bulk update settings.php files for Drupal multi-site installation

check sites folder for selected core for valid sites

check for valid settings.php file

check settings.php file for target variable

if array check variable for target array key

update variable or skip file according to selection logic

1. Confirm that target 'sites' folder is valid folder containing subfolders.
2. For each subfolder, confirm that it is a site folder a. contains a valid settings.php file i. settings.php file is greater than 5K. ii. reading in variables from settings.php includes defined no-empty $db_url variable
3. Load variables from settings.php file.
4. Check whether $db_prefix has values defined. a. If not, skip to next directory. b. If so, check for authmap and shib_authmap keys.
5. If keys not defined, append key definitions to bottom of settings.php file:
   • $db_prefix['authmap'] = 'drupal_bruin_people.';
   • $db_prefix['shib_authmap'] = 'drupal_bruin_people.';