[root@VM-24-4-ubuntu dev]$ ===>>> cat sources.list deb http://mirrors.tuna.tsinghua.edu.cn/ubuntu/ jammy main restricted universe multiverse deb http://mirrors.tuna.tsinghua.edu.cn/ubuntu/ jammy-updates main restricted universe multiverse deb http://mirrors.tuna.tsinghua.edu.cn/ubuntu/ jammy-backports main restricted universe multiverse deb http://mirrors.tuna.tsinghua.edu.cn/ubuntu/ jammy-security main restricted universe multiverse