a class="l_k" href="functions/use.html">use</a> <span class="w">sigtrap</span> <span class="q">qw(handler my_handler normal-signals</span></li><li> <span class="q">stack-trace error-signals)</span><span class="sc">;</span></li></ol></pre>
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