错误：E: Unable to locate package vim

平时很少使用Debian，今天使用镜像是基于Debian Linux9的。没有文本编辑命令vim和vi，就想安装个，但是使用apt-get install vim直接给我报了开篇的错误提示。经查，这是因为用的源地址在国外，问题找到了，那解决方向就很明白了，换个能访问的地址就行了。
其实这些都很简单，问题是，网上大量的错误导向，害得我浪费了不少时间。
比如

root@1b4671904bfa:/#  mv /etc/apt/sources.list /etc/apt/sources.list.bak
root@1b4671904bfa:/#  echo "deb http://mirrors.163.com/debian/ jessie main non-free contrib" >/etc/apt/sources.list
root@1b4671904bfa:/#  echo "deb http://mirrors.163.com/debian/ jessie-proposed-updates main non-free contrib" >>/etc/apt/sources.list
root@1b4671904bfa:/#  echo "deb-src http://mirrors.163.com/debian/ jessie main non-free contrib" >>/etc/apt/sources.list
root@1b4671904bfa:/#  echo "deb-src http://mirrors.163.com/debian/ jessie-proposed-updates main non-free contrib" >>/etc/apt/sources.list

意思很简单，先备份sources.list，然后往里面写自定的内容。
其他我就不一一举例了，大概都这样。

但是我证明，这些真没用。

我们先来看一下，原生的sources.list里都有些啥。

# deb http://snapshot.debian.org/archive/debian/20200130T000000Z stretch main
deb http://deb.debian.org/debian stretch main
# deb http://snapshot.debian.org/archive/debian-security/20200130T000000Z stretch/updates main
deb http://security.debian.org/debian-security stretch/updates main
# deb http://snapshot.debian.org/archive/debian/20200130T000000Z stretch-updates main
deb http://deb.debian.org/debian stretch-updates main

可能去掉注释看得更清楚一点。

deb http://deb.debian.org/debian stretch main
deb http://security.debian.org/debian-security stretch/updates main
deb http://deb.debian.org/debian stretch-updates main

在网上找了一大堆，都没有好使的，看了看人家原生的内容，我就想，直接把我访问了域名替换成国内的源行不行？

执行命令：

nano /etc/apt/sources.list

增加下列行：

deb http://mirrors.163.com/debian stretch main
deb http://security.debian.org/debian-security stretch/updates main
deb http://mirrors.163.com/debian stretch-updates main

修改后，执行下面的命令来试试：

apt-get update -y

没有出现任务404，或W、E的提示。

debian官方镜像列表：

https://www.debian.org/CD/http-ftp/#mirrors

注意，下面如果还有类似的问题，镜像选备选方案也列在表中。

北交大
deb https://mirror.bjtu.edu.cn/debian/ hardy main restricted universe multiverse
deb https://mirror.bjtu.edu.cn/debian/ hardy-backports restricted universe multiverse
deb https://mirror.bjtu.edu.cn/debian/ hardy-proposed main restricted universe multiverse
deb https://mirror.bjtu.edu.cn/debian/ hardy-security main restricted universe multiverse
deb https://mirror.bjtu.edu.cn/debian/ hardy-updates main restricted universe multiverse
deb-src https://mirror.bjtu.edu.cn/debian/ hardy main restricted universe multiverse
deb-src https://mirror.bjtu.edu.cn/debian/ hardy-backports main restricted universe multiverse
deb-src https://mirror.bjtu.edu.cn/debian/ hardy-proposed main restricted universe multiverse
deb-src https://mirror.bjtu.edu.cn/debian/ hardy-security main restricted universe multiverse
deb-src https://mirror.bjtu.edu.cn/debian/ hardy-updates main restricted universe multiverse

中科大
deb https://mirrors.ustc.edu.cn/debian/ hardy main restricted universe multiverse
deb-src https://mirrors.ustc.edu.cn/debian/ hardy main restricted universe multiverse
deb https://mirrors.ustc.edu.cn/debian/ hardy-updates main restricted universe multiverse
deb-src https://mirrors.ustc.edu.cn/debian/ hardy-updates main restricted universe multiverse
deb https://mirrors.ustc.edu.cn/debian/ hardy-backports main restricted universe multiverse
deb-src https://mirrors.ustc.edu.cn/debian/ hardy-backports main restricted universe multiverse
deb https://mirrors.ustc.edu.cn/debian/ hardy-security main restricted universe multiverse
deb-src https://mirrors.ustc.edu.cn/debian/ hardy-security main restricted universe multiverse
deb https://mirrors.ustc.edu.cn/debian/ hardy-proposed main multiverse restricted universe
deb-src https://mirrors.ustc.edu.cn/debian/ hardy-proposed main restricted universe multiverse

台湾大学

deb http://debian.csie.ntu.edu.tw/debian hardy main restricted universe multiverse
deb-src http://debian.csie.ntu.edu.tw/debian hardy main restricted universe multiverse
deb http://debian.csie.ntu.edu.tw/debian hardy-updates main restricted universe multiverse
deb-src http://debian.csie.ntu.edu.tw/debian hardy-updates main restricted universe multiverse
deb http://debian.csie.ntu.edu.tw/debian hardy-backports main restricted universe multiverse
deb-src http://debian.csie.ntu.edu.tw/debian hardy-backports main restricted universe multiverse
deb http://debian.csie.ntu.edu.tw/debian hardy-security main restricted universe multiverse
deb-src http://debian.csie.ntu.edu.tw/debian hardy-security main restricted universe multiverse
deb http://debian.csie.ntu.edu.tw/debian hardy-proposed main multiverse restricted universe
deb-src http://debian.csie.ntu.edu.tw/debian hardy-proposed main restricted universe multiverse

阿里云：debian 10.x (buster)
deb http://mirrors.aliyun.com/debian/ buster main non-free contrib
deb-src http://mirrors.aliyun.com/debian/ buster main non-free contrib
deb http://mirrors.aliyun.com/debian-security buster/updates main
deb-src http://mirrors.aliyun.com/debian-security buster/updates main
deb http://mirrors.aliyun.com/debian/ buster-updates main non-free contrib
deb-src http://mirrors.aliyun.com/debian/ buster-updates main non-free contrib
deb http://mirrors.aliyun.com/debian/ buster-backports main non-free contrib
deb-src http://mirrors.aliyun.com/debian/ buster-backports main non-free contrib