Glossary

abbrev mode

A mode in which you define abbreviations that are automatically replaced when you type them. You might define abbreviations for phrases, long words, or common misspellings. Emacs's abbreviation facility, also found in vi, is similar to, but significantly predates, features like auto-text in Microsoft Word. For more information on abbrev mode, see Chapter 3.

ange-ftp mode

An easy-to-use interface to the file transfer protocol (FTP) written by Andy Norman. You use the find-file command to find files and directories on the Internet or other networks just as if they were on the local system. To specify a remote file, type /user@systemname:/pathtofile/filename. The slash at the beginning and the colon between the system name and path are easy to forget, and ange-ftp mode won't work without them. If you omit the path and filename, Emacs uses Dired to display the top directory on the remote system. Rather than using FTP commands to retrieve files, you can display them or copy them using Dired commands. Ange-ftp mode, then, is useful for looking at files as well as downloading them. As of Emacs 19.29, ange-ftp mode is included in the Emacs distribution.

auto-fill mode

A minor mode in which Emacs does word wrap. When you reach the end of a line and auto-fill mode is on, you can keep typing and Emacs puts in RETURNs appropriately. Auto-fill mode is off by default.

auto-save file (#file#)

Emacs periodically saves your buffer in a temporary file called an auto-save file. Emacs also saves files in an auto-save file if a session is terminated abnormally. For example, if you are working on a file called budget and the system goes down, look for an auto-save file called #budget# when the system is back up. For more information on auto-save files, see Chapter 2.

backup file (file ~)

When you tell Emacs to save a file, it first copies the current version to a file of the same name followed by a tilde (~). For example, if you save the file budget, Emacs moves the previous version to budget~. If you later decide you don't want the changes you saved, you can use the backup file. For more information on backup files, see Chapter 2.

body

1. A mail message is divided into a header (the information that designates who the message is for and who the message is from) and the content of the message, called the body. 2. In outline mode, there are headers (the skeleton of the outline) and paragraphs of text, which form the body.

bookmark

A named location in a file. Finding a file always brings you to the beginning; moving to a bookmark opens the file and brings you to a particular location. Bookmarks are helpful for marking places in online documentation and other files you read or refer to as well as for specifying where you left off when working on a file. For more information on bookmarks, see Chapter 4.

browser

1. A program that allows users to access the World Wide Web. There are graphical browsers, such as Mosaic and Netscape, and text-based browsers such as Lynx and W3 mode. 2. A reader for information in a given format. Info mode serves as a browser for documentation in Info format.

buffer

The work area on the screen in which Emacs displays a copy of a file or a blank area in which you can type. When you edit a file, Emacs copies the file into a buffer of the same name; the file on disk remains unchanged. When you save a buffer, Emacs copies the changes you have made into the file on disk. In addition to buffers for working with files, Emacs creates its own specialized buffers for processes such as reading and editing mail, for working with the UNIX shell, and for using the calendar feature, for example.

byte-compile

A method for compiling Emacs LISP files, whose names end in .el. After you byte-compile a file, its name ends in .elc. Byte-compiling Emacs LISP functions makes them load and run more efficiently.

calendar

An Emacs facility that allows users to work with a calendar. When you type ESC x calendar, Emacs displays a three-month calendar at the bottom of the screen with the cursor on the current date. You can mark dates with diary entries and view holidays from the calendar. For more information about the calendar, see Chapter 5.

clipboard

See kill ring.

comment

Text that is ignored by a programming language or text formatting program. Emacs inserts comment syntax appropriate for the mode you are in when you type ESC ;. In some general modes, such as text mode and fundamental mode, there is no comment syntax defined.

completion

A shortcut feature that allows you to type the first few letters of a command, variable, or filename and press TAB. Emacs either completes it (if it's unique) or lists possibilities in a *Help* buffer.

copyleft

An agreement that software should be shared freely with others and that those others in turn must be able to share it. A copyright restricts usage of information whereas a copyleft is designed to guarantee its continued free availability to all, as stated in the Free Software Foundation's own terms in Appendix F. The term copyleft is also used to refer to the GNU General Public License.

cursor

The cursor indicates where you are in the buffer. Sometimes Emacs refers to the cursor as point. Technically, point is located between two characters: the cursor and the previous character.

customization

By default, Emacs behaves in a given way. Through customization you tailor that behavior to your needs and preferences. You customize Emacs using the .emacs file. Customization is discussed in detail in Chapter 11.

cut

To kill text so that it can later be pasted.

default

The normal value for a variable or option. For example, by default, auto-fill mode is not turned on.

default direction

Normally when you type, text appears from left to right. In picture mode, it's possible to move in eight different directions. When you start picture mode, the default direction is right. You can specify a different direction, like up, down, northwest, southeast, and so on, which then becomes the default direction. C-c C-f to move forward and C-c C-b to move backwards are relative to the default direction.

delete

To omit text and not store it in the kill ring for later retrieval.

diary

An Emacs feature that allows you to make notes about certain dates. Emacs then displays a reminder on the date you've marked. Diary entries can be set for a given date, a block of dates or periodically (biweekly, for example). For more information on the diary, see Chapter 5.

digest

A group of electronic mail messages sent as a single message for convenience. Messages from mailing lists are often sent in digest form. If you read mail with RMAIL, the command ESC x undigestify-rmail-message breaks the digest into individual messages. In Gnus, you can type C-d to expand a digest that arrived as a newsgroup article.

Dired

The directory editor. Using Dired, you can perform various operations on files and directories, such as moving, compressing, deleting, copying, and byte-compiling. For more information on Dired, see Chapter 5.

dot

Synonymous with the cursor position or point. You might see the term dot in the Emacs online help system.

.emacs file

The initialization file where you change Emacs default behavior. The commands in this file run when you start Emacs. However, Emacs does not need this file in order to run. Throughout the book, we suggest lines you can add to your .emacs file to change some aspect of Emacs behavior.

email

Electronic mail. Emacs has its own mail-reading facility called RMAIL and its own mailer called sendmail (not to be confused with the UNIX sendmail program). These features are discussed in Chapter 6. Emacs also has interfaces to the MH and vm mailers. The mh interface is discussed in MH & xmh: Email for Users and Programmers by Jerry Peek.

file

A storage area on disk. When you find a file in Emacs, it copies the file into a buffer, a working area on the screen. When you save changes, Emacs copies the changes in the current buffer and overwrites the file on disk.

fill prefix

In text mode and auto-fill mode, a fill prefix is a string of characters you define that Emacs inserts at the beginning of each line of a paragraph. Fill prefixes could be a string of spaces (this is an easy way to indent text) or a simple greater-than sign (>), often used in email to differentiate text being quoted from a previous message.

flow control

A method terminals use for communicating with a host computer. Some terminals send C-s to mean stop receiving input and C-q to mean start receiving again. C-s and C-q have common uses in Emacs. If C-s is used as a flow control character, the terminal will freeze when you type an Emacs command that includes C-s. If you type ESC x enable-flow-control, you can then type C-\ in place of C-s, and C-^ in place of C-q in Emacs commands. For more information on flow control, see Chapter 11.

formfeed

A control character, typically ^L, that tells the printer to start a new page. To put a formfeed in an Emacs file, type C-q C-l.

frame

An X window in which an Emacs buffer is displayed. By default, X Window System users have one frame, but they can have a number of X windows for a single Emacs session. When there is one frame, the system's name appears as the title. When there are multiple frames, the frames are titled by buffer name. For more information on windows and frames, see Chapter 4. (It is possible to use frames on character terminals, but they are arguably more useful for windowed interfaces.)

global abbreviations

Abbreviations you have defined that work in every major mode. By contrast, local abbreviations work only in the mode in which you define them. Global abbreviations, then, are good when you always want Emacs to make automatic replacements; local abbreviations are good for replacements you want in text mode, for example, but not in C mode. For more information on abbreviations, see Chapter 3.

GNU

An acronym for "GNU's Not UNIX."

Gnus

A newsreader included in GNU Emacs 19. Gnus allows Emacs users to read and post Usenet news without leaving Emacs.

header

1. The beginning of a file, such as a L_AT_EX file, that defines certain characteristics about the document's format. 2. In electronic mail, the header of a mail message specifies the sender, the recipient(s), and the time the mail was sent, among other things. 3. Version control information embedded in a file that is automatically updated at check-in, check-out, and revert time.

home directory

Your personal directory. On a UNIX system, often /home/username.

home page

1. The default page you see when you start a World Wide Web browser. 2. The first page a user sees at a given World Wide Web site (as in "Web Review's home page is always interesting.").

hotlink

Another term for hyperlink.

hotlist

A hyperlinked list of a user's favorite places to visit on the World Wide Web.

hyperlink

A link, in text or in a graphic, to a local or remote resource. Selecting a hyperlink takes you to the designated resource.

Hypertext Markup Language (HTML)

An ASCII markup language for creating documents formatted for the World Wide Web. You use a viewer, called a browser, to look at HTML files, also known as Web pages.

incremental search

A search that Emacs launches as soon as you type the first character of the search string.

initialization file

See .emacs file

kill

To delete and store in the kill ring.

kill file

A file read by a newsreader, such as Gnus, that screens out messages based on user-defined criteria. For example, a kill file can screen out messages posted by certain users or on certain subjects.

kill ring

The area where Emacs holds deletions. By default, the kill ring holds the last 30 deletions or kills. Note that some deletion commands (such as C-d to delete a character) do not store deleted text in the kill ring; see Chapter 2 for details.

local abbreviations

Abbreviations you have defined that are specific to (or "local to") a given mode. You might want different abbreviations in text mode and in C mode, for example. For more information on abbreviations, see Chapter 3.

macros

A group of recorded keystrokes or mouse movements, designed to reduce repetitive work. For information on creating macros, see Chapter 10.

major mode

Emacs's way of adapting its behavior to the primary task at hand. Text mode is a major mode designed for writing text; C mode is for writing C programs. Different modes have different commands that make sense in that mode, in addition to global commands that work in every mode.

mark

A secondary pointer that, along with the cursor, is used to define the boundaries of a region. Regions can be deleted, moved, or copied. In GNU Emacs, the mark is not displayed.

markup

Formatting codes that tell a text formatter to print or display text in a certain way. T_EX and troff are examples of text formatting programs that take ASCII files containing markup and produce output similar to typesetting. HTML files are displayed through a browser that formats them on-screen.

minibuffer

An area at the bottom of the screen into which the user enters certain information. For example, when you write a file by typing C-x C-w, Emacs asks for the filename in the minibuffer. Emacs also displays messages in this area.

minor mode

Features that can be turned on and off independent of the major mode you are in. Auto-fill mode, which does word wrap automatically, is a minor mode.

mode

Emacs' way of adapting its behavior to the task at hand. There are major modes, that define the primary task at hand, and minor modes, options that you turn on and off within a major mode. For example, text mode is a major mode; auto-fill mode, which enables word wrap, is a minor mode.

mode line

The last line of an Emacs window, often displayed in reverse video or in another color. The mode line tells what buffer you are editing, the major and minor modes you have turned on, and where you are in the buffer. Optionally, the mode line provides other information, such as the time of day.

Mosaic

The first graphical Web browser, which was created by the National Center for Supercomputing Applications at the University of Illinois, Urbana-Champaign. A number of commercially available browsers are based on Mosaic. Netscape was created by many of the original Mosaic developers.

output groups

In shell mode, an output group comprises a shell command and its output. An output group provides a convenient way to move between commands in shell mode, since the output of any given command may be several screens long.

overwrite mode

A minor mode that allows users to type over existing text. To start overwrite mode, type ESC x overwrite-mode RETURN.

paragraph formatting

See auto-fill mode.

paste

To reinsert text that has been deleted or killed. The Emacs term for paste is yank.

pause

A macro feature that stops a macro temporarily to allow user input. The user then restarts the macro by typing ESC C-c. For more information, see Chapter 10.

picture mode

A major mode designed for creating simple drawings using keyboard characters. See Chapter 8 for more information.

point

The cursor position. To be precise, point is considered to be between the character under the cursor and the previous character. In practice, you can usually consider the cursor and point synonymous. Knowing precisely where point is, however, can help you understand the workings of certain commands better (such as yanking or transposition commands). Additionally, every buffer has a point (a current location), whereas the cursor can only be in one buffer at a time.

query

A macro feature that allows the user to decide whether to continue a macro or to stop it.

query-replace

A search and replacement feature that allows users to decide, on a case-by-case basis, whether a given replacement should be done.

read-only

A file or buffer that can be viewed but not modified. However, you can copy text from a read-only buffer and paste it into another buffer.

read-write

A file or buffer that can be viewed (read) and changed (written to).

rectangle editing

Using rectangles, you can rearrange and edit columns of information. For more information on using rectangles, see Chapter 8.

region

The area between the cursor (also called point) and the mark. Regions can be deleted, moved, or copied. The region currently defined is highlighted on some displays. If it isn't, you can press C-x C-x (for exchange-point-and-mark) to see the region's boundaries.

registers

Areas in which you store rectangles or text. Similar to the kill ring, but registers are given single-character names for easy (and often repeated) retrieval of information.

regular expression

A UNIX feature that allows sophisticated and flexible matching of strings. Emacs supports regular expression searches and regular expression replacement. See Chapter 3 for a table that lists characters used in building regular expressions and Chapter 13 for a more in-depth treatment of regular expressions.

RMAIL

The Emacs mail-reading facility.

rot13

A simple text-scrambling routine used to encrypt potentially offensive messages. It can be decoded by anyone who has rot13. Gnus supports encrypting and decrypting rot13 files.

search and replace

See query-replace.

search string

In a search, the text that is being searched for.

setup file

See .emacs file.

shell buffer

An Emacs-created buffer that runs a UNIX shell, allowing you to use Emacs editing commands and features, such as completion, while interacting with UNIX. To start a shell buffer, type ESC x shell.

Telnet mode

An Emacs interface to Telnet, a protocol by which users can log onto and use other computers on a local network or on the Internet.

uniform resource locator (URL)

Often abbreviated URL, a uniform resource locator is the address of an Internet resource. The format for URLs is typically protocol://resourcename. For example, a World Wide Web URL looks like this: http://www.ora.com. An FTP archive looks like this: ftp://ftp.ora.com. Preceding the slashes is the protocol (for example, FTP) that the Web should use to access the resource. Following the slashes is the resource's name, which can be very general (www.oreilly.com, a general name for O'Reilly & Associates Web site) or more specific, as in the URL for the page for oreilly.com catalog, http://www.oreilly.com/catalog.

variable

Emacs provides hundreds of features that you can tailor by setting variables. You can set variables for a single session by typing ESC x set-variable variablename or permanently using the .emacs file. For more information on variables, see Chapter 11.

W3

A World Wide Web browser for Emacs by William Perry. Although not a part of the standard Emacs distribution, W3 provides an excellent way to integrate World Wide Web access with Emacs usage. W3 shares hotlists and history files with Mosaic.

wastebasket

See kill ring.

window

An area of the screen in which a buffer is displayed. By default, Emacs has one window. Many features, including help, automatically break the screen into two windows. You can set up horizontal windows (the most frequently used kind) and vertical or side-by-side windows. It is possible to have multiple windows on one buffer. X users can have multiple X windows. To avoid confusion, multiple X windows are called frames.

word search

A search facility that ignores line breaks and punctuation. If you can't find some text that you know is there with other searches, such as incremental-search, chances are there is a line break that incremental-search interprets as a character. Try word search instead.

word wrap

See auto-fill mode.

World Wide Web

A hypertext-based Internet information service that allows users to access many Internet resources without needing to know how to use individual Internet applications, such as FTP. Users select hyperlinks to navigate the World Wide Web. Tim Berners-Lee created the World Wide Web at the European Particle Physics Laboratory (CERN) in Geneva, Switzerland.

yank

Paste text that has been cut or killed.