在单硬盘上安装WIN10和Ubuntu 20.04 Server双系统

NATURAL

用Rufus在MBR模式将Ubuntu-20.04.2-live-server镜像写入U盘，插好网线，启动电脑。先安装WIN10，空出30G以上空间只分区后不格式化不分配盘符。
安装好WIN10后，安装Ubuntu-20.04.2-live-server，在选择安装盘时千万不要选全全盘安装，选择空余出来的上述30G空间，编辑，选择格式化为ext4格式并挂载到/
选择安装OPENSSH及安全更新
安装完毕重启
注意不要安装 net-tools，已淘汰，ifconfig也不要用了。

更改源为中科大镜像
sudo sed -i 's@//.*archive.ubuntu.com@//mirrors.ustc.edu.cn@g' /etc/apt/sources.list

更新后的源为：
sudo nano /etc/apt/sources.list
# See http://help.ubuntu.com/community/UpgradeNotes for how to upgrade to
# newer versions of the distribution.
deb http://mirrors.ustc.edu.cn/ubuntu focal main restricted
# deb-src http://mirrors.ustc.edu.cn/ubuntu focal main restricted

## Major bug fix updates produced after the final release of the
## distribution.
deb http://mirrors.ustc.edu.cn/ubuntu focal-updates main restricted
# deb-src http://mirrors.ustc.edu.cn/ubuntu focal-updates main restricted

## N.B. software from this repository is ENTIRELY UNSUPPORTED by the Ubuntu
## team. Also, please note that software in universe WILL NOT receive any
## review or updates from the Ubuntu security team.
deb http://mirrors.ustc.edu.cn/ubuntu focal universe
# deb-src http://mirrors.ustc.edu.cn/ubuntu focal universe
deb http://mirrors.ustc.edu.cn/ubuntu focal-updates universe
# deb-src http://mirrors.ustc.edu.cn/ubuntu focal-updates universe

## N.B. software from this repository is ENTIRELY UNSUPPORTED by the Ubuntu
## team, and may not be under a free licence. Please satisfy yourself as to
## your rights to use the software. Also, please note that software in
## multiverse WILL NOT receive any review or updates from the Ubuntu
## security team.
deb http://mirrors.ustc.edu.cn/ubuntu focal multiverse
# deb-src http://mirrors.ustc.edu.cn/ubuntu focal multiverse
deb http://mirrors.ustc.edu.cn/ubuntu focal-updates multiverse
# deb-src http://mirrors.ustc.edu.cn/ubuntu focal-updates multiverse

## N.B. software from this repository may not have been tested as
## extensively as that contained in the main release, although it includes
## newer versions of some applications which may provide useful features.
## Also, please note that software in backports WILL NOT receive any review
## or updates from the Ubuntu security team.
deb http://mirrors.ustc.edu.cn/ubuntu focal-backports main restricted universe multiverse
# deb-src http://mirrors.ustc.edu.cn/ubuntu focal-backports main restricted universe multiverse

## Uncomment the following two lines to add software from Canonical's
## 'partner' repository.
## This software is not part of Ubuntu, but is offered by Canonical and the
## respective vendors as a service to Ubuntu users.
# deb http://archive.canonical.com/ubuntu focal partner
# deb-src http://archive.canonical.com/ubuntu focal partner

deb http://mirrors.ustc.edu.cn/ubuntu focal-security main restricted
# deb-src http://mirrors.ustc.edu.cn/ubuntu focal-security main restricted
deb http://mirrors.ustc.edu.cn/ubuntu focal-security universe
# deb-src http://mirrors.ustc.edu.cn/ubuntu focal-security universe
deb http://mirrors.ustc.edu.cn/ubuntu focal-security multiverse

更新
sudo apt-get -y update
sudo apt-get -y dist-upgrade
sudo reboot

NATURAL

如果重装Ubuntu的话，要先删除Ubuntu的启动项，并且把该盘格式化为NTFS后删除再建立分区，这样安装不容易出错。