源文件的位置
/etc/apt/sources.list
因为测试需要，装完Debian7 后，更新为163的源，但是后来装软件时，一些软件依赖包还是装不上。后来把163源稍加改动，就好用了。163源内容如下：
deb http://mirrors.163.com/debian wheezy main non-free contrib deb http://mirrors.163.com/debian wheezy-proposed-updates main contrib non-free deb-src http://mirrors.163.com/debian wheezy main non-free contrib deb-src http://mirrors.163.com/debian wheezy-proposed-updates main contrib non-free deb http://mirrors.163.com/debian-security wheezy/updates main contrib non-free deb-src http://mirrors.163.com/debian-security wheezy/updates main contrib non-free
sudo apt-get install debian-keyring debian-archive-keyring
sudo apt-get update