Symfony\Installer\SelfUpdateCommand::execute PHP Метод

    protected function execute(InputInterface $input, OutputInterface $output)
    {
        $forceUpdate = true === $input->getOption('force-update');
        if (!$forceUpdate && $this->isInstallerUpdated()) {
            $this->output->writeln(sprintf('// Symfony Installer is <info>already updated</info> to the latest version (%s).', $this->latestInstallerVersion));
            return;
        }
        $this->output->writeln(sprintf('// <info>updating</info> Symfony Installer to <info>%s</info> version', $this->latestInstallerVersion));
        try {
            $this->downloadNewVersion()->checkNewVersionIsValid()->backupCurrentVersion()->replaceCurrentVersionbyNewVersion()->cleanUp();
        } catch (IOException $e) {
            if ($this->output->isVeryVerbose()) {
                $this->output->writeln($e->getMessage());
            }
            throw new \RuntimeException(sprintf("The installer couldn't be updated, probably because of a permissions issue.\n" . "Try to execute the command again with super user privileges:\n" . "  sudo %s\n", $this->getExecutedCommand()));
        } catch (\Exception $e) {
            $this->rollback();
            if ($this->output->isVeryVerbose()) {
                $this->output->writeln($e->getMessage());
            }
            return 1;
        }
    }