ubuntu20.04.2 linux arm更换清华源，parallels desktop虚拟机

        换了MacBook后在Parallels Desktop里安装linux虚拟机后发现更换源失败，我的Ubuntu版本是20.04，一开始以为是以前的方法不适用了，后来才知道有分架构， 也是在清华源下面的小字才发现：清华大学开源软件镜像站。

        MacBookM1芯片后都是arm架构，接着寻找后找到了arm版本的清华源。 

方法在图片下面： 

操作如下：

先备份一下：

cd /etc/apt

sudo cp /etc/apt/sources.list /etc/apt/sources.list.bak

接着：开启编辑权限后

sudo gedit /etc/apt/sources.list

将清华源复制进去保存

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

接着执行更新一下：

 sudo apt-get update

sudo apt upgrade