private function _run($command) 
	{
		if ($this->options['type'] === self::TYPE_PHP) {
			// Old Option: Run direct from terminal (doesn't like brackets too much).
			// $cmd = "php -r \"{$command}\"";

			// New Option: Save to temp file & run it.
			$this->savedFiles[] = $this->options['tmp-dir'] . 'async-tmp-' . time() . '.php';
			$result = file_put_contents(
				end($this->savedFiles),
				$this->_generateCode($command),
				LOCK_EX
			);

			if ($result !== false) {
				$cmd = "php " . end($this->savedFiles);
			}
			else {
				$cmd = "php --help";
			}
		}
		else {
			$cmd = $command;
		}

		if ($this->options['async']) {
			// This forks the process.
			// Helpful guide @ https://segment.com/blog/how-to-make-async-requests-in-php/
			$cmd .= ' > /dev/null 2>&1 &';
		}

		exec($cmd, $output, $exit);

		if ($this->options['debug']) {
			echo '<br />Command Run: ' . $cmd;
		}

		return $exit === 0;
	}