watch

<?php

// Format and check args
@[$_, $src, $dst, $opt] = $_SERVER['argv'];

if (!$src || !$dst)
    return terminate(['Usage: php watch <source> <destination> [options]', '', 'Options:', ' d - shows defined paragraph number']);

// Check source file and load it
if (!is_file($src))
    return terminate('Soruce file doesn\'t exist!');

$last_contents = null;

while (true)
{
    // If file has changed, recompile
    if ($last_contents != file_get_contents($src))
    {
        print exec("php compile $src $dst $opt") . PHP_EOL;
        $last_contents = file_get_contents($src);
    }
    sleep(1);
}

/**
 * Prints formatted exit message.
 *
 * @param string|string[] $message
 * @return string
 */
function terminate($message)
{
    if (is_array($message))
        $message = implode(PHP_EOL, $message);
    return print PHP_EOL . $message . PHP_EOL;
}