Ubuntu登录没有root账户和换源

打开编辑配置文件

vim /usr/share/lightdm/lightdm.conf.d/50-ubuntu.conf

添加启用root用户

添加如下内容

greeter-show-manual-login=true

 最后设置root密码

sudo passwd root

换阿里源

备份并修改sources.list配置文件：

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

sudo vim /etc/apt/sources.list

在文件最前面添加以下内容

deb http://mirrors.aliyun.com/ubuntu/ bionic main restricted universe multiverse
deb http://mirrors.aliyun.com/ubuntu/ bionic-security main restricted universe multiverse
deb http://mirrors.aliyun.com/ubuntu/ bionic-updates main restricted universe multiverse
deb http://mirrors.aliyun.com/ubuntu/ bionic-proposed main restricted universe multiverse
deb http://mirrors.aliyun.com/ubuntu/ bionic-backports main restricted universe multiverse
deb-src http://mirrors.aliyun.com/ubuntu/ bionic main restricted universe multiverse
deb-src http://mirrors.aliyun.com/ubuntu/ bionic-security main restricted universe multiverse
deb-src http://mirrors.aliyun.com/ubuntu/ bionic-updates main restricted universe multiverse
deb-src http://mirrors.aliyun.com/ubuntu/ bionic-proposed main restricted universe multiverse
deb-src http://mirrors.aliyun.com/ubuntu/ bionic-backports main restricted universe multiverse

第二步：更新缓存

执行下面的命令：

sudo apt-get update

sudo apt-get upgrade