Forking with PHP

Process Control support in PHP does not work for web scripts, only for those started as standalone. If PHP is compiled with this options

install

./configure --prefix=/usr/local/php-5.3.10 --with-apxs2=/usr/sbin/apxs --with-mysql=/usr/local/mysql-5.1.41/ --with-pgsql=/usr/local/postgresql-8.4.1/ --with-xmlrpc --enable-pcntl

then the phpinfo() shows that the configure command is

configure

'./configure' '--prefix=/usr/local/php-5.3.10' '--with-apxs2=/usr/sbin/apxs' '--with-mysql=/usr/local/mysql-5.1.41/' '--with-pgsql=/usr/local/postgresql-8.4.1/' '--with-xmlrpc'

i.e. PCNTL is not compiled for the Apache module. Executing a script with a call to pcntl_fork() like

fork.php

<?php

$pidNo = pcntl_fork();
	if ($pidNo == -1)
		echo "error\n";
	else if ($pidNo)
	{
		echo "parent id=" . getmypid() ."\n";
		pcntl_wait($status);
	}
	else
	{
		echo "child id=" . getmypid() . "\n";
		exit(0);
	}


?>

will work when started from the command line, but will generate a fatal error when started via web: Fatal error: Call to undefined function pcntl_fork() in /var/www/htdocs/whois/fork.php on line 3. However, web script which calls fork script via command line will work:

test.php

<?php

$hello = isset($_REQUEST["hello"]) ? $_REQUEST["hello"] : "world";
echo "<p>hello=$hello</p>";
system("php fork.php");

?>