Difference between revisions of "Quick Tutorial"

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== ediff ==
 
== ediff ==
  
ediff (emacs-diff) is a mode for Emacs where you can view and merge difference between two or three buffers.
+
ediff (emacs-diff) is a mode for Emacs where you can view and merge differences between two or three buffers.
  
* ediffselect files to view their differences
+
; ediff        : select files to view their differences
* ediff-buffersselect buffers to view their differences
+
; ediff-buffers : select buffers to view their differences
  
In ediff-mode:
+
=== In ediff-mode ===
  
* switch between horizontal/vertical view
+
; | : switch between horizontal/vertical view
* ?view ediff help
+
; ?view ediff help
* pview previous difference
+
; pview previous difference
* nview next difference
+
; nview next difference
* aset buffer b’s area to what’s in a’s
+
; aset buffer b’s area to what’s in a’s
* bset buffer a’s area to what’s in b’s
+
; bset buffer a’s area to what’s in b’s
* qquit ediff session
+
; qquit ediff session
  
 
== Spell Checking ==
 
== Spell Checking ==

Revision as of 12:05, 19 April 2012

This reference-like tutorial is aimed at Emacs beginners and probably others too. If you know how to do some basic editing and navigation in Emacs and want to quickly go through more of its capabilities, then this tutorial is for you. If you are looking for the semantics or key-bindings of a specific feature, this tutorial aims to be for you since it is a subset of the online Emacs documentation. If you are giving an introductory presentation about Emacs, this tutorial might help you.

The repository for the contents of this tutorial can be found here: https://github.com/fredmorcos/emacs-reference

Description and History

  • Emacs is an extensible, customizable, self-documenting, real-time display text editor.
  • Originally, a set of editing macros for the TECO editor.
  • GNU Emacs was developed by R. Stallman and G. Steele.
  • Technically, GNU Emacs is an elisp interpreter with text editing extensions.
  • GNU Emacs contains thousands of commands and allows the user to combine them into elisp procedures (called macros) to automate work.
  • Commands are, themselves, elisp procedures and the GNU Emacs configuration init file is an elisp program.

Technical Description

Extensible 
The user can define, un-define and redefine commands as well as re-use available commands into macros.
Customizable 
The user can change properties of emacs elements including the key-bindings and the display.
Self-documenting 
All defined commands and macros get automatic preliminary documentation (bound keys and parameters).

Why Emacs?

  • Easily programmable
  • Kill ring
  • Rectangular editing
  • Registers
  • Command repetition
  • Macros and Lisp procedures
  • Modes
  • Init file
  • Remote files
  • Shell, Terminal Emulator, IRC, Email, News, File Manager, Process Manager, Project Manager, Tetris, Doctor and many others.

Terminology and Structure

Buffer 
A container for data (text, completions)
Point 
The current position in the buffer (cursor)
Window 
A visual container for a buffer
Frame 
A visual container for one or more windows
Kill 
The equivalent of cutting
Yank 
The equivalent of copying
Kill Ring 
A circular clipboard (very handy)
Mark 
The coordinates of a selection
Region 
The text inside a mark
Modeline 
A status line
Minibuffer 
A small buffer for commands and arguments
Mode 
The current type of data being edited

Modeline

The Modeline is used to report different pieces of information.

-cs:ch-fr  buf      pos line   (major minor)-----
cs 
Character set (or coding system)
Newline mode
ch 
File modification status
- or @ 
File is local or remote
fr 
Frame name on text terminals
buf 
Buffer/file name
pos 
Point/cursor position
line 
Current line and column number
modes (major minor) 
Currently loaded major and minor modes

Keybind Terms and Minibuffer

Emacs has some different naming of command/control keys (probably coming from the old days).

Meta key, Alt or ESC
Control key
Shift key
[M-a] 
Press a while holding the meta key
[C-M-a] 
Press a while holding the control and meta keys
[C-a b] 
Press a while holding the control key then press b
[C-a C-b] 
Press a and b both while holding the control key
[C-a M-b] 
Press a with control then b with meta

The Minibuffer is used to input commands, arguments and setting different modes (which some of are bound to keys or menu actions).

[M-x] 
Execute a command by name

Basic Usage

Loading

$ emacs # opens Emacs at the scratch buffer
$ emacs [file1] [file2] ... # opens Emacs in split-window mode
[C-x C-f] filename 
loads a new buffer from filename

Saving

[C-x C-s] 
saves the current buffer
[C-x C-w] filename 
saves the current buffer as filename

Other

[C-x C-c] 
quits emacs
[C-g C-g] 
cancels key-sequence

Windows

Windows are used to display buffer contents. Windows can be split and resized inside an Emacs frame. The minibuffer has its own window.

[C-x 2] 
open a window vertically
[C-x 3] 
open a window horizontally
[C-x 0] 
close the current window
[C-x 1] 
close all other windows
ESC ESC ESC 
close all other windows
[C-x o] 
move to another window
[C-x ^] 
increase window size vertically
[C-x ]
increase window size horizontally
[C-x {] 
decrease window size horizontally
[C-x -] 
shrink window to buffer size
[C-x +] 
make all windows equal in size

Navigation and Movement

Word

[C-←] 
moves one word backwards
[C-→] 
moves one word forward

Line

[C-a] 
goes to beginning of the line (Home)
[C-e] 
goes to end of the line (End)
[M-a] 
goes to beginning of the sentence
[M-e] 
goes to end of the sentence
[M-g g] 
goes to given line by number

Paragraph

[C-↑] 
moves up one paragraph
[C-↓] 
moves down one paragraph

Buffer

[C-x [] 
moves to the beginning of the buffer
[C-x ]] 
moves to the end of the buffer
[C-l] 
moves the buffer to position point
[C-x b] 
switches to another buffer by name
[C-x] 
switches to previous or next buffer
[C-x k] 
kills the current buffer

Editing

Character

[C-d] 
deletes next character
[C-t] 
transposes current character with previous one
[C-q TAB] 
inserts a TAB verbatim

Word

[M-d]  
kills the next word
[M-- M-d]  
kills to the previous word
[M-/]  
expands current word
[M-/ SPC M-/] 
expands current word and grabs next one
[M-C-/]  
completes current word
[M-t]  
transposes current word with next one
[M-- M-t]  
transposes current word with previous one
[M-c]  
capitalizes next word
[M-- M-c]  
capitalizes previous word
[M-l]  
lowercase next word
[M-- M-l]  
lowercase previous word
[M-u]  
uppercase next word
[M-- M-u]  
uppercase previous word

Line

[M-o M-s] 
center a line
[C-S-BACKSPC] 
kills current line
[C-k] 
kills from point to EOL
[M-u C-k] 
kills to the previous line
[C-a C-k] 
goes to BOL then kills to EOL
[TAB] 
indents line depending on current mode
[C-o] 
breaks line before/after point
[C-x C-t] 
transpose current line with previous one
[M-0 C-x] C-t 
transpose current line with one at mark
delete-matching-lines 
delete lines matching a regexp

Prefix Arguments and Command Repetition

Passing numerical arguments to commands can alter their behavior (e.g., repetition or inversion). Passing an argument can be done before M-x or key bindings.

[M-n com]  
run com with prefix arg n
[M-- com]  
run com with negative prefix arg
[C-u n com] 
run com with prefix arg n
[C-u com]  
run com with prefix arg 4 (the default)
[C-u C-u com]  
run com with prefix arg 16 (four times the four times the default)
[C-u C-u com]  
run com with prefix arg 64 (four times the four times the four times the default)
[C-u]  
also terminates the prefix argument
[C-x [z]+]  
repeats the previous zth command (including its args)
[C-x ESC ESC]  
repeats last command that used the minibuffer

Examples

[C-u 5 0 C-k] 
will kill 50 lines
[C-u 5 C-u 0] 
will insert 5 zeros

Search and Replace

Incremental search

[C-s keyword] 
search forward
[C-r keyword] 
search backward

Non-incremental search

[C-s RET keyword] 
search forward
[C-r RET keyword] 
search backward

Regular Expression Search

[C-M-s expression] 
search regexp forward
[C-M-r expression] 
search regexp backward

Notes

  • ESC will cancel and go to original point. RET will end at the current point.
  • Searches are case-insensitive unless an uppercase letter is found in the search string.
  • While searching, [C-w] will increment the search term with the current word.

Unconditional Replace

replace-string 
replaces a string with another
replace-regexp 
replaces a regexp match with a string

Query Replace (Conditional Replace)

[M-%] 
conditional replacement of a string
query-replace-regexp 
conditional replacement of a regular expression

Notes

  • Replaces are case-insensitive unless an uppercase letter is found in the match string.
  • Replaces work from position to end of buffer unless a mark is active.
  • After a replace, the position will be at the end of the last match. [C-u C-SPC] to go back to the position before the replace started.
  • During a query replace, SPC will apply a replace and DEL will skip.

Undo and Redo

In Emacs, there is no special redo function. Instead, there is only an undo function and redo can be achieved by undo-ing an undo.

[C-/] 
undo a single change
[C-g] 
break the chain of undos

Notes

  • If a mark is active, undo will only affect the marked region.

Regions

Emacs uses the mark and point to denote a region (i.e., a selection).

[C-SPC]  
creates a region (marks area)
[C-x C-x]  
swaps mark and point in a region
[C-u C-x C-x] 
swaps mark and point without region
[C-x h]  
marks the entire buffer
[M-h]  
marks the paragraph around the point
[TAB]  
indents the current region
[M-@]  
incrementally mark next word

Kill, Yank and Paste Regions

[C-w]  
kills the currently selected region
[M-w]  
copies the currently selected region
[C-y] ([M-y])* 
yanks and cycles from the kill ring

Notes

  • Yank is the copy command in vi and the paste command in emacs.

Rectangles

Rectangles are marked regions between the columns of the point and the mark. Applying operations on rectangles is some sort of vertical editing.

[C-x r k] 
kill the rectangle
[C-x r d] 
delete the rectangle
[C-x r y] 
yank the last killed rectangle
[C-x r o] 
push text to fill rectangle with spaces (open)
[C-x r c] 
replace rectangle text with spaces (clear)
[C-x r t] 
replace each line in rectangle with text

Registers

Registers are places where you can store anything: text, position, rectangle, configuration, filename, etc... Registers are named with single character symbols: a, A and 3 are three different registers.

view-register  
view the contents of a register
[C-x r SPC r]  
record current point position in register r
[C-x r j r]  
jump to position in register r
[C-x r s r]  
save region to register r
[C-u C-x r s r] 
kill region to register r
[C-x r i r]  
insert text from register r
append-to-register  
append region to register
prepend-to-register  
prepend region to register
[C-x r r r]  
save rectangle into register r

Bookmarks

Bookmarks are like registers but persistent. They can also be named.

[C-x r m foo] 
bookmark file and point to foo
[C-x r b foo] 
jump to bookmark called foo
[C-x r l]  
list all bookmarks
bookmark-save  
save all bookmarks
bookmark-delete  
delete a bookmark

Macros

Macros are user defined commands using the Emacs command language. A user can “record” and “replay” a macro, useful for simple repeatable tasks. More complex tasks (e.g., conditions, loops) must be implemented in elisp. Macros are recorded in a macro ring.

  • F3start macro definition or insert counter
  • [C-x (] start macro definition only
  • F4end macro definition or call macro
  • [C-x e] end macro definition and call macro
  • [C-x )] end macro definition only
  • C-u C-u F3 append commands to last macro
  • [C-u F3] re-run last macro then append commands to it
  • [C-x C-k r] run macro on region
  • [C-x C-k C-n] rotate to select the next macro in the ring
  • [C-x C-k C-p] rotate to select the previous macro in the ring

Every macro definition can have a counter to insert into the buffer.

  • F3inside a macro definition, inserts the counter
  • [C-x C-k C-i] outside a macro definition, inserts the counter
  • [C-x C-k C-c] set the macro counter value
  • [C-x C-k C-f] set the macro counter format

Macros can be named and saved.

  • [C-x C-k n] name the most recently defined macro
  • [C-x C-k b] keybind the most recently defined macro
  • insert-kbd-macroinsert macro into buffer as elisp code

Notes:

  • It is best to use the reserved key bindings [C-x C-k] [a-zA-Z0-9] as to not cause problems with other bindings. [C-x C-k] b 4 will define [C-x C-k] 4 as a binding.

Alignment

Emacs contains alignment commands. Sometimes those depend on the current mode (i.e., the language).

  • alignaligns depending on mode
  • align-regexpaligns using a regular expression
  • [C-u] align-regexpaligns using a regular expression helper
  • align-currentaligns current paragraph depending on mode

Sorting

When sorting, prefixing with [C-u] sorts in descending order.

  • sort-linessort region by lines
  • sort-paragraphssort region by paragraphs
  • [C-u] n sort-fieldssort lines in region by $ \textit{\underline{n}}^{th} $ field
  • [C-u] -n sort-fieldssort lines in region by $ \textit{\underline{n}}^{th} $ field from right
  • sort-numeric-fieldsinterpret field as number and not text
  • sort-columnssort by column specified by marked region
  • reverse-regionreverses current region

Tables

Emacs has support for creating and editing text-based tables by keeping track of their properties (e.g., position, size) in the buffer. When a buffer is saved to file, those properties are lost.

  • table-insertinteractively insert a table into buffer
  • table-recognizedetect properties of all tables in the buffer
  • table-unrecognizeremove special table properties
  • table-recognize-regiondetect properties of tables in region
  • table-unrecognize-regionforget properties of tables in region
  • table-recognize-tabledetect properties of table at point
  • table-unrecognize-tableremove properties of table at point

Cell resizing:

  • C-u n C-widen cell at point by n characters
  • C-u n C-narrow cell at point by n characters
  • C-u n C-}heighten cell at point by n lines
  • C-u n C-{shorten cell at point by n lines

Cell movement:

  • TABmove to cell on right
  • S-TABmove to cell on left

Cell merging/splitting:

  • [C-c C-c] *interactively merge two cells
  • C-split cell horizontally
  • C--split cell vertically

Rows & Columns:

  • C-u n table-insert-rowinsert n rows
  • C-u n table-delete-rowdelete n rows
  • C-u n table-insert-columninsert n columns
  • C-u n table-delete-columndelete n columns

Other:

  • C-:interactively justify cell, column or row text
  • C-!toggle table fixed width mode
  • table-generate-sourcetable code in Latex, HTML or Cals

Goodies

  • C-x TABforce an indentation on a region
  • [M-q] indents and breaks paragraph into multiple lines
  • [M-;] comments a region or adds comment to line
  • [M-(] inserts a new lisp function (parenthesis)
  • [M-)] checks balanced parenthesis and opens line
  • [C-x] iinserts file contents at point position
  • [M-!] run shell command
  • C-u M-!run shell command and insert output
  • M-$ | $run shell command on marked region
  • C-u M-$ | $run shell command on and replace marked region
  • insert-bufferinserts buffer contents at point position
  • copy-to-buffercopy region content to a buffer
  • kill-some-buffersinteractively kill buffers
  • electric-buffer-listinteractive buffer list
  • toggle-truncate-linesdo not split lines over visual lines
  • visual-line-modesplit lines by words
  • viper-modevi compatibility

Setting Key Bindings

Emacs has a global keymap which maps between keys and commands. Each major mode can define, redefine or undefine its own key bindings, creating a local keymap (e.g., c-mode). Each minor mode can do so too (e.g., flymake). Each portion of text can also do so (e.g., tables).

Description of some prefix keys:

  • C-xcommand prefix key
  • M-command prefix key
  • C-cmode specific prefix key
  • C-hhelp prefix key

Commands to bind keys:

  • global-set-key k combind key k to com globally
  • local-set-key k combind key k to com locally (major mode)

Notes:

  • Menu and mouse key bindings can also be set.

Storing Key Bindings

In the Emacs init file, you can either set global key bindings or “hook” local key bindings to mode hooks (i.e., callbacks, slots).

  • global-set-keyadds a binding to the global map
  • local-set-keyadds a binding to the local (major mode) map
  • kbdconverts a string to a key sequence

Examples:

Global key binding:

  • (global-set-key (kbd "C-c d") ’duplicate-line)
  • (global-set-key (kbd "C-c d") (kbd "C-a C-@ C-e M-w RET C-y"))
  • (global-set-key (kbd "C-c d") "\C-a\C- \C-n\M-w\C-y")

Local key binding:

  • (add-hook ’LaTeX-mode-hook

    (lambda () (local-set-key (kbd "C-c n")
                              ’forward-paragraph)))

The Emacs Help System

Emacs has a handy help system for quick lookup of various features, topics, functions and key bindings.

  • [C-h ?] show the help system shortcuts
  • C-h keyrun help system with shortcut key

Some useful help keys:

  • [C-h a] show apropos page about a keyword
  • [C-h k] keybindshow help for function bound to keybind
  • [C-h b] show all key bindings
  • [C-h f] show documentation for function
  • [C-h m] show documentation for current modes
  • [C-h v] show documentation for variable
  • [C-h w] show what keys a command is bound to
  • [C-h t] start the emacs tutorial
  • prefix C-hshow all key binds starting with prefix

Modes

Modes are used to define the type of data being edited in buffers, or what Emacs calls “the language”.

Every buffer has exactly one major mode which defines its language (C, Java, English, IRC, etc...) and provides basic elements like syntax highlighting and (re)defines functions and their key bindings for relevant actions (e.g., comments).

Each buffer can have zero or more minor modes enabled which provide non-specific functionality such as spell checking or line wrapping (i.e., mode independent).

ediff

ediff (emacs-diff) is a mode for Emacs where you can view and merge differences between two or three buffers.

ediff  
select files to view their differences
ediff-buffers 
select buffers to view their differences

In ediff-mode

switch between horizontal/vertical view
 ?view ediff help
pview previous difference
nview next difference
aset buffer b’s area to what’s in a’s
bset buffer a’s area to what’s in b’s
qquit ediff session

Spell Checking

[M-$] 
check spelling at word or active region
ispell  
check active region or buffer, during which pressing i will accept the current word and insert it into the user's dictionary, pressing ? will show help and pressing RET will end the current ispell session.
[ESC TAB]  
complete current word from dictionary
flyspell-mode  
enable “on the fly” spell checking
flyspell-prog-mode  
spell check comments and strings (programming mode)

References