问题与背景
ubuntu在使用apt的过程中，很多源是国外的，非常慢。需要换成国内的源。
解决方案
注意，不同的ubuntu版本，对应的源不同。控制终端输入以下的代码：
sudo tee /etc/apt/sources.list <<-'EOF'
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
EOF
其他版本的代码，请参考下面的资料。
参考资料
https://blog.csdn.net/u011585735/article/details/116293568 Ubuntu配置apt的国内源地址
