共计 1490 个字符，预计需要花费 4 分钟才能阅读完成。
实测 ubuntu18 没有办法在树莓派 4 8GB 运行，原因不明。
会出现如下错误：
recover4.elf not found
recovery.elf not found
start4.elf not found
安装 ubuntu20 可以正常进入系统
所以这就成了树莓派 4 8GB 版本安装 ubuntu20 教程
首先换软件源（清华源）
deb http://mirrors.aliyun.com/ubuntu-ports focal main restricted
deb http://mirrors.aliyun.com/ubuntu-ports focal-updates main restricted
deb http://mirrors.aliyun.com/ubuntu-ports focal universe
deb http://mirrors.aliyun.com/ubuntu-ports focal-updates universe
deb http://mirrors.aliyun.com/ubuntu-ports focal multiverse
deb http://mirrors.aliyun.com/ubuntu-ports focal-updates multiverse
deb http://mirrors.aliyun.com/ubuntu-ports focal-backports main restricted universe multiverse
deb http://mirrors.aliyun.com/ubuntu-ports focal-security main restricted
deb http://mirrors.aliyun.com/ubuntu-ports focal-security universe
deb http://mirrors.aliyun.com/ubuntu-ports focal-security multiverse
deb-src http://mirrors.aliyun.com/ubuntu-ports focal main restricted
deb-src http://mirrors.aliyun.com/ubuntu-ports focal-updates main restricted
deb-src http://mirrors.aliyun.com/ubuntu-ports focal universe
deb-src http://mirrors.aliyun.com/ubuntu-ports focal-updates universe
deb-src http://mirrors.aliyun.com/ubuntu-ports focal multiverse
deb-src http://mirrors.aliyun.com/ubuntu-ports focal-updates multiverse
deb-src http://mirrors.aliyun.com/ubuntu-ports focal-backports main restricted universe multiverse
deb-src http://mirrors.aliyun.com/ubuntu-ports focal-security main restricted
deb-src http://mirrors.aliyun.com/ubuntu-ports focal-security universe
deb-src http://mirrors.aliyun.com/ubuntu-ports focal-security multiverse
正文完
