Debian更换源
cp /etc/apt/sources.list /etc/apt/sources_init.list

cat <<EOF > /etc/apt/sources.list
deb http://mirrors.ustc.edu.cn/debian/ buster main
deb-src http://mirrors.ustc.edu.cn/debian/ buster main

deb http://security.debian.org/debian-security buster/updates main
deb-src http://security.debian.org/debian-security buster/updates main

# buster-updates, previously known as 'volatile'

deb http://mirrors.ustc.edu.cn/debian/ buster-updates main
deb-src http://mirrors.ustc.edu.cn/debian/ buster-updates main

deb http://mirrors.ustc.edu.cn/debian/ buster-backports main non-free contrib
deb-src http://mirrors.ustc.edu.cn/debian/ buster-backports main non-free contrib
EOF