Answers for "ubuntu how to change version of php"

switch php version ubuntu

# From PHP 7.1 => PHP 5.6

#Apache
sudo a2dismod php7.1
sudo a2enmod php5.6
sudo service apache2 restart
 
 #command Line
 sudo update-alternatives --set php /usr/bin/php5.6

change the php version in linux

sudo update-alternatives --set php /usr/bin/php7.2
sudo update-alternatives --set phar /usr/bin/phar7.2
sudo update-alternatives --set phar.phar /usr/bin/phar.phar7.2
sudo update-alternatives --set phpize /usr/bin/phpize7.2
sudo update-alternatives --set php-config /usr/bin/php-config7.2