Ubuntu更换软件源

这里以163的源为例

sudo cp /etc/apt/sources.list /etc/apt/sources.list_backup
sudo gedit /etc/apt/sources.list

将其中的内容换成以下内容：
ubuntu14.04

deb http://mirrors.163.com/ubuntu/ trusty main restricted universe multiverse 
deb http://mirrors.163.com/ubuntu/ trusty-security main restricted universe multiverse 
deb http://mirrors.163.com/ubuntu/ trusty-updates main restricted universe multiverse 
deb http://mirrors.163.com/ubuntu/ trusty-proposed main restricted universe multiverse 
deb http://mirrors.163.com/ubuntu/ trusty-backports main restricted universe multiverse 
deb-src http://mirrors.163.com/ubuntu/ trusty main restricted universe multiverse 
deb-src http://mirrors.163.com/ubuntu/ trusty-security main restricted universe multiverse 
deb-src http://mirrors.163.com/ubuntu/ trusty-updates main restricted universe multiverse 
deb-src http://mirrors.163.com/ubuntu/ trusty-proposed main restricted universe multiverse 
deb-src http://mirrors.163.com/ubuntu/ trusty-backports main restricted universe multiverse

ubuntu18.04

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

然后更新

sudo apt-get update