Many times, we add a hook_update_n to change schema, perform relevant options for new release etc. Sometimes running this function manually is required to debug it's working or re run the logic which may not have been implemented because of failed updates. You can use Drush to run any particular function in this way:
drush php-eval "module_load_include('install', 'YOUR_CUSTOM_MODULE', 'YOUR_CUSTOM_MODULE'); YOUR_CUSTOM_MODULE_update_8001();"
Use the following function to log message to the terminal/command prompt from a Drush command.
$this->output()->writeln('Display this on terminal.');
You can install as explained in https://modulesunraveled.com/blog/install-drush-7-and-8-and-automatically-switch-versions-based-project.
After that go to settings.php and add the following line in $database array.
'unix_socket' => '/Applications/MAMP/tmp/mysql/mysql.sock',
There might be a situation when you have to install a module programmatically in Drupal 8. You can achieve this with the help of Drush Invoke command. Make sure Drush is working fine on your system before using this function.
//This command will install and enable both devel and admin toolbar.
drush_invoke('pm-enable',['devel','admin_toolbar']);