此源适用于pc版本ubuntu16.04 64位以及ubuntu16.04嵌入式版本32位，嵌入式板子最好插键盘鼠标，用secureCRT或者xshell可能会比较慢

# deb cdrom:[Ubuntu 16.04 LTS _Xenial Xerus_ - Release amd64 (20160420.1)]/ xenial main restricted

# See http://help.ubuntu.com/community/UpgradeNotes for how to upgrade to
# newer versions of the distribution.
deb http://mirrors.ustc.edu.cn/ubuntu/ xenial main restricted
# deb-src http://cn.archive.ubuntu.com/ubuntu/ xenial main restricted


## Major bug fix updates produced after the final release of the
## distribution.
deb http://mirrors.ustc.edu.cn/ubuntu/ xenial-updates main restricted
# deb-src http://cn.archive.ubuntu.com/ubuntu/ xenial-updates main restricted


## N.B. software from this repository is ENTIRELY UNSUPPORTED by the Ubuntu
## team,and may not be under a free licence. Please satisfy yourself as to
## your rights to use the software. Also,please note that software in
## universe WILL NOT receive any review or updates from the Ubuntu security
## team.
deb http://mirrors.ustc.edu.cn/ubuntu/ xenial universe
# deb-src http://cn.archive.ubuntu.com/ubuntu/ xenial universe
deb http://mirrors.ustc.edu.cn/ubuntu/ xenial-updates universe
# deb-src http://cn.archive.ubuntu.com/ubuntu/ xenial-updates universe


## N.B. software from this repository is ENTIRELY UNSUPPORTED by the Ubuntu
## team,please note that software in
## multiverse WILL NOT receive any review or updates from the Ubuntu
## security team.
deb http://mirrors.ustc.edu.cn/ubuntu/ xenial multiverse
# deb-src http://cn.archive.ubuntu.com/ubuntu/ xenial multiverse
deb http://mirrors.ustc.edu.cn/ubuntu/ xenial-updates multiverse
# deb-src http://cn.archive.ubuntu.com/ubuntu/ xenial-updates multiverse


## N.B. software from this repository may not have been tested as
## extensively as that contained in the main release,although it includes
## newer versions of some applications which may provide useful features.
## Also,please note that software in backports WILL NOT receive any review
## or updates from the Ubuntu security team.
deb http://mirrors.ustc.edu.cn/ubuntu/ xenial-backports main restricted universe multiverse
# deb-src http://cn.archive.ubuntu.com/ubuntu/ xenial-backports main restricted universe multiverse


## Uncomment the following two lines to add software from Canonical's
## 'partner' repository.
## This software is not part of Ubuntu,but is offered by Canonical and the
## respective vendors as a service to Ubuntu users.
# deb http://archive.canonical.com/ubuntu xenial partner
# deb-src http://archive.canonical.com/ubuntu xenial partner


deb http://mirrors.ustc.edu.cn/ubuntu/ xenial-security main restricted
# deb-src http://security.ubuntu.com/ubuntu xenial-security main restricted
deb http://mirrors.ustc.edu.cn/ubuntu/ xenial-security universe
# deb-src http://security.ubuntu.com/ubuntu xenial-security universe
deb http://mirrors.ustc.edu.cn/ubuntu/ xenial-security multiverse

# deb-src http://security.ubuntu.com/ubuntu xenial-security multiverse

apt-get update成功后源自动变为如下：

##deb http://ports.ubuntu.com/ubuntu-ports xenial main # deb https://mirrors.ustc.edu.cn/ubuntu-ports xenial main restricted universe multiverse # deb-src https://mirrors.ustc.edu.cn/ubuntu-ports xenial main restricted universe multiverse # deb https://mirrors.tuna.tsinghua.edu.cn/ubuntu-ports xenial main restricted universe multiverse # deb-src https://mirrors.tuna.tsinghua.edu.cn/ubuntu-ports xenial main restricted universe multiverse ##deb https://ports.ubuntu.com/ xenial main restricted universe multiverse ##deb-src https://ports.ubuntu.com/ xenial main restricted universe multiverse ##deb https://ports.ubuntu.com/ xenial-updates main restricted universe multiverse ##deb-src https://ports.ubuntu.com/ xenial-updates main restricted universe multiverse ##deb https://ports.ubuntu.com/ xenial-security main restricted universe multiverse ##deb-src https://ports.ubuntu.com/ xenial-security main restricted universe multiverse ##deb https://ports.ubuntu.com/ xenial-backports main restricted universe multiverse ##deb-src https://ports.ubuntu.com/ xenial-backports main restricted universe multiverse deb [arch=armhf] https://mirrors.tuna.tsinghua.edu.cn/ubuntu-ports xenial main universe deb-src https://mirrors.tuna.tsinghua.edu.cn/ubuntu-ports xenial main universe deb [arch=armhf] https://mirrors.tuna.tsinghua.edu.cn/ubuntu-ports xenial-security main universe deb-src https://mirrors.tuna.tsinghua.edu.cn/ubuntu-ports xenial-security main universe deb [arch=armhf] https://mirrors.tuna.tsinghua.edu.cn/ubuntu-ports xenial-updates main universe deb-src https://mirrors.tuna.tsinghua.edu.cn/ubuntu-ports xenial-updates main universe deb [arch=armhf] http://mirrors.ustc.edu.cn/ubuntu-ports xenial main universe deb-src http://mirrors.ustc.edu.cn/ubuntu-ports xenial main universe deb [arch=armhf] http://mirrors.ustc.edu.cn/ubuntu-ports xenial-security main universe deb-src http://mirrors.ustc.edu.cn/ubuntu-ports xenial-security main universe deb [arch=armhf] http://mirrors.ustc.edu.cn/ubuntu-ports xenial-updates main universe deb-src http://mirrors.ustc.edu.cn/ubuntu-ports xenial-updates main universe # deb https://cn.archive.ubuntu.com/ubuntu/ xenial universe # deb-src https://cn.archive.ubuntu.com/ubuntu/ xenial universe # deb https://cn.archive.ubuntu.com/ubuntu/ xenial-updates universe # deb-src https://cn.archive.ubuntu.com/ubuntu/ xenial-updates universe