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Creating Custom Drush Commands

Creating a new Drush command or porting a legacy command is easy. Follow the steps below.

  1. Run drush generate drush-command-file.
  2. Drush will prompt for the machine name of the module that should "own" the file. The module selected must already exist and be enabled. Use drush generate module-standard to create a new module.
  3. Drush will then report that it created a commandfile. Edit as needed.
  4. Use the classes for the core Drush commands at /src/Commands as inspiration and documentation.
  5. See the dependency injection docs for interfaces you can implement to gain access to Drush config, Drupal site aliases, etc. Also note the create() method for injecting Drupal or Drush dependencies.
  6. Write PHPUnit tests based on Drush Test Traits.

Attributes or Annotations

The following are both valid ways to declare a command:

use Drush\Attributes as CLI;

#[CLI\Command(name: 'xkcd:fetch-attributes', aliases: ['xkcd-attributes'])]
#[CLI\Argument(name: 'search', description: 'Optional argument to retrieve the cartoons matching an index, keyword, or "random".')]
#[CLI\Option(name: 'image-viewer', description: 'Command to use to view images (e.g. xv, firefox).', suggestedValues: ['open', 'xv', 'firefox'])]
#[CLI\Option(name: 'google-custom-search-api-key', description: 'Google Custom Search API Key')]
#[CLI\Help(description: 'Retrieve and display xkcd cartoons (attribute variant).')]
#[CLI\Usage(name: 'drush xkcd', description: 'Retrieve and display the latest cartoon')]
#[CLI\Usage(name: 'drush xkcd sandwich', description: 'Retrieve and display cartoons about sandwiches.')]
public function fetch($search = null, $options = ['image-viewer' => 'open', 'google-custom-search-api-key' => 'AIza']) {
    $this->doFetch($search, $options);
}
/**
 * @command xkcd:fetch
 * @param $search Optional argument to retrieve the cartoons matching an index number, keyword, or "random".
 * @option image-viewer Command to use to view images (e.g. xv, firefox).
 * @option google-custom-search-api-key Google Custom Search API Key.
 * @usage drush xkcd
 *   Retrieve and display the latest cartoon.
 * @usage drush xkcd sandwich
 *   Retrieve and display cartoons about sandwiches.
 * @aliases xkcd
*/
public function fetch($search = null, $options = ['image-viewer' => 'open', 'google-custom-search-api-key' => 'AIza']) {
    $this->doFetch($search, $options);
}

Specifying the Services File

A module's composer.json file stipulates the filename where the Drush services (e.g. the Drush command files) are defined. The default services file is drush.services.yml, which is defined in the extra section of the composer.json file as follows:

  "extra": {
    "drush": {
      "services": {
        "drush.services.yml": "^11"
      }
    }
  }
If for some reason you need to load different services for different versions of Drush, simply define multiple services files in the services section. The first one found will be used. For example:
  "extra": {
    "drush": {
      "services": {
        "drush-11-99.services.yml": "^11.99",
        "drush.services.yml": "^11"
      }
    }
  }
In this example, the file drush-11-99.services.yml loads commandfile classes that require features only available in Drush 11.99 and later, and drush.services.yml loads an older commandfile implementation for earlier versions of Drush.

It is also possible to use version ranges to exactly specify which version of Drush the services file should be used with (e.g. "drush.services.yml": ">=11 <11.99").

In cases where a Composer package contains one or more sub-modules with their own drush.services.yml files (such as Drupal distributions or suites of modules), a minimal composer.json file can be added to the sub-module's directory, containing only the extra.drush.servicessection as described above.

Altering Drush Command Info

Drush command info (annotations/attributes) can be altered from other modules. This is done by creating and registering 'command info alterers'. Alterers are class services that are able to intercept and manipulate an existing command annotation.

In order to alter an existing command info, follow the steps below:

  1. In the module that wants to alter a command info, add a service class that implements the \Consolidation\AnnotatedCommand\CommandInfoAltererInterface.
  2. In the module drush.services.yml declare a service pointing to this class and tag the service with the drush.command_info_alterer tag.
  3. In that class, implement the alteration logic in the alterCommandInfo() method.
  4. Along with the alter code, it's strongly recommended to log a debug message explaining what exactly was altered. This makes things easier on others who may need to debug the interaction of the alter code with other modules. Also it's a good practice to inject the the logger in the class constructor.

For an example, see the alterer class provided by the testing 'woot' module: tests/fixtures/modules/woot/src/WootCommandInfoAlterer.php.

Symfony Console Commands

Drush lists and runs Symfony Console commands, in addition to more typical annotated commands. See this test and this commandfile.

Site-Wide Drush Commands

Commandfiles that are installed in a Drupal site and are not bundled inside a Drupal module are called 'site-wide' commandfiles. Site-wide commands may either be added directly to the Drupal site's repository (e.g. for site-specific policy files), or via composer require. See the examples/Commands folder for examples. In general, it's better to use modules to carry your Drush commands, as module-based commands may participate in Drupal's dependency injection via the drush.services.yml.

If you still prefer using site-wide commandfiles, here are some examples of valid commandfile names and namespaces:

  1. Simple
    • Filename: $PROJECT_ROOT/drush/Commands/ExampleCommands.php
    • Namespace: Drush\Commands
  2. Nested in a subdirectory committed to the site's repository
    • Filename: $PROJECT_ROOT/drush/Commands/example/ExampleCommands.php
    • Namespace: Drush\Commands\example
  3. Nested in a subdirectory installed via a Composer package
    • Filename: $PROJECT_ROOT/drush/Commands/contrib/dev_modules/ExampleCommands.php
    • Namespace: Drush\Commands\dev_modules

Note: Make sure you do not include src in the path to your command. Your command may not be discovered and have additional problems.

Installing commands as part of a Composer project requires that the project's type be drupal-drush, and that the installer-paths in the Drupal site's composer.json file contains "drush/Commands/contrib/{$name}": ["type:drupal-drush"]. It is also possible to commit projects with a similar layout using a directory named custom in place of contrib; if this is done, then the directory custom will not be considered to be part of the commandfile's namespace.

If a site-wide commandfile is added via a Composer package, then it may declare any dependencies that it may need in its composer.json file. Site-wide commandfiles that are committed directly to a site's repository only have access to the dependencies already available in the site. Site-wide commandfiles should declare their Drush version compatibility via a conflict directive. For example, a Composer-managed site-wide command that works with both Drush 8 and Drush 9 might contain something similar to the following in its composer.json file:

    "conflict": {
        "drush/drush": "<8.2 || >=9.0 <9.6 || >=10.0",
    }
Using require in place of conflict is not recommended.

A site-wide commandfile should have tests that run with each (major) version of Drush that is supported. You may model your test suite after the example drush extension project.

Global Drush Commands

Commandfiles that are not part of any Drupal site are called 'global' commandfiles.

Commands discovered by configuration

Global commandfiles discoverable by configuration are not supported by default; in order to enable them, you must configure your drush.yml configuration file to add an include search location.

For example:

drush:
  paths:
    include:
      - '${env.home}/.drush/commands'
With this configuration in place, global commands may be placed as described in the Site-Wide Drush Commands section above. Global commandfiles may not declare any dependencies of their own; they may only use those dependencies already available via the autoloader.

Tip

  1. The filename must be have a name like Commands/ExampleCommands.php
    1. The prefix Example can be whatever string you want.
    2. The file must end in Commands.php
  2. The directory above Commands must be one of:
    1. A Folder listed in the 'include' option. Include may be provided via config or via CLI.
    2. ../drush, /drush or /sites/all/drush. These paths are relative to Drupal root.

It is recommended that you avoid global Drush commands, and favor site-wide commandfiles instead. If you really need a command or commands that are not part of any Drupal site, consider making a stand-alone script or custom .phar instead. See ahoy, Robo and g1a/starter as potential starting points.

Symlinked packages

While it is good practice to make your custom commands into a Composer package, please beware that symlinked packages (by using the composer repository type Path) will not be discovered by Drush. When in development, it is recommended to specify your package's path in your drush.yml to have quick access to your commands.

Auto-discovered commands

Such commands are auto-discovered by their class PSR4 namespace and class/file name suffix. Drush will auto-discover commands if:

  • The commands class is PSR4 auto-loadable.
  • The commands class namespace, relative to base namespace, is Drush\Commands. For instance, if a Drush command provider third party library maps this PSR4 autoload entry:
    "autoload": {
      "psr-4": {
        "My\\Custom\\Library\\": "src"
      }
    }
    
    then the Drush global commands class namespace should be My\Custom\Library\Drush\Commands and the class file should be located under the src/Drush/Commands directory.
  • The class and file name ends with *DrushCommands, e.g. FooDrushCommands.

Last update: May 18, 2023