So, Let’s check the below steps with output.

<?php
namespace Kaushik\Helloworld\Helper;
use Magento\Framework\App\Helper\AbstractHelper;
class Data extends AbstractHelper
{

/**
 * @var \Magento\Framework\App\Filesystem\DirectoryList
 */
protected $dir;

public function __construct(
    ...
    \Magento\Framework\App\Filesystem\DirectoryList $dir,
    ...        
) {
    ...
    $this->dir = $dir;
    ...
}

public function getRootPath()
{
    return $this->dir->getRoot(); // Output : /var/www/html
}
}

However, If you want to get a media, var, pub, etc. directory path then, you can use the below codes to get the appropriate directory path.

$this->dir->getPath('pub'); // Output : /var/www/html/pub

$this->dir->getPath('media'); // Output : /var/www/html/pub/media

$this->dir->getPath('lib_internal'); // Output : /var/www/html/lib/internal

$this->dir->getPath('log'); // Output : /var/www/html/var/log

$this->dir->getPath('generated'); // Output: /var/www/html/generated

That’s it !!!

In other words, You can use the above code in your function based on your requirement.

Cron job is a great feature by Linux, the free operating system for the user. The cron job will create a command or a script that is appropriate with the task you want to do. Instead of manual working, the cronjob allows running automatically in exact time and date.

In this example, we are using a sample module with Kaushik as the Vendor name and HelloWorld as the module name.

Step 1: Create crontab.xml

File: app/code/Kaushik/HelloWorld/etc/crontab.xml

<?xml version="1.0"?>
<config xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="urn:magento:module:Magento_Cron:etc/crontab.xsd">
    <group id="default">
        <job name="custom_cronjob" instance="Kaushik\HelloWorld\Cron\Test" method="execute">
            <schedule>* * * * *</schedule>
        </job>
    </group>
</config>

• group id is your cron group name. You can run only cron for single group at a time.
• job instance is class to be instantiated.
• job method is method in job instance to call.
• job name is Unique ID for this cron job.
• schedule is schedule in cron format where

* * * * * command to be executed
| | | | |
| | | | +----- Day of week (0 - 7) (Sunday=0 or 7)
| | | +------- Month (1 - 12)
| | +--------- Day of month (1 - 31)
| +----------- Hour (0 - 23)
+------------- Minute (0 - 59)

Step 2: Create a class to run cron

File: app/code/Kaushik/HelloWorld/Cron/Test.php

<?php
namespace Kaushik\HelloWorld\Cron;

use \Psr\Log\LoggerInterface;
class Test {
  protected $logger;

  public function __construct(LoggerInterface $logger) {
    $this->logger = $logger;
  }

  /**
    * Write to system.log
    *
    * @return void
  */
  public function execute() {
    // Do your Stuff
    $this->logger->info('Cron Works');
  }
}

In the above code, we created a log. Once the cron is executed, the contents of the ‘execute’ method will be added in the system.log file.

Step 3: Run the cron job

We can run the Magento cron jobs using the below command.

php bin/magento cron:run

I hope this is useful blog for you.

Thank you for reading!

At first, we must create the primary files of a module and I would create module under Kaushik name space and call it CustomApi.

File – app/code/Kaushik/CustomApi/etc/module.xml

<?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="Kaushik_CustomApi" setup_version="1.0.0" />
</config>

File – app/code/Kaushik/CustomApi/registration.php

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

File – app/code/Kaushik/CustomApi/etc/webapi.xml

<?xml version="1.0" ?>
<routes xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="urn:magento:module:Magento_Webapi:etc/webapi.xsd">
    <route method="GET" url="/V1/kaushik-customapi/post">
        <service class="Kaushik\CustomApi\Api\PostManagementInterface" method="getPost"/>
        <resources>
            <resource ref="anonymous"/>
        </resources>
    </route>
</routes>

File – app/code/Kaushik/CustomApi/etc/di.xml

<?xml version="1.0" ?>
<config xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="urn:magento:framework:ObjectManager/etc/config.xsd">
    <preference for="Kaushik\CustomApi\Api\PostManagementInterface" type="Kaushik\CustomApi\Model\PostManagement"/>
</config>

File – app/code/Kaushik/CustomApi/Model/PostManagement.php

<?php 
namespace Kaushik\CustomApi\Model;
 
class PostManagement {

    /**
     * {@inheritdoc}
     */
    public function getPost($param)
    {
        return 'api GET return the $param ' . $param;
    }
}

File – app/code/Kaushik/CustomApi/Api/PostManagementInterface.php

<?php 
namespace Kaushik\CustomApi\Api;
 
interface PostManagementInterface {

    /**
     * GET for Post api
     * @param string $param
     * @return string
     */
    public function getPost($param);
}

That’s all. We’ve just created custom API and now it’s ready to use.

By default, Magento 2 comes with multiple CLI Commands out of box. To use any command, simply type that command in the CLI, like php bin/magento cache:clean

List Commands
php bin/magento  list                           php bin/magento l

Admin
php bin/magento admin:user:create               php bin/magento a:u:c
php bin/magento admin:user:unlock               php bin/magento a:u:u

Cache
php bin/magento cache:clean                     php bin/magento c:c
php bin/magento cache:disable                   php bin/magento c:d
php bin/magento cache:enable                    php bin/magento c:e
php bin/magento cache:flush                     php bin/magento c:f
php bin/magento cache:status                    php bin/magento c:s

Catalog
php bin/magento catalog:images:resize           php bin/magento c:i:r
php bin/magento catalog:product:attributes:cleanup      php bin/magento c:p:a:c

Cron
php bin/magento cron:run                         php bin/magento c:r

Customer
php bin/magento customer:hash:upgrade            php bin/magento c:h:u

Deploy
php bin/magento deploy:mode:set                  php bin/magento d:m:se
php bin/magento deploy:mode:show                 php bin/magento d:m:sh

Dev
php bin/magento dev:source-theme:deploy          php bin/magento d:source-theme:d
php bin/magento dev:tests:run                    php bin/magento d:t:r
php bin/magento dev:urn-catalog:generate         php bin/magento d:urn-catalog:g
php bin/magento dev:xml:convert                  php bin/magento d:x:c

i18n
php bin/magento i18n:collect-phrases             php bin/magento i:collect-phrases
php bin/magento i18n:pack                        php bin/magento i:p
php bin/magento i18n:uninstall                   php bin/magento i:u

Indexer
php bin/magento indexer:info                     php bin/magento i:i
php bin/magento indexer:reindex                  php bin/magento i:rei
php bin/magento indexer:reset                    php bin/magento i:res
php bin/magento indexer:set-mode                 php bin/magento i:set
php bin/magento indexer:show-mode                php bin/magento i:show
php bin/magento indexer:status                   php bin/magento i:st

Info
php bin/magento info:adminuri                               php bin/magento i:a
php bin/magento info:backups:list                           php bin/magento i:b:l
php bin/magento info:currency:list                          php bin/magento i:c:l
php bin/magento info:dependencies:show-framework            php bin/magento i:d:show-framework
php bin/magento info:dependencies:show-modules              php bin/magento i:d:show-modules
php bin/magento info:dependencies:show-modules-circular     php bin/magento i:d:show-circular
php bin/magento info:language:list                          php bin/magento i:l:l
php bin/magento info:timezone:list                          php bin/magento i:t:l

Maintenance
php bin/magento maintenance:allow-ips            php bin/magento ma:a
php bin/magento maintenance:disable              php bin/magento ma:d
php bin/magento maintenance:enable               php bin/magento ma:e
php bin/magento maintenance:status               php bin/magento ma:s

Module
php bin/magento module:disable                   php bin/magento mo:d
php bin/magento module:enable                    php bin/magento mo:e
php bin/magento module:status                    php bin/magento mo:s
php bin/magento module:uninstall                 php bin/magento mo:u

Setup
php bin/magento setup:backup                     php bin/magento se:b
php bin/magento setup:config:set                 php bin/magento se:c:se
php bin/magento setup:cron:run                   php bin/magento se:c:r
php bin/magento setup:db-data:upgrade            php bin/magento se:db-data:u
php bin/magento setup:db-schema:upgrade          php bin/magento se:db-schema:u
php bin/magento setup:db:status                  php bin/magento se:d:st
php bin/magento setup:di:compile                 php bin/magento se:d:c
php bin/magento setup:install                    php bin/magento se:i
php bin/magento setup:performance:generate-fixtures      php bin/magento se:p:generate-fixtures
php bin/magento setup:rollback                   php bin/magento se:r
php bin/magento setup:static-content:deploy      php bin/magento se:s:d
php bin/magento setup:store-config:set           php bin/magento se:sto:s 
php bin/magento setup:uninstall                  php bin/magento se:un
php bin/magento setup:upgrade                    php bin/magento se:up

Sample Data
php bin/magento sampledata:deploy                php bin/magento ma:d
php bin/magento sampledata:remove                php bin/magento sa:rem
php bin/magento sampledata:reset                 php bin/magento sa:res

Theme
php bin/magento theme:uninstall                  php bin/magento t:u

That’s all.

1. Save Fastly service credentials as bash environment variables
export FASTLY_SERVICE_ID=<Service ID>
export FASTLY_API_TOKEN=<API Token>

2. Check active VCL version
curl -H "Fastly-Key: $FASTLY_API_TOKEN" https://api.fastly.com/service/$FASTLY_SERVICE_ID/version/active

3. Save active version number returned in the "number" key
export FASTLY_VERSION_ACTIVE=<version>

4. Clone active VCL version and all snippets
curl -H "Fastly-Key: $FASTLY_API_TOKEN" https://api.fastly.com/service/$FASTLY_SERVICE_ID/version/$FASTLY_VERSION_ACTIVE/clone -X PUT

5. Save the new version number returned in the "number" key
export FASTLY_EDIT_VERSION=<Version>

6. Delete an individual VCL snippet
curl -H "Fastly-Key: $FASTLY_API_TOKEN" https://api.fastly.com/service/$FASTLY_SERVICE_ID/version/$FASTLY_EDIT_VERSION/snippet/<snippet_name> -X DELETE
Note: name of snippet created from admin UI is prefixed with "magentomodule_" in Fastly. For eg. addForwardSlash in admin will be magentomodule_addForwardSlash in Fastly.
To list all regular VCL snippets: curl -H "Fastly-Key: $FASTLY_API_TOKEN" https://api.fastly.com/service/$FASTLY_SERVICE_ID/version/$FASTLY_EDIT_VERSION/snippet

7. Validate custom VCL snippets
curl -H "Fastly-Key: $FASTLY_API_TOKEN" https://api.fastly.com/service/$FASTLY_SERVICE_ID/version/$FASTLY_EDIT_VERSION/validate

8. Activate VCL snippets
curl -H "Fastly-Key: $FASTLY_API_TOKEN" https://api.fastly.com/service/$FASTLY_SERVICE_ID/version/$FASTLY_EDIT_VERSION/activate -X PUT

Using the Magento Rest API provided, you can create, authenticate, and remove a token and its access.

************* curl POST HTTP token authentication ****************
curl -XPOST -H 'Content-Type: application/json' http://magento231.local/rest/V1/integration/admin/token -d '{ "username": "admin", "password": "admin@123" }'

************* curl GET HTTP token authentication ****************
curl -X GET "http://www.magento231.local/rest/all/V1/store/storeViews" -H "accept: application/json" -H "Authorization: Bearer 0kze3s5uy6vwn8fvzt6e23gwbwhrj72i"

************* curl PUT HTTP token authentication ****************
curl -X PUT "http://www.magento231.local/rest/all/V1/eav/attribute-sets/1" -H "accept: application/json" -H "Content-Type: application/json" -H "Authorization: Bearer 0kze3s5uy6vwn8fvzt6e23gwbwhrj72i" -d "{ \"attributeSet\": { \"attribute_set_id\": 0 }}"

************* curl DELETE HTTP token authentication ****************
curl -X DELETE "http://www.magento231.local/rest/all/V1/eav/attribute-sets/1" -H "accept: application/json" -H "Authorization: Bearer 0kze3s5uy6vwn8fvzt6e23gwbwhrj72i"

Before getting started, let’s understand the used table’s role in this script.

customer_data_live => here we have a list of customers’ emails with an email sent flag.

block_email => here we have a list of customers who are blocked from sending emails.

<?php
ini_set("memory_limit", "-1");
ini_set('max_execution_time', 18000);
ini_set('display_startup_errors', 1);
error_reporting(E_ALL);
use Magento\Framework\App\Bootstrap;
include '/data/html/app/bootstrap.php';
$bootstrap = Bootstrap::create(BP, $_SERVER);
$objectManager = $bootstrap->getObjectManager();
$state = $objectManager->get('Magento\Framework\App\State');
$state->setAreaCode('frontend');
$resource = $objectManager->get('Magento\Framework\App\ResourceConnection');
$connection = $resource->getConnection();

shootMail($connection);

function  shootMail($connection){
    $sql  = "select `template_text` from `email_template` where template_id =10";  //get you email template id from admin
    $email_template =  $connection->fetchOne($sql);

    $customer_emails = getCustomerList($connection);
    foreach  ($customer_emails as $email)
    {
        $customer_email = $email['email']; 
        $entity_id = $email['entity_id']; 
        $notblocklisted = checkifblocklisted($connection,$customer_email);   //ignore this if you have no any blocked emails record in any custom table
        if($notblocklisted==false)
        {
            $response  = sendEmail($connection,$customer_email,$email_template);
            $sql  = "update `customer_data_live` set `mail_sent` ='$response' where entity_id ='$entity_id'";
            $connection->query($sql);
        } else 
        {
            $sql  = "update `customer_data_live` set `mail_sent` ='blocklisted_email' where entity_id ='$entity_id'";
            $connection->query($sql);
        }
    }

}

function sendEmail($connection,$customer_email,$message_text)
{
    $response_mesage=NULL;
    $subject="Celebrating the Sale"; 
    $url = 'https://api.sendgrid.com/';
    $user = 'example@gmail.com';
    $pass = 'test@132';     
    $json_string = array(   
        'category' =>'no-reply'    
    );  

    $fromaddress='Sales'; 
    $from='sales@example.com';
    $request = $url . 'api/mail.send.json';
    $html = $message_text;
    $html = urlencode($html);             
    $session = curl_init($request);   
            
    curl_setopt($session, CURLOPT_POSTFIELDS, "api_user=".$user."&api_key=".$pass."&x-smtpapi=".json_encode($json_string)."&X-PM-TrackOpens=true&to[]=$customer_email&subject=".$subject."&html=".$html."&fromname=".$fromaddress."&from=$from");curl_setopt($session, CURLOPT_HEADER, false);
    curl_setopt($session, CURLOPT_RETURNTRANSFER, true);
    $response = json_decode(curl_exec($session),true);
    if(!empty($response) &&  is_array($response))
    {
        $response_mesage = $response['message']; 

    }
    curl_close($session);   
    return  $response_mesage;       

}

function getCustomerList($connection){
    $sql =  "SELECT `email`,`entity_id` FROM `customer_data_live` where  mail_sent is  null limit 20";
    return $connection->fetchAll($sql);
}

function  checkifblocklisted($connection,$email){
    $sql  = "select email from `block_email` where email ='$email'";
    $email =  $connection->fetchOne($sql);
    if(!empty($email))
    {
        return true;
    }
    return false;
}

In Your Controller write the following code:

<?php
namespace Company\Module\Controller\Index;
use Magento\Framework\Controller\ResultFactory; 

class Actionname name extends \Magento\Framework\App\Action\Action
{      
    public function execute()
    {
        $resultRedirect = $this->resultFactory->create(ResultFactory::TYPE_REDIRECT);

        //your code work around here

        $resultRedirect->setUrl($this->_redirect->getRefererUrl());
        return $resultRedirect;
    }
}