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Basic Commands

emacs-mode uses control keys for the most basic editing functions. If you aren't familiar with emacs, you can think of these as extensions of the rudimentary "erase" character (usually BACKSPACE or DEL) that UNIX provides through its interface to users' terminals. For the sake of consistency, we'll assume your erase character is DEL from now on; if it is CTRL-H or something else, you will need to make a mental substitution. The most basic control-key commands are shown in Table 2-1. (Important: remember that typing CTRL-D when your command line is empty may log you off!) The basic keyboard habits of emacs-mode are easy to learn, but they do require that you assimilate a couple of concepts that are peculiar to the emacs editor.

Table 2-1. Basic emacs-mode commands

Command

Description

CTRL-B

Move backward one character (without deleting)

CTRL-F

Move forward one character

DEL

Delete one character backward

CTRL-D

Delete one character forward

The first of these is the use of CTRL-B and CTRL-F for backward and forward cursor motion. These keys have the advantage of being obvious mnemonics. You can also use the left and right cursor motion keys ("arrow" keys), but for the rest of this discussion we will use the control keys, as they work on all keyboards. In emacs-mode, the point (sometimes also called dot) is an imaginary place just to the left of the character the cursor is on. In the command descriptions in Table 2-1, some say "forward" while others say "backward." Think of forward as "to the right of point" and backward as "to the left of point."

For example, let's say you type in a line and, instead of typing RETURN, you type CTRL-B and hold it down so that it repeats. The cursor will move to the left until it is over the first character on the line, like this:

$ [f]grep -l Duchess < ~cam/book/alice_in_wonderland

Now the cursor is on the f, and point is at the beginning of the line, just before the f. If you type DEL, nothing will happen because there are no characters to the left of point. However, if you press CTRL-D (the "delete character forward" command) you will delete the first letter:

$ [g]rep -l Duchess < ~cam/book/alice_in_wonderland

Point is still at the beginning of the line. If this were the desired command, you could hit RETURN now and run it; you don't need to move the cursor back to the end of the line. However, you could type CTRL-F repeatedly to get there:

$ grep -l Duchess < ~cam/book/alice_in_wonderland[]

At this point, typing CTRL-D wouldn't do anything, but hitting DEL would erase the final d.