⒈備份官方默認更新源文件
cp /etc/apt/sources.list /etc/apt/sources.list.bak 備份官方更新源文件
⒉編輯
1.打開
vi /etc/apt/sources.list
2.清空內容
ESC后進入命令模式輸入
:.,$d
3.復制為以下內容（清華大學鏡像站）https://mirrors.tuna.tsinghua.edu.cn/help/ubuntu/
# 默認注釋了源碼鏡像以提高 apt update 速度，如有需要可自行取消注釋 deb https://mirrors.tuna.tsinghua.edu.cn/ubuntu/ bionic main restricted universe multiverse # deb-src https://mirrors.tuna.tsinghua.edu.cn/ubuntu/ bionic main restricted universe multiverse deb https://mirrors.tuna.tsinghua.edu.cn/ubuntu/ bionic-updates main restricted universe multiverse # deb-src https://mirrors.tuna.tsinghua.edu.cn/ubuntu/ bionic-updates main restricted universe multiverse deb https://mirrors.tuna.tsinghua.edu.cn/ubuntu/ bionic-backports main restricted universe multiverse # deb-src https://mirrors.tuna.tsinghua.edu.cn/ubuntu/ bionic-backports main restricted universe multiverse deb https://mirrors.tuna.tsinghua.edu.cn/ubuntu/ bionic-security main restricted universe multiverse # deb-src https://mirrors.tuna.tsinghua.edu.cn/ubuntu/ bionic-security main restricted universe multiverse # 預發布軟件源，不建議啟用 # deb https://mirrors.tuna.tsinghua.edu.cn/ubuntu/ bionic-proposed main restricted universe multiverse # deb-src https://mirrors.tuna.tsinghua.edu.cn/ubuntu/ bionic-proposed main restricted universe multiverse
4.保存
ESC后進入命令模式輸入
:wq
⒊更新源
apt update