1.sudo cp /etc/apt/sources.list /etc/apt/sources.list_backup    备份更新源设置

2.sudo gedit /etc/apt/sources.list
编辑你的源列表，将原来的内容全部删除，添加下面列表中最适合你的源（注意不要全部添加），选择一个最合适你的即可，复制到你的列表中，然后保存列表。

3.sudo apt-get update 更新源列表信息
可以在运行“sudo apt-get update ”时查看一下错误信息，把不能连接的源删除再重新运行“sudo apt-get update ”。

4.sudo apt-get upgrade  升级

# 以下来自http://wiki.ubuntu.org.cn/index.php?title=Template:9.10source&variant=zh-cn
# 台湾的官方源速度也相当不错，有时甚至快于内地的：
deb http://tw.archive.ubuntu.com/ubuntu karmic main restricted universe multiverse
deb http://tw.archive.ubuntu.com/ubuntu karmic-security main restricted universe multiverse
deb http://tw.archive.ubuntu.com/ubuntu karmic-updates main restricted universe multiverse
deb http://tw.archive.ubuntu.com/ubuntu karmic-backports main restricted universe multiverse
deb http://tw.archive.ubuntu.com/ubuntu karmic-proposed main restricted universe multiverse
deb-src http://tw.archive.ubuntu.com/ubuntu karmic main restricted universe multiverse
deb-src http://tw.archive.ubuntu.com/ubuntu karmic-security main restricted universe multiverse
deb-src http://tw.archive.ubuntu.com/ubuntu karmic-updates main restricted universe multiverse
deb-src http://tw.archive.ubuntu.com/ubuntu karmic-backports main restricted universe multiverse
deb-src http://tw.archive.ubuntu.com/ubuntu karmic-proposed main restricted universe multiverse

# 中国台湾 台湾大学更新服务器（推荐网通用户使用，电信PING平均响应速度41MS。强烈推荐此源，比较完整，较少出现同步问题）：
deb http://ubuntu.csie.ntu.edu.tw/ubuntu/ karmic main restricted universe multiverse
deb-src http://ubuntu.csie.ntu.edu.tw/ubuntu/ karmic main restricted universe multiverse
deb http://ubuntu.csie.ntu.edu.tw/ubuntu/ karmic-updates main restricted universe multiverse
deb-src http://ubuntu.csie.ntu.edu.tw/ubuntu/ karmic-updates main restricted universe multiverse
deb http://ubuntu.csie.ntu.edu.tw/ubuntu/ karmic-backports main restricted universe multiverse
deb-src http://ubuntu.csie.ntu.edu.tw/ubuntu/ karmic-backports main restricted universe multiverse
deb http://ubuntu.csie.ntu.edu.tw/ubuntu/ karmic-security main restricted universe multiverse
deb-src http://ubuntu.csie.ntu.edu.tw/ubuntu/ karmic-security main restricted universe multiverse
deb http://ubuntu.csie.ntu.edu.tw/ubuntu/ karmic-proposed main multiverse restricted universe
deb-src http://ubuntu.csie.ntu.edu.tw/ubuntu/ karmic-proposed main restricted universe multiverse

# 网易163更新服务器：
deb http://mirrors.163.com/ubuntu/ karmic main restricted universe multiverse
deb http://mirrors.163.com/ubuntu/ karmic-security main restricted universe multiverse
deb http://mirrors.163.com/ubuntu/ karmic-updates main restricted universe multiverse
deb http://mirrors.163.com/ubuntu/ karmic-proposed main restricted universe multiverse
deb http://mirrors.163.com/ubuntu/ karmic-backports main restricted universe multiverse
deb-src http://mirrors.163.com/ubuntu/ karmic main restricted universe multiverse
deb-src http://mirrors.163.com/ubuntu/ karmic-security main restricted universe multiverse
deb-src http://mirrors.163.com/ubuntu/ karmic-updates main restricted universe multiverse
deb-src http://mirrors.163.com/ubuntu/ karmic-proposed main restricted universe multiverse
deb-src http://mirrors.163.com/ubuntu/ karmic-backports main restricted universe multiverse

# sohu 更新服务器：
deb http://mirrors.sohu.com/ubuntu/ karmic main restricted universe multiverse
deb http://mirrors.sohu.com/ubuntu/ karmic-security main restricted universe multiverse
deb http://mirrors.sohu.com/ubuntu/ karmic-updates main restricted universe multiverse
deb http://mirrors.sohu.com/ubuntu/ karmic-proposed main restricted universe multiverse
deb http://mirrors.sohu.com/ubuntu/ karmic-backports main restricted universe multiverse
deb-src http://mirrors.sohu.com/ubuntu/ karmic main restricted universe multiverse
deb-src http://mirrors.sohu.com/ubuntu/ karmic-security main restricted universe multiverse
deb-src http://mirrors.sohu.com/ubuntu/ karmic-updates main restricted universe multiverse
deb-src http://mirrors.sohu.com/ubuntu/ karmic-proposed main restricted universe multiverse
deb-src http://mirrors.sohu.com/ubuntu/ karmic-backports main restricted universe multiverse

# 骨头兄亲自搭建并维护这个Ubuntu源（该源位于浙江杭州百兆共享宽带的电信机房)：
deb http://ubuntu.srt.cn/ubuntu/ karmic main restricted universe multiverse
deb http://ubuntu.srt.cn/ubuntu/ karmic-security main restricted universe multiverse
deb http://ubuntu.srt.cn/ubuntu/ karmic-updates main restricted universe multiverse
deb http://ubuntu.srt.cn/ubuntu/ karmic-proposed main restricted universe multiverse
deb http://ubuntu.srt.cn/ubuntu/ karmic-backports main restricted universe multiverse
deb-src http://ubuntu.srt.cn/ubuntu/ karmic main restricted universe multiverse
deb-src http://ubuntu.srt.cn/ubuntu/ karmic-security main restricted universe multiverse
deb-src http://ubuntu.srt.cn/ubuntu/ karmic-updates main restricted universe multiverse
deb-src http://ubuntu.srt.cn/ubuntu/ karmic-proposed main restricted universe multiverse
deb-src http://ubuntu.srt.cn/ubuntu/ karmic-backports main restricted universe multiverse
deb http://mirror.lupaworld.com/ubuntu/ubuntu-cn karmic main restricted universe multiverse

# Archive.ubuntu.com更新服务器（欧洲，此为官方源，电信网通用户使用)：
deb http://archive.ubuntu.com/ubuntu/ karmic main restricted universe multiverse
deb http://archive.ubuntu.com/ubuntu/ karmic-security main restricted universe multiverse
deb http://archive.ubuntu.com/ubuntu/ karmic-updates main restricted universe multiverse
deb http://archive.ubuntu.com/ubuntu/ karmic-proposed main restricted universe multiverse
deb http://archive.ubuntu.com/ubuntu/ karmic-backports main restricted universe multiverse
deb-src http://archive.ubuntu.com/ubuntu/ karmic main restricted universe multiverse
deb-src http://archive.ubuntu.com/ubuntu/ karmic-security main restricted universe multiverse
deb-src http://archive.ubuntu.com/ubuntu/ karmic-updates main restricted universe multiverse
deb-src http://archive.ubuntu.com/ubuntu/ karmic-proposed main restricted universe multiverse
deb-src http://archive.ubuntu.com/ubuntu/ karmic-backports main restricted universe multiverse

# Mirrors.shlug.org更新服务器（电信服务器，Ubuntu China Official Mirror, maintained by Shanghai Linux User Group）：
deb http://cn.archive.ubuntu.com/ubuntu karmic main restricted universe multiverse
deb http://cn.archive.ubuntu.com/ubuntu karmic-security main restricted universe multiverse
deb http://cn.archive.ubuntu.com/ubuntu karmic-updates main restricted universe multiverse
deb http://cn.archive.ubuntu.com/ubuntu karmic-backports main restricted universe multiverse
deb http://cn.archive.ubuntu.com/ubuntu karmic-proposed main restricted universe multiverse
deb-src http://cn.archive.ubuntu.com/ubuntu karmic main restricted universe multiverse
deb-src http://cn.archive.ubuntu.com/ubuntu karmic-security main restricted universe multiverse
deb-src http://cn.archive.ubuntu.com/ubuntu karmic-updates main restricted universe multiverse
deb-src http://cn.archive.ubuntu.com/ubuntu karmic-backports main restricted universe multiverse
deb-src http://cn.archive.ubuntu.com/ubuntu karmic-proposed main restricted universe multiverse

# Mirror.lupaworld.com更新服务器（浙江省杭州市双线服务器）：
deb http://mirror.lupaworld.com/ubuntu karmic main restricted universe multiverse
deb http://mirror.lupaworld.com/ubuntu karmic-security main restricted universe multiverse
deb http://mirror.lupaworld.com/ubuntu karmic-updates main restricted universe multiverse
deb http://mirror.lupaworld.com/ubuntu karmic-backports main restricted universe multiverse
deb http://mirror.lupaworld.com/ubuntu karmic-proposed main restricted universe multiverse
deb-src http://mirror.lupaworld.com/ubuntu karmic main restricted universe multiverse
deb-src http://mirror.lupaworld.com/ubuntu karmic-security main restricted universe multiverse
deb-src http://mirror.lupaworld.com/ubuntu karmic-updates main restricted universe multiverse
deb-src http://mirror.lupaworld.com/ubuntu karmic-backports main restricted universe multiverse
deb-src http://mirror.lupaworld.com/ubuntu karmic-proposed main restricted universe multiverse

# 厦门大学更新服务器（教育网服务器）：
deb ftp://ubuntu.realss.cn/ubuntu/ karmic main restricted universe multiverse
deb ftp://ubuntu.realss.cn/ubuntu/ karmic-backports restricted universe multiverse
deb ftp://ubuntu.realss.cn/ubuntu/ karmic-proposed main restricted universe multiverse
deb ftp://ubuntu.realss.cn/ubuntu/ karmic-security main restricted universe multiverse
deb ftp://ubuntu.realss.cn/ubuntu/ karmic-updates main restricted universe multiverse
deb-src ftp://ubuntu.realss.cn/ubuntu/ karmic main restricted universe multiverse
deb-src ftp://ubuntu.realss.cn/ubuntu/ karmic-backports main restricted universe multiverse
deb-src ftp://ubuntu.realss.cn/ubuntu/ karmic-proposed main restricted universe multiverse
deb-src ftp://ubuntu.realss.cn/ubuntu/ karmic-security main restricted universe multiverse
deb-src ftp://ubuntu.realss.cn/ubuntu/ karmic-updates main restricted universe multiverse

# 成都市 电子科技大学更新服务器（教育网，推荐校园网和网通用户使用）：
deb http://ubuntu.uestc.edu.cn/ubuntu/ karmic main multiverse restricted universe
deb http://ubuntu.uestc.edu.cn/ubuntu/ karmic-backports main multiverse restricted universe
deb http://ubuntu.uestc.edu.cn/ubuntu/ karmic-proposed main multiverse restricted universe
deb http://ubuntu.uestc.edu.cn/ubuntu/ karmic-security main multiverse restricted universe
deb http://ubuntu.uestc.edu.cn/ubuntu/ karmic-updates main multiverse restricted universe
deb-src http://ubuntu.uestc.edu.cn/ubuntu/ karmic main multiverse restricted universe
deb-src http://ubuntu.uestc.edu.cn/ubuntu/ karmic-backports main multiverse restricted universe
deb-src http://ubuntu.uestc.edu.cn/ubuntu/ karmic-proposed main multiverse restricted universe
deb-src http://ubuntu.uestc.edu.cn/ubuntu/ karmic-security main multiverse restricted universe
deb-src http://ubuntu.uestc.edu.cn/ubuntu/ karmic-updates main multiverse restricted universe

# == 如果无法解析uestc.edu.cn域名，请使用以下地址 ==

deb http://ubuntu.dormforce.net/ubuntu/ karmic main multiverse restricted universe
deb http://ubuntu.dormforce.net/ubuntu/ karmic-backports main multiverse restricted universe
deb http://ubuntu.dormforce.net/ubuntu/ karmic-proposed main multiverse restricted universe
deb http://ubuntu.dormforce.net/ubuntu/ karmic-security main multiverse restricted universe
deb http://ubuntu.dormforce.net/ubuntu/ karmic-updates main multiverse restricted universe
deb-src http://ubuntu.dormforce.net/ubuntu/ karmic main multiverse restricted universe
deb-src http://ubuntu.dormforce.net/ubuntu/ karmic-backports main multiverse restricted universe
deb-src http://ubuntu.dormforce.net/ubuntu/ karmic-proposed main multiverse restricted universe
deb-src http://ubuntu.dormforce.net/ubuntu/ karmic-security main multiverse restricted universe
deb-src http://ubuntu.dormforce.net/ubuntu/ karmic-updates main multiverse restricted universe

# 上海市上海交通大学更新服务器：
deb http://ftp.sjtu.edu.cn/ubuntu/ karmic main multiverse restricted universe
deb http://ftp.sjtu.edu.cn/ubuntu/ karmic-backports main multiverse restricted universe
deb http://ftp.sjtu.edu.cn/ubuntu/ karmic-proposed main multiverse restricted universe
deb http://ftp.sjtu.edu.cn/ubuntu/ karmic-security main multiverse restricted universe
deb http://ftp.sjtu.edu.cn/ubuntu/ karmic-updates main multiverse restricted universe
deb-src http://ftp.sjtu.edu.cn/ubuntu/ karmic main multiverse restricted universe
deb-src http://ftp.sjtu.edu.cn/ubuntu/ karmic-backports main multiverse restricted universe
deb-src http://ftp.sjtu.edu.cn/ubuntu/ karmic-proposed main multiverse restricted universe
deb-src http://ftp.sjtu.edu.cn/ubuntu/ karmic-security main multiverse restricted universe
deb-src http://ftp.sjtu.edu.cn/ubuntu/ karmic-updates main multiverse restricted universe

# 中国科学技术大学更新服务器：
deb http://debian.ustc.edu.cn/ubuntu/ karmic main multiverse restricted universe
deb http://debian.ustc.edu.cn/ubuntu/ karmic-backports main multiverse restricted universe
deb http://debian.ustc.edu.cn/ubuntu/ karmic-proposed main multiverse restricted universe
deb http://debian.ustc.edu.cn/ubuntu/ karmic-security main multiverse restricted universe
deb http://debian.ustc.edu.cn/ubuntu/ karmic-updates main multiverse restricted universe
deb-src http://debian.ustc.edu.cn/ubuntu/ karmic main multiverse restricted universe
deb-src http://debian.ustc.edu.cn/ubuntu/ karmic-backports main multiverse restricted universe
deb-src http://debian.ustc.edu.cn/ubuntu/ karmic-proposed main multiverse restricted universe
deb-src http://debian.ustc.edu.cn/ubuntu/ karmic-security main multiverse restricted universe
deb-src http://debian.ustc.edu.cn/ubuntu/ karmic-updates main multiverse restricted universe

# 中国地质大学（北京）更新服务器：
deb http://www.tofree.org/ubuntu/ karmic main restricted universe multiverse
deb http://www.tofree.org/ubuntu/ karmic-security main restricted universe multiverse
deb http://www.tofree.org/ubuntu/ karmic-updates main restricted universe multiverse
deb http://www.tofree.org/ubuntu/ karmic-proposed main restricted universe multiverse
deb http://www.tofree.org/ubuntu/ karmic-backports main restricted universe multiverse
deb-src http://www.tofree.org/ubuntu/ karmic main restricted universe multiverse
deb-src http://www.tofree.org/ubuntu/ karmic-security main restricted universe multiverse
deb-src http://www.tofree.org/ubuntu/ karmic-updates main restricted universe multiverse
deb-src http://www.tofree.org/ubuntu/ karmic-proposed main restricted universe multiverse
deb-src http://www.tofree.org/ubuntu/ karmic-backports main restricted universe multiverse

# mirror.rootguide.org更新服务器（上海市 电信）：
deb http://mirror.rootguide.org/ubuntu/ karmic main restricted universe multiverse
deb-src http://mirror.rootguide.org/ubuntu/ karmic main restricted universe multiverse
deb http://mirror.rootguide.org/ubuntu/ karmic-updates main restricted universe multiverse
deb-src http://mirror.rootguide.org/ubuntu/ karmic-updates main restricted universe multiverse
deb http://mirror.rootguide.org/ubuntu/ karmic-backports main restricted universe multiverse
deb-src http://mirror.rootguide.org/ubuntu/ karmic-backports main restricted universe multiverse
deb http://mirror.rootguide.org/ubuntu/ karmic-security main restricted universe multiverse
deb-src http://mirror.rootguide.org/ubuntu/ karmic-security main restricted universe multiverse
deb http://mirror.rootguide.org/ubuntu/ karmic-proposed main multiverse restricted universe
deb-src http://mirror.rootguide.org/ubuntu/ karmic-proposed main restricted universe multiverse