Here's a little mystery for you. Imagine you have three files on a Windows machine called: HTML_File.htm, PDF_File.pdf and Text_File.txt. Windows will have no problem opening the appropriate program when you double-click them because of those three-letter extensions. If however you drop the extensions or mix them up, you'll have problems. Now copy the three files to a Linux machine. You can see how the operating system perceives them by typing the file command, so file * will list them all ...