Can a PHP script start another PHP script and exit?

Question

How can a PHP script start another PHP script, and then exit, leaving the other script running?

Also, is there any way for the 2nd script to inform the PHP script when it reaches a particular line?

Answer 1

Here's how to do it. You tell the browser to read in the first N characters of output and then close the connection, while your script keeps running until it's done.

<?php
ob_end_clean();
header("Connection: close");
ignore_user_abort(); // optional
ob_start();
echo ('Text the user will see');
$size = ob_get_length();
header("Content-Length: $size");
ob_end_flush();     // Will not work
flush();            // Unless both are called !

// At this point, the browser has closed connection to the web server

// Do processing here
include('other_script.php');

echo('Text user will never see');
?>

Answer 2

You can effectively achieve this by forking and then calling include or require.

parent.php:

<?php

    $pid = pcntl_fork();
    if ($pid == -1) {
        die("couldn't fork");
    } else if ($pid) { // parent script
        echo "Parent waiting at " . date("H:i:s") . "\n";
        pcntl_wait($status);
        echo "Parent done at " . date("H:i:s") . "\n";
    } else {
        // child script
        echo "Sleeper started at " . date("H:i:s") . "\n";
        include('sleeper.php');
        echo "Sleeper done at " . date("H:i:s") . "\n";
    }

?>

sleeper.php:

<?php
sleep(3);
?>  

Output:

$ php parent.php
Sleeper started at 01:22:02
Parent waiting at 01:22:02
Sleeper done at 01:22:05
Parent done at 01:22:05

However, forking does not inherently allow any inter-process communication, so you'd have to find some other way to inform the parent that the child has reached the specific line, like you asked in the question.