Difference between revisions of "Quick Tutorial"

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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.
 
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 https://github.com/fredmorcos/emacs-reference]
 
  
 
== Description and History ==
 
== Description and History ==
Line 32: Line 30:
  
 
== Terminology and Structure ==
 
== Terminology and Structure ==
 +
 +
{{details|Emacs Terminology}}
  
 
; Buffer : A container for data (text, completions)
 
; Buffer : A container for data (text, completions)
Line 108: Line 108:
 
; {{Keys|C-x o}} : move to another window
 
; {{Keys|C-x o}} : move to another window
 
; {{Keys|C-x ^}} : increase window size vertically
 
; {{Keys|C-x ^}} : increase window size vertically
; {{Keys|C-x }}} : increase window size horizontally
+
; {{Keys|C-x } }} : increase window size horizontally
 
; {{Keys|C-x {}} : decrease window size horizontally
 
; {{Keys|C-x {}} : decrease window size horizontally
 
; {{Keys|C-x -}} : shrink window to buffer size
 
; {{Keys|C-x -}} : shrink window to buffer size
Line 127: Line 127:
 
; {{Keys|M-e}} : goes to end of the sentence
 
; {{Keys|M-e}} : goes to end of the sentence
 
; {{Keys|M-g g}} : goes to given line by number
 
; {{Keys|M-g g}} : goes to given line by number
 +
; {{Keys|M-m}} : moves point to the first non-whitespace character in this line
  
 
=== Paragraph ===
 
=== Paragraph ===
Line 132: Line 133:
 
; {{Keys|C-↑}} : moves up one paragraph
 
; {{Keys|C-↑}} : moves up one paragraph
 
; {{Keys|C-↓}} : moves down one paragraph
 
; {{Keys|C-↓}} : moves down one paragraph
 +
 +
=== Window ===
 +
; {{Keys|M-0 M-r}} : moves to the top of window
 +
; {{Keys|M-r}} : moves to the middle of window
 +
; {{Keys|M-- M-r}} : moves to the bottom of window
  
 
=== Buffer ===
 
=== Buffer ===
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; {{Keys|C-l}} : moves the buffer to position point
 
; {{Keys|C-l}} : moves the buffer to position point
 
; {{Keys|C-x b}} : switches to another buffer by name
 
; {{Keys|C-x b}} : switches to another buffer by name
; {{Keys|C-x}} : switches to previous or next buffer
+
; {{Keys|C-x ←}} or {{Keys|C-x →}} : switches to previous or next buffer
 
; {{Keys|C-x k}} : kills the current buffer
 
; {{Keys|C-x k}} : kills the current buffer
  
Line 179: Line 185:
 
; delete-matching-lines : delete lines matching a regexp
 
; delete-matching-lines : delete lines matching a regexp
  
== Prefix Arguments & Command Repetition ==
+
== 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.
 
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''
+
; {{Keys|M-''n'' ''com''}}  : run ''com'' with prefix arg ''n''
* {{Keys|M--}} ''com''run ''com'' with negative prefix arg
+
; {{Keys|M-- ''com''}}      : run ''com'' with negative prefix arg
* {{Keys|C-u}} ''n'' ''com''run ''com'' with prefix arg ''n''
+
; {{Keys|C-u ''n'' ''com''}} : run ''com'' with prefix arg ''n''
* {{Keys|C-u}} ''com''run ''com'' with prefix arg 4
+
; {{Keys|C-u ''com''}}      : run ''com'' with prefix arg 4 (the default)
* {{Keys|C-u C-u}} ''com''run ''com'' with prefix arg 8
+
; {{Keys|C-u C-u ''com''}}   : run ''com'' with prefix arg 16 (four times the four times the default)
* {{Keys|C-u}} also terminates the prefix argument
+
; {{Keys|C-u C-u C-u ''com''}}  : run ''com'' with prefix arg 64 (four times the four times the four times the default)
* C-x [z]+repeats the previous <math>z^{th}</math> command with args
+
; {{Keys|C-u}}               : also terminates the prefix argument
* C-x ESC ESCrepeats last command that uses the minibuffer
+
; {{Keys|C-x [z]+}}          : repeats the previous z''th'' command (including its args)
 +
; {{Keys|C-x ESC ESC}}      : repeats last command that used the minibuffer
  
Examples:
+
=== Examples ===
  
* C-u 5 0 C-kwill kill 50 lines
+
; {{Keys|C-u 5 0 C-k}} : will kill 50 lines
* C-u 5 C-u 0will insert 5 zeros
+
; {{Keys|C-u 5 C-u 0}} : will insert 5 zeros
  
== Search &amp; Replace ==
+
== Search and Replace ==
  
Incremental search
+
=== Incremental search ===
  
* {{Keys|C-s}} <math>keyword</math>search forward
+
{{Details|Incremental Search}}
* {{Keys|C-r}} <math>keyword</math>search backward
 
  
Non-incremental search
+
; {{Keys|C-s keyword}} : search forward
 +
; {{Keys|C-r keyword}} : search backward
  
* C-s RET <math>keyword</math>search forward
+
=== Non-incremental search ===
* C-r RET <math>keyword</math>search backward
 
  
Regular Expression Search
+
; {{Keys|C-s RET keyword}} : search forward
 +
; {{Keys|C-r RET keyword}} : search backward
  
* {{Keys|C-M-s}} <math>expression</math>search regexp forward
+
=== Regular Expression Search ===
* {{Keys|C-M-r}} <math>expression</math>search regexp backward
 
  
Notes:
+
{{Details|Regexp Search}}
  
* ESC will cancel and go to original point. RET will end at the current point.
+
; {{Keys|C-M-s expression}} : search regexp forward
 +
; {{Keys|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.
 
* Searches are case-insensitive unless an uppercase letter is found in the search string.
 
* While searching, {{Keys|C-w}} will increment the search term with the current word.
 
* While searching, {{Keys|C-w}} will increment the search term with the current word.
  
Unconditional Replace
+
=== Unconditional Replace ===
  
* replace-stringreplaces a string with another
+
; replace-string : replaces a string with another
* replace-regexpreplaces a regexp match with a string
+
; replace-regexp : replaces a regexp match with a string
  
Query Replace (Conditional Replace)
+
=== Query Replace (Conditional Replace) ===
  
* {{Keys|M-%}} conditional replace of a string
+
; {{Keys|M-%}} : conditional replacement of a string
* query-replace-regexpconditional replace of a regexp
+
; query-replace-regexp : conditional replacement of a regular expression
  
Notes:
+
=== Notes ===
  
 
* Replaces are case-insensitive unless an uppercase letter is found in the match string.
 
* 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.
 
* 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.
+
* After a replace, the position will be at the end of the last match. {{Keys|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.
+
* During a query replace, '''SPC''' will apply a replace and '''DEL''' will skip.
  
== Undo &amp; Redo ==
+
== 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.
+
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.
  
* {{Keys|C-/}} undo a single change
+
; {{Keys|C-/}} : undo a single change
* {{Keys|C-g}} break the chain of undos
+
; {{Keys|C-g}} : break the chain of undos
  
Notes:
+
=== Notes ===
  
 
* If a mark is active, undo will only affect the marked region.
 
* If a mark is active, undo will only affect the marked region.
Line 250: Line 261:
 
== Regions ==
 
== Regions ==
  
Emacs uses the mark and point to denote a region (i.e., a selection).
+
Emacs uses the mark and point to denote a [[Region|region]] (i.e., a selection).
  
* C-SPC creates a region (marks area)
+
; {{Keys|C-SPC}}      : creates a region (marks area)
* {{Keys|C-x C-x}} swaps mark and point in a region
+
; {{Keys|C-x C-x}}     : swaps mark and point in a region
* {{Keys|C-u C-x C-x}} swaps mark and point without region
+
; {{Keys|C-u C-x C-x}} : swaps mark and point without region
* {{Keys|C-x h}} marks the entire document
+
; {{Keys|C-x h}}       : marks the entire buffer
* {{Keys|M-h}} marks the paragraph around
+
; {{Keys|M-h}}         : marks the paragraph around the point
* TABindents the current region
+
; {{Keys|TAB}}        : indents the current region
* {{Keys|M-@}} incrementally mark next word
+
; {{Keys|M-@}}         : incrementally mark next word
  
Kill, Yank and Paste Regions
+
=== Kill, Yank and Paste Regions ===
  
* {{Keys|C-w}} kills the currently selected region
+
; {{Keys|C-w}}                 : kills the currently selected region
* {{Keys|M-w}} copies the currently selected region
+
; {{Keys|M-w}}                 : copies the currently selected region
* {{Keys|C-y}} ({{Keys|M-y}})*yanks and cycles from the kill ring
+
; {{Keys|C-y}} ({{Keys|M-y}})* : yanks and cycles from the kill ring
  
Notes:
+
=== Notes ===
  
 
* Yank is the copy command in vi and the paste command in emacs.
 
* Yank is the copy command in vi and the paste command in emacs.
Line 272: Line 283:
 
== Rectangles ==
 
== Rectangles ==
  
Rectangles are marked regions between the columns of the point and mark. Applying operations on rectangles is some sort of vertical editing.
+
[[Rectangles]] are marked regions between the columns of the point and the mark. Applying operations on rectangles is some sort of vertical editing.
  
* {{Keys|C-x r k}} kill the rectangle
+
; {{Keys|C-x r k}} : kill the rectangle
* {{Keys|C-x r d}} delete the rectangle
+
; {{Keys|C-x r d}} : delete the rectangle
* {{Keys|C-x r y}} yank the last killed rectangle
+
; {{Keys|C-x r y}} : yank the last killed rectangle
* {{Keys|C-x r o}} push text to fill rectangle with spaces (open)
+
; {{Keys|C-x r o}} : push text to fill rectangle with spaces (open)
* {{Keys|C-x r c}} replace rectangle text with spaces (clear)
+
; {{Keys|C-x r c}} : replace rectangle text with spaces (clear)
* {{Keys|C-x r t}} replace each line in rectangle with text
+
; {{Keys|C-x r t}} : replace each line in rectangle with text
  
 
== Registers ==
 
== Registers ==
  
Registers are places where you can store anything: text, position, rectangle, configuration, filename, ... Registers are named: ''a'', ''A'' and ''3'' are three different 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-registerview the contents of a register
+
; view-register              : view the contents of a register
* {{Keys|C-x r S}} PC ''r''record current point position in register ''r''
+
; {{Keys|C-x r SPC ''r''}}  : record current point position in register ''r''
* {{Keys|C-x r j}} ''r''jump to position in register ''r''
+
; {{Keys|C-x r w ''r''}}     : record current window configuration in register ''r''
* {{Keys|C-x r s}} ''r''save region to register ''r''
+
; {{Keys|C-x r j ''r''}}    : jump to position (or window configuration) in register ''r''
* C-u C-x r s ''r''kill region to register ''r''
+
; {{Keys|C-x r s ''r''}}    : save region to register ''r''
* {{Keys|C-x r i}} ''r''insert text from register ''r''
+
; {{Keys|C-u C-x r s ''r''}} : kill region to register ''r''
* append-to-registerappend region to register
+
; {{Keys|C-x r i ''r''}}    : insert text from register ''r''
* prepend-to-registerprepend region to register
+
; append-to-register        : append region to register
* {{Keys|C-x r r}} ''r''save rectangle into register ''r''
+
; prepend-to-register        : prepend region to register
 +
; {{Keys|C-x r r ''r''}}    : save rectangle into register ''r''
  
 
== Bookmarks ==
 
== Bookmarks ==
  
Bookmarks are like registers but persistent. They can also be named.
+
[[Bookmarks]] are like registers but persistent. They can also be named.
  
* {{Keys|C-x r m}} ''foo''bookmark file and point to ''foo''
+
; {{Keys|C-x r m ''foo''}} : bookmark file and point to ''foo''
* {{Keys|C-x r b}} ''foo''jump to bookmark called ''foo''
+
; {{Keys|C-x r b ''foo''}} : jump to bookmark called ''foo''
* {{Keys|C-x r l}} list all bookmarks
+
; {{Keys|C-x r l}}         : list all bookmarks
* bookmark-savesave all bookmarks
+
; bookmark-save            : save all bookmarks
* bookmark-deletedelete a bookmark
+
; bookmark-delete          : delete a bookmark
  
 
== Macros ==
 
== 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.
+
[[Keyboard 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
+
; {{Keys|F3}}          : start macro definition or insert counter
* {{Keys|C-x (}} start macro definition only
+
; {{Keys|C-x (}}       : start macro definition only
* F4end macro definition or call macro
+
; {{Keys|F4}}          : end macro definition or call macro
* {{Keys|C-x e}} end macro definition and call macro
+
; {{Keys|C-x e}}       : end macro definition and call macro
* {{Keys|C-x )}} end macro definition only
+
; {{Keys|C-x )}}       : end macro definition only
* C-u C-u F3 append commands to last macro
+
; {{Keys|C-u C-u F3}}  : append commands to last macro
* {{Keys|C-u F3}} re-run last macro then append commands to it
+
; {{Keys|C-u F3}}       : re-run last macro then append commands to it
* {{Keys|C-x C-k r}} run macro on region
+
; {{Keys|C-x C-k r}}   : run macro on region
* {{Keys|C-x C-k C-n}} rotate to select the next macro in the ring
+
; {{Keys|C-x C-k C-n}} : rotate to select the next macro in the ring
* {{Keys|C-x C-k C-p}} rotate to select the previous macro in the ring
+
; {{Keys|C-x C-k C-p}} : rotate to select the previous macro in the ring
 +
 
 +
=== Macro Counters ===
  
 
Every macro definition can have a counter to insert into the buffer.
 
Every macro definition can have a counter to insert into the buffer.
  
* F3inside a macro definition, inserts the counter
+
; {{Keys|F3}}          : inside a macro definition, inserts the counter
* {{Keys|C-x C-k C-i}} outside a macro definition, inserts the counter
+
; {{Keys|C-x C-k C-i}} : outside a macro definition, inserts the counter
* {{Keys|C-x C-k C-c}} set the macro counter value
+
; {{Keys|C-x C-k C-c}} : set the macro counter value
* {{Keys|C-x C-k C-f}} set the macro counter format
+
; {{Keys|C-x C-k C-f}} : set the macro counter format
 +
 
 +
=== Saving Macros ===
  
 
Macros can be named and saved.
 
Macros can be named and saved.
  
* {{Keys|C-x C-k n}} name the most recently defined macro
+
; {{Keys|C-x C-k n}} : name the most recently defined macro
* {{Keys|C-x C-k b}} keybind the most recently defined macro
+
; {{Keys|C-x C-k b}} : keybind the most recently defined macro
* insert-kbd-macroinsert macro into buffer as elisp code
+
; insert-kbd-macro  : insert macro into buffer as elisp code
  
Notes:
+
=== Notes ===
  
* It is best to use the reserved key bindings {{Keys|C-x C-k}} [a-zA-Z0-9] as to not cause problems with other bindings. {{Keys|C-x C-k}} b 4 will define {{Keys|C-x C-k}} 4 as a binding.
+
* It is best to use the reserved key bindings {{Keys|C-x C-k [a-zA-Z0-9]}} as to not cause problems with other bindings. {{Keys|C-x C-k b 4}} will define {{Keys|C-x C-k 4}} as a binding.
  
 
== Alignment ==
 
== Alignment ==
Line 341: Line 357:
 
Emacs contains alignment commands. Sometimes those depend on the current mode (i.e., the language).
 
Emacs contains alignment commands. Sometimes those depend on the current mode (i.e., the language).
  
* alignaligns depending on mode
+
; align                    : aligns depending on mode
* align-regexpaligns using a regular expression
+
; align-regexp              : aligns using a regular expression
* {{Keys|C-u}} align-regexpaligns using a regular expression helper
+
; {{Keys|C-u align-regexp}} : aligns using a regular expression helper
* align-currentaligns current paragraph depending on mode
+
; align-current            : aligns current paragraph depending on mode
  
 
== Sorting ==
 
== Sorting ==
Line 350: Line 366:
 
When sorting, prefixing with {{Keys|C-u}} sorts in descending order.
 
When sorting, prefixing with {{Keys|C-u}} sorts in descending order.
  
* sort-linessort region by lines
+
; sort-lines                      : sort region by lines
* sort-paragraphssort region by paragraphs
+
; sort-paragraphs                : sort region by paragraphs
* {{Keys|C-u}} ''n'' sort-fieldssort lines in region by <math>\textit{\underline{n}}^{th}</math> field
+
; {{Keys|C-u ''n'' sort-fields}}  : sort lines in region by n''th'' field
* {{Keys|C-u}} -''n'' sort-fieldssort lines in region by <math>\textit{\underline{n}}^{th}</math> field from right
+
; {{Keys|C-u -''n'' sort-fields}} : sort lines in region by n''th'' field from right
* sort-numeric-fieldsinterpret field as number and not text
+
; sort-numeric-fields            : interpret field as number and not text
* sort-columnssort by column specified by marked region
+
; sort-columns                    : sort by column specified by marked region
* reverse-regionreverses current region
+
; reverse-region                  : reverses current region
  
 
== Tables ==
 
== Tables ==
Line 362: Line 378:
 
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.
 
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-insert            : interactively insert a table into buffer
* table-recognizedetect properties of all tables in the buffer
+
; table-recognize          : detect properties of all tables in the buffer
* table-unrecognizeremove special table properties
+
; table-unrecognize        : remove special table properties
* table-recognize-regiondetect properties of tables in region
+
; table-recognize-region  : detect properties of tables in region
* table-unrecognize-regionforget properties of tables in region
+
; table-unrecognize-region : forget properties of tables in region
* table-recognize-tabledetect properties of table at point
+
; table-recognize-table    : detect properties of table at point
* table-unrecognize-tableremove properties of table at point
+
; table-unrecognize-table  : remove properties of table at point
  
Cell resizing:
+
=== Cell resizing ===
  
* C-u ''n'' C-widen cell at point by ''n'' characters
+
; {{Keys|C-u ''n'' C-&gt;}} : widen cell at point by ''n'' characters
* C-u ''n'' C-narrow cell at point by ''n'' characters
+
; {{Keys|C-u ''n'' C-&lt;}} : narrow cell at point by ''n'' characters
* C-u ''n'' C-}heighten cell at point by ''n'' lines
+
; {{Keys|C-u ''n'' C-&#65373;}} : heighten cell at point by ''n'' lines
* C-u ''n'' C-{shorten cell at point by ''n'' lines
+
; {{Keys|C-u ''n'' C-&#65371;}} : shorten cell at point by ''n'' lines
  
Cell movement:
+
=== Cell movement ===
  
* TABmove to cell on right
+
; {{Keys|TAB}}  : move to cell on right
* S-TABmove to cell on left
+
; {{Keys|S-TAB}} : move to cell on left
  
Cell merging/splitting:
+
=== Cell merging and splitting ===
  
* {{Keys|C-c C-c}} *interactively merge two cells
+
; {{Keys|C-c C-c *}} : interactively merge two cells
* C-split cell horizontally
+
; {{Keys|C-+}}        : split cell horizontally
* C--split cell vertically
+
; {{Keys|C--}}      : split cell vertically
  
Rows &amp; Columns:
+
=== Rows and Columns ===
  
* C-u ''n'' table-insert-rowinsert ''n'' rows
+
; {{Keys|C-u ''n'' table-insert-row}}    : insert ''n'' rows
* C-u ''n'' table-delete-rowdelete ''n'' rows
+
; {{Keys|C-u ''n'' table-delete-row}}    : delete ''n'' rows
* C-u ''n'' table-insert-columninsert ''n'' columns
+
; {{Keys|C-u ''n'' table-insert-column}} : insert ''n'' columns
* C-u ''n'' table-delete-columndelete ''n'' columns
+
; {{Keys|C-u ''n'' table-delete-column}} : delete ''n'' columns
  
Other:
+
=== Other ===
  
* C-:interactively justify cell, column or row text
+
; {{Keys|C-:}}          : interactively justify cell, column or row text
* C-!toggle table fixed width mode
+
; {{Keys|C-!}}          : toggle table fixed width mode
* table-generate-sourcetable code in Latex, HTML or Cals
+
; table-generate-source : table code in Latex, HTML or Cals
  
 
== Goodies ==
 
== Goodies ==
  
* C-x TABforce an indentation on a region
+
; {{Keys|C-x TAB}}      : force an indentation on a region
* {{Keys|M-q}} indents and breaks paragraph into multiple lines
+
; {{Keys|M-q}}         : indents and breaks paragraph into multiple lines
* {{Keys|M-;}} comments a region or adds comment to line
+
; {{Keys|M-;}}         : comments a region or adds comment to line
* {{Keys|M-(}} inserts a new lisp function (parenthesis)
+
; {{Keys|M-(}}         : inserts a new lisp function (parenthesis)
* {{Keys|M-)}} checks balanced parenthesis and opens line
+
; {{Keys|M-)}}         : checks balanced parenthesis and opens line
* {{Keys|C-x}} iinserts file contents at point position
+
; {{Keys|C-x i}}       : inserts file contents at point position
* {{Keys|M-!}} run shell command
+
; {{Keys|M-!}}         : run shell command
* C-u M-!run shell command and insert output
+
; {{Keys|C-u M-!}}      : run shell command and insert output
* M-<math>|</math>run shell command on marked region
+
; {{Keys|M-❘}}          : run shell command on marked region
* C-u M-<math>|</math>run shell command on and replace marked region
+
; {{Keys|C-u M-❘}}      : run shell command on and replace marked region
* insert-bufferinserts buffer contents at point position
+
; {{Keys|C-x C-+}}      : Increase buffer font size
* copy-to-buffercopy region content to a buffer
+
; {{Keys|C-x C--}}      : Decrease buffer font size
* kill-some-buffersinteractively kill buffers
+
; insert-buffer        : inserts buffer contents at point position
* electric-buffer-listinteractive buffer list
+
; copy-to-buffer        : copy region content to a buffer
* toggle-truncate-linesdo not split lines over visual lines
+
; kill-some-buffers    : interactively kill buffers
* visual-line-modesplit lines by words
+
; electric-buffer-list  : interactive buffer list
* viper-modevi compatibility
+
; toggle-truncate-lines : do not split lines over visual lines
 +
; visual-line-mode      : split lines by words
 +
; viper-mode            : vi compatibility mode
  
 
== Setting Key Bindings ==
 
== 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).
+
{{Details|Key Bindings}}
 +
 
 +
Emacs has a global keymap which maps between keys and commands. Each major mode can define, re-define or un-define 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:
+
=== Some prefix keys ===
  
* C-xcommand prefix key
+
; {{Keys|C-x}} : command prefix key
* M-command prefix key
+
; {{Keys|M-}}  : command prefix key
* C-cmode specific prefix key
+
; {{Keys|C-c}} : mode specific prefix key
* C-hhelp prefix key
+
; {{Keys|C-h}} : help prefix key
  
Commands to bind keys:
+
=== Commands to bind keys ===
  
* global-set-key ''k'' ''com''bind key ''k'' to ''com'' globally
+
; global-set-key ''k'' ''com'' : bind key ''k'' to ''com'' globally
* local-set-key ''k'' ''com''bind key ''k'' to ''com'' locally (major mode)
+
; local-set-key ''k'' ''com'' : bind key ''k'' to ''com'' locally (major mode)
  
Notes:
+
=== Notes ===
  
 
* Menu and mouse key bindings can also be set.
 
* Menu and mouse key bindings can also be set.
Line 443: Line 463:
 
== Storing Key Bindings ==
 
== 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).
+
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
+
; global-set-key      : adds a binding to the global map
* local-set-keyadds a binding to the local (major mode) map
+
; local-set-key      : adds a binding to the local (major mode) map
* kbdconverts a string to a key sequence
+
; kbd                : converts a string to a key sequence
  
Examples:
+
=== Examples ===
  
Global key binding:
+
==== Global key binding ====
  
* (global-set-key (kbd &quot;C-c d&quot;) ’duplicate-line)
+
<source lang="lisp">
* (global-set-key (kbd &quot;C-c d&quot;) (kbd &quot;C-a C-@ C-e M-w RET C-y&quot;))
+
(global-set-key (kbd 'C-c d') 'duplicate-line)
* (global-set-key (kbd &quot;C-c d&quot;) &quot;\C-a\C- \C-n\M-w\C-y&quot;)
+
(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')
 +
</source>
  
Local key binding:
+
==== Local key binding ====
  
* (add-hook ’LaTeX-mode-hook<br />
+
<source lang="lisp">
    (lambda () (local-set-key (kbd &quot;C-c n&quot;)<br />
+
(add-hook 'LaTeX-mode-hook (lambda () (local-set-key (kbd 'C-c n') 'forward-paragraph)))
                              ’forward-paragraph)))
+
</source>
  
 
== The Emacs Help System ==
 
== The Emacs Help System ==
Line 467: Line 489:
 
Emacs has a handy help system for quick lookup of various features, topics, functions and key bindings.
 
Emacs has a handy help system for quick lookup of various features, topics, functions and key bindings.
  
* {{Keys|C-h ?}} show the help system shortcuts
+
; {{Keys|C-h ?}}       : show the help system shortcuts
* C-h ''key''run help system with shortcut ''key''
+
; {{Keys|C-h ''key''}} : run help system with shortcut ''key''
  
Some useful help keys:
+
=== Some useful help keys ===
  
* {{Keys|C-h a}} show apropos page about a keyword
+
; {{Keys|C-h a}}             : show apropos page about a keyword
* {{Keys|C-h k}} ''keybind''show help for function bound to ''keybind''
+
; {{Keys|C-h k ''keybind''}} : show help for function bound to ''keybind''
* {{Keys|C-h b}} show all key bindings
+
; {{Keys|C-h b}}             : show all key bindings
* {{Keys|C-h f}} show documentation for function
+
; {{Keys|C-h f}}             : show documentation for function
* {{Keys|C-h m}} show documentation for current modes
+
; {{Keys|C-h m}}             : show documentation for current modes
* {{Keys|C-h v}} show documentation for variable
+
; {{Keys|C-h v}}             : show documentation for variable
* {{Keys|C-h w}} show what keys a command is bound to
+
; {{Keys|C-h w}}             : show what keys a command is bound to
* {{Keys|C-h t}} start the emacs tutorial
+
; {{Keys|C-h t}}             : start the emacs tutorial
* ''prefix'' C-hshow all key binds starting with ''prefix''
+
; {{Keys|''prefix'' C-h}}    : show all key binds starting with ''prefix''
  
 
== Modes ==
 
== Modes ==
  
Modes are used to define the types of data being edited in buffers, or what Emacs calls “the language”.
+
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, ...) and provides basic elements like syntax highlighting and (re)defines functions and their key bindings for relevant actions (e.g., comments).
+
Every buffer has exactly one [[Major mode|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).
+
Each buffer can have zero or more [[Minor mode|minor modes]] enabled which provide non-specific functionality such as spell checking or line wrapping (i.e., mode independent).
  
== ediff ==
+
== Mode: 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
+
; p : view previous difference
* nview next difference
+
; n : view next difference
* aset buffer b’s area to what’s in a’s
+
; a : set buffer b’s area to what’s in a’s
* bset buffer a’s area to what’s in b’s
+
; b : set buffer a’s area to what’s in b’s
* qquit ediff session
+
; q : quit ediff session
  
== Spell Checking ==
+
== Mode: Spell Checking ==
  
* {{Keys|M-$}} check spelling at word or active region
+
{{Details|Spell check}}
* ispellcheck active region or entire buffer
 
** iaccept word and insert into personal dictionary
 
** ?show ispell help
 
** RETend current ispell session
 
  
* ESC TABcomplete current word from dictionary
+
; {{Keys|M-$}} : check spelling at word or active region
* flyspell-modeenable “on the fly” spell checking
+
; 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.
* flyspell-prog-modespell check comments and strings
+
; {{Keys|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 ==
 
== References ==
Line 526: Line 546:
  
 
[[Category:Tutorial]]
 
[[Category:Tutorial]]
 +
[[Category:Beginner]]

Latest revision as of 10:41, 17 May 2017

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.

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

For more details on this topic, see Emacs Terminology.

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).

M
Meta key, Alt or ESC
C
Control key
S
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
[M-m]
moves point to the first non-whitespace character in this line

Paragraph

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

Window

[M-0 M-r]
moves to the top of window
[M-r]
moves to the middle of window
[M-- M-r]
moves to the bottom of window

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 ←] or [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 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

For more details on this topic, see 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

For more details on this topic, see Regexp 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 w r]
record current window configuration in register r
[C-x r j r]
jump to position (or window configuration) 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

Keyboard 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.

[F3]
start macro definition or insert counter
[C-x (]
start macro definition only
[F4]
end 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

Macro Counters

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

[F3]
inside 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

Saving Macros

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-macro
insert 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).

align
aligns depending on mode
align-regexp
aligns using a regular expression
[C-u align-regexp]
aligns using a regular expression helper
align-current
aligns current paragraph depending on mode

Sorting

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

sort-lines
sort region by lines
sort-paragraphs
sort region by paragraphs
[C-u n sort-fields]
sort lines in region by nth field
[C-u -n sort-fields]
sort lines in region by nth field from right
sort-numeric-fields
interpret field as number and not text
sort-columns
sort by column specified by marked region
reverse-region
reverses 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-insert
interactively insert a table into buffer
table-recognize
detect properties of all tables in the buffer
table-unrecognize
remove special table properties
table-recognize-region
detect properties of tables in region
table-unrecognize-region
forget properties of tables in region
table-recognize-table
detect properties of table at point
table-unrecognize-table
remove 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

[TAB]
move to cell on right
[S-TAB]
move to cell on left

Cell merging and splitting

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

Rows and Columns

[C-u n table-insert-row]
insert n rows
[C-u n table-delete-row]
delete n rows
[C-u n table-insert-column]
insert n columns
[C-u n table-delete-column]
delete n columns

Other

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

Goodies

[C-x TAB]
force 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 i]
inserts 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
[C-x C-+]
Increase buffer font size
[C-x C--]
Decrease buffer font size
insert-buffer
inserts buffer contents at point position
copy-to-buffer
copy region content to a buffer
kill-some-buffers
interactively kill buffers
electric-buffer-list
interactive buffer list
toggle-truncate-lines
do not split lines over visual lines
visual-line-mode
split lines by words
viper-mode
vi compatibility mode

Setting Key Bindings

For more details on this topic, see Key Bindings.

Emacs has a global keymap which maps between keys and commands. Each major mode can define, re-define or un-define 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).

Some prefix keys

[C-x]
command prefix key
[M-]
command prefix key
[C-c]
mode specific prefix key
[C-h]
help prefix key

Commands to bind keys

global-set-key k com
bind key k to com globally
local-set-key k com
bind 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-key
adds a binding to the global map
local-set-key
adds a binding to the local (major mode) map
kbd
converts 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 key]
run help system with shortcut key

Some useful help keys

[C-h a]
show apropos page about a keyword
[C-h k keybind]
show 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-h]
show 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).

Mode: 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
p
view previous difference
n
view next difference
a
set buffer b’s area to what’s in a’s
b
set buffer a’s area to what’s in b’s
q
quit ediff session

Mode: Spell Checking

For more details on this topic, see Spell check.

[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