Everyone knows what a Linux shell is -- you open up a Linux terminal window (such as Konsole or xterm), type in some commands, and there you are, using your Linux shell. Write your commands to a file, make it executable, run it, and you're a shell programmer. But did you know that there are different shells that you can use, and that each shell operates in a slightly different way? My personal favorite is the Korn shell; by the end of this article, it may be your favorite as well.