修改 Ubuntu 的软件源

1、将 /etc/apt/ 路径下的 sources.list 的内容修改为如下内容（此内容为 Ubuntu Kylin 里面的内容，直接拿过来用，也可以用其它的国内的源）。

deb http://mirrors.aliyun.com/ubuntu/ groovy main restricted universe multiverse
deb http://mirrors.aliyun.com/ubuntu/ groovy-updates main restricted universe multiverse
deb http://mirrors.aliyun.com/ubuntu/ groovy-security main restricted universe multiverse

# This system was installed using small removable media
# (e.g. netinst, live or single CD). The matching "deb cdrom"
# entries were disabled at the end of the installation process.
# For information about how to configure apt package sources,
# see the sources.list(5) manual.

2、执行命令更新软件源。

sudo apt-get update