有时候在更新Ubuntu时会发生如下错误：
Fetched 9,718 kB in 36s (268 kB/s)
W: Failed to fetch bzip2:/var/lib/apt/lists/partial/mirrors.163.com_ubuntu_dists_precise_restricted_source_Sources Hash Sum mismatch
W: Failed to fetch gzip:/var/lib/apt/lists/partial/mirrors.163.com_ubuntu_dists_precise-updates_restricted_source_Sources Hash Sum mismatch
E: Some index files failed to download. They have been ignored, or old ones used instead.
`</pre>
这是由于一些文件被墙的原因导致更新源服务器中的文件不完整，此时可以用Goagent代理去下载：
执行命令：
<pre>`sudo apt-get -o Acquire::http::proxy="http://127.0.0.1:8087/" update
