Ubuntu源文件位置：/etc/apt/sources.list，更改前先备份源文件。
sudo cp /etc/apt/sources.list /etc/apt/sources.list.bak
替换相关源信息
清华源
# 默认注释了源码镜像以提高 apt update 速度，如有需要可自行取消注释
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
# 预发布软件源，不建议启用
# 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
其中各Ubuntu版本号为：18.04：bionic；16.04：xenial；14.04：trusty
更改完 sources.list 文件后请运行 sudo apt-get update 更新索引以生效。
中科大源
# 默认注释了源码仓库，如有需要可自行取消注释
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
# 预发布软件源，不建议启用
# 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
其中各Ubuntu版本号为：18.04：bionic；16.04：xenial；14.04：trusty
更改完 sources.list 文件后请运行 sudo apt-get update 更新索引以生效。
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
其中各Ubuntu版本号为：18.04：bionic；16.04：xenial；14.04：trusty
更改完 sources.list 文件后请运行 sudo apt-get update 更新索引以生效。
腾讯源
方法一：
deb http://mirrors.cloud.tencent.com/ubuntu/ bionic main restricted universe multiverse
deb http://mirrors.cloud.tencent.com/ubuntu/ bionic-security main restricted universe multiverse
deb http://mirrors.cloud.tencent.com/ubuntu/ bionic-updates main restricted universe multiverse
#deb http://mirrors.cloud.tencent.com/ubuntu/ bionic-proposed main restricted universe multiverse
#deb http://mirrors.cloud.tencent.com/ubuntu/ bionic-backports main restricted universe multiverse
deb-src http://mirrors.cloud.tencent.com/ubuntu/ bionic main restricted universe multiverse
deb-src http://mirrors.cloud.tencent.com/ubuntu/ bionic-security main restricted universe multiverse
deb-src http://mirrors.cloud.tencent.com/ubuntu/ bionic-updates main restricted universe multiverse
#deb-src http://mirrors.cloud.tencent.com/ubuntu/ bionic-proposed main restricted universe multiverse
#deb-src http://mirrors.cloud.tencent.com/ubuntu/ bionic-backports main restricted universe multiverse
其中各Ubuntu版本号为：18.04：bionic；16.04：xenial；14.04：trusty
更改完 sources.list 文件后请运行 sudo apt-get update 更新索引以生效。
方法二：
通过wget获取配置文件
wget -O /etc/apt/sources.list http://mirrors.cloud.tencent.com/repo/ubuntu14_sources.list
wget -O /etc/apt/sources.list http://mirrors.cloud.tencent.com/repo/ubuntu16_sources.list
wget -O /etc/apt/sources.list http://mirrors.cloud.tencent.com/repo/ubuntu148_sources.list
然后更新缓存
apt-get clean all
apt-get update
网易源
deb http://mirrors.163.com/ubuntu/ bionic main restricted universe multiverse
# deb-src http://mirrors.163.com/ubuntu/ bionic main restricted universe multiverse
deb http://mirrors.163.com/ubuntu/ bionic-security main restricted universe multiverse
# deb-src http://mirrors.163.com/ubuntu/ bionic-security main restricted universe multiverse
deb http://mirrors.163.com/ubuntu/ bionic-updates main restricted universe multiverse
# deb-src http://mirrors.163.com/ubuntu/ bionic-updates main restricted universe multiverse
deb http://mirrors.163.com/ubuntu/ bionic-proposed main restricted universe multiverse
# deb-src 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-backports main restricted universe multiverse
其中各Ubuntu版本号为：18.04：bionic；16.04：xenial；14.04：trusty
更改完 sources.list 文件后请运行 sudo apt-get update 更新索引以生效。
