Some useful commands on linux

Change the root password after ubuntu installed

sudo passwd root
先輸入自己的密碼再修改 root 的密碼

Get file from a ssh machine

In GNOME, allegedly (I've yet to get this working):
* Open a Nautilus window (e.g. click on Computer on the desktop)
* In the File menu, click on "Connect to Server"
* Set "Service type" to SSH and fill in the blanks

or user sftp in terminal

Install some software package

sudo apt-get

List of installed software packages

dpkg-query -W

Description of installed software packages

dpkg -l

List of available software packages

apt-cache pkgnames
apt-cache pkgnames | sort

Searching a software package: apt-cache search

apt-cache search flashplayer