install php8.1 debian

The solution for this is noted below

Solution

# Debian 9/10/11

## Install required temporary packages:
sudo apt install -y lsb-release ca-certificates apt-transport-https software-properties-common gnupg2 curl

## Add Surý Debian PPA repository to your Debian system.
echo "deb https://packages.sury.org/php/ $(lsb_release -sc) main" | sudo tee /etc/apt/sources.list.d/sury-php.list

## Import packages signing GPG key;
curl -fsSL  https://packages.sury.org/php/apt.gpg| sudo gpg --dearmor -o /etc/apt/trusted.gpg.d/sury-keyring.gpg

## Update with all the packages imported
sudo apt update

## Install php8.1 and its modules
sudo apt install php8.1-fpm php8.1-common php8.1-mysql php8.1-xml php8.1-xmlrpc php8.1-curl php8.1-gd php8.1-imagick php8.1-cli php8.1-dev php8.1-imap php8.1-mbstring php8.1-opcache php8.1-soap php8.1-zip php8.1-intl php8.1-bcmath

Try other methods by searching on the site. That is if this doesn’t work