7 mac os x short cuts for trouble-shooting

When your application run into trouble such as no response, you would like to figure out why or want to quickly move on. Here is some Mac OS X short-cuts that makes your life much easier.

1. Do you want to quickly switch among different programs without clicking around? Command + Tab, Command + Shift + Tab will list all the open programs and allow you select the high-lighted one. 
2. Have you ever try to open a program by opening the finder, then navigate to the application folder, then click open a program? There is a much faster way. Command + Space, then type the program name.
3. windows user might wonder what is the Control + Alt + Delete equivalent in mac os x, the shot-cut is Command + Alt + ESC, use this force quit shortcut, if long clicking a program then select Quit don't work.
4. Do you want to compare files side by side in shell window? Command + D split a terminal window into 2.
5. Sometimes, you entered a long command line in terminal, then realized you want to modify the first a few characters. Instead of press left for 10 seconds, you can press fn + left to directly move to the front of the command. The fn + right move your cursor to the end of the command.
6. Command + T will open a new tab in terminal.
7. screen shot in mac os x: Command + Shift + 3 takes a full screen screenshot and Command + Shift + 4 takes a screenshot for a select area.