最基本的物质需求得到满足之后，唯一能够不断增加个人幸福感的事情就是帮助他人

GNU screen, a full-screen window manager that multiplexes a physical terminal between several processes.

1 The screen command The screen utility is enbedded in each ubuntu distribution now. Every time you envoke the screen command, you will create a new window. Each window you created using the screen command is independent with each other. Note: you can assign a title to the window you created by using the -t option. The following example create a window named test. e.g. #screen -t test
 2 Switch among windows  Given that you have created several windows using the screen command, switch among them is fairly easy. Just use control-a, then type ", you will see a list of windows in the screen, just select one, and you will enter into that environment.