Emacs Text Editor

Emacs is a text editor and more! It has modes for editing any programming language and markup language in use (C, C++, Java, HTML, Latex) and provides syntax highlighting and intelligent screen formating. It has very powerful text editing features: search/replace with regular expressions, editing of binary files showed in hexadecimal, macro recording/execution, and much more. It was written by the legendary open source/free software guru Richard Stallman, and is part of the GNU Project, thought to develop a complete Unix system which is open source/free software. See the GNU Project for more information about Free Software, GNU Project and Emacs.

There are versions of Emacs running any operating systems you could think of.

Emacs work area is comprised of:

• windows: which are in fact panes inside of the main window
• mini-buffer: which is a one line area at the bottom of the main window used for typing commands and command parameters.

The text showed in Emacs windows is stored in buffers. These buffers can have a file associated with them or not.

Notation

Emacs commands generally involve the CONTROL key (sometimes labeled CTRL or CTL) or the ESCAPE key (labeled ESC).

C-<chr>

means hold the CONTROL key while typing the character <chr>. Thus, C-f would be: hold the CONTROL key and type f.

M-<chr>

Means type ESCAPE, release it, then type the character <chr>.

Basic commands

Start and Exit Emacs

• Start: At a command prompt type xemacs
• Exit: C-x C-c

Files

• Find(open) file: C-x C-f
• Reload file: C-x C-v <RET>
• Save file: C-x C-s
• Save all modified files: C-x s
• Write(Save as) file: C-x C-w and then type the file name in the mini-buffer.

Move

• Move to beginning of line: C-a or <Home>
• Move to end of line: C-e or <End>
• Move to beginning of file: M-< or C-<Home>
• Move to end of file: M-> or C-<End>

Windows

• Split window: C-x 2
• Delete all other windows: C-x 1
• Scroll the window such that the cursor will be in the middle of the screen: C-l
• Move to other window: C-x o

Buffers

• Switch to buffer: C-x b. You can type TAB to list all available buffers, you can type the buffer name in the mini-buffer and press TAB for auto-completion, then you have to type ENTER
• Kill buffer: C-x k

Delete and Undo

• Delete a character before the cursor: BACKSPACE
• Delete a word before the cursor: M-BACKSPACE
• Delete (Kill) a from the cursor till the end of the line: C-k
• Undo: C-x u

Search and Replace

• Search from cursor: C-s <word>. To search for the next occurrence of <word>, type C-s again. To search the previous occurrence of <word> type C-r.To stop at the found word, type ENTER. To cancel the search and return to the starting point type C-g.
• Search backward from cursor: C-r <word>. All the rest of commands are identical as for C-s.
• Query replace a string with other: M-% <string> ENTER <other>
• For newline use C-q C-j, for carriage return use C-q C-m

Copy and Paste

• Select a region: C-SPACE marks the first position of the region. Moving the cursor, modifies the selected region to be between the marked position and the current position of the cursor.
• Select all: C-x h
• Copy selected region to the clipboard: M-w
• Cut selected region from the document and copy it to the clipboard: C-w
• Paste(yank) the clipboard: C-y

Help

• Info: C-h i.
  • Follow a link: <ENTER>
  • Last visited page: l
  • Next section: n
  • Previous section: p
• Man: M-x man

Miscellaneous

• Executing the same command <number> times: C-u <number> <command>
• Cancel(quit) current operation: C-g
• Completes the directory or file name typed in the mini-buffer: TAB
• Aligns the current paragraph: C-u M-q

Programming/Advanced

• Indent the current line: TAB
• Indent the current block in C, C++ or Java. Position the cursor on the opening curly brace and type: M-C-q
• Indent selected region: M-C-\
• Move on the matching brace: M-left and M-right or M-C-b and M-C-f
• Comment/uncomment the selected region: M-x comment-region respectively C-u -1 M-x comment-region
• In a selected region, convert multiple spaces to tabs/convert tabs to multiple spaces preserving columns: M-x tabify, respective M-x untabify.
• To evaluate a Lisp expression: place the cursor after the expression and press C-x C-e
• To search for a control character such as LF, type C-q, and then the control character (C-j is LF - see man ASCII for more information)
• Documentation about the current editing mode: C-h m