Sometimes you need to change a php configuration. To do that you need to know the location of the php.ini file.

The main php.ini file can be found in

//if you are running php 7.3 to open your default php.ini using nano editor 
nano /etc/php/7.3/cli/php.ini 

//if you want the php.ini used by php-fpm
nano /etc/php/7.3/fpm/php.ini 

//to find out which version of php you are running
php -v