ubuntu在sources.list文件中进行修改镜像源，修改方法：1、打开终端；2、输入“sudo cp /etc/apt/sources.list /etc/apt/sources.list_backup”命令备份源列表；3、输入“sudo vim /etc/apt/sources.list”命令打开sources.list文件进行修改；4、使用新的源替换掉文件中所有的内容；5、输入命令更新源列表，使修改生效即可。
具体操作步骤：
使用快捷键【Ctrl+Alt+T】打开终端。
输入以下命令备份源列表。
sudo cp /etc/apt/sources.list /etc/apt/sources.list_backup
再输入命令打开sources.list文件进行修改。
sudo vim /etc/apt/sources.list
使用以下源替换掉文件中所有的内容，保存编辑好的文件。
deb http://mirrors.aliyun.com/ubuntu/ trusty main restricted universe multiverse
deb http://mirrors.aliyun.com/ubuntu/ trusty-security main restricted universe multiverse
deb http://mirrors.aliyun.com/ubuntu/ trusty-updates main restricted universe multiverse
deb http://mirrors.aliyun.com/ubuntu/ trusty-proposed main restricted universe multiverse
deb http://mirrors.aliyun.com/ubuntu/ trusty-backports main restricted universe multiverse
deb-src http://mirrors.aliyun.com/ubuntu/ trusty main restricted universe multiverse
deb-src http://mirrors.aliyun.com/ubuntu/ trusty-security main restricted universe multiverse
deb-src http://mirrors.aliyun.com/ubuntu/ trusty-updates main restricted universe multiverse
deb-src http://mirrors.aliyun.com/ubuntu/ trusty-proposed main restricted universe multiverse
deb-src http://mirrors.aliyun.com/ubuntu/ trusty-backports main restricted universe multiverse
最后输入以下命令更新源列表，使修改生效即可。
sudo apt-get update
sudo apt-get upgrade
sudo apt-get install build-essential
