1.6. Emacs Commands

You're about to start learning some Emacs commands, so let's discuss them a bit first. How do you give commands? Each command has a formal name, which (if you're fastidious) is the name of a Lisp routine. Some command names are quite long; you usually wouldn't want to type the whole thing. As a result, we need some way to abbreviate commands.

Emacs ties a command name to a short sequence of keystrokes. This tying of commands to keystrokes is known as binding . Even things you don't normally think about as commands, such as inserting the characters that you type, are handled through the binding mechanism. Keys like "A" are bound to the Emacs command self-insert-command , which inserts them into the buffer you are editing. ^[4] Most actions that you would normally think of as editor commands are bound to keystroke sequences starting with Ctrl or Meta . Emacs also binds some commands to mouse clicks (alone or modified by Shift or Ctrl ) and to options on menus .

^[4] In certain special editing modes, such as dired-mode for viewing and manipulating directories on your computer, the normal typing keys don't insert themselves . They are instead bound to special commands that do things like opening and renaming files. This flexibility in defining and changing keymaps , while it might seem somewhat arbitrary and overwhelming at first, is one of the great sources of power in Emacs.

The authors of Emacs try to bind the most frequently used commands to the key sequences that are the easiest to reach. Here are the varieties of key sequences you'll encounter:

The most commonly used commands (such as cursor movement commands) are bound to C- n (where n is any character). To press C- n , press and hold the Ctrl key and press n , then release both keys.
Slightly less commonly used commands are bound to M- n . To press M- n , press and hold the Meta key (usually next to the space bar), then press n .
Other commonly used commands are bound to C-x something ( C-x followed by something else -one or more characters or another control sequence). Among other types of commands, file manipulation commands, like the ones you are about to learn, are generally bound to C-x something .
Some specialized commands are bound to C-c something . These commands often relate to one of the more specialized modes, such as Java mode or HTML mode. You won't encounter them until later in this book.
This list still doesn't take care of all the possibilities. You can get at the remaining commands by typing M-x long-command-name Enter . (This works for any command really, but the keystrokes are usually easier to learn.)

You can define your own key bindings, too, and you should do so if you find yourself using the long form of a command all the time. More on this topic in Chapter 10.

You can also access common commands through menus, but for maximum productivity, we recommend you learn the keystrokes, often given in parentheses following the menu option.

1.7. Opening a File

You can open a file by specifying the filename when you start Emacs from the command line or by typing C-x C-f (the long command name is find-file ).

The paper icon on the toolbar also runs this command. In some applications, a similar icon simply creates a new, unnamed file (e.g., Document1 in Word). Emacs expects you to provide a filename, as we'll see in a moment.

Press: C-x C-f

Emacs prompts you for a filename.

To press C-x C-f , hold down Ctrl , press x and then press f . Now release Ctrl .

After you press C-x C-f , Emacs uses the minibuffer to ask you for the filename. Whenever Emacs wants input from you, it puts the cursor in the minibuffer. When you're done typing in the minibuffer, press Enter .

Type: newfile Enter

Emacs starts another buffer with the new file in it.

What if you try to read the same file twice? Instead of creating a new buffer, Emacs just moves you to the buffer the file is in.

You can also open a file in Emacs by dragging and dropping it on an Emacs window or on the Emacs icon.

Now is a good time to try typing if you haven't already done so. You may find yourself wanting to learn more about cursor movement and editing; that's fine. Feel free to skim the rest of this chapter and go on to Chapter 2. We recommend that you read the sections on saving files and exiting Emacs. There's also a table of commands at the end of this chapter for future reference. If you'd like to learn more about working with files as well as some shortcuts, stay with us through the rest of the chapter.

1.7.1 If You Read the Wrong File

If you happen to read the wrong file, an easy way to get the right file is by typing C-x C-v (for find-alternate-file ). This command means "Read a different file instead of the one I just read." After typing C-x C-v , Emacs puts the name of the current file in the minibuffer; you can then correct a typo or the path , the most common reasons for finding the wrong file. Make the correction and press Enter . Emacs replaces the buffer's contents with the alternate file.

1.7.2 Letting Emacs Fill in the Blanks

Emacs has a very helpful feature known as completion. If you want an existing file, you need only type the first few letters of the name, enough to uniquely identify the filename. Press Tab , and Emacs completes the filename for you. For example, suppose you are trying to find a file called dickens .

Type: C-x C-f di

After C-x C-f , Emacs prompts you for the filename; type the first few letters.

Press: Tab

When you press Tab , Emacs fills in the rest of the filename.

Press: Enter

Emacs reads the file dickens .

{% if main.adsdop %}{% include 'adsenceinline.tpl' %}{% endif %}

If more than one file starts with di , Emacs displays a window with various files that start with that string. You select one by typing a few more characters (enough to identify your file as unique) and pressing Tab again. Or you can select one of the alternatives with the mouse or by pressing PgUp to move to the completions window, moving to the desired option, then pressing Enter .

Completion also works for long command names . It's a wonderful Emacs feature that can save you time -and show you some commands you might not know existed in the process. Chapter 14 provides more details on the glories of completion.

1.7.3 Inserting and Appending Files

If you want to insert one file into another, you simply move to the appropriate location in the file and type C-x i . (Yes, we know, we haven't told you how to move around in a file yet. Use the arrow keys for now and we'll teach you the "real" Emacs cursor movement commands in Chapter 2.) To append a file, move to the end of the file ( M-> ) and type C-x i . As with C-x C-f , Emacs prompts you for the filename in the minibuffer.

1.7.4 How Emacs Chooses a Default Directory

When you use any command that asks for a filename (such as C-x C-f ), Emacs displays a default directory in the minibuffer and asks you to type the rest of the filename. How does Emacs choose the default directory? The default directory is taken from the buffer that the cursor is currently in. If you are editing a file in your home directory when you type C-x C-f , Emacs assumes you want to edit another file in your home directory. If you are editing the file /sources/macros/html.macs then Emacs makes the default directory /sources/macros . If you want to find a file in another directory, edit the default directory that Emacs displays.