ubuntu 换源

国内有很多Ubuntu的镜像源，包括阿里的、网易的，还有很多教育网的源，比如：清华源、中科大源。
我们这里以清华源为例讲解如何修改Ubuntu 18.04里面默认的源。

1、输入命令修改sources.list文件，当然需要超级权限，所以要加sudo(如提示没权限,被占用,等等,直接重启系统)；

sudo gedit /etc/apt/sources.list

或,也有(新手不推荐使用--太难用,如果vim报错,是没安装,执行:apt-get install vim):-------------------------------------

sudo vi /etc/apt/sources.list   

sudo vim /etc/apt/sources.list

2、编辑/etc/apt/sources.list文件,在文件最前面添加以下条目(操作前要备份),save,关闭：

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
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

3、修改完成后，保存文件，依次运行下面的命令

sudo apt-get update
sudo apt-get upgrade

4、到此完成国内源更新

5 、Ubuntu 18.04 在系统设置里面是找不到软件源设置界面按钮的，所以需要一些指令帮助启动图形界面以便设置软件源。

(a)输入命令

sudo update-manager -c -d

(b)会弹出Software Updater提示框，这就好办了，点击左下角Settings…按钮，久违的软件源设置就会出来啦。 

(c)那就开始愉快地设置软件源吧

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附加其他源内容，需要的自己添加进sources.list文件里面就ok了。

阿里源：

deb http://mirrors.aliyun.com/ubuntu/ bionic main restricted universe multiverse
deb http://mirrors.aliyun.com/ubuntu/ bionic-security main restricted universe multiverse
deb http://mirrors.aliyun.com/ubuntu/ bionic-updates main restricted universe multiverse
deb 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 main restricted universe multiverse
deb-src http://mirrors.aliyun.com/ubuntu/ bionic-security main restricted universe multiverse
deb-src http://mirrors.aliyun.com/ubuntu/ bionic-updates main restricted universe multiverse
deb-src http://mirrors.aliyun.com/ubuntu/ bionic-proposed main restricted universe multiverse
deb-src http://mirrors.aliyun.com/ubuntu/ bionic-backports main restricted universe multiverse

中科大源:

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