Ubuntu14.04更新源
1、点击右上角的”搜索“图标，在搜索框中输入update，在显示的应用列表中，点击”Software&Updates（软件&更新）“。
2、在弹出的”Software&Updates“窗口中，选择”Ubuntu Software“，你可以看到”Download from（下载源）“是”Server for United States(美国服务器)“。点击”Server for United States“下拉菜单，选择”Other...（其他）“。
3、在弹出”Choose a Download Server（选择下载服务器）“窗口中向上拉，找到China（中国）,然后，选择中国的服务器，这里可以选择教育源，网易、阿里等等。（我在这里选的是163（网易）的），然后点击”Choose Server（选择服务）“按钮。
4、然后，弹出”Authenticate（认证）“窗口，输入系统密码（ubuntu上由于安全性安装软件，需要输入密码），然后点击”Authenticate（认证）“按钮。
5、此时，你会发现”Software&Updates“窗口中的”Download from（下载源）“已经变成你设置的中国源。点击”Close(关闭)“按钮。
6、然后，会弹出一个提示,大概意思是”安装软件和更新添加的源或修改源，必须要重新加载可用软件的信息“，点击”Reload（重载）“按钮。进入”Updating cache(更新缓存)“界面，等待更新完过后，下载源就真正变成中国的了。以后下载东西就更快了。
1、（1）首先备份官方源，以免设置错误可恢复。
2、（2）用编辑器打开 /etc/apt/sources.list文件。
3、（3）删除原有的源，在编辑器中添加新源。如图所示：
4、（4）添加的源有很多，可根据自己的情况选择。
#163
deb http://mirrors.163.com/ubuntu/ trusty main restricted universe multiverse
deb http://mirrors.163.com/ubuntu/ trusty-security main restricted universe multiverse
deb http://mirrors.163.com/ubuntu/ trusty-updates main restricted universe multiverse
deb http://mirrors.163.com/ubuntu/ trusty-proposed main restricted universe multiverse
deb http://mirrors.163.com/ubuntu/ trusty-backports main restricted universe multiverse
deb-src http://mirrors.163.com/ubuntu/ trusty main restricted universe multiverse
deb-src http://mirrors.163.com/ubuntu/ trusty-security main restricted universe multiverse
deb-src http://mirrors.163.com/ubuntu/ trusty-updates main restricted universe multiverse
deb-src http://mirrors.163.com/ubuntu/ trusty-proposed main restricted universe multiverse
deb-src http://mirrors.163.com/ubuntu/ trusty-backports main restricted universe multiverse
#中科大
deb http://debian.ustc.edu.cn/ubuntu/ trusty main multiverse restricted universe
deb http://debian.ustc.edu.cn/ubuntu/ trusty-backports main multiverse restricted universe
deb http://debian.ustc.edu.cn/ubuntu/ trusty-proposed main multiverse restricted universe
deb http://debian.ustc.edu.cn/ubuntu/ trusty-security main multiverse restricted universe
deb http://debian.ustc.edu.cn/ubuntu/ trusty-updates main multiverse restricted universe
deb-src http://debian.ustc.edu.cn/ubuntu/ trusty main multiverse restricted universe
deb-src http://debian.ustc.edu.cn/ubuntu/ trusty-backports main multiverse restricted universe
deb-src http://debian.ustc.edu.cn/ubuntu/ trusty-proposed main multiverse restricted universe
deb-src http://debian.ustc.edu.cn/ubuntu/ trusty-security main multiverse restricted universe
deb-src http://debian.ustc.edu.cn/ubuntu/ trusty-updates main multiverse restricted universe
#sohu
deb http://mirrors.sohu.com/ubuntu/ trusty main restricted universe multiverse
deb http://mirrors.sohu.com/ubuntu/ trusty-security main restricted universe multiverse
deb http://mirrors.sohu.com/ubuntu/ trusty-updates main restricted universe multiverse
deb http://mirrors.sohu.com/ubuntu/ trusty-proposed main restricted universe multiverse
deb http://mirrors.sohu.com/ubuntu/ trusty-backports main restricted universe multiverse
deb-src http://mirrors.sohu.com/ubuntu/ trusty main restricted universe multiverse
deb-src http://mirrors.sohu.com/ubuntu/ trusty-security main restricted universe multiverse
deb-src http://mirrors.sohu.com/ubuntu/ trusty-updates main restricted universe multiverse
deb-src http://mirrors.sohu.com/ubuntu/ trusty-proposed main restricted universe multiverse
deb-src http://mirrors.sohu.com/ubuntu/ trusty-backports main restricted universe multiverse
#oschina
deb http://mirrors.oschina.net/ubuntu/ trusty main restricted universe multiverse
deb http://mirrors.oschina.net/ubuntu/ trusty-backports main restricted universe multiverse
deb http://mirrors.oschina.net/ubuntu/ trusty-proposed main restricted universe multiverse
deb http://mirrors.oschina.net/ubuntu/ trusty-security main restricted universe multiverse
deb http://mirrors.oschina.net/ubuntu/ trusty-updates main restricted universe multiverse
deb-src http://mirrors.oschina.net/ubuntu/ trusty main restricted universe multiverse
deb-src http://mirrors.oschina.net/ubuntu/ trusty-backports main restricted universe multiverse
deb-src http://mirrors.oschina.net/ubuntu/ trusty-proposed main restricted universe multiverse
deb-src http://mirrors.oschina.net/ubuntu/ trusty-security main restricted universe multiverse
deb-src http://mirrors.oschina.net/ubuntu/ trusty-updates main restricted universe multiverse
#北京交通大学
deb http://mirror.bjtu.edu.cn/ubuntu/ trusty main multiverse restricted universe
deb http://mirror.bjtu.edu.cn/ubuntu/ trusty-backports main multiverse restricted universe
deb http://mirror.bjtu.edu.cn/ubuntu/ trusty-proposed main multiverse restricted universe
deb http://mirror.bjtu.edu.cn/ubuntu/ trusty-security main multiverse restricted universe
deb http://mirror.bjtu.edu.cn/ubuntu/ trusty-updates main multiverse restricted universe
deb-src http://mirror.bjtu.edu.cn/ubuntu/ trusty main multiverse restricted universe
deb-src http://mirror.bjtu.edu.cn/ubuntu/ trusty-backports main multiverse restricted universe
deb-src http://mirror.bjtu.edu.cn/ubuntu/ trusty-proposed main multiverse restricted universe
deb-src http://mirror.bjtu.edu.cn/ubuntu/ trusty-security main multiverse restricted universe
deb-src http://mirror.bjtu.edu.cn/ubuntu/ trusty-updates main multiverse
# 北京理工
deb http://mirror.bjtu.edu.cn/ubuntu/ precise main multiverse restricted universe
deb http://mirror.bjtu.edu.cn/ubuntu/ precise-backports main multiverse restricted universe
deb http://mirror.bjtu.edu.cn/ubuntu/ precise-proposed main multiverse restricted universe
deb http://mirror.bjtu.edu.cn/ubuntu/ precise-security main multiverse restricted universe
deb http://mirror.bjtu.edu.cn/ubuntu/ precise-updates main multiverse restricted universe
deb-src http://mirror.bjtu.edu.cn/ubuntu/ precise main multiverse restricted universe
deb-src http://mirror.bjtu.edu.cn/ubuntu/ precise-backports main multiverse restricted universe
deb-src http://mirror.bjtu.edu.cn/ubuntu/ precise-proposed main multiverse restricted universe
deb-src http://mirror.bjtu.edu.cn/ubuntu/ precise-security main multiverse restricted universe
deb-src http://mirror.bjtu.edu.cn/ubuntu/ precise-updates main multiverse restricted universe
restricted universe
#上海交大
deb http://ftp.sjtu.edu.cn/ubuntu/ trusty universerestricted multiverse maindeb http://ftp.sjtu.edu.cn/ubuntu/ trusty-securityuniverse restricted multiverse maindeb http://ftp.sjtu.edu.cn/ubuntu/ trusty-updatesuniverse restricted multiverse maindeb http://ftp.sjtu.edu.cn/ubuntu/ trusty-proposeduniverse restricted multiverse maindeb http://ftp.sjtu.edu.cn/ubuntu/ trusty-backportsuniverse restricted multiverse main
#阿里云服务器
deb http://mirrors.aliyun.com/ubuntu/ trusty main restricted universe multiverse
deb http://mirrors.aliyun.com/ubuntu/ trusty-security main restricted universe multiverse
deb http://mirrors.aliyun.com/ubuntu/ trusty-updates main restricted universe multiverse
deb http://mirrors.aliyun.com/ubuntu/ trusty-proposed main restricted universe multiverse
deb http://mirrors.aliyun.com/ubuntu/ trusty-backports main restricted universe multiverse
deb-src http://mirrors.aliyun.com/ubuntu/ trusty main restricted universe multiverse
deb-src http://mirrors.aliyun.com/ubuntu/ trusty-security main restricted universe multiverse
deb-src http://mirrors.aliyun.com/ubuntu/ trusty-updates main restricted universe multiverse
deb-src http://mirrors.aliyun.com/ubuntu/ trusty-proposed main restricted universe multiverse
deb-src http://mirrors.aliyun.com/ubuntu/ trusty-backports main restricted universe multiverse
5、（5）更新。
