An editor is a program that allows you to easily create and alter text files. There are a variety of editors on the system, of which the most popular, when working in text-mode, are vi and emacs. Neither is exactly the easiest thing in the world to learn to use. When working in graphics-mode, the most popular are emacs and gedit. The latter is simple and intuitive, but also very bare-bones.

I recommend learning emacs, because

• It works nicely in both text and graphics mode.

• As you gain more facility with emacs and with Unix in general, you will find that emacs offers many advanced facilities for doing specific tasks.

• In particular, emacs offers a number of aids for programmers, including syntax-based highlighting of different programming languages (using different colors/fonts for reserved words, comments, strings, etc.), commands for checking matching {}, for compiling programs and collecting the error messages, and for stepping through those error messages, and for debugging the compiled code.

• emacs is widely available (for free) for all Unix systems and also for MS Windows.

Example 1: Try This: Launching emacs

To run emacs, make sure that you have correctly identified your terminal type. Then give the command

emacs -nw

if you are in text-mode and

emacs &

if you are in graphics mode. The -nw stands for “no window” and requests that emacs not try to open a new graphics-mode window.

Stay in emacs for now. We’ll come back to this in just a moment.

emacs has a built-in tutorial, and you should begin that very shortly. But first, just a couple of notes:

• The tutorial describes a number of commands like this: C-_chr_, which means to hold down the Ctrl (a.k.a, Cntrl, Control, etc.) key while typing the character chr. For example, C-c means “hold down Ctrl while typing ‘c’.”

  You may have seen the notation ^_chr_ (e.g., ^c) used other places to mean the same thing.

• The tutorial describes a number of commands like this: M-_chr_, and says the “M-” means to “hold the META or EDIT or ALT key down while typing” the other character, and says that if you don’t have a META, EDIT, or ALT key that you can type (and release) the Escape key instead.

  It’s worth noting that you may, indeed, have some of those keys on your keyboard, but your ssh client program might not pass them on. Some ssh programs may just ignore those keys. In other cases (especially the ALT keys), the Windows or other operating system may be jealously seizing upon those keys for its own purposes. In some cases, you may have 2 ALT keys, one on the left of the spacebar and one on the right. Sometimes one of these will work and the other will not, so try them both. But if nothing else works, the Escape key will always be there for you. (If you change ssh programs, though, or when you start using X to connect in graphics mode, you might want to check out those keys once again.)

Example 2: Try This: The emacs tutorial

Returning to the emacs session you opened a few moments ago, follow the directions given to bring up the tutorial (i.e., type ^h followed by “t”.).

Continue following the instructions to make your way through the tutorial.

Exit emacs when you have completed it.

When you are done with the tutorial, here are few extra things you should know about emacs:

If you don’t already have a ~/.emacs file, you might want to download mine into your home directory to get started. After you gain some proficiency in emacs, you may want to take a good look at that file to see what’s in there and to adjust it to your own liking.

Some of the features provided in my .emacs file are

• Makes sure that the C++ editing mode gets turned on when editing .h and .cpp files.

• Turns on colored syntax highlighting when supported by your terminal.

• Maps the Home, End, Page Up and Page Down keys to what you would expect (again, depends on whether your terminal program actually passes these through.

• Binds function keys

  • F1 : undo (same as C-x u)

  • F2 : toggles case sensitivity during search and replace operations (M-x toggle-case-sensitivity)

  • F5 : next-error after a compile (shift F5 for previous error) (`C-x ``)

  • F6 : turns on on-the-fly spell checking (M-x flyspell-mode)

  • F8 : toggles automatic line fill/breaking (M-x auto-fill-mode)

  • F9 : toggles uses of DOS/Unix line ending styles (M-x toggle-line-end-coding)

  If your terminal does not support the functions keys, you can invoke these functions directly via the “longer” forms shown above.

• Provides M-space as an alternate sequence for setting the mark

• Binds C-z to a “go to line number…” function.

Many of these functions are subject to the limitation of your terminal program. It may or may not allow colored displays. It may or may not pass function key presses on to the remote Unix system, etc. If these things don’t seem to work when you are running emacs in a terminal window, they probably will work later when you learn to run emacs via X.

(global-set-key "\M-\\" 'set-mark-command) 

So to set up a region to operate on, you move the cursor to one end of the region, give the set-mark-command, then move the cursor to the other end of the region. Everything between the mark and the cursor constitutes the current region, and can be operated on by any region-based command. Some region commands of note are:

C-w

Kill the region, i.e., delete it but save the deleted text in the clipboard. You can “yank” (paste) the deleted text at the cursor position with C-y.

M-w

Copy the region, i.e., Save a copy of the region’s text in the clipboard. You can “yank” (paste) the deleted text at the cursor position with C-y.

C-xC-x

Exchanges the mark and the cursor. Hitting this repeatedly will flip you back and forth between the start and end of the current region. Although often useful in its own right, this command also provides a quick way to check and see if the region is really where you think it is.

C-cC-c

Comment out a region - in C++ and other programming modes, places comment markers in front of each line in the region.

M-x ispell-region or M-x flyspell-region

Run a spell check on all text in the region.