一、更換Ubuntu源（阿里源）
因爲以後需要下載軟件包，下載鏈接都是國外的，下載速度會很慢，所以需要更換國內的ubuntu源。ubuntu使用官方的apt-get來安裝軟件，官方源的速度過慢。但是使用阿里雲的源就不一樣了，也不會存在很多問題，下面總結一下怎麼更換ubuntu的軟件源。
1.備份
#cd /etc/apt/
#sudo cp /etc/apt/sources.list /etc/apt/sources.list.bak
2.替換
#sudo gedit /etc/apt/sources.list
將以下的內容去替換：
deb-src http://archive.ubuntu.com/ubuntu xenial main restricted #Added by software-properties
deb http://mirrors.aliyun.com/ubuntu/ xenial main restricted
deb-src http://mirrors.aliyun.com/ubuntu/ xenial main restricted multiverse universe #Added by software-properties
deb http://mirrors.aliyun.com/ubuntu/ xenial-updates main restricted
deb-src http://mirrors.aliyun.com/ubuntu/ xenial-updates main restricted multiverse universe #Added by software-properties
deb http://mirrors.aliyun.com/ubuntu/ xenial universe
deb http://mirrors.aliyun.com/ubuntu/ xenial-updates universe
deb http://mirrors.aliyun.com/ubuntu/ xenial multiverse
deb http://mirrors.aliyun.com/ubuntu/ xenial-updates multiverse
deb http://mirrors.aliyun.com/ubuntu/ xenial-backports main restricted universe multiverse
deb-src http://mirrors.aliyun.com/ubuntu/ xenial-backports main restricted universe multiverse #Added by software-properties
deb http://archive.canonical.com/ubuntu xenial partner
deb-src http://archive.canonical.com/ubuntu xenial partner
deb http://mirrors.aliyun.com/ubuntu/ xenial-security main restricted
deb-src http://mirrors.aliyun.com/ubuntu/ xenial-security main restricted multiverse universe #Added by software-properties
deb http://mirrors.aliyun.com/ubuntu/ xenial-security universe
deb http://mirrors.aliyun.com/ubuntu/ xenial-security multiverse
3.更新
#sudo apt-get update
#sudo apt-get install software-name 命令是從網上下載name的軟件包。
二、設置Root密碼
$sudo passwd
Enter new UNIX password:輸入你要設置的新密碼
Retype new UNIX password:再輸入一遍
Ubuntu默認是沒有root密碼的，但是可以人爲地去設置。“su”輸入密碼，可以切換root用戶，“sudo yidada”切換普通用戶權限。這裏就講這麼多了，後面會繼續更新。