ubuntu20.04安装systemback
sudo add-apt-repository --remove ppa:nemh/systemback
sudo apt-key adv --keyserver keyserver.ubuntu.com --recv-keys 382003C2C8B7B4AB813E915B14E4942973C62A1B
sudo add-apt-repository "deb http://ppa.launchpad.net/nemh/systemback/ubuntu xenial main"
sudo apt update
sudo apt install systemback