PHPExiftool\ExiftoolServer::executeCommand PHP Method

    public function executeCommand($commands, $timeout = 4)
    {
        $optwithargs = array('-i', '-charset', '-if', '-w', '-common_args');
        if (true !== $this->isRunning()) {
            throw new RuntimeException('Server is not running');
        }
        $prev = null;
        //        // first split execute (sub queries)
        //
        //        if (false !== $pos = strpos($commands, '-common_args')) {
        //            $common_args = substr($commands, $pos + 12);
        //
        //            $recomposed = array();
        //
        //            foreach (explode(' -execute ', substr($commands, 0, $pos)) as $subcommand) {
        //                $recomposed[] = $subcommand . ' ' . $common_args;
        //            }
        //            $commands = implode(' -execute ', $recomposed);
        //        }
        foreach (explode(' ', $commands) as $command) {
            if ($command == '-q') {
                continue;
            }
            if (substr($command, 0, 1) === "'" && substr($command, -1) === "'") {
                $command = substr($command, 1, -1);
            }
            if (substr($command, 0, 1) === '"' && substr($command, -1) === '"') {
                $command = substr($command, 1, -1);
            }
            $end = "\n";
            file_put_contents($this->pipefile, $command . $end, FILE_APPEND);
        }
        file_put_contents($this->pipefile, "\n-execute\n", FILE_APPEND);
        // here we send sigcont
        //$this->server->signal(SIGCONT);
        $start = microtime(true);
        while ((strlen($this->server->getOutput()) <= $this->offset || substr(substr($this->server->getOutput(), $this->offset), -8) !== "{ready}\n") && microtime(true) - $start < $timeout) {
            usleep(25000);
        }
        //        var_dump(microtime(true) - $start);
        // server output should be cached here because streams are polled
        // everytime I request the output
        $outputIsValid = substr($this->server->getOutput(), -8) === "{ready}\n";
        $output = $outputIsValid ? substr($this->server->getOutput(), $this->offset, -8) : '';
        $this->offset = strlen($this->server->getOutput());
        if (trim($output) === '' && $outputIsValid === false && $this->server->getErrorOutput()) {
            throw new RuntimeException('Command failed');
        }
        return $output;
    }