ubuntu 11.04中国更新源
ubuntu11.04安装后默认的国内更新源（新浪镜像）速度非常慢，每次更新都要很久时间，想换个速度快的更新源，网上找了下，发现台湾和网易的不错，推荐给大家。
一、台湾更新源（首选推荐，速度很快）
deb http://tw.archive.Ubuntu.com/ubuntu/ natty main universe restricted multiverse
deb-src http://tw.archive.Ubuntu.com/ubuntu/ natty main universe restricted multiverse
deb http://tw.archive.Ubuntu.com/ubuntu/ natty-security universe main multiverse restricted
deb-src http://tw.archive.Ubuntu.com/ubuntu/ natty-security universe main multiverse restricted
deb http://tw.archive.Ubuntu.com/ubuntu/ natty-updates universe main multiverse restricted
deb-src http://tw.archive.Ubuntu.com/ubuntu/ natty-updates universe main multiverse restricted
二、网易更新源
deb http://mirrors.163.com/ubuntu/ natty main universe restricted multiverse
deb-src http://mirrors.163.com/ubuntu/ natty main universe restricted multiverse
deb http://mirrors.163.com/ubuntu/ natty-security universe main multiverse restricted
deb-src http://mirrors.163.com/ubuntu/ natty-security universe main multiverse restricted
deb http://mirrors.163.com/ubuntu/ natty-updates universe main multiverse restricted
deb http://mirrors.163.com/ubuntu/ natty-proposed universe main multiverse restricted
deb-src http://mirrors.163.com/ubuntu/ natty-proposed universe main multiverse restricted
deb http://mirrors.163.com/ubuntu/ natty-backports universe main multiverse restricted
deb-src http://mirrors.163.com/ubuntu/ natty-backports universe main multiverse restricted
deb-src http://mirrors.163.com/ubuntu/ natty-updates universe main multiverse restricted
注：有个很奇怪的现象，网址应该是不分大小写，但163源的地址如果将ubuntu写成Ubuntu则不会成功链接上的
更新源步骤如下：
1）打开终端（应用程序 -> 附件 -> 终端）
2）在终端输入：
sudo cp /etc/apt/sources.list /etc/apt/sources.list_backup注
#备份原来的软件列表，会要求输入密码
sudo gedit /etc/apt/sources.list
#在打开的gedit编辑器中输入上面的更新源地址，完成后关闭编辑器保存列表
3）在终端执行更新列表，输入：
sudo apt-get update
4）安装系统更新，打开“更新管理器”（系统->系统管理->更新管理器），下载安装需要的更新，完成后有可能需要重启系统。
到此位为止，更换更新源大功告成，享受快感吧。