Adding logging and error handling are an important part of authoring Drush commands. Logs allow developers to get timely feedback from a command and inform users about potential alterations and flags, events to monitor, and the progress of long-running commands. Correct error handling allows for clean exits, meaningful error descriptions, and provides a path forward for developers to fix the errors and accomplish their goals.
In this tutorial we'll:
- Explore the different types of logging messages Drush commands can output
- Learn how to handle errors from within a Drush command
By the end of this tutorial you'll know what types of log messages you can use; how to log success messages, errors, or debug statements from a custom Drush command; and how to handle errors and exceptions.
When the logic of a command depends on user input, it's useful to set up an interactive questionnaire inside the command code. This allows you to provide the user with more context about the input they're providing, and ensure that you collect all the necessary values. This is especially useful when the command uses a pre-defined list of options and the values require memorization. An example of this is the drush cache-clear
command that comes with Drush core. It requires an argument indicating which cache to clear, which you can specify at the command line; however, if you invoke the command with no arguments it will present you with a list of cache bins to choose from and a UI for selecting one.
Drush 9+ can access the Input/Output (I/O) object via the $this->io()
method. This object -- an instance of \Drush\Style\DrushStyle
-- holds information about user-provided input, and utilities for manipulating that input. To ask a user a question, use an io()
object in the command callback method. It can take over the execution flow of the command as needed to stop and gather additional input. The I/O system has various methods for asking confirmation or choice questions such as confirm()
and choice()
.
In addition to prompting for input, the I/O object can be used to provide other styling to the command, like progress bars.
In this tutorial we'll:
- Learn how to prompt the user for additional input
- Process the user's answer as part of the command execution flow
By the end of this tutorial you should understand how to prompt a user for additional input for a custom Drush command.
While Drush empowers all Drupal users with its commands, it's even more powerful when used in combination with scripting solutions such as Composer and Bash. Scripts can be used to power post-deployment tasks like importing new configuration or clearing the cache, as part of CI processes to sync a database from one environment to another, to run background processes on the server such as imports and migrations, search indexing, running cron, and much more. If you want to write Bash (or any other scripts) that interact with a Drupal site, then Drush is the tool for you.
In this tutorial we'll:
- Learn how to use Drush commands within Composer and Bash scripts
- Learn how to chain multiple Drush commands together in a script
By the end of this tutorial you'll know how to use Drush as part of a script that automates common or tedious tasks.
When you manage many Drupal websites, you may perform repetitive tasks that are common across all of your sites. In our experience, this usually relates to having a personal preference for how certain tasks are accomplished. For example: maybe you like to make backups of the database and files in a specific way before testing upgrades, or you have a set of scripts for running scans of core web vitals. Although these tasks can be bundled into a custom module, it could be useful to create a site-wide Drush command instead. Site-wide commands can be installed with Composer, managed in a separate Git repository, and act as a project dependency. This way they are easy to maintain through a separate upstream. Changes to this code will be reflected on all the sites where it's used.
In this tutorial we'll:
- Declare a custom site-wide Drush command
- Demonstrate how to use Composer to manage a package that contains a Drush command
By the end of this tutorial you'll be able to create a site-wide Drush command and manage the code with Git and Composer.
Clear Drupal's Cache
FreeKnowing how to clear Drupal's cache is an important skill for any developer. You'll likely find yourself doing it frequently in order to get Drupal to register the changes you make to your code, or other updates you make via the UI. It is also a good first step to trouble shooting problems with your Drupal site: Clear the cache before you do any other debugging to ensure it's not just a bad cache entry.
Managing Media in Drupal
CourseDrupal User Guide
GuideWhat Is Drupal?
FreeTo learn more about how to get started with Drupal, also see our Introduction to Drupal guide.
In this lesson we take a look at Drupal, the open source Content Management System. We learn about the major components of a Drupal site and the library of constantly evolving tools available for working with Drupal. We find out how to see who uses it, by looking at DrupalShowcase.com and Drupal case studies on Drupal.org, among others. We look at Drupal's major features, such as Modules.
With this overview we have some context as we move forward into the series.
Additional resources
In this lesson we're going to break down the "Drupal stack" to understand what pieces are working here and how they relate to each other. We'll take a tour of the major components of Drupal itself, like nodes and users, and then have a brief discussion about ways of organizing content.
Additional resources
In this lesson we're going to start building our site for Mom and Pop, Inc. We're starting off by working on our content, to get things filled out a little. First, we'll create an About Us page with the basic info for the store, like address and opening hours. Then we'll create our first article, which welcomes people to the new site, and see how the two core content types, Basic page and Article, are different from each other. Then we'll tweak our main navigation so our tabs display correctly, and finish things off by looking at block management. We'll remove the "Powered by Drupal" block and add a new block to the site for our weekly specials.
Additional resources
This lesson offers a tour of some of the most basic tools for content management in Drupal. We're going to walk through and explain the following pieces:
- Content
- Comments
- Navigation
- Blocks
Additional resources
For this lesson we're going to get hands-on and play around in our administration area a little. We're going to review the site information for our new site, and then change things by setting the site name to match our case study.