树莓派

1. stretch

  sudo nano /etc/apt/sources.list 
  deb http://mirrors.tuna.tsinghua.edu.cn/raspbian/raspbian/ stretch main contrib non-free rpi
  deb-src http://mirrors.tuna.tsinghua.edu.cn/raspbian/raspbian/ stretch main contrib non-free rpi

  sudo nano /etc/apt/sources.list .d/raspi.list
  deb http://mirror.tuna.tsinghua.edu.cn/raspberrypi/ stretch main ui
  deb-src http://mirror.tuna.tsinghua.edu.cn/raspberrypi/ stretch main ui

2.jessis

  sudo nano /etc/apt/sources.list 
  deb http://mirrors.tuna.tsinghua.edu.cn/raspbian/raspbian/ jessis main contrib non-free rpi
  deb-src http://mirrors.tuna.tsinghua.edu.cn/raspbian/raspbian/ jessis main contrib non-free rpi

  sudo nano /etc/apt/sources.list .d/raspi.list
  deb http://mirror.tuna.tsinghua.edu.cn/raspberrypi/ jessis main ui
  deb-src http://mirror.tuna.tsinghua.edu.cn/raspberrypi/ jessis main ui

  sudo apt-get update
  sudo apt-get upgrade
  sudo reboot

ubuntu

# 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/ xenial main restricted universe multiverse
# deb-src https://mirrors.tuna.tsinghua.edu.cn/ubuntu/ xenial main restricted universe multiverse
deb https://mirrors.tuna.tsinghua.edu.cn/ubuntu/ xenial-updates main restricted universe multiverse 
# deb-src https://mirrors.tuna.tsinghua.edu.cn/ubuntu/ xenial-updates main restricted universe multiverse
deb https://mirrors.tuna.tsinghua.edu.cn/ubuntu/ xenial-backports main restricted universe multiverse
# deb-src https://mirrors.tuna.tsinghua.edu.cn/ubuntu/ xenial-backports main restricted universe multiverse
deb https://mirrors.tuna.tsinghua.edu.cn/ubuntu/ xenial-security main restricted universe multiverse 
# deb-src https://mirrors.tuna.tsinghua.edu.cn/ubuntu/ xenial-security main restricted universe multiverse 
# 预发布软件源，不建议启用 
# deb https://mirrors.tuna.tsinghua.edu.cn/ubuntu/ xenial-proposed main restricted universe multiverse
# deb-src https://mirrors.tuna.tsinghua.edu.cn/ubuntu/ xenial-proposed main restricted universe multiverse