Segue abaixo modelo do arquivo /etc/apt/source.list para o ubuntu 20.04 ou derivados:   deb http://archive.ubuntu.com/ubuntu/ focal main restricted universe multiverse deb-src http://archive.ubuntu.com/ubuntu/ focal main restricted universe multiverse deb http://archive.ubuntu.com/ubuntu/ focal-updates main restricted universe multiverse deb-src http://archive.ubuntu.com/ubuntu/ focal-updates main restricted universe…