In Chapter 1, Getting Friendly with Unix, we provided our eclectic minimanual of essential Unix tools. Those are the basic survival skills needed to navigate through file systems and manipulate files. We assume you have mastered those skills and are ready now for some more powerful ones. While you may not have found Unix friendly in your Chapter 1 encounters, we believe after experiencing some of the powerful and useful features of Unix in this chapter, you really will begin to like Unix. Again, we will not try to be exhaustive but instead to concentrate on those features we have found valuable in our scientific work. To learn about further features or about more options than those we illustrate, we recommend the man pages. More complex commands like awk may require you to read a detailed description in one of the Unix books listed in the References.