Get user by username (or any other attributes) in Moodle

You can do as the following snippet to get the user object by username (or any other attributes)

#!/usr/bin/php
<?php
define('CLI_SCRIPT', true);
require_once('../config.php');

global $DB;

$user = $DB->get_record('user', array('username'=>'myusername'));                                                             
print_r($user);

exit;
?>

Reference: https://docs.moodle.org/dev/Data_manipulation_API