在TX2 上换清华源

1.备份原始的软件源

sudo cp /etc/apt/sources.list /etc/apt/sources.list.back

这样的话就会在/etc/apt目录下备份sources.list的内容，备份为文件sources.list.back

2.更换软件源

输入

sudo gedit /etc/apt/sources.list

将打开的文件里面的内容全部删掉，然后将下面的内容放进去：

# deb cdrom:[Ubuntu 16.04 LTS _Xenial Xerus_ - Release amd64 (20160420.1)]/ xenial main restricted
deb [arch=amd64,i386]  http://mirrors.tuna.tsinghua.edu.cn/ubuntu/ xenial main restricted
deb [arch=amd64,i386]  http://mirrors.tuna.tsinghua.edu.cn/ubuntu/ xenial-updates main restricted
deb [arch=amd64,i386]  http://mirrors.tuna.tsinghua.edu.cn/ubuntu/ xenial universe
deb [arch=amd64,i386]  http://mirrors.tuna.tsinghua.edu.cn/ubuntu/ xenial-updates universe
deb [arch=amd64,i386]  http://mirrors.tuna.tsinghua.edu.cn/ubuntu/ xenial multiverse
deb [arch=amd64,i386]  http://mirrors.tuna.tsinghua.edu.cn/ubuntu/ xenial-updates multiverse
deb [arch=amd64,i386]  http://mirrors.tuna.tsinghua.edu.cn/ubuntu/ xenial-backports main restricted universe multiverse
deb [arch=amd64,i386]  http://mirrors.tuna.tsinghua.edu.cn/ubuntu/ xenial-security main restricted
deb [arch=amd64,i386]  http://mirrors.tuna.tsinghua.edu.cn/ubuntu/ xenial-security universe
deb [arch=amd64,i386]  http://mirrors.tuna.tsinghua.edu.cn/ubuntu/ xenial-security multiverse

更新：

sudo apt-get update

升级：

sudo apt-get upgrade