Installing PHP 8.1 for Debian 11 bullseye02.12.21

Import & Install GPG key:

The first step is to import and install the GPG key before adding the repository. To do this, use the following terminal (CTRL+ALT+T) command:

sudo wget -O /etc/apt/trusted.gpg.d/php.gpg https://packages.sury.org/php/apt.gpg

Note, you may need to install these dependencies if you have trouble:

sudo apt install apt-transport-https lsb-release ca-certificates

Import & Install Repository:

With the GPG key sorted, it is time to add the Ondřej Surý repository as follows:

sudo sh -c 'echo "deb https://packages.sury.org/php/ $(lsb_release -sc) main" > /etc/apt/sources.list.d/php.list'

Install PHP 8

Now you can proceed to install PHP 8 for your particular need as follows:
Install Apache Module Option

To install PHP 8 as an Apache module, enter the following command.

sudo apt update && sudo apt install php8.0 libapache2-mod-php8.0

Once installation is complete, restart your Apache server for the new PHP module to be loaded.

sudo systemctl restart apache2

Install Apache Module Option with FPM

PHP-FPM (an acronym of FastCGI Process Manager) is a hugely popular alternative PHP (Hypertext Processor) FastCGI implementation.

To install PHP-FPM for Apache 2, use the following commands.

sudo apt update && sudo apt install php8.0-fpm libapache2-mod-fcgid

Note, by default, PHP-FPM is not enabled for Apache. You must enable it by the following command.

sudo a2enmod proxy_fcgi setenvif && sudo a2enconf php8.0-fpm

Lastly, restart Apache.

sudo systemctl restart apache2

Verify that PHP-FPM is working:

sudo systemctl status php8.0-fpm

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