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https://github.com/sigmasternchen/php-doc-en
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cf82f3872a
Removed SIG_ constants from signal list Modified pcntl_signal example to be more verbose git-svn-id: https://svn.php.net/repository/phpdoc/en/trunk@58748 c90b9560-bf6c-de11-be94-00142212c4b1
635 lines
18 KiB
XML
635 lines
18 KiB
XML
<?xml encoding="iso-8859-1"?>
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<!-- $Revision: 1.5 $ -->
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<reference id="ref.pcntl">
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<title>Process Control Functions</title>
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<titleabbrev>PCNTL</titleabbrev>
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<partintro>
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<para>
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Process Control support in PHP implements the Unix style of
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process creation, program execution, signal handling and process
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termination. Process Control should not be enabled within a
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webserver environment and unexpected results may happen if any
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Process Control functions are used within a webserver environment.
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</para>
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<para>
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This documentation is intended to explain the general usage of
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each of the Process Control functions. For detailed information
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about Unix process control you are encouraged to consult your
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systems documentation including fork(2), waitpid(2) and signal(2)
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or a comprehensive reference such as <citation>Advanced
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Programming in the UNIX Environment by W. Richard Stevens
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(Addison-Wesley)</citation>.
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</para>
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<para>
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Process Control support in PHP is not enabled by default. You
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will need to use the <link
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linkend="install.configure.enable-pcntl">--enable-pcntl</link>
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configuration option when compiling PHP to enable Process Control
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support.
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</para>
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<note>
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<para>
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Currently, this module will not function on non-Unix platforms
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(Windows).
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</para>
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</note>
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<para>
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The following list of signals are supported by the Process Control
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functions. Please see your systems signal(7) man page for details
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of the default behavior of these signals.
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<table>
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<title>Supported Signals</title>
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<tgroup cols="2">
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<tbody>
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<row>
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<entry><literal>SIGFPE</literal></entry>
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<entry><literal>SIGCONT</literal></entry>
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<entry><literal>SIGKILL</literal></entry>
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</row>
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<row>
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<entry><literal>SIGSTOP</literal></entry>
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<entry><literal>SIGUSR1</literal></entry>
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<entry><literal>SIGTSTP</literal></entry>
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</row>
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<row>
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<entry><literal>SIGHUP</literal></entry>
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<entry><literal>SIGUSR2</literal></entry>
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<entry><literal>SIGTTIN</literal></entry>
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</row>
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<row>
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<entry><literal>SIGINT</literal></entry>
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<entry><literal>SIGSEGV</literal></entry>
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<entry><literal>SIGTTOU</literal></entry>
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</row>
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<row>
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<entry><literal>SIGQUIT</literal></entry>
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<entry><literal>SIGPIPE</literal></entry>
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<entry><literal>SIGURG</literal></entry>
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</row>
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<row>
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<entry><literal>SIGILL</literal></entry>
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<entry><literal>SIGALRM</literal></entry>
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<entry><literal>SIGXCPU</literal></entry>
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</row>
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<row>
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<entry><literal>SIGTRAP</literal></entry>
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<entry><literal>SIGTERM</literal></entry>
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<entry><literal>SIGXFSZ</literal></entry>
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</row>
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<row>
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<entry><literal>SIGABRT</literal></entry>
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<entry><literal>SIGSTKFLT</literal></entry>
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<entry><literal>SIGVTALRM</literal></entry>
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</row>
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<row>
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<entry><literal>SIGIOT</literal></entry>
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<entry><literal>SIGCHLD</literal></entry>
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<entry><literal>SIGPROF</literal></entry>
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</row>
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<row>
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<entry><literal>SIGBUS</literal></entry>
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<entry><literal>SIGCLD</literal></entry>
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<entry><literal>SIGWINCH</literal></entry>
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</row>
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<row>
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<entry><literal>SIGPOLL</literal></entry>
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<entry><literal>SIGIO</literal></entry>
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<entry><literal>SIGPWR</literal></entry>
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</row>
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<row>
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<entry><literal>SIGSYS</literal></entry>
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<entry><literal></literal></entry>
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<entry><literal></literal></entry>
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</row>
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</tbody>
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</tgroup>
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</table>
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</para>
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<sect1 id="pcntl-example">
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<title>Process Control Example</title>
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<para>
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This example forks off a daemon process with a signal handler.
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</para>
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<example>
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<title>Process Control Example</title>
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<programlisting role="php">
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<?php
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$pid = pcntl_fork();
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if ($pid == -1) {
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die("could not fork");
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} else if ($pid) {
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exit(); // we are the parent
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} else {
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// we are the child
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}
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// detatch from the controlling terminal
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if (!posix_setsid()) {
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die("could not detach from terminal");
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}
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// setup signal handlers
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pcntl_signal(SIGTERM, "sig_handler");
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pcntl_signal(SIGHUP, "sig_handler");
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// loop forever performing tasks
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while(1) {
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// do something interesting here
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}
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function sig_handler($signo) {
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switch($signo) {
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case SIGTERM:
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// handle shutdown tasks
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exit;
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break;
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case SIGHUP:
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// handle restart tasks
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break;
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default:
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// handle all other signals
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}
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}
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?>
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</programlisting>
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</example>
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</sect1>
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</partintro>
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<refentry id="function.pcntl-fork">
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<refnamediv>
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<refname>pcntl_fork</refname>
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<refpurpose>Forks the currently running process</refpurpose>
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</refnamediv>
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<refsect1>
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<title>Description</title>
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<funcsynopsis>
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<funcprototype>
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<funcdef>int <function>pcntl_fork</function></funcdef>
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<void/>
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</funcprototype>
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</funcsynopsis>
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<para>
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The <function>pcntl_fork</function> function creates a child
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process that differs from the parent process only in it's PID and
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PPID. Please see your system's fork(2) man page for specific details as to
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how fork works on your system.
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</para>
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<para>
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On success, the PID of the child process is returned in the
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parent's thread of execution, and a 0 is returned in the child's
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thread of execution. On failure, a -1 will be returned in the
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parent's context, no child process will be created, and a PHP
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error is raised.
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</para>
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<example>
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<title><function>pcntl_fork</function> Example</title>
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<programlisting role="php">
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<?php
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$pid = pcntl_fork();
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if ($pid == -1) {
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die("could not fork");
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} else if ($pid) {
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// we are the parent
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} else {
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// we are the child
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}
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?>
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</programlisting>
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</example>
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<para>
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See also <function>pcntl_waitpid</function> and
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<function>pcntl_signal</function>.
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</para>
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</refsect1>
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</refentry>
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<refentry id="function.pcntl-signal">
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<refnamediv>
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<refname>pcntl_signal</refname>
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<refpurpose>Installs a signal handler</refpurpose>
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</refnamediv>
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<refsect1>
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<title>Description</title>
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<funcsynopsis>
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<funcprototype>
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<funcdef>bool <function>pcntl_signal</function></funcdef>
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<paramdef>int <parameter>signo</parameter></paramdef>
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<paramdef>mixed <parameter>handle</parameter></paramdef>
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</funcprototype>
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</funcsynopsis>
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<para>
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The <function>pcntl_signal</function> function installs a new
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signal handler for the signal indicated by
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<parameter>signo</parameter>. The signal handler is set to
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<parameter>handler</parameter> which may be the name of a user
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created function, or either of the two global constants SIG_IGN
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or SIG_DFL.
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</para>
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<para>
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<function>pcntl_signal</function> returns &true; on success or
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&false; on failure.
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</para>
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<example>
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<title><function>pcntl_signal</function> Example</title>
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<programlisting role="php">
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<?php
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// signal handler function
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function sig_handler($signo) {
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switch($signo) {
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case SIGTERM:
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// handle shutdown tasks
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exit;
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break;
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case SIGHUP:
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// handle restart tasks
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break;
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case SIGUSR1:
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print "Caught SIGUSR1...\n";
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break;
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default:
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// handle all other signals
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}
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}
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print "Installing signal handler...\n";
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// setup signal handlers
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pcntl_signal(SIGTERM, "sig_handler");
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pcntl_signal(SIGHUP, "sig_handler");
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pcntl_signal(SIGUSR1, "sig_handler");
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print "Generating signal SIGTERM to self...\n";
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// send SIGUSR1 to current process id
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posix_kill(posix_getpid(), SIGUSR1);
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print "Done\n"
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?>
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</programlisting>
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</example>
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<para>
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See also <function>pcntl_fork</function> and
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<function>pcntl_waitpid</function>.
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</para>
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</refsect1>
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</refentry>
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<refentry id="function.pcntl-waitpid">
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<refnamediv>
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<refname>pcntl_waitpid</refname>
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<refpurpose>Waits on or returns the status of a forked child</refpurpose>
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</refnamediv>
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<refsect1>
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<title>Description</title>
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<funcsynopsis>
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<funcprototype>
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<funcdef>int <function>pcntl_waitpid</function></funcdef>
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<paramdef>int <parameter>pid</parameter></paramdef>
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<paramdef>int <parameter>status</parameter></paramdef>
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<paramdef>int <parameter>options</parameter></paramdef>
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</funcprototype>
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</funcsynopsis>
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<para>
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The <function>pcntl_waitpid</function> function suspends execution
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of the current process until a child as specified by the
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<parameter>pid</parameter> argument has exited, or until a signal
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is delivered whose action is to terminate the current process or
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to call a signal handling function. If a child as requested by
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<parameter>pid</parameter> has already exited by the time of the
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call (a so-called "zombie" process), the function returns
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immediately. Any system resources used by the child are
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freed. Please see your system's waitpid(2) man page for specific
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details as to how waitpid works on your system.
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</para>
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<para>
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<function>pcntl_waitpid</function> returns the process ID of the
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child which exited, -1 on error or zero if WNOHANG was used and no
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child was available
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</para>
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<para>
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The value of <parameter>pid</parameter> can be one of the following:
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<table>
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<title>possible values for <parameter>pid</parameter></title>
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<tgroup cols="2">
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<tbody>
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<row>
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<entry><literal>< -1</literal></entry>
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<entry>
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wait for any child process whose process group ID is equal to
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the absolute value of <parameter>pid</parameter>.
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</entry>
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</row>
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<row>
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<entry><literal>-1</literal></entry>
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<entry>
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wait for any child process; this is the same behaviour that
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the wait function exhibits.
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</entry>
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</row>
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<row>
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<entry><literal>0</literal></entry>
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<entry>
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wait for any child process whose process group ID is equal to
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that of the calling process.
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</entry>
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</row>
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<row>
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<entry><literal>> 0</literal></entry>
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<entry>
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wait for the child whose process ID is equal to the value of
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<parameter>pid</parameter>.
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</entry>
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</row>
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</tbody>
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</tgroup>
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</table>
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</para>
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<para>
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<function>pcntl_waitpid</function> will store status information
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in the <parameter>status</parameter> parameter which can be
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evaluated using the following functions:
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<function>pcntl_wifexited</function>,
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<function>pcntl_wifstopped</function>,
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<function>pcntl_wifsignaled</function>,
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<function>pcntl_wexitstatus</function>,
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<function>pcntl_wtermsig</function> and
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<function>pcntl_wstopsig</function>.
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</para>
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<para>
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The value of <parameter>options</parameter> is the value of zero
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or more of the following two global constants
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<literal>OR</literal>'ed together:
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<table>
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<title>possible values for <parameter>options</parameter></title>
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<tgroup cols="2">
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<tbody>
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<row>
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<entry><literal>WNOHANG</literal></entry>
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<entry>
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return immediately if no child has exited.
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</entry>
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</row>
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<row>
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<entry><literal>WUNTRACED</literal></entry>
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<entry>
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return for children which are stopped, and whose status has
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not been reported.
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</entry>
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</row>
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</tbody>
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</tgroup>
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</table>
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</para>
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<para>
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See also <function>pcntl_fork</function>,
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<function>pcntl_signal</function>,
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<function>pcntl_wifexited</function>,
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<function>pcntl_wifstopped</function>,
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<function>pcntl_wifsignaled</function>,
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<function>pcntl_wexitstatus</function>,
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<function>pcntl_wtermsig</function> and
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<function>pcntl_wstopsig</function>.
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</para>
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</refsect1>
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</refentry>
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<refentry id="function.pcntl-wexitstatus">
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<refnamediv>
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<refname>pcntl_wexitstatus</refname>
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<refpurpose>
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Returns the return code of a terminated child
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</refpurpose>
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</refnamediv>
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<refsect1>
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<title>Description</title>
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<funcsynopsis>
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<funcprototype>
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<funcdef>int <function>pcntl_wexitstatus</function></funcdef>
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<paramdef>int <parameter>status</parameter></paramdef>
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</funcprototype>
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</funcsynopsis>
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<para>
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Returns the return code of a terminated child. This function is
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only useful if <function>pcntl_wifexited</function> returned
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&true;.
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</para>
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<para>
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The parameter <parameter>status</parameter> is the status
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parameter supplied to a successfull call to
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<function>pcntl_waitpid</function>.
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</para>
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<para>
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See also <function>pcntl_waitpid</function> and
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<function>pcntl_wifexited</function>.
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</para>
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</refsect1>
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</refentry>
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<refentry id="function.pcntl-wifexited">
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<refnamediv>
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<refname>pcntl_wifexited</refname>
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<refpurpose>
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Returns &true; if status code represents a successful exit
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</refpurpose>
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</refnamediv>
|
|
<refsect1>
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<title>Description</title>
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<funcsynopsis>
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<funcprototype>
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<funcdef>int <function>pcntl_wifexited</function></funcdef>
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<paramdef>int <parameter>status</parameter></paramdef>
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</funcprototype>
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</funcsynopsis>
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<para>
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Returns &true; if the child status code represents a successful
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exit.
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</para>
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<para>
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The parameter <parameter>status</parameter> is the status
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parameter supplied to a successfull call to
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<function>pcntl_waitpid</function>.
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</para>
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<para>
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See also <function>pcntl_waitpid</function> and
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<function>pcntl_wexitstatus</function>.
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</para>
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</refsect1>
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</refentry>
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<refentry id="function.pcntl-wifsignaled">
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<refnamediv>
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<refname>pcntl_wifsignaled</refname>
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<refpurpose>
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Returns &true; if status code represents a termination due to a
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signal
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</refpurpose>
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</refnamediv>
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<refsect1>
|
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<title>Description</title>
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<funcsynopsis>
|
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<funcprototype>
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<funcdef>int <function>pcntl_wifsignaled</function></funcdef>
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<paramdef>int <parameter>status</parameter></paramdef>
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</funcprototype>
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</funcsynopsis>
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<para>
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Returns &true; if the child process exited because of a signal
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which was not caught.
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</para>
|
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<para>
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The parameter <parameter>status</parameter> is the status
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parameter supplied to a successfull call to
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<function>pcntl_waitpid</function>.
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</para>
|
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<para>
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See also <function>pcntl_waitpid</function> and
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<function>pcntl_signal</function>.
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</para>
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</refsect1>
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</refentry>
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|
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<refentry id="function.pcntl-wifstopped">
|
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<refnamediv>
|
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<refname>pcntl_wifstopped</refname>
|
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<refpurpose>
|
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Returns &true; if child process is currently stopped
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</refpurpose>
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</refnamediv>
|
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<refsect1>
|
|
<title>Description</title>
|
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<funcsynopsis>
|
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<funcprototype>
|
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<funcdef>int <function>pcntl_wifstopped</function></funcdef>
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<paramdef>int <parameter>status</parameter></paramdef>
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</funcprototype>
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</funcsynopsis>
|
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<para>
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Returns &true; if the child process which caused the return is
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currently stopped; this is only possible if the call to
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<function>pcntl_waitpid</function> was done using the option
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<literal>WUNTRACED</literal>.
|
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</para>
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|
<para>
|
|
The parameter <parameter>status</parameter> is the status
|
|
parameter supplied to a successfull call to
|
|
<function>pcntl_waitpid</function>.
|
|
</para>
|
|
<para>
|
|
See also <function>pcntl_waitpid</function>.
|
|
</para>
|
|
</refsect1>
|
|
</refentry>
|
|
|
|
|
|
<refentry id="function.pcntl-wstopsig">
|
|
<refnamediv>
|
|
<refname>pcntl_wstopsig</refname>
|
|
<refpurpose>
|
|
Returns the signal which caused the child to stop
|
|
</refpurpose>
|
|
</refnamediv>
|
|
<refsect1>
|
|
<title>Description</title>
|
|
<funcsynopsis>
|
|
<funcprototype>
|
|
<funcdef>int <function>pcntl_wstopsig</function></funcdef>
|
|
<paramdef>int <parameter>status</parameter></paramdef>
|
|
</funcprototype>
|
|
</funcsynopsis>
|
|
<para>
|
|
Returns the number of the signal which caused the child to stop.
|
|
This function is only useful if
|
|
<function>pcntl_wifstopped</function> returned &true;.
|
|
</para>
|
|
<para>
|
|
The parameter <parameter>status</parameter> is the status
|
|
parameter supplied to a successfull call to
|
|
<function>pcntl_waitpid</function>.
|
|
</para>
|
|
<para>
|
|
See also <function>pcntl_waitpid</function> and
|
|
<function>pcntl_wifstopped</function>.
|
|
</para>
|
|
</refsect1>
|
|
</refentry>
|
|
|
|
|
|
<refentry id="function.pcntl-wtermsig">
|
|
<refnamediv>
|
|
<refname>pcntl_wtermsig</refname>
|
|
<refpurpose>
|
|
Returns the signal which caused the child to terminate
|
|
</refpurpose>
|
|
</refnamediv>
|
|
<refsect1>
|
|
<title>Description</title>
|
|
<funcsynopsis>
|
|
<funcprototype>
|
|
<funcdef>int <function>pcntl_wtermsig</function></funcdef>
|
|
<paramdef>int <parameter>status</parameter></paramdef>
|
|
</funcprototype>
|
|
</funcsynopsis>
|
|
<para>
|
|
Returns the number of the signal that caused the child process to
|
|
terminate. This function is only useful if
|
|
<function>pcntl_wifsignaled</function> returned &true;.
|
|
</para>
|
|
<para>
|
|
The parameter <parameter>status</parameter> is the status
|
|
parameter supplied to a successfull call to
|
|
<function>pcntl_waitpid</function>.
|
|
</para>
|
|
<para>
|
|
See also <function>pcntl_waitpid</function>,
|
|
<function>pcntl_signal</function> and
|
|
<function>pcntl_wifsignaled</function>.
|
|
</para>
|
|
</refsect1>
|
|
</refentry>
|
|
|
|
|
|
</reference>
|
|
|
|
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Local variables:
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sgml-indent-step:1
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sgml-indent-data:t
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sgml-parent-document:nil
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sgml-default-dtd-file:"../../manual.ced"
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sgml-exposed-tags:nil
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sgml-local-catalogs:nil
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sgml-local-ecat-files:nil
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End:
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vim600: syn=xml fen fdm=syntax fdl=2 si
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vim: et tw=78 syn=sgml
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vi: ts=1 sw=1
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-->
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