1.先备份
cp /etc/apt/sources.list /etc/apt/sources.list.bak
2.写入国内源
cat <<EOF>/etc/apt/sources.list
deb http://mirrors.aliyun.com/debian/ buster main non-free contrib
deb-src http://mirrors.aliyun.com/debian/ buster main non-free contrib
deb http://mirrors.aliyun.com/debian-security buster/updates main
deb-src http://mirrors.aliyun.com/debian-security buster/updates main
deb http://mirrors.aliyun.com/debian/ buster-updates main non-free contrib
deb-src http://mirrors.aliyun.com/debian/ buster-updates main non-free contrib
deb http://mirrors.aliyun.com/debian/ buster-backports main non-free contrib
deb-src http://mirrors.aliyun.com/debian/ buster-backports main non-free contrib
EOF
3.清空缓存
apt-get clean
apt-get update
可能碰到的问题:
W: GPG error: http://mirrors.aliyun.com/ubuntu focal InRelease: The following signatures couldn't be verified because the public key is not available: NO_PUBKEY 3B4FE6ACC0B21F32 NO_PUBKEY 871920D1991BC93C
解决方案：
apt-key adv --keyserver keyserver.ubuntu.com --recv-keys 871920D1991BC93C
