how to slelect php version in linux code example

Example 1: change php version ubuntu

//In ubunutu
Default PHP 7.1 is set on your system and you need to switch to PHP 5.6

$ sudo a2dismod php7.1
$ sudo a2enmod php5.6
$ sudo service apache2 restart
  
sudo update-alternatives --set php /usr/bin/php5.6

Example 2: linux set default php

update-alternatives --set php /usr/bin/php7.4
update-alternatives --set phar /usr/bin/phar7.4
update-alternatives --set phar.phar /usr/bin/phar.phar7.4
update-alternatives --set phpize /usr/bin/phpize7.4
update-alternatives --set php-config /usr/bin/php-config7.4