drupal_rewrite_settings

drupal_rewrite_settings($settings = array(), $settings_file = NULL)

  $settings['config_directories'] = array(
    CONFIG_SYNC_DIRECTORY => (object) array(
      'value' => 'config_hash/sync',
      'required' => TRUE,
    ),
  );
  

  $config_directories['sync'] = 'config_hash/sync'
  

function drupal_rewrite_settings($settings = array(), $settings_file = NULL) {
  if (!isset($settings_file)) {
    $settings_file = \Drupal::service('site.path') . '/settings.php';
  }
  // Build list of setting names and insert the values into the global namespace.
  $variable_names = array();
  $settings_settings = array();
  foreach ($settings as $setting => $data) {
    if ($setting != 'settings') {
      _drupal_rewrite_settings_global($GLOBALS[$setting], $data);
    }
    else {
      _drupal_rewrite_settings_global($settings_settings, $data);
    }
    $variable_names['$' . $setting] = $setting;
  }
  $contents = file_get_contents($settings_file);
  if ($contents !== FALSE) {
    // Initialize the contents for the settings.php file if it is empty.
    if (trim($contents) === '') {
      $contents = "<?php\n";
    }
    // Step through each token in settings.php and replace any variables that
    // are in the passed-in array.
    $buffer = '';
    $state = 'default';
    foreach (token_get_all($contents) as $token) {
      if (is_array($token)) {
        list($type, $value) = $token;
      }
      else {
        $type = -1;
        $value = $token;
      }
      // Do not operate on whitespace.
      if (!in_array($type, array(T_WHITESPACE, T_COMMENT, T_DOC_COMMENT))) {
        switch ($state) {
          case 'default':
            if ($type === T_VARIABLE && isset($variable_names[$value])) {
              // This will be necessary to unset the dumped variable.
              $parent = &$settings;
              // This is the current index in parent.
              $index = $variable_names[$value];
              // This will be necessary for descending into the array.
              $current = &$parent[$index];
              $state = 'candidate_left';
            }
            break;
          case 'candidate_left':
            if ($value == '[') {
              $state = 'array_index';
            }
            if ($value == '=') {
              $state = 'candidate_right';
            }
            break;
          case 'array_index':
            if (_drupal_rewrite_settings_is_array_index($type, $value)) {
              $index = trim($value, '\'"');
              $state = 'right_bracket';
            }
            else {
              // $a[foo()] or $a[$bar] or something like that.
              throw new Exception('invalid array index');
            }
            break;
          case 'right_bracket':
            if ($value == ']') {
              if (isset($current[$index])) {
                // If the new settings has this index, descend into it.
                $parent = &$current;
                $current = &$parent[$index];
                $state = 'candidate_left';
              }
              else {
                // Otherwise, jump back to the default state.
                $state = 'wait_for_semicolon';
              }
            }
            else {
              // $a[1 + 2].
              throw new Exception('] expected');
            }
            break;
          case 'candidate_right':
            if (_drupal_rewrite_settings_is_simple($type, $value)) {
              $value = _drupal_rewrite_settings_dump_one($current);
              // Unsetting $current would not affect $settings at all.
              unset($parent[$index]);
              // Skip the semicolon because _drupal_rewrite_settings_dump_one() added one.
              $state = 'semicolon_skip';
            }
            else {
              $state = 'wait_for_semicolon';
            }
            break;
          case 'wait_for_semicolon':
            if ($value == ';') {
              $state = 'default';
            }
            break;
          case 'semicolon_skip':
            if ($value == ';') {
              $value = '';
              $state = 'default';
            }
            else {
              // If the expression was $a = 1 + 2; then we replaced 1 and
              // the + is unexpected.
              throw new Exception('Unexpected token after replacing value.');
            }
            break;
        }
      }
      $buffer .= $value;
    }
    foreach ($settings as $name => $setting) {
      $buffer .= _drupal_rewrite_settings_dump($setting, '$' . $name);
    }

    // Write the new settings file.
    if (file_put_contents($settings_file, $buffer) === FALSE) {
      throw new Exception(t('Failed to modify %settings. Verify the file permissions.', array('%settings' => $settings_file)));
    }
    else {
      // In case any $settings variables were written, import them into the
      // Settings singleton.
      if (!empty($settings_settings)) {
        $old_settings = Settings::getAll();
        new Settings($settings_settings + $old_settings);
      }
      // The existing settings.php file might have been included already. In
      // case an opcode cache is enabled, the rewritten contents of the file
      // will not be reflected in this process. Ensure to invalidate the file
      // in case an opcode cache is enabled.
      OpCodeCache::invalidate(DRUPAL_ROOT . '/' . $settings_file);
    }
  }
  else {
    throw new Exception(t('Failed to open %settings. Verify the file permissions.', array('%settings' => $settings_file)));
  }
}