解决Some index files failed to download, they have been ignored, or old ones used instead.的问题

首先先把/var/lib/apt/lists 的文件备份一下 (养成备份的好习惯)
mkdir /var/lib/apt/list
cp -r /var/lib/apt/lists/* /var/lib/apt/list
然后删除/var/lib/apt/lists/文件夹下所有的文件
rm -rf /var/lib/apt/lists/*
然后 打开/etc/apt/sources.list
vim /etc/apt/sources.list
写入阿里源
deb http://mirrors.aliyun.com/debian wheezy main contrib non-free
deb-src http://mirrors.aliyun.com/debian wheezy main contrib non-free
deb http://mirrors.aliyun.com/debian wheezy-updates main contrib non-free
deb-src http://mirrors.aliyun.com/debian wheezy-updates main contrib non-free
deb http://mirrors.aliyun.com/debian-security wheezy/updates main contrib non-free
deb-src http://mirrors.aliyun.com/debian-security wheezy/updates main contrib non-free
保存退出
:wq
最后 sudo apt-get update