爱华网sudo cp /etc/apt/sources.list /etc/apt/sources.list.backup（备份当前的源列表，以便日後需要时恢复）
sudo gedit /etc/apt/sources.list （修改sources.list文件中源的列表）
关于更新源的问题总结如下：
更新源不要加入太多，否则第一次执行sudo apt-get update 会很慢，建议加入2-3个更新源即可
国内加入网易和杭州的更新源：
##163的
deb http://mirrors.163.com/ubuntu/ jaunty mainrestricted universe multiverse
deb http://mirrors.163.com/ubuntu/ jaunty-securitymain restricted universe multiverse
deb http://mirrors.163.com/ubuntu/ jaunty-updatesmain restricted universe multiverse
deb http://mirrors.163.com/ubuntu/ jaunty-proposedmain restricted universe multiverse
deb http://mirrors.163.com/ubuntu/ jaunty-backportsmain restricted universe multiverse
deb-src http://mirrors.163.com/ubuntu/ jaunty mainrestricted universe multiverse
deb-src http://mirrors.163.com/ubuntu/jaunty-security main restricted universe multiverse
deb-src http://mirrors.163.com/ubuntu/jaunty-updates main restricted universe multiverse
deb-src http://mirrors.163.com/ubuntu/jaunty-proposed main restricted universe multiverse
deb-src http://mirrors.163.com/ubuntu/jaunty-backports main restricted universe multiverse
##杭州：
deb http://mirror.lupaworld.com/ubuntu jaunty mainrestricted universe multiverse
deb http://mirror.lupaworld.com/ubuntujaunty-security main restricted universe multiverse
deb http://mirror.lupaworld.com/ubuntujaunty-updates main restricted universe multiverse
deb http://mirror.lupaworld.com/ubuntujaunty-backports main restricted universe multiverse
deb http://mirror.lupaworld.com/ubuntujaunty-proposed main restricted universe multiverse
deb-src http://mirror.lupaworld.com/ubuntu jauntymain restricted universe multiverse
deb-src http://mirror.lupaworld.com/ubuntujaunty-security main restricted universe multiverse
deb-src http://mirror.lupaworld.com/ubuntujaunty-updates main restricted universe multiverse
deb-src http://mirror.lupaworld.com/ubuntujaunty-backports main restricted universe multiverse
deb-src http://mirror.lupaworld.com/ubuntujaunty-proposed main restricted universe multiverse
最后必须执行：
sudo apt-get update，否则系统仍然会使用原有的更新源。
