Ubuntu镜像源cn.arichinve.ubuntu.com不可用原因分析和解决

今天想要在Ubuntu环境下搭建一个测试环境，进入Ubuntu系统后，先看了下系统版本

Ubuntu查看系统版本

lsb_release -a

Ubuntu更新系统不能更新

sudo apt-get update 

在执行后，发现报错如下，发现一个很奇怪的现象，我明明记得源配置的是cn.archive.ubuntu.com,但是发现，系统更新时，自动去找了清华大学的Ubuntu源。why？难道是我源配置的是清华的吗？

Err:5 http://ppa.launchpad.net/deadsnakes/ppa/ubuntu bionic InRelease                             
  503  Service Unavailable [IP: 185.125.190.52 80]
Err:1 http://mirrors.tuna.tsinghua.edu.cn/ubuntu bionic InRelease                                 
  503  Service Unavailable [IP: 101.6.15.130 80]
Err:2 http://mirrors.tuna.tsinghua.edu.cn/ubuntu bionic-updates InRelease
  503  Service Unavailable [IP: 101.6.15.130 80]
Err:3 http://mirrors.tuna.tsinghua.edu.cn/ubuntu bionic-backports InRelease
  503  Service Unavailable [IP: 101.6.15.130 80]
Err:4 http://mirrors.tuna.tsinghua.edu.cn/ubuntu bionic-security InRelease
  503  Service Unavailable [IP: 101.6.15.130 80]
Reading package lists... Done

Ubuntu查看APT更新源配置

sudo vim /etc/apt/sources.list

通过VIM编辑器查看，源地址没错，为什么更新的时候去找了清华源呢？

 See http://help.ubuntu.com/community/UpgradeNotes for how to upgrade to
# newer versions of the distribution.
deb http://cn.archive.ubuntu.com/ubuntu bionic main restricted
# deb-src http://cn.archive.ubuntu.com/ubuntu bionic main restricted

## Major bug fix updates produced after the final release of the
## distribution.
deb http://cn.archive.ubuntu.com/ubuntu bionic-updates main restricted
# deb-src http://cn.archive.ubuntu.com/ubuntu bionic-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://cn.archive.ubuntu.com/ubuntu bionic universe
# deb-src http://cn.archive.ubuntu.com/ubuntu bionic universe
deb http://cn.archive.ubuntu.com/ubuntu bionic-updates universe
# deb-src http://cn.archive.ubuntu.com/ubuntu bionic-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://cn.archive.ubuntu.com/ubuntu bionic multiverse
# deb-src http://cn.archive.ubuntu.com/ubuntu bionic multiverse
deb http://cn.archive.ubuntu.com/ubuntu bionic-updates multiverse
# deb-src http://cn.archive.ubuntu.com/ubuntu bionic-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://cn.archive.ubuntu.com/ubuntu bionic-backports main restricted universe multiverse
# deb-src http://cn.archive.ubuntu.com/ubuntu bionic-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 bionic partner
# deb-src http://archive.canonical.com/ubuntu bionic partner

deb http://cn.archive.ubuntu.com/ubuntu bionic-security main restricted
# deb-src http://cn.archive.ubuntu.com/ubuntu bionic-security main restricted
deb http://cn.archive.ubuntu.com/ubuntu bionic-security universe
# deb-src http://cn.archive.ubuntu.com/ubuntu bionic-security universe
deb http://cn.archive.ubuntu.com/ubuntu bionic-security multiverse
# deb-src http://cn.archive.ubuntu.com/ubuntu bionic-security multiverse

cn.archive.ubuntu.com已经自动跳转到清华镜像站

带着很多问号，在浏览器打开http://cn.archive.ubuntu.com，发现网站已经自动跳转到清华镜像站了。

以为网站需要https打开，发现该网站无法打开。

有知道原因的小伙伴吗？希望大家不吝分享。

Ubuntu变更镜像源地址

虽然访问http://cn.archiv.ubuntu.com会自动跳转到清华源，但是我们还是做一个镜像源地址变更。
使用如下命令将镜像文件中的cn.archive.ubuntu.com批量更换为清华源。

备份原文件

变更前记得备份原始的/ etc / apt / sources.list文件

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

批量在VIM中变更

在vim编辑器批量变更字符串，方法如下，按下esc后，输入：

:%s/cn\.archive\.ubuntu\.com/mirrors\.tuna\.tsinghua\.edu\.cn/g

第一次替换时，少打了一个“.”报错提示：E486: Pattern not found。这个报错时指没有找到特定的字符，重新检查错误后，发现"."在正则表达式中通常是特殊字符，所以需要使用\ 来转义它，以确保准确匹配点号。所以，www.csdn.net 转换后，应该时www.csdn.net。这也算是一个语法上的注意事项。

Ubuntu国内镜像站推荐

除了官方的cn.archive.ubuntu.com外，国内还有多个Ubuntu的稳定镜像站：

• 清华大学开源软件镜像站：

 https://mirrors.tuna.tsinghua.edu.cn/ubuntu/

• 阿里巴巴开源镜像站：

 https://mirrors.aliyun.com/ubuntu/

• Ubuntu官方镜像站：

http://archive.ubuntu.com/ubuntu/

当然还有一些其他的，以上三个是我个人觉得比较好用的。上文希望对大家有所帮助。

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