apt install software-properties-common
add-apt-repository ppa:ondrej/php
apt update
apt install php7.3 php7.3-dev php7.3-mbstring php7.3-mysql php7.3-gd php7.3-redis php7.3-curl php7.3-xml php7.3-bcmath php7.3-imagick php7.3-sqlite3 php7.3-intl

卸载apache（本人用的是nginx），找出apache2的所有关联软件通过下面命令进行删除

apt-get --purge remove apache2
apt-get --purge remove apache2-bin
apt autoremove
dpkg -l | grep apache2