devdocs/c/program%2Fsig_strategies.html


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    <h1 id="firstHeading" class="firstHeading">SIG_DFL, SIG_IGN</h1>            <table class="t-dcl-begin"> <tr class="t-dsc-header"> <th> Defined in header <code>&lt;signal.h&gt;</code> </th> <th> </th> <th> </th> </tr> <tr class="t-dcl"> <td class="t-dcl-nopad"> <pre data-language="c">#define SIG_DFL /*implementation defined*/</pre>
</td> <td class="t-dcl-nopad"> </td> <td class="t-dcl-nopad"> </td> </tr> <tr class="t-dcl"> <td class="t-dcl-nopad"> <pre data-language="c">#define SIG_IGN /*implementation defined*/</pre>
</td> <td class="t-dcl-nopad"> </td> <td class="t-dcl-nopad"> </td> </tr>  </table> <p>The <code>SIG_DFL</code> and <code>SIG_IGN</code> macros expand into integral expressions that are not equal to an address of any function. The macros define signal handling strategies for <code><a href="http://en.cppreference.com/w/c/program/signal"><span class="kw497">signal</span></a><span class="br0">(</span><span class="br0">)</span></code> function.</p>
<table class="t-dsc-begin"> <tr class="t-dsc-hitem"> <th> Constant </th> <th> Explanation </th>
</tr> <tr class="t-dsc"> <td> <code>SIG_DFL</code> </td> <td> default signal handling </td>
</tr> <tr class="t-dsc"> <td> <code>SIG_IGN</code> </td> <td> signal is ignored </td>
</tr> </table>  <h3 id="Example"> Example</h3> <div class="t-example"> <div class="c source-c"><pre data-language="c">#include &lt;signal.h&gt;
#include &lt;stdio.h&gt;
 
int main(void)
{
    /* using the default signal handler */
    raise(SIGTERM);
    printf("Exit main()\n");   /* never reached */
}</pre></div> <p>Output:</p>
<div class="text source-text"><pre data-language="c">(none)</pre></div> </div> <h3 id="Example_2"> Example</h3> <div class="t-example"> <div class="c source-c"><pre data-language="c">#include &lt;signal.h&gt;
#include &lt;stdio.h&gt;
 
int main(void)
{
    /* ignoring the signal */
    signal(SIGTERM, SIG_IGN);
    raise(SIGTERM);
    printf("Exit main()\n");
}</pre></div> <p>Output:</p>
<div class="text source-text"><pre data-language="c">Exit main()</pre></div> </div> <h3 id="References"> References</h3>  <ul>
<li> C17 standard (ISO/IEC 9899:2018): </li>
<ul><li> 7.14/3 Signal handling &lt;signal.h&gt; (p: 193) </li></ul>
<li> C11 standard (ISO/IEC 9899:2011): </li>
<ul><li> 7.14/3 Signal handling &lt;signal.h&gt; (p: 265) </li></ul>
<li> C99 standard (ISO/IEC 9899:1999): </li>
<ul><li> 7.14/3 Signal handling &lt;signal.h&gt; (p: 246) </li></ul>
<li> C89/C90 standard (ISO/IEC 9899:1990): </li>
<ul><li> 4.7 SIGNAL HANDLING &lt;signal.h&gt; </li></ul>
</ul>               <h3 id="See_also"> See also</h3> <table class="t-dsc-begin"> <tr class="t-dsc"> <td colspan="2"> <span><a href="https://en.cppreference.com/w/cpp/utility/program/SIG_strategies" title="cpp/utility/program/SIG strategies">C++ documentation</a></span> for <code>SIG_DFL, SIG_IGN</code> </td>
</tr> </table>           <div class="_attribution">
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