commands-1.x-dev/src/Plugin/Command/EchoCommand.php

<?php

namespace Drupal\commands\Plugin\Command;

use Drupal\commands\CommandPluginBase;
use Drupal\Core\Form\FormStateInterface;

/**
 * Example plugin for Command Types.  Echos a string.
 *
 * @Command(
 *   id = "echo",
 *   label = @Translation("Echo a string"),
 *   description = @Translation("Echos an arbitrary string."),
 *   command = "echo [message]"
 * )
 */
class EchoCommand extends CommandPluginBase {

  /**
   * Show a form on the "Run command" form.
   * @return void
   */
  public function form($form, FormStateInterface $form_state) {
    $form['parameters']['message'] = [
      '#type' => 'textfield',
      '#title' => t('Message'),
      '#default_value' => t('Hello, :user!', [
        ':user' => \Drupal::currentUser()->getAccountName()
      ]),
      '#required' => TRUE,
      '#description'=> t('Enter a string to echo.'),
    ];
    return $form;
  }
}