EMACS

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EMACS

• To quote the Emacs Manual
• Emacs is the extensible, customizable,
  self-documenting real-time display editor.
• Emacs is an editor for plain-text, programming or
  markup languages, and anything else that someone
  has created a module for. Emacs also has tools
  for compiling, running and testing programs.

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Emacs Commands

• All of the basic editing commands (and
  there are lots of them) are available no matter
  what you're trying to do (there are no command
  modes like in vi to worry about)
• All the tools Emacs provides for opening,
  saving, searching, and processing text (and more)
  are available to you no matter what you're in the
  middle of doing.

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Extensibility

• If Emacs doesn't work the way you'd like, you can
  use the Emacs Lisp (Elisp) language to customize
  Emacs, automate common tasks, or add new
  features. Elisp is very easy to get started with
  and yet remarkably powerful you can use it to
  alter and extend almost any feature of Emacs.
• As an example, there are addons to emacs which
  allow you to read news, mail, and RSS feeds,
  manage your files, or even play Tetris! (good old
  M-x tetris)

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Movement Commands

• C means to press the C key and a key
• M means to press the Meta key and a key
• If your terminal does not support a meta key, you
  can press ESC, release ESC, and then press the
  key to enter the meta command.
• C-f Forward one character C-b Back one
  character
• C-n Next line C-p Previous line
• C-a Beginning of line C-e End of line
• M-f Forward one word M-b Back one word
• M-a Previous sentence M-e Next sentence
• M-v Previous screen C-v Next screen
• M- End of buffer
• Getting fancy
• C-u 3 C-p Back 3 lines
• C-u 10 C-f Forward 10 characters
• M-1 M-0 C-f Forward 10 characters
• C-u C-n Forward 4 lines
• C-u C-u C-n Forward 16 lines
• C-u C-u C-u C-n Forward 64 lines

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More advanced movement

• C-s Incremental search forward
• C-r Incremental search backward
• Emacs remembers something called the mark, which
  is a previous cursor position. You can set mark
  to indicate a particular place in your buffer so
  you can return to it easily. C-x C-x at a later
  time will return point to mark. Actually, that
  command also moves mark to where point formerly
  was therefore, a second C-x C-x returns point to
  its original position.
• C-SPC Set mark to the current location
• C-x C-x Swap point and mark
• Emacs tries to be helpful many commands that
  have the potential to take you long distances set
  mark so that a simple C-x C-x takes you back to
  where you were. Emacs makes it difficult to lose
  your place in a buffer even if you take a
  detour, you don't need to scroll around to get
  back to where you were.
• Emacs saves many previous values of the mark for
  you. You can cycle through the mark ring, which
  contains the last 16 marks you've set in the
  current buffer
• C-u C-SPC Cycle through mark ring

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Menu Bar

• Emacs features a menu bar at the top of the
  screen which allows easy access to command
  commands.
• On a graphical display, you can use your mouse to
  click on these toolbars as normal for GUI apps.
• On a terminal display, you can press F10 to move
  to the first bar, and then navigate via arrow
  keys. Return selects, ESC cancels navigation.
• Right arrows on the menu means that the item
  leads to another menu, ... on the menu means that
  the item will execute a command which will
  require input from the bottom of the window.

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Scrolling

• C-l Clears the screen and redraws it, centering
  on the cursor.
• C-v scroll forward (pagedown also works)
• M-v scroll backwards (pageup works)

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Windows! (Not the OS)

• Emacs has support for displaying multiple viewing
  windows at the same time.
• C-x 2 Split the current window into 2, one above
  the other
• C-x 3 Split the current window into 2, one next
  to the other
• C-x o Switch focus to another window
• C-x 0 delete the currently selected window
• C-x 1 make the currently selected window the only
  window (delete / close others)
• C-x makes the current window taller
• C-x makes the current window wider

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Killing / Cutting Text

• C-k kills the portion of the current line after
  point (or deletes the newline following point if
  point is at the end of line). The prefix argument
  for C-k can be used to kill multiple lines
• C-k Kill line
• C-u 10 C-k Kill 10 lines
• The following commands operate on the region, and
  are the closest analogs to "cut" and "copy" in
  Emacs
• C-w Kill region ("cut")
• M-w Save region to kill ring without deleting
  ("copy")
• These commands are also handy
• M-d Kill next word
• M-k Kill to end of sentence
• All of the above commands kill the text being
  deleted, which means that Emacs removes the text
  and squirrels it away for later retrieval
  ("yanking"). Most commands which delete
  significant amounts of text kill it rather than
  simply removing it, so that you can use those
  commands either to "delete" text or to "cut" it
  for later use.

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Yanking / Pasting Text

• After a piece of text has been killed, it goes to
  a place called the kill ring which is analogous
  to the "clipboard" you can yank an item to
  restore it from the kill ring with C-y. Unlike
  the clipboard, however, the kill ring is capable
  of holding many different items. If the item you
  want to yank is not placed when you type C-y,
  type M-y (repeatedly, if necessary) to cycle
  through previously killed items.
• C-y Yanks last killed text
• M-y Replace yanked text with previously killed
  text
• Recall that most commands which delete a large
  amount of text in fact kill it (i.e. place it in
  the kill ring) so you can restore it later. Emacs
  makes it very difficult to lose a lot of text
  permanently in editors with only a single
  clipboard, one can easily accidentally delete a
  large chunk of text or clobber the contents of
  the clipboard (by cutting two items in
  succession). But in Emacs, in either of those
  cases, the lost text can easily be retrieved from
  the kill ring.

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Undo!

• Aka, Uh-oh, where did my thesis go?
• Many editors feature an Undo function, but
  commonly if you perform an Undo, then change
  some text, you are unable to Redo. Emacs
  however stores all actions, enabling you to do
  some things, undo them, do some other things, and
  then at any point undo over and over back to any
  of the previous states.
• If this sounds complicated, just remember that
  "undo" is always capable of getting you back to
  any previous state your buffer was in (unless
  Emacs has run out of memory to store the undo
  history). The principle here is that Emacs makes
  it very difficult to accidentally lose your work.
• Undo is available via three different keys
• C-/ Undo
• C-_ Undo
• C-x u Undo
• So if you need to get back to a previous buffer
  state, simply move the cursor (so as to break any
  existing sequence of undos), and press C-/ until
  you find what you want.

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Search Replace

• M- Query replace
• The query replace command prompts you for a
  search string and a replacement. Then, for each
  match in the buffer, you can choose whether or
  not to replace the search string. Here are some
  of the options available at each prompt
• Type y to replace the current match.
• Type n to skip to the next match without
  replacing.
• Type q to exit without doing any more
  replacements.
• Type . to replace this match, then exit.
• Type ! to replace all remaining matches
  with no more questions.
• Also, in addition to the search methods listed
  earlier, there exists
• C-M-s Regular expression incremental search

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Forgetting Commands

• If you don't remember what a particular key or
  command does, you can read a description of it by
  using one of the following commands
• C-h k Shows documentation for the command
  associated with any particular key.
• C-h f Shows documentation for any particular
  command, by name (i.e. what you would type after
  M-x).
• C-h a Allows a search for a feature you do not
  know exactly how to perform.
• For example, C-h k C-s and C-h f isearch-forward
  RET both display a page describing incremental
  search.

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Tools

• M-x shell
• Starts a shell in the buffer named shell,
  switching to it if it already exists. Use C-u M-x
  shell to use a buffer with a different name.
• M-x compile
• Invokes make (with targets and options of
  your choice) and displays output in a new buffer.
  Emacs identifies error lines containing filenames
  and line numbers, and you can click on them to
  jump directly to the corresponding buffer and
  line.
• M-x grep
• Invokes grep and prints results in a new
  buffer. Like M-x compile, when you click on a
  match Emacs opens the correct file and takes you
  to the matching line.
• M-x man
• Displays man pages.
• M-x shell-command or M-!
• Executes a command and displays the output in
  a new buffer.

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Modules

• You can switch modes in an existing buffer by
  using M-x and the name of the mode
• M-x java-mode Mode for editing Java files
• M-x python-mode Mode for editing Python files
• M-x text-mode Mode for editing text files
• M-x fundamental-mode Mode with no specializations
  at all
• M-x highlight-changes Mode which colors text
  added most recently
• Emacs is very good at determining the right mode
  to use when you open a file so often these
  commands are unnecessary.
• These are examples of the commands provided by
  language major modes
• Language Some special commands available
• Lisp Manipulate s-exps in various ways execute
  expressions
• Python Indent, unindent blocks run code in
  Python shell
• HTML Insert and close tags preview in browser
• In almost all cases, major modes for unsupported
  formats are available as extension packages. You
  can find many of them on EmacsWiki.

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Ports

• There are many different builds of Emacs
  available freely online. The source code is also
  available online.
• Emacs is built on many Linux distros, Windows,
  DOS, OSX, and others.
• Emacs exists in terminal, Xwindow, and other GUI
  flavors.