如何在Ubuntu下升级到 PHP 7.4 ？

sudo add-apt-repository ppa:ondrej/php # 按 Enter 确认.
sudo apt-get update

sudo apt install apt-transport-https lsb-release
sudo wget -O /etc/apt/trusted.gpg.d/php.gpg https://packages.sury.org/php/apt.gpg # 下载签名密钥
sudo sh -c 'echo "deb https://packages.sury.org/php/ $(lsb_release -sc) main" > /etc/apt/sources.list.d/php.list' # 将 Ondrej 的仓库添加到来源列表.
sudo apt update

sudo apt install php7.4 php7.4-common php7.4-cli

Simply prefix php7.4- with an extension that you need to install.\
For example to get the php-curl extension use php7.4-curl\
sudo apt install php7.4-curl php7.4-json php7.4-gd php7.4-mbstring php7.4-intl php7.4-bcmath php7.4-bz2 php7.3-readline php7.3-zip

sudo apt install php7.4-fpm

sudo apt install libapache2-mod-php7.4
sudo a2enmod php7.4

sudo apt purge php7.3 libapache2-mod-php7.3 # For removing PHP 7.3
sudo apt purge php7.2 libapache2-mod-php7.2 # For removing PHP 7.2
sudo apt purge php7.1 libapache2-mod-php7.1 # For removing PHP 7.1
sudo apt purge php7.0 libapache2-mod-php7.0 # For removing PHP 7.0

php -v

sudo nano /var/www/html/info.php

<?php
    phpinfo();