刚开始使用的时候，没有觉得哪里有问题，但是有时候通过命令行下载软件，更新软件，发现有的时候好慢好慢，为了解决，上网查找资料，发现可以通过更换软件源来解决这个问题。

sudo vi /etc/apt/sources.list

uBuntu20.04

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

Kali2021

deb http://mirrors.aliyun.com/kali kali-rolling main non-free contrib
deb-src http://mirrors.aliyun.com/kali kali-rolling main non-free contrib

更新源

sudo apt-get update

更新软件

sudo apt-get upgrade