vim useful tips

1. indent one line or many line(insert tab), just choose them in visual mode then use '>' or '<'-- one tab, '2<' or '3>' means more tabs.

2. merge two lines, there is one key--'J', this guy can help u.

3. type ':split filename' or ':vsplit filename', u can split the window horizontally or vertically. Using short key
'ctrl+w' to switch between windows.

4. ':qa' or ':qall' help u quit all windows, u can use ':x' to quit.