(Quick Reference)
                create-command
Purpose
The 
create-command command creates a new Grails Gradle task and shell command that can be run with the 
grails command from a terminal window.
Examples
The command:
grails create-command MyExample
Creates a class called 
grails-app/commands/PACKAGE_PATH/MyExampleCommand.groovy such as:
import grails.dev.commands.*class MyExampleCommand implements ApplicationCommand {  boolean handle(ExecutionContext ctx) {
      def dataSource = applicationContext.getBean(DataSource)
      return true
  }
}The command can then be run with:
Or as a Gradle task:
Note that the plugin should be on both the build classpath and the runtime classpath in 
build.gradle:
buildscript {
  …
  dependencies {
    classpath "org.grails.plugins:myplugin:0.1-SNAPSHOT"
  }
  …
  dependencies {
    runtime "org.grails.plugins:myplugin:0.1-SNAPSHOT"
  }
}Description
In order to separate the code generation and build layer, in Grails 3.x scripts created with 
create-script do not have access to the running application instance.
Instead, Grails 3.x features a new concept called an 
ApplicationCommand that is invoked via Gradle to perform tasks such as interact with the database etc.