Answers for "php 7.4 in ubuntu 18.04"

install php 7.4 ubuntu

sudo apt update
sudo apt install php php-cli php-fpm php-json php-pdo php-mysql php-zip php-gd  php-mbstring php-curl php-xml php-pear php-bcmath

install php 7.1 on ubuntu 18.04

sudo apt install software-properties-commonsudo add-apt-repository ppa:ondrej/php