Yii2 htaccess - How to hide frontend/web and backend/web COMPLETELY

gistfile1.txt

Step 1 
Create .htaccess file in root folder, i.e advanced/.htaccess and write below code.
---------------
Options +FollowSymlinks
RewriteEngine On

# deal with admin first
RewriteCond %{REQUEST_URI} ^/(admin) <------
RewriteRule ^admin/assets/(.*)$ backend/web/assets/$1 [L]
RewriteRule ^admin/css/(.*)$ backend/web/css/$1 [L]

RewriteCond %{REQUEST_URI} !^/backend/web/(assets|css)/  <------
RewriteCond %{REQUEST_URI} ^/(admin)  <------
RewriteRule ^.*$ backend/web/index.php [L]


RewriteCond %{REQUEST_URI} ^/(assets|css)  <------
RewriteRule ^assets/(.*)$ frontend/web/assets/$1 [L]
RewriteRule ^css/(.*)$ frontend/web/css/$1 [L]

RewriteCond %{REQUEST_URI} !^/(frontend|backend)/web/(assets|css)/  <------
RewriteCond %{REQUEST_URI} !index.php
RewriteCond %{REQUEST_FILENAME} !-f [OR]
RewriteCond %{REQUEST_FILENAME} !-d
RewriteRule ^.*$ frontend/web/index.php
---------------

Note : if you are trying in local server then replace ^/ with ^/project_name/ where you see arrow sign. 
Remove those arrow sign <------ after setup is done.

Step 2 
Now create a components/Request.php file in common directory and write below code in this file.
---------------
<?php
namespace common\components;

class Request extends \yii\web\Request {
    public $web;
    public $adminUrl;

    public function getBaseUrl(){
        return str_replace($this->web, "", parent::getBaseUrl()) . $this->adminUrl;
    }

    /*
        If you don't have this function, the admin site will 404 if you leave off 
        the trailing slash.

        E.g.:

        Wouldn't work:
        site.com/admin

        Would work:
        site.com/admin/

        Using this function, both will work.
    */
    public function resolvePathInfo(){
        if($this->getUrl() === $this->adminUrl){
            return "";
        }else{
            return parent::resolvePathInfo();
        }
    }
} ?>
---------------

Step 3 
Installing component. Write below code in frontend/config/main.php and backend/config/main.php files respectively.
-------------------------
//frontend, under components array
'request'=>[
    'class' => 'common\components\Request',
    'web'=> '/frontend/web'
],
'urlManager' => [
        'enablePrettyUrl' => true,
        'showScriptName' => false,
],
-------------------------
// backend, under components array
'request'=>[
    'class' => 'common\components\Request',
    'web'=> '/backend/web',
    'adminUrl' => '/admin'
],
'urlManager' => [
        'enablePrettyUrl' => true,
        'showScriptName' => false,
],
-------------------------

Step 4 (Optional, if doesn't work till step three) 

create .htaccess file in web directory
-------------------------
RewriteEngine On 
RewriteCond %{REQUEST_FILENAME} !-f 
RewriteCond %{REQUEST_FILENAME} !-d 
RewriteRule ^(.*)$ /index.php?/$1 [L]
-------------------------

Note: make sure you have enabled your mod rewrite in apache

Thats it! You can try your project with 
www.project.com/admin, www.project.com

in local server
localhost/project_name/admin, localhost/project_name

http://stackoverflow.com/questions/28118691/yii2-htaccess-how-to-hide-frontend-web-and-backend-web-completely

Great Article...
Nice Step by step Instructions...

Perfect step by step... Great Article.... Thank you Ery Camel