Example WP-CLI Progress Bar https://chrisk.io/adding-progress-bars-wp-cli-processes/

example-cli-progress.php

<?php
/**
 * Plugin Name: chrisk.io - Example WP-CLI Progress Bar
 * Plugin URI:  https://chrisk.io/adding-progress-bars-wp-cli-processes/
 * Description: An example plugin for creating progress bars in your WP-CLI processes.
 * Version:     1.0
 * Author:      Chris Klosowski
 * Author URI:  https://chrisk.io
 * License:     GPL-2.0+
 */

// Exit if accessed directly
if ( ! defined( 'ABSPATH' ) ) exit;

if ( defined( 'WP_CLI' ) && WP_CLI ) {
	/**
	 * Example WPCLI extension class
	 *
	 * Example_CLI_Progress_Bar Class
	 *
	 * @since   1.0
	 */
	class Example_CLI_Progress_Bar extends WP_CLI_Command {

		public function progress_bar( $args, $assoc_args ) {
			$total = isset( $assoc_args ) && array_key_exists( 'total', $assoc_args ) ? absint( $assoc_args[ 'total' ] ) : 100;

			WP_CLI::line( 'Starting Example' );

			$progress = \WP_CLI\Utils\make_progress_bar( 'Progress Bar', $total );
			$i        = 0;
			while ( $i < $total ) {
				$progress->tick();
				sleep(1); // Remove this from your production code, only here to slow down the process so you can see it work.
				$i++;
			}

			$progress->finish();

			WP_CLI::line( 'Example Complete' );

		}
	}

	WP_CLI::add_command( 'chriskio', 'Example_CLI_Progress_Bar' );
};