sudo su -
echo "deb http://ppa.launchpad.net/ondrej/php/ubuntu xenial main" | tee -a /etc/apt/sources.list
echo "deb-src http://ppa.launchpad.net/ondrej/php/ubuntu xenial main" | tee -a /etc/apt/sources.list
apt-key adv --keyserver keyserver.ubuntu.com --recv-keys E5267A6C
apt-get install dirmngr
apt-get update
添加ppa软件源问题处理
sudo apt-get install unknown-horizons
exit