nano /etc/pacman.d/mirrorlist #编辑pacman源
找到## China,取消下面每行前面的注释,开启国内pacman源
## China
Server = http://mirrors.163.com/archlinux/$repo/os/$arch
Server = http://mirror.bjtu.edu.cn/archlinux/$repo/os/$arch
Server = http://mirror6.bjtu.edu.cn/archlinux/$repo/os/$arch
Server = ftp://mirrors.ustc.edu.cn/archlinux/$repo/os/$arch
Server = http://mirrors.ustc.edu.cn/archlinux/$repo/os/$arch
ctrl+o #保存
ctrl+x #退出
pacman -Syu #更新系统