debian系统apt-get update失败的解决方法

有的VPS商家的Debian系统执行apt-get update会失败，因为源的设置有问题。编辑下源的地址就行了

编辑/etc/apt/sources.list，内容为

deb http://ftp.us.debian.org/debian/ wheezy main
deb-src http://ftp.us.debian.org/debian/ wheezy main
deb http://security.debian.org/ wheezy/updates main
deb-src http://security.debian.org/ wheezy/updates main
# wheezy-updates, previously known as 'volatile'
deb http://ftp.us.debian.org/debian/ wheezy-updates main
deb-src http://ftp.us.debian.org/debian/ wheezy-updates main

运行
apt-get update
apt-get dist-upgrade
重新启动即可
如果报gpg错误 先运行
apt-get install debian-archive-keyring