Number of mildew send 4buster system to replace the mirror source

The system comes with the source is too card. So the replacement.

Backup Source
sudo cp /etc/apt/sources.list /etc/apt/sources.list.bk　　　　
or directly commented original source (preceded by #)

Use nano editor to change the file /etc/apt/sources.list

sudo nano /etc/apt/sources.list  


#中科大
deb http://mirrors.ustc.edu.cn/raspbian/raspbian/ buster main contrib non-free rpi

#阿里云
#deb http://mirrors.aliyun.com/debian buster main
#deb http://mirrors.aliyun.com/debian-security buster/updates main
#deb http://mirrors.aliyun.com/debian buster-updates main

#清华
deb http://mirrors.tuna.tsinghua.edu.cn/raspbian/raspbian/ buster main non-free contrib
deb-src http://mirrors.tuna.tsinghua.edu.cn/raspbian/raspbian/ buster main non-free contrib

Hold down the ctrl + w, then enter y, press Enter to save and exit. The same below

Update /etc/apt/sources.list.d/raspi.list

 sudo nano /etc/apt/sources.list.d/raspi.list

USTC:

deb http://mirrors.ustc.edu.cn/archive.raspberrypi.org/debian/ buster main

Last updated at the source:

sudo apt update