Switch PHP version on linux

You can list all loaded Apache modules with apache2ctl -M

this method is work fine
you can ls /usr/bin/php* to see how many php version you have and use this command switch to it

update-alternatives --set php /usr/bin/php7.4

this method sometime not work like u expected

$ sudo a2dismod php7.1
$ sudo a2enmod php5.6
$ sudo service apache2 restart