Steps to create a module in Magento2

 1- Create a namespace folder inside app/code directory

    eg:- app/code/RB

2- Create a Module folder inside that namespace folder

    eg:- app/code/RB/Vendor

3- Create a registration.php file

<?php
\Magento\Framework\Component\ComponentRegistrar::register(
	\Magento\Framework\Component\ComponentRegistrar::MODULE,
	'RB_Vendor',
	__DIR__
);

 

 eg:-  app/code/RB/Vendor/registration.php and add the following contents

4- Create etc/module.xml file

eg:-  app/code/RB/Vendor/etc/module.xml and add the following contents

        <?xml version="1.0"?>

<config xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="urn:magento:framework:Module/etc/module.xsd">
    <module name="RB_Vendor" setup_version="1.0.0">
    </module>
</config>

5-Enable the module using the following command

        php bin/magento module:enable RB_Vendor

                    (or)


 6. To add the modules manually directly enter/write in the module in the below file

          app/etc/config.php as 'RB_Vendor' => 1, 

7. Check the module status using the command:     

            php bin/magento module:status 

8. Execute SUDO chmod -R 777 . , php bin/magento setup:upgrade, php bin/magento setup:static-content:deploy -f in order

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Create a Route

---------------------------------------------------------------------------------------------

1) To add route, it is necessary to create routes.xml file

app/code/RB/Vendor/etc/frontend/routes.xml

2)Inside RB/Vendor/etc folder, there will be two folders

        i) frontend

        ii) adminhtml

since this is a frontend route, we added it in frontend/ folder else we need to add it to adminhtml/ folder


3)The content would be       


<?xml version="1.0" ?>
<config xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="urn:magento:framework:App/etc/routes.xsd">
    <router id="standard">
        <route frontName="rb_vendor" id="rb_vendor">
            <module name="RB_Vendor"/>
        </route>
    </router>
</config>

4)  Route’s in magento are divided into 3 parts: Route frontname, controller and action as following example:

http://magento2.com/index.php/rb_vendor/controller/action

-----------------------------------------------------------------------------

               Create Controller 

---------------------------------------------------------------------------- 

1) In the folder app/code/RB/Vendor/Controller/Index/Test.php

where 'Test'is the class name  

 <?php
namespace RB\Vendor\Controller\Index;

class Test extends \Magento\Framework\App\Action\Action
{
	protected $_pageFactory;

	public function __construct(
		\Magento\Framework\App\Action\Context $context,
		\Magento\Framework\View\Result\PageFactory $pageFactory)
	{
		$this->_pageFactory = $pageFactory;
		return parent::__construct($context);
	}

	public function execute()
	{
		echo "Hello World";
		exit;
	}
}

 http://magento2.com/index.php/rb_vendor/Index/Test