CHAPTER 1 The vi Text Editor Unix* has a number of editors that can process the contents of text files, whether those files contain data, source code, or sentences. There are line editors, such as ed and ex, which display a line of the file on the screen; and there are screen editors, such as vi and Emacs, which display a part of the file on your terminal screen. Text editors based on the X Window System are also commonly available and are becoming increasing popular. Both GNU Emacs and its derivative, XEmacs, provide multiple X windows; two interesting alternatives are the sam and Acme editors from Bell Labs. Vim also provides an X-based interface. vi is the most useful standard text editor on your system. (vi is short for visual editor and is pronounced “vee-eye.” This is illustrated graphically in Figure 1-1.) Unlike Emacs, it is available in nearly