Ubuntu修改apt更新源为腾讯源方法

修改教程：

1.编辑/etc/apt/sources.list

vi /etc/apt/sources.list

按下字母i键，进入编辑模式。删除全部内容，将下列准备的更新源内容粘贴进去，即可保存退出。

保存退出的命令是按Esc然后输入:!wq(冒号也要输入)

腾讯源：

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

如图：

执行软件源更新：（刷新软件源信息+更新软件）

sudo apt update
sudo apt upgrade