文件位置：/etc/apt/sources.list
在修改前建议先备份一下文件
sudo cp /etc/apt/sources.list /etc/apt/sources.list.bakup
使用vim编辑sources文件
sudo vim /etc/apt/sources.list
在每行的开头添加“#”注释掉内容，也可以直接全部删除，将新的源连接地址复制进去。
刷新源：sudo apt update
更新所有已安装软件：sudo apt upgrade
使用 “apt install 包名” 可以进行单个软件包的更新
ubuntu官方中国源
deb http://cn.archive.ubuntu.com/ubuntu/ focal main restricted
deb http://cn.archive.ubuntu.com/ubuntu/ focal-updates main restricted
deb http://cn.archive.ubuntu.com/ubuntu/ focal universe
deb http://cn.archive.ubuntu.com/ubuntu/ focal-updates universe
deb http://cn.archive.ubuntu.com/ubuntu/ focal multiverse
deb http://cn.archive.ubuntu.com/ubuntu/ focal-updates multiverse
deb http://cn.archive.ubuntu.com/ubuntu/ focal-backports main restricted universe multiverse
deb http://security.ubuntu.com/ubuntu/ focal-security main restricted
deb http://security.ubuntu.com/ubuntu/ focal-security universe
deb http://security.ubuntu.com/ubuntu/ focal-security multiverse
阿里源：
# 默认注释了源码镜像以提高 apt update 速度，如有需要可自行取消注释
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
网易163源
# 默认注释了源码镜像以提高 apt update 速度，如有需要可自行取消注释
deb http://mirrors.163.com/ubuntu/ focal main restricted universe multiverse
deb http://mirrors.163.com/ubuntu/ focal-security main restricted universe multiverse
deb http://mirrors.163.com/ubuntu/ focal-updates main restricted universe multiverse
deb http://mirrors.163.com/ubuntu/ focal-backports main restricted universe multiverse
# deb-src http://mirrors.163.com/ubuntu/ focal main restricted universe multiverse
# deb-src http://mirrors.163.com/ubuntu/ focal-security main restricted universe multiverse
# deb-src http://mirrors.163.com/ubuntu/ focal-updates main restricted universe multiverse
# deb-src http://mirrors.163.com/ubuntu/ focal-backports main restricted universe multiverse
清华源
# 默认注释了源码镜像以提高 apt update 速度，如有需要可自行取消注释
deb https://mirrors.tuna.tsinghua.edu.cn/ubuntu/ focal main restricted universe multiverse
# deb-src https://mirrors.tuna.tsinghua.edu.cn/ubuntu/ focal main restricted universe multiverse
deb https://mirrors.tuna.tsinghua.edu.cn/ubuntu/ focal-updates main restricted universe multiverse
# deb-src https://mirrors.tuna.tsinghua.edu.cn/ubuntu/ focal-updates main restricted universe multiverse
deb https://mirrors.tuna.tsinghua.edu.cn/ubuntu/ focal-backports main restricted universe multiverse
# deb-src https://mirrors.tuna.tsinghua.edu.cn/ubuntu/ focal-backports main restricted universe multiverse
deb https://mirrors.tuna.tsinghua.edu.cn/ubuntu/ focal-security main restricted universe multiverse
# deb-src https://mirrors.tuna.tsinghua.edu.cn/ubuntu/ focal-security main restricted universe multiverse
中科大源
# 默认注释了源码镜像以提高 apt update 速度，如有需要可自行取消注释
deb https://mirrors.ustc.edu.cn/ubuntu/ focal main restricted universe multiverse
#deb-src https://mirrors.ustc.edu.cn/ubuntu/ focal main restricted universe multiverse
deb https://mirrors.ustc.edu.cn/ubuntu/ focal-updates main restricted universe multiverse
#deb-src https://mirrors.ustc.edu.cn/ubuntu/ focal-updates main restricted universe multiverse
deb https://mirrors.ustc.edu.cn/ubuntu/ focal-backports main restricted universe multiverse
#deb-src https://mirrors.ustc.edu.cn/ubuntu/ focal-backports main restricted universe multiverse
deb https://mirrors.ustc.edu.cn/ubuntu/ focal-security main restricted universe multiverse
#deb-src https://mirrors.ustc.edu.cn/ubuntu/ focal-security main restricted universe multiverse
deb https://mirrors.ustc.edu.cn/ubuntu/ focal-proposed main restricted universe multiverse
#deb-src https://mirrors.ustc.edu.cn/ubuntu/ focal-proposed main restricted universe multiverse
腾讯源
deb http://mirrors.cloud.tencent.com/ubuntu-ports jammy main restricted
deb http://mirrors.cloud.tencent.com/ubuntu-ports jammy-updates main restricted
deb http://mirrors.cloud.tencent.com/ubuntu-ports jammy universe
deb http://mirrors.cloud.tencent.com/ubuntu-ports jammy-updates universe
deb http://mirrors.cloud.tencent.com/ubuntu-ports jammy multiverse
deb http://mirrors.cloud.tencent.com/ubuntu-ports jammy-updates multiverse
deb http://mirrors.cloud.tencent.com/ubuntu-ports jammy-backports main restricted universe multiverse
deb http://mirrors.cloud.tencent.com/ubuntu-ports jammy-security main restricted
deb http://mirrors.cloud.tencent.com/ubuntu-ports jammy-security universe
deb http://mirrors.cloud.tencent.com/ubuntu-ports jammy-security multiverse
