ubuntu又雙叕更新啦！安裝好ubuntu雙系統或者ubuntu虛擬機之後，默認的軟件更新源是國外的，在國內使用速度很慢，用"apt install"安裝軟件時各種網絡問題層出不窮，因此我們需要更換成國內的源，這樣才能正常安裝和更新軟件。
首先將我們的原來的軟件源另存起來備份：
sudo cp -v /etc/apt/sources.list /etc/apt/sources.list.backup
終端執行chmod命令更改文件權限使軟件源文件可編輯：
sudo chmod 777 /etc/apt/sources.list
之後通過gedit命令編輯軟件源：
sudo gedit /etc/apt/sources.list
然後將下面任意一個源複製進去保存就好了：
阿里雲源：
deb http://mirrors.aliyun.com/ubuntu/ eoan main restricted universe multiverse
deb http://mirrors.aliyun.com/ubuntu/ eoan-security main restricted universe multiverse
deb http://mirrors.aliyun.com/ubuntu/ eoan-updates main restricted universe multiverse
deb http://mirrors.aliyun.com/ubuntu/ eoan-proposed main restricted universe multiverse
deb http://mirrors.aliyun.com/ubuntu/ eoan-backports main restricted universe multiverse
deb-src http://mirrors.aliyun.com/ubuntu/ eoan main restricted universe multiverse
deb-src http://mirrors.aliyun.com/ubuntu/ eoan-security main restricted universe multiverse
deb-src http://mirrors.aliyun.com/ubuntu/ eoan-updates main restricted universe multiverse
deb-src http://mirrors.aliyun.com/ubuntu/ eoan-proposed main restricted universe multiverse
deb-src http://mirrors.aliyun.com/ubuntu/ eoan-backports main restricted universe multiverse
清華源：
deb https://mirrors.tuna.tsinghua.edu.cn/ubuntu/ eoan main restricted universe multiverse
deb-src https://mirrors.tuna.tsinghua.edu.cn/ubuntu/ eoan main restricted universe multiverse
deb https://mirrors.tuna.tsinghua.edu.cn/ubuntu/ eoan-updates main restricted universe multiverse
deb-src https://mirrors.tuna.tsinghua.edu.cn/ubuntu/ eoan-updates main restricted universe multiverse
deb https://mirrors.tuna.tsinghua.edu.cn/ubuntu/ eoan-backports main restricted universe multiverse
deb-src https://mirrors.tuna.tsinghua.edu.cn/ubuntu/ eoan-backports main restricted universe multiverse
deb https://mirrors.tuna.tsinghua.edu.cn/ubuntu/ eoan-security main restricted universe multiverse
deb-src https://mirrors.tuna.tsinghua.edu.cn/ubuntu/ eoan-security main restricted universe multiverse
deb https://mirrors.tuna.tsinghua.edu.cn/ubuntu/ eoan-proposed main restricted universe multiverse
deb-src https://mirrors.tuna.tsinghua.edu.cn/ubuntu/ eoan-proposed main restricted universe multiverse
修改完軟件源後，更新軟件列表和軟件：
sudo apt update
sudo apt upgrade
注意：“eoan”爲ubuntu版本名！“eoan”代表ubuntu19.10，“xenial”代表ubuntu16.04，“bionic”代表ubuntu18.04，“disco”代表ubuntu19.04，如果自己的版本不再所描述的上面，可以通過查看，並更改相應位置就ok了！
lsb_release -c