how to install php mcrypt module

'if you don\'t have php installed, run:
sudo apt install php-7.2

'if php is already installed, start from here:
'this is the required dependency
sudo apt install php-dev libmcrypt-dev php-pear

'installing using pecl channel
sudo pecl channel-update pecl.php.net
sudo pecl install mcrypt-1.0.1

'After successfull installation you will get the following:
  'Build process completed successfully
  'Installing \'/usr/lib/php/20170718/mcrypt.so'
  'install ok: channel://pecl.php.net/mcrypt-1.0.1
  'configuration option "php_ini" is not set to php.ini location
  'You should add "extension=mcrypt.so" to php.ini
  
'you can choose any editor of your choice
sudo vi /etc/php/7.2/cli/php.ini

'Now copy:
  [PHP]
  extension=mcrypt.so
'then save the file and exit

'If you are using apache2 server, make the above mentioned change in the following file:
sudo vi /etc/php/7.2/apache2/php.ini

'then save, and you\'re done!