Emacs

There are many different text editors available for Unix computers.

You can have multiple editors on one system

vi - old, reliable, present on every Unix machine, completely and utterly user hostile

jed - fairly simple

pico - extremely simple, perhaps too simple

emacs - a good compromise between features and ease of use

The full name of the Emacs program is: "GNU macs, the Extensible, Customizable, Self-Documenting, Real-time Display Editor.

•Emacs is free software produced by the Free Software Foundation (Boston, MA) and distributed under the GNU General Public License.

–Open source software - Linux

–GNU is an acronym for: “GNU is Not Unix”

Editors are used to create files of text and to modify their contents

You need an editor for sending email, writing programs and many other tasks

•There are many different editors - vi, ed and emacsare common UNIX examples

•There are different styles of editor - e.g. line editors and WYSIWYG editors

•They are not the same as word processors which are concerned with printed documents

Emacs is a text editor that dates back from 1976, and comes from the name "Editor MACroS".

It was originally written to encompass a whole bunch of text editors with different command sets and keyboard commands.

That's right, Emacs in the strictest sense of the word is just a text editor, from the same vein as Notepad, vi, and PICO.

Emacs differs from other editors in at least two major ways:

1.It has tight integration with the command shell, so if set up properly, it can run nearly any program accessible via direct access to the command shell.

2.It is extensible (and changeable) -- you can write packages in Lisp to extend the capabilities of the program.

•To start Emacs, at the > command prompt, just type:emacs
•To use Emacs to edit a file, type:

emacs filename

(where filename is the name of your file)

•When Emacs is launched, it opens either a blank text window or a window containing the text of an existing file.

•The display in Emacs is divided into three basic areas.

The top area is called the text ‘edit’ window. The text window takes up most of the screen, and is where the document being edited appears.

•Below the text window, there is a single mode ‘status’ line (in reverse type). The mode line gives information about the document, and about the Emacs session.

•The bottom line of the Emacs display is called the minibuffer. The minibuffer holds space for commands that you give to Emacs, and displays status information.

•Emacs uses Control and Escape characters to distinguish editor commands from text to be inserted in the buffer.

Control-x means to hold down the control key, and type the letter x

(You don't need to capitalize the x, or any other control character)

[ESCAPE] x means to press the escape key down, release it, and then type x

•Your current position in the file is shown by the cursor

•Most basic movement is one character or line at a time

–use the arrow keys or

•[Ctrl]-b backward (left) one character

•[Ctrl]-f forward (right) one character

•[Ctrl]-p previous line (up one character)

•[Ctrl]-n next line (down one character)

•Scrolling happens as necessary

•Can also move in steps of a word, sentence, paragraphs and screen

•[Esc]-f forwards one word

•[Esc]-b backwards one word

•[Ctrl]-a start of current line

•[Ctrl]-e end of current line

•[Esc]-a start of current sentence

•[Esc]-e end of current sentence

•[Ctrl]-v scroll down one screen

•[Esc]-v scroll up one screen

•[Esc]< move to start of file

•[Esc]> move to end of file

•[Ctrl]-l refreshes the screen (e.g. to remove system messages)

•To insert text, position the cursor and type

•Type RETURN to enter a new line, otherwise the line will wrap around

•DEL deletes the character before the cursor and [Ctrl]-d the character after the cursor. Hold down for repeated operation

•[Esc]del and [Esc]d deletes whole words

•[Ctrl]-k deletes from cursor to end of line. A further [Ctrl]-k deletes the new line character

•Mark and then delete a whole area:

–[Ctrl]-SPACE at start and move cursor to end

–[Ctrl]-w to delete the marked out region

•Commands that remove more than one character at a time save the text. It can be yanked back with [Ctrl]-y

–Another [Ctrl]-y to yank back another copy

–[Esc]y to yank back next previously deleted text

•Can use [Ctrl]-w and [Ctrl]-y to move text around

•Need to be able to load and save files

•[Ctrl]-x [Ctrl]-f finds and loads a file

•Prompts for the pathname in the minibuffer

•Type the name and press RETURN

•Use TAB for filename completion

•File is either loaded or created

•Changes made on screen are not immediately made to the file, they are made to a copy called the buffer

•Have to explicitly write them back by saving, [Ctrl]-x s (all files) [Ctrl]-x [Ctrl]-s (current file) (answer y and n to prompts)

•Can have more than one file open at a time. [Ctrl]-x f also switches between buffers

•[Ctrl]-x b swaps to the previous buffer

•Save frequently - work will be lost if emacs or the system crashes

•A buffer is best described as a temporary file that holds changes you make to a saved file on disk.

•When you save the file, Emacs overwrites the file with the contents of the buffer. So, when you open a file in Emacs, you are actually opening a buffer that holds the changes.

•You can revert to a saved version of a buffer by choosing "Revert Buffer" from the "Files" menu. This discards any changes since the last save.

•[Ctrl]-x u undoes the previous commands

•Repeating [Ctrl]-x u takes you further back through the editing history

•Need to search for text in a large file

•Incremental search

–type [Esc] x

–enter command isearch-forward or isearch-backwards in the minibuffer (use TAB for command completion)

–enter search string at the prompt and note how Emacs homes in and wraps around end of file

–you can delete the last character in the search string

–[Ctrl]-s (search forwards) and [Ctrl]-r (backwards) may work instead and [Ctrl]-g to quit at any time

•Change all occurrences of one string of text with another

–type [Esc]x

–enter query-replace

–enter search and target strings

–type y or n at each prompt

–use replace-string to avoid the prompting

•[Esc]x then spell-buffer for the spell checker

•Can divide the edit window into smaller sub-windows, each with a different document

•[Ctrl]-x 2 split horizontally

•[Ctrl]-x 3 split vertically

•[Ctrl]-x 1 make current window the full window

•[Ctrl]-x o move cursor to the next window

•Modes configure Emacs for different kinds of editing, controlling wrap-around and indenting

–[Esc]x then mode name

–fundamental mode

–text-mode (gives automatic text wrapping)

–C++ mode

•May guess mode from the filename suffix

•A keyboard macro is a command defined by the user to abbreviate a sequence of keys.

–For example, if you discover that you are about to type a particular command 100 times, you can speed your work by defining a keyboard macro with that particular command and calling the macro with a repeat count of 100. The following construction is used:

1.[Ctrl]-x ( your command [Ctrl]-x).................defines macro

2.[Ctrl]-u 100 [Ctrl]-x e ....................................executes the macro 100 times

•[Ctrl]-h for top level help menu

•[Ctrl]-h [Ctrl]-h to find out what each menu option means

•[Ctrl]-h t for the on-line tutorial