轉自：https://blog.csdn.net/shanpenghui/article/details/80433555 https://blog.csdn.net/dty306034831/article/details/79188808
國內有很多Ubuntu的鏡像源，包括阿里的、網易的，還有很多教育網的源，比如：清華源、中科大源。
我們這里以清華源為例講解如何修改Ubuntu 18.04里面默認的源。
第一：備份源文件
cd /etc/apt/
然后輸入ls
會顯示下面的源文件 sources.list
輸入命令
sudo cp sources.list sources.list.bak
就是將sources.list備份到sources.list.bak
第二步：替換源文件((操作前請做好相應備份)：)
清華大學源
sudo gedit sources.list
終端輸入上述命令打開文件，並刪除文件中的全部內容，將下面的代碼粘貼進入文件中。
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
3、修改完成后，保存文件，警告什么的都不理，然后運行下面的命令。
sudo apt-get update sudo apt-get upgrade
4、到此完成國內源更新。
附加其他源內容，需要的自己添加進sources.list文件里面就ok了。
阿里源
deb http://mirrors.aliyun.com/ubuntu/ bionic main restricted universe multiverse #deb-src http://mirrors.aliyun.com/ubuntu/ bionic main restricted universe multiverse deb http://mirrors.aliyun.com/ubuntu/ bionic-security main restricted universe multiverse #deb-src http://mirrors.aliyun.com/ubuntu/ bionic-security main restricted universe multiverse deb http://mirrors.aliyun.com/ubuntu/ bionic-updates main restricted universe multiverse #deb-src http://mirrors.aliyun.com/ubuntu/ bionic-updates main restricted universe multiverse deb http://mirrors.aliyun.com/ubuntu/ bionic-proposed main restricted universe multiverse #deb-src http://mirrors.aliyun.com/ubuntu/ bionic-proposed main restricted universe multiverse deb http://mirrors.aliyun.com/ubuntu/ bionic-backports main restricted universe multiverse #deb-src http://mirrors.aliyun.com/ubuntu/ bionic-backports main restricted universe multiverse
中科大
deb https://mirrors.ustc.edu.cn/ubuntu/ bionic main restricted universe multiverse deb-src https://mirrors.ustc.edu.cn/ubuntu/ bionic main restricted universe multiverse deb https://mirrors.ustc.edu.cn/ubuntu/ bionic-updates main restricted universe multiverse deb-src https://mirrors.ustc.edu.cn/ubuntu/ bionic-updates main restricted universe multiverse deb https://mirrors.ustc.edu.cn/ubuntu/ bionic-backports main restricted universe multiverse deb-src https://mirrors.ustc.edu.cn/ubuntu/ bionic-backports main restricted universe multiverse deb https://mirrors.ustc.edu.cn/ubuntu/ bionic-security main restricted universe multiverse deb-src https://mirrors.ustc.edu.cn/ubuntu/ bionic-security main restricted universe multiverse deb https://mirrors.ustc.edu.cn/ubuntu/ bionic-proposed main restricted universe multiverse deb-src https://mirrors.ustc.edu.cn/ubuntu/ bionic-proposed main restricted universe multiverse
163源
deb http://mirrors.163.com/ubuntu/ bionic main restricted universe multiverse deb http://mirrors.163.com/ubuntu/ bionic-security main restricted universe multiverse deb http://mirrors.163.com/ubuntu/ bionic-updates main restricted universe multiverse deb http://mirrors.163.com/ubuntu/ bionic-proposed main restricted universe multiverse deb http://mirrors.163.com/ubuntu/ bionic-backports main restricted universe multiverse deb-src http://mirrors.163.com/ubuntu/ bionic main restricted universe multiverse deb-src http://mirrors.163.com/ubuntu/ bionic-security main restricted universe multiverse deb-src http://mirrors.163.com/ubuntu/ bionic-updates main restricted universe multiverse deb-src http://mirrors.163.com/ubuntu/ bionic-proposed main restricted universe multiverse deb-src http://mirrors.163.com/ubuntu/ bionic-backports main restricted universe multiverse
Ubuntu 18.04 在系統設置里面是找不到軟件源設置界面按鈕的（找了好久都沒找到T-T），所以需要一些指令幫助啟動圖形界面以便設置軟件源。
1、輸入命令
sudo update-manager -c -d
2、會彈出Software Updater提示框，這就好辦了，點擊左下角Settings…按鈕，久違的軟件源設置就會出來啦。
3、那就開始愉快地設置軟件源吧！
