Volume Number: 17 (2001)
Issue Number: 12
Column Tag: MacTech Online

by Jeff Clites

Emacs

In our last installment, we talked about ssh, and how it could be used in a network-rich world to ease administration of remote machines, and do so securely. One of the more common things that you’ll find yourself doing along these lines is editing configuration files or other text-based things. What you will need, of course, is a text editor. A good command-line, terminal-based text editor can make all the difference between an easy task and an onerous one, especially when working with files on a remote system. It may go against the grain of a long-time Mac user to even touch such a thing, but they are indispensable in those situations where they fit the bill, and truth be told they can actually be fun (you can keep this last part secret if you want). So this month, we are going to talk about text editors, and focus on emacs, the mother of all text editors.

Text Editor Choices

In the command-line world, the choice of text editors quickly narrows down to three, or really two. Although many others exist, the three that you’ll hear about universally are vi, emacs, and pico, all of which are installed by default with Mac OS X. The last of these, pico, is a small (hence the name) text editor—small both in memory footprint and in features. It’s simple to use (with on-screen instructions), and its key selling point is that it’s available even if you are booted into Mac OS X in single-user mode, frustrated and trying to fix something which is badly broken and not letting you boot normally. But, if you need to fire it up more than once in a blue moon you will quickly find yourself wanting more, which brings us to our two choices for full-blown, serious text editors. Both vi and emacs will let you get your job done, but they differ radically in their philosophies: vi tries to be minimalist, and emacs throws in every feature including the kitchen sink (and every other sink you could think of). And, as with all extremes, you can find camps who will vehemently defend either. The choice comes down to a matter of taste, and no one can really convince anyone to switch once they have chosen, but why try? Here I’m going to talk mainly about emacs, which I chose for very simple reasons: vi has separate command and edit modes, which confuse me, whereas emacs uses modifier keys for commands and leaves plain typing alone, and emacs just felt like more fun—it’s bloated with features but that gives you lots of room to grow as a user.

Of course, I’m not trying to talk anyone out of using ProjectBuilder, TextEdit, BBEdit, or whatever as their primary text editor, but I am encouraging you to take a look at emacs: as a supplement, for specialized tasks, or for a change of pace and a new perspective.

Easing into emacs

Emacs has as one of its primary goals to be extensible. It’s written almost entirely in its own flavor of Lisp (elisp, or Emacs Lisp), and almost every aspect of it is customizable, either through configuration or programming (and there’s a fine line between the two, as elisp is an interpreted language). There are add-on modules to allow you to transfer files via ftp, drive build tools and debuggers, interface with version control systems, move files around the filesystem, read documentation, and even read email, post to usenet, or browse the web. Also, there are distinct modes to ease editing of source code of various programming languages or markup languages, customizing aspects such as keyboard navigation and syntax coloring.

GNU Emacs
http://www.gnu.org/software/emacs/

With such as wealth of features, some users will say, “neat!”, and others will ask, “why?”, and that’s pretty much what decides whether emacs is the right editor for you. The nice thing is that you don’t have to tackle all of the features of emacs at once—you can learn just a few to start out, and expand as you like. In fact, the only things you really need to know to get started are how to save a file, and how to quit the application. (You can open a file with emacs when you invoke it from the command line, and typing and moving around use the same keystrokes as a GUI text editor, so these are both as you would naturally guess.) For these bare essentials, things are in fact easier than they would be with vi. To get you started, there are a couple of convenient reference sheets on the web that you can download and print out—one is from refcards.com and the other is from Rice University, which also has a downloadable tutorial to walk you through the basics. (This tutorial, as well as both reference sheets, are downloadable in PDF format.) Also, emacs itself has a built-in tutorial which will teach you a more extensive set of skills. (I recommend working through the emacs tutorial in several sessions, so that you have time to absorb it gradually rather than being overwhelmed.) For other questions that may come up as you go along, emacs has a built-in documentation system, and an FAQ (readable within emacs and also available on the web).

GNU Emacs quick reference card
http://www.refcards.com/about/emacs.html

GNU Emacs Reference Card
http://www.rice.edu/Computer/Documents/Unix/unix5.01.pdf

Intro to GNU Emacs
http://www.rice.edu/Computer/Documents/Unix/unix5.pdf

GNU Emacs FAQ
http://www.lerner.co.il/emacs/

In addition to the expected features for a text editor, emacs has some interesting “basic” features that you’ll want to learn almost right away, in particular opening and working with multiple files at the same time. Emacs has the ability the split up its terminal-window real estate so that you can work with multiple files side-by-side in one terminal window. (In emacs parlance these sections are called “windows”, but they all live in one real Terminal.app window, so don’t be thrown off by the terminology.) You can also toggle which file is being displayed in which “window”, so you can have an arbitrary number of files open with only one or two “windows”, if you like, which can be very useful when editing source code.

Emacs does tend to be all-encompassing, and it has been described as being an operating system as much as a text editor. In fact, it really can be an entire work environment inside of your larger work environment, allowing you to use its own features as well as to drive external tools, and one recommended usage mode is to launch emacs at the start of your work day, do everything you need to do without ever leaving emacs, and quit only at the end of the day. While this may be possible, there’s no reason that you have to use emacs this way—it’s fine to use it as little or as much as you like. As you get used to using emacs alongside your other tools, and as the keyboard-centric nature of emacs grows on you, you’ll be happy to discover that some of the basic key bindings of emacs are also available for use in other applications, including while editing on the command line of tcsh, and even within GUI-based editors such as TextEdit and ProjectBuilder.

XEmacs

Although I’ve been using the term “emacs” generically, there are actually several different flavors of emacs available. Mac OS X comes with GNU Emacs already installed, and this is arguably the standard emacs in wide use today, and can be found on most Linux systems as well. GNU Emacs, distributed by the Free Software Foundation, is full-featured, and there isn’t a pressing reason to go looking for a different version, but there is one alternative which is worth looking at: XEmacs. Formerly called “Lucid Emacs”, XEmacs originated as a branch off of GNU Emacs, mostly stemming from differences in philosophy about how emacs should evolve, and they are still largely similar to the end user. Don’t be confused by the name—although XEmacs can create and manage its own GUI under X11, complete with pull-down menus and mouse support, it also can also operate within a standard terminal window just like GNU Emacs. (In fact, GNU Emacs can also take advantage of X11 if present, so the name “XEmacs” is just misleading.) Take a look at the XEmacs site and see if it has any unique features which you need. One advantage it has at the moment is that it supports the use of color in terminal windows (for things such as syntax coloring of source code), although this feature is also slated to be included in the next major release of GNU Emacs. XEmacs is reported to be fairly straightforward to compile under Mac OS X, and it’s also available for installation by the Fink package manager—if you haven’t heard of Fink, you should definitely check it out; it makes installation of lots of standard Unix software a virtual snap. (Currently the XEmacs installation used by Fink is configured to require X11, which Fink can also install, although a configuration which doesn’t require X11 may become available in the future.)

XEmacs: The next generation of Emacs
http://www.xemacs.org/

Fink
http://fink.sourceforge.net/

Further Documentation

As usual, O’Reilly and Associates is your one-stop shopping center for printed references. Learning GNU Emacs will give you a firm grounding in all of emacs’ basic features, as well as a tour of its more advanced features. They also have a companion pocket reference, which is great for looking up the key commands for things you know you’ve done before but can’t quite remember how. It picks up where the downloadable reference cards leave off, and also covers a slightly newer version of emacs than the Learning GNU Emacs book. For advanced users who wish to customize or extend emacs, there is Writing GNU Emacs Extensions, which introduces elisp and leads you through all the details of bossing around emacs, in small or extensive ways.

Learning GNU Emacs, 2nd Edition
http://www.oreilly.com/catalog/gnu2/

GNU Emacs Pocket Reference
http://www.oreilly.com/catalog/gnupr/

Writing GNU Emacs Extensions
http://www.oreilly.com/catalog/gnuext/

Finally, the Free Software Foundation has the official manual for GNU Emacs, as well as documentation on Emacs Lisp; you can buy printed copies or download the books in a number of different formats from the FSF web site. There you’ll also find an interesting paper by Richard M. Stallman, open-source icon and original author of GNU Emacs, about the design of this versatile text editor.

GNU Emacs Manual
http://www.gnu.org/manual/emacs/index.html

Programming in Emacs Lisp
http://www.gnu.org/manual/emacs-lisp-intro/

EMACS: The Extensible, Customizable Display Editor
http://www.gnu.org/software/emacs/emacs-paper.html

emacs Culture

If you find that emacs isn’t to your liking and you’d prefer to use vi, that fine. I don’t mind. Really. But if you’re sure about that, you should also take a look at vim (which stand for Vi IMproved), which is a version of vi with several enhancements added. You can find information and source at the VIM Home Page, and you can also install it via the Fink package manager mentioned above. (A vanilla vi, specifically nvi according to the man page, is installed with Mac OS X by default). If you’re wavering, check out the essay by Charles Sebold, detailing his journey through various text editors, and his eventual conversion into an emacs devotee. And if you’ve been fully converted, cruise on over to geekcheat.com for an emacs reference in the form of a mug, mouse pad, or T-shirt.

The VIM (Vi IMproved) Home Page
http://www.vim.org/

Why I became an Emacs user
http://www.messengers-of-messiah.org/~csebold/emacs/why.phtml

Emacs (and vi) merchandise
http://www.geekcheat.com/