register-shutdown-function.xml

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<refentry xml:id="function.register-shutdown-function" xmlns="http://docbook.org/ns/docbook">
 <refnamediv>
  <refname>register_shutdown_function</refname>
  <refpurpose>Register a function for execution on shutdown</refpurpose>
 </refnamediv>
 
 <refsect1 role="description">
  &reftitle.description;
  <methodsynopsis>
   <type class="union"><type>bool</type><type>null</type></type><methodname>register_shutdown_function</methodname>
   <methodparam><type>callable</type><parameter>callback</parameter></methodparam>
   <methodparam rep="repeat"><type>mixed</type><parameter>args</parameter></methodparam>
  </methodsynopsis>
  <para>
   Registers a <parameter>callback</parameter> to be executed after script
   execution finishes or <function>exit</function> is called.
  </para>
  <para>
   Multiple calls to <function>register_shutdown_function</function> can be
   made, and each will be called in the same order as they were registered.
   If you call <function>exit</function> within one registered shutdown
   function, processing will stop completely and no other registered
   shutdown functions will be called.
  </para>
  <para>
   Shutdown functions may also call <function>register_shutdown_function</function>
   themselves to add a shutdown function to the end of the queue.
  </para>
 </refsect1>

 <refsect1 role="parameters">
  &reftitle.parameters;
  <para>
   <variablelist>
    <varlistentry>
     <term><parameter>callback</parameter></term>
     <listitem>
      <para>
       The shutdown callback to register.
      </para>
      <para>
       The shutdown callbacks are executed as the part of the request, so
       it's possible to send output from them and access output buffers.
      </para>
     </listitem>
    </varlistentry>
    <varlistentry>
     <term><parameter>args</parameter></term>
     <listitem>
      <para>
       It is possible to pass parameters to the shutdown function by passing
       additional parameters.
      </para>
     </listitem>
    </varlistentry>
   </variablelist>
  </para>
 </refsect1>

 <refsect1 role="returnvalues">
  &reftitle.returnvalues;
  <para>
   &return.void;
  </para>
 </refsect1>
 
 <refsect1 role="errors">
  &reftitle.errors;
  <para>
   If the passed callback is not callable a <constant>E_WARNING</constant>
   level error will be generated.
  </para>
 </refsect1>

 <refsect1 role="examples">
  &reftitle.examples;
  <para>
   <example>
    <title><function>register_shutdown_function</function> example</title>
    <programlisting role="php">
<![CDATA[
<?php
function shutdown()
{
    // This is our shutdown function, in 
    // here we can do any last operations
    // before the script is complete.

    echo 'Script executed with success', PHP_EOL;
}

register_shutdown_function('shutdown');
?>
]]>
    </programlisting>
   </example>
  </para>
 </refsect1>

 <refsect1 role="notes">
  &reftitle.notes;
  <note>
   <para>
    The working directory of the script can change inside the shutdown function
    under some web servers, e.g. Apache.
   </para>
  </note>
  <note>
   <para>
    Shutdown functions will not be executed if the process is killed with a SIGTERM
    or SIGKILL signal. While you cannot intercept a SIGKILL, you can use <function>pcntl_signal</function>
    to install a handler for a SIGTERM which uses <function>exit</function> to
    end cleanly.
   </para>
  </note>
  <note>
   <para>
    Shutdown functions run separately from the time tracked by
    <link linkend="ini.max-execution-time">max_execution_time</link>. That means
    even if a process is terminated for running too long, shutdown functions will still be
    called.  Additionally, if the <literal>max_execution_time</literal> runs out while
    a shutdown function is running it will not be terminated.
   </para>
  </note>
 </refsect1>

 <refsect1 role="seealso">
  &reftitle.seealso;
  <para>
   <simplelist>
    <member><link linkend="ini.auto-append-file">auto_append_file</link></member>
    <member><function>exit</function></member>
    <member><function>fastcgi_finish_request</function></member>
    <member>The section on <link linkend="features.connection-handling">connection handling</link></member>
   </simplelist>
  </para>
 </refsect1>

</refentry>
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