Update Debian and Ubuntu's help doc

site/help/debian.md

@@ -0,0 +1,31 @@
+---
+sidebarShare: true
+prev: false
+next: false
+---
+
+# [Debian](/debian/) 镜像
+
+## 介绍
+
+[Debian](https://www.debian.org/) 是一个由社区支持的 Linux 发行版。
+
+## 使用指南
+
+首先，通过下面命令备份原本的配置。
+
+``` sh
+sudo cp -a /etc/apt/sources.list /etc/apt/sources.list.bak
+```
+
+其次，通过下面的命令将软件源换成本镜像站。
+
+``` sh
+sudo sed -i 's/deb.debian.org/mirrors.sdust.edu.cn/g' /etc/apt/sources.list
+```
+
+最后，通过下面命令刷新缓存。
+
+``` sh
+sudo apt-get update
+```

site/help/ubuntu.md

@@ -4,44 +4,31 @@ prev: false
 next: false
 ---
 
-# [Ubuntu](/ubuntu/) Mirror
+# [Ubuntu](/ubuntu/) 镜像
 
-## Introduction
+## 介绍
 
-[Ubuntu](https://ubuntu.com/) is a popular and user-friendly Linux distribution based on Debian.
+[Ubuntu](https://ubuntu.com/) 是一个基于 Debian 的 Linux 发行版。
 
-## Backup Existing Configuration
+## 使用指南
+
+首先，通过下面命令备份原本的配置。
 
 ``` sh
-sudo mv /etc/apt/sources.list /etc/apt/sources.list.backup
+sudo cp -a /etc/apt/sources.list /etc/apt/sources.list.bak
 ```
 
-## Edit Configuration
-
-For Ubuntu 18.04 LTS, write the following lines to `/etc/apt/sources.list`:
+其次，通过下面的命令将软件源换成本镜像站。
 
-```
-deb http://mirrors.sdust.edu.cn/ubuntu/ bionic main restricted universe multiverse
-# deb-src http://mirrors.sdust.edu.cn/ubuntu/ bionic main restricted universe multiverse
-deb http://mirrors.sdust.edu.cn/ubuntu/ bionic-updates main restricted universe multiverse
-# deb-src http://mirrors.sdust.edu.cn/ubuntu/ bionic-updates main restricted universe multiverse
-deb http://mirrors.sdust.edu.cn/ubuntu/ bionic-backports main restricted universe multiverse
-# deb-src http://mirrors.sdust.edu.cn/ubuntu/ bionic-backports main restricted universe multiverse
-deb http://mirrors.sdust.edu.cn/ubuntu/ bionic-security main restricted universe multiverse
-# deb-src http://mirrors.sdust.edu.cn/ubuntu/ bionic-security main restricted universe multiverse
-
-# pre-release
-# deb http://mirrors.sdust.edu.cn/ubuntu/ bionic-proposed main restricted universe multiverse
-# deb-src http://mirrors.sdust.edu.cn/ubuntu/ bionic-proposed main restricted universe multiverse
+``` sh
+sudo sed -i "s@http://.*archive.ubuntu.com@https://mirrors.sdust.edu.cn@g" /etc/apt/sources.list
 ```
 
 ::: tip
-If you're using other releases, go to [Releases](https://wiki.ubuntu.com/Releases) to find the corresponding codename, and replace `bionic` in the above content.
-
-By convention, the codename used in `sources.list` is the first word of the release's codename. For example, the code name of Ubuntu 19.04 is "Disco Dingo", so you should replace `bionic` with `disco`.
+因为镜像站与上游同步有延迟，可能会导致系统不能及时检查、安装上最新的安全更新，所以不建议替换 security 源。如果需要更换的话，请通过执行下面命令更换 `sudo sed -i "s@http://.*security.ubuntu.com@https://mirrors.sdust.edu.cn@g" /etc/apt/sources.list`
 :::
 
-## Refresh Repository Indexes
+最后，通过下面命令刷新缓存。
 
 ``` sh
 sudo apt-get update