Ubuntu源文件位置：/etc/apt/sources.list，更改前先備份源文件。
sudo cp /etc/apt/sources.list /etc/apt/sources.list.bak
替換相關源信息
清華源
# 默認註釋了源碼鏡像以提高 apt update 速度，如有需要可自行取消註釋
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
# 預發佈軟件源，不建議啓用
# 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版本號爲：18.04：bionic；16.04：xenial；14.04：trusty
更改完 sources.list 文件後請運行 sudo apt-get update 更新索引以生效。
中科大源
# 默認註釋了源碼倉庫，如有需要可自行取消註釋
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
# 預發佈軟件源，不建議啓用
# 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版本號爲：18.04：bionic；16.04：xenial；14.04：trusty
更改完 sources.list 文件後請運行 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版本號爲：18.04：bionic；16.04：xenial；14.04：trusty
更改完 sources.list 文件後請運行 sudo apt-get update 更新索引以生效。
騰訊源
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版本號爲：18.04：bionic；16.04：xenial；14.04：trusty
更改完 sources.list 文件後請運行 sudo apt-get update 更新索引以生效。
方法二：
通過wget獲取配置文件
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/ubuntu18_sources.list
然後更新緩存
apt-get clean all
apt-get update
網易源
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版本號爲：18.04：bionic；16.04：xenial；14.04：trusty
更改完 sources.list 文件後請運行 sudo apt-get update 更新索引以生效。