Ubuntu更换国内镜像源

1.备份原系统中的镜像源

sudo cp /etc/apt/sources.list /etc/apt/sources.bak1

#第一个参数时拷贝的文件路径和文件名称,第二个是拷贝到(粘贴)的文件路径和文件名

sudo cp /etc/apt/sources.list /etc/apt/sources.bak1

2.更改镜像源文件的访问权限(增加写权限)

sudo chmod u+w /etc/apt/sources.list

更改完成可以再恢复文件的访问权限。

清华镜像源：https://mirrors.tuna.tsinghua.edu.cn/help/ubuntu/

3.更改镜像源内容

#方法 sudo gedit /etc/apt/sources.list


#阿里源
#deb http://mirrors.aliyun.com/ubuntu/ bionic main restricted universe multiverse
#deb http://mirrors.aliyun.com/ubuntu/ bionic-security main restricted universe multiverse
#deb http://mirrors.aliyun.com/ubuntu/ bionic-updates main restricted universe multiverse
#deb http://mirrors.aliyun.com/ubuntu/ bionic-proposed main restricted universe multiverse
#deb http://mirrors.aliyun.com/ubuntu/ bionic-backports main restricted universe multiverse
#deb-src http://mirrors.aliyun.com/ubuntu/ bionic main restricted universe multiverse
#deb-src http://mirrors.aliyun.com/ubuntu/ bionic-security main restricted universe multiverse
#deb-src http://mirrors.aliyun.com/ubuntu/ bionic-updates main restricted universe multiverse
#deb-src http://mirrors.aliyun.com/ubuntu/ bionic-proposed main restricted universe multiverse
#deb-src http://mirrors.aliyun.com/ubuntu/ bionic-backports main restricted universe multiverse

#网易源
#deb http://mirrors.163.com/ubuntu/ bionic main restricted universe multiverse
#deb http://mirrors.163.com/ubuntu/ bionic-security main restricted universe multiverse
#deb http://mirrors.163.com/ubuntu/ bionic-updates main restricted universe multiverse
#deb http://mirrors.163.com/ubuntu/ bionic-proposed main restricted universe multiverse
#deb http://mirrors.163.com/ubuntu/ bionic-backports main restricted universe multiverse
#deb-src http://mirrors.163.com/ubuntu/ bionic main restricted universe multiverse
#deb-src http://mirrors.163.com/ubuntu/ bionic-security main restricted universe multiverse
#deb-src http://mirrors.163.com/ubuntu/ bionic-updates main restricted universe multiverse
#deb-src http://mirrors.163.com/ubuntu/ bionic-proposed main restricted universe multiverse
#deb-src http://mirrors.163.com/ubuntu/ bionic-backports main restricted universe multiverse

#清华源
#deb https://mirrors.tuna.tsinghua.edu.cn/ubuntu/ bionic main restricted universe multiverse
#deb-src https://mirrors.tuna.tsinghua.edu.cn/ubuntu/ bionic main restricted universe multiverse
#deb https://mirrors.tuna.tsinghua.edu.cn/ubuntu/ bionic-updates main restricted universe multiverse
#deb-src https://mirrors.tuna.tsinghua.edu.cn/ubuntu/ bionic-updates main restricted universe multiverse
#deb https://mirrors.tuna.tsinghua.edu.cn/ubuntu/ bionic-backports main restricted universe multiverse
#deb-src https://mirrors.tuna.tsinghua.edu.cn/ubuntu/ bionic-backports main restricted universe multiverse
#deb https://mirrors.tuna.tsinghua.edu.cn/ubuntu/ bionic-security main restricted universe multiverse
#deb-src https://mirrors.tuna.tsinghua.edu.cn/ubuntu/ bionic-security main restricted universe multiverse
#deb https://mirrors.tuna.tsinghua.edu.cn/ubuntu/ bionic-proposed main restricted universe multiverse
#deb-src https://mirrors.tuna.tsinghua.edu.cn/ubuntu/ bionic-proposed main restricted universe multiverse

##中科大源
deb https://mirrors.ustc.edu.cn/ubuntu/ bionic main restricted universe multiverse
deb-src https://mirrors.ustc.edu.cn/ubuntu/ bionic main restricted universe multiverse
deb https://mirrors.ustc.edu.cn/ubuntu/ bionic-updates main restricted universe multiverse
deb-src https://mirrors.ustc.edu.cn/ubuntu/ bionic-updates main restricted universe multiverse
deb https://mirrors.ustc.edu.cn/ubuntu/ bionic-backports main restricted universe multiverse
deb-src https://mirrors.ustc.edu.cn/ubuntu/ bionic-backports main restricted universe multiverse
deb https://mirrors.ustc.edu.cn/ubuntu/ bionic-security main restricted universe multiverse
deb-src https://mirrors.ustc.edu.cn/ubuntu/ bionic-security main restricted universe multiverse
deb https://mirrors.ustc.edu.cn/ubuntu/ bionic-proposed main restricted universe multiverse
deb-src https://mirrors.ustc.edu.cn/ubuntu/ bionic-proposed main restricted universe multiverse

sources.list

4.更新软件源列表

sudo apt-get update
#这个命令，会访问源列表里的每个网址，并读取软件列表，然后保存在本地电脑。
我们在新立得软件包管理器里看到的软件列表，都是通过update命令更新的。

sudo apt-get update

sudo apt-get upgrade
#这个命令，会把本地已安装的软件，与刚下载的软件列表里对应软件进行对比，如果发现已安装的软件版本太低，
就会提示你更新。如果你的软件都是最新版本，会提示：
升级了 0 个软件包，新安装了 0 个软件包，要卸载 0 个软件包，有 0 个软件包未被升级。

sudo apt-get upgrade

【参考1】https://blog.csdn.net/qq_21095573/article/details/99736630