Emacs - ArchWiki

# Emacs

Emacs is an extensible, customizable, self-documenting real-time display editor. At the core of Emacs lies an Emacs Lisp interpreter, the language in which the majority of Emacs' built-in functionality and extensions are implemented. GTK is the default X toolkit used as of GNU Emacs 22, though it functions equally well within a CLI environment. The text-editing capabilities of Emacs are often compared to that of vim.

## Installation

Emacs comes in several variants (sometimes referred to as emacsen). The most common of these is GNU Emacs.

Install emacs, available in the official repositories. If you usually work in a terminal, you may prefer the emacs-nox variant without GTK+ (nor sound and other fancy stuff). Be aware that the text version comes with some drawbacks: it supports less colors and less features for font handling (size change in live, various sizes in one document, and so on). Besides, emacs-nox has some limitation with advanced features like the Speedbar or GUD (the debugging environment), and is somewhat slower when handling complex faces (a "face" is the visual appearance of text in Emacs).

If you want to fully enjoy all the extended features of Emacs without installing a daunting amount of dependencies, you can use the PKGBUILD to customize your needs. Using anything else than `gtk3` you can get rid of gconf. Image and sound support can be disabled as well. Run `./configure --help` in Emacs source folder to list all available options.

    PKGBUILD

    # ...
      ./configure --prefix=/usr --sysconfdir=/etc --libexecdir=/usr/lib \
        --localstatedir=/var --with-x-toolkit=gtk2 --with-xft \
        --without-gconf --without-sound
    # ...

Another common variant is xemacs.

## Running Emacs

Before launching emacs, you should know how to close it (especially if you run it in a terminal): use the `Ctrl+x` `Ctrl+c` key sequence.

### Normal way

To start Emacs run:

    $ emacs

or, to use it from the console:

    $ emacs -nw

or, for fast loading (no .emacs) and editing within CLI:

    $ emacs -Q -nw

If you installed the nox version, 'emacs' and 'emacs -nw' will be the same.

A file name can also be provided to open that file immediately:

    $ emacs filename.txt

### No Colors

By default, Emacs starts with a color theme showing hyperlinks in dark blue. To start Emacs without any color theme or scheme:

    $ emacs -nw --color=no

This will cause all text to appear in white color only.

### As a daemon

This article or section needs language, wiki syntax or style improvements.

Reason: For most purposes this could be described in two sentences (Discuss in Talk:Emacs#)

Emacs can take some time to start since it has to load the `.emacs` file each time. Besides, you may want to access the same files from different instances. Since version 23, Emacs is able to run as a daemon to which users can connect. To run Emacs as a daemon:

    $ emacs --daemon

You are likely to start the daemon at startup time and to connect a window to the daemon. Besides, it is possible to connect both graphical and console clients to the daemon at the same time and make the GUI to start quickly.

If you want to connect to the daemon simply use the following command (note that it will start a graphical client if called in a graphical environment or a console client if called in a console like a tty):

    $ emacsclient

If you merely want a console client despite being in a graphical environment then use:

    $ emacsclient -t

Furthermore, you can add the `-a ""` parameter. Now, the first time you call the command, it will start emacs as a daemon, so that it remains running in background and so improving startup times for future calls (and to remember buffers as well).

If you start the client from a terminal or another program, you may want not to wait for it to return, so that you can continue using the calling program and even close it without closing the Emacs client. To do so, start the client with the `-n` (`--no-wait`) parameter:

    $ emacsclient -nc

Note that some programs such as Mutt or Git (for commit messages) wait for the editor to finish, so you cannot use the `-n` parameter. If your default editor is set to use it, you will have to specify an alternate editor (e.g. `emacsclient -a "" -t`) for those programs.

You could use the following shell configuration:

    alias emt='emacsclient -nc -a ""'
    alias emc='emacsclient -t -a ""'
    EDITOR='emacsclient -a ""'

but it has some caveats: many program will fail to load the external editor because of the spaces in the command.

A more convenient and reliable solution is to write your own script:

    /usr/local/bin/emc

    #!/bin/sh
    if [ -z "$DISPLAY" ]; then
        IS_GRAPHICAL=true
    else
        IS_GRAPHICAL=$(emacs --batch -Q --eval='(if (fboundp '"'"'tool-bar-mode) (message "true") (message "false"))' 2>&1)
    fi

    if $IS_GRAPHICAL; then
        emacsclient -a "" -nc "$@"
    else
        emacsclient -a "" -t "$@"
    fi

then make it executable:

    # chmod 755 /usr/local/bin/emc

Now 'emc' will work just as expected. Setting the `EDITOR` environment variable to the aforementionned script should suffice to make the client be your defaut editor.

### As a systemd unit

The old system unit method had some caveats. It gave a limited shell environment which restricted shell calls, so we'll be using a user unit, which tends to work a lot better than naively calling emacs --daemon.

Create a systemd unit for emacs:

    ~/.config/systemd/user/emacs.service

    [Unit]
    Description=Emacs: the extensible, self-documenting text editor

    [Service]
    Type=forking
    ExecStart=/usr/bin/emacs --daemon
    ExecStop=/usr/bin/emacsclient --eval "(kill-emacs)"
    Restart=always

    [Install]
    WantedBy=default.target

You need to enable the unit so that it gets started on every boot (note - DO NOT run these commands as root - we want them for our user, not for the root user):

    $ systemctl --user enable emacs

To actually use the unit, either reboot or start the unit manually:

    $ systemctl --user start emacs

## Usage

Although Emacs is complex, it will not take long to begin to understand the benefits which the level of customization and extensibility bring. Furthermore, the comprehensive variety of extensions already available allows it to be transformed into a powerful environment for almost any form of text-editing.

Emacs has an excellent built-in tutorial which can be accessed by clicking the first link on the splash screen; by selecting Help->Emacs Tutorial from the menu or by pressing 'F1' followed by 't'. This page is designed to be an additional resource for getting started with Emacs.

Emacs also includes a set of reference cards, useful for beginners and experts alike, see `/usr/share/emacs/<version>/etc/refcards/` (substitute <version> for your version of emacs).

### Basic terminology and convention

Emacs uses some terminology and conventions which may seem unusual at first and will be introduced where appropriate. However, there is some terminology which should be introduced before-hand, as it is fundamental to working with Emacs.

The one piece of terminology which must be introduced early is the concept of buffers. A buffer is a representation of data within Emacs. For example, when a file is opened in Emacs, that file is read from disk and its contents stored in a buffer, which allows it to be edited and saved back to disk later. Buffers are not limited to text, and can also contain images and widgets. Work is in progress to allow buffers to even display applications! Another way to think of it: data available on disk is referred to as a 'file', whereas data available in Emacs is referred to as a 'buffer'.

The convention for key sequences in Emacs may be unfamiliar. Namely:

C-x refers to Control-x

M-x refers to Meta-x

Note: 'Meta' corresponds to the Alt key in most cases. Alternatively, the Esc key can be used.

For example, to exit Emacs use the following key sequence: C-x C-c. This can be read as "Hold Control and press 'x'. Release. Hold Control and press 'c'." Although Emacs provides a menu bar, it is recommended practise to focus on learning the key sequences. This guide will refer to keybindings with the convention used in Emacs from now on.

### Movement

Cursor movement is very similar to other graphical editors. The mouse and arrow keys can be used to change the position of the cursor (referred to as point in Emacs). The standard movement commands performed by the arrow keys also have more accessible bindings in Emacs. To move forward one character, use C-f and to move one character backward, C-b. C-n and C-p can be used to move to the next and previous lines, respectively. Again, it is generally recommended to use these key-sequences in preference to the mouse and/or arrow keys.

As might be expected, Emacs provides more advanced movement commands, including moving by word and sentence. M-f moves forward one word and M-b will move point one word backward. Similarly, M-e moves point one sentence forward and M-a one sentence backward.

Until now, all of the movement commands introduced have been relative to point. M-< can be used to move point to the beginning of the buffer, with its counterpart, M->, moving to the end of the buffer. To move point to a specific line number, use M-g g. M-g g will prompt for the desired line number. Also, to move to the start or end of the current line, use C-a or C-e, respectively.

Note: Keybindings for these commands, or indeed any command, may differ slightly depending on which modes are currently active. However, it is unusual for the replacement command not to provide equivalent functionality. See Modes for more information.

### Files and buffers

Emacs provides a series of commands to act upon files, the most common of which will be detailed here. C-x C-f is used to open a file (this command is called 'find-file' in Emacs). Should the file specified not exist, Emacs will open an empty buffer. Saving a buffer will create the file with the buffer's contents. C-x C-s can be used to save a buffer. To save a buffer with a different filename, use C-x C-w (this is a mnemonic for the command 'write-file'), which will prompt for the new filename before writing it to disk. It is also possible to ensure all buffers are saved with C-x s, which, should a buffer be modified since its last save, a prompt will be displayed asking which action to take.

Note: C-x C-f does not read the file from disk again if a buffer corresponding to the file is still opened. To re-read the file from disk, (1) kill the buffer (C-x k) first, then open the file (C-x C-f); or (2) use M-x revert-buffer to revert to data on disk; or (3) use C-x C-v to load that file to the current buffer; or (4) use C-x RET r RET to reload the file with the same coding.

Many interactive commands such as "find-file" or "write-file" prompt for input in the bottom-most line of the Emacs window. This line is referred to as the minibuffer. The minibuffer supports many basic editing commands as well as tab-completion similar to that which is available in many *nix shells. <TAB> can be pressed twice in succession to display a list of completions, and if desired, the mouse can be also be used to select a completion from that list. Completion in the minibuffer is available for many forms of input including commands and filenames.

The minibuffer also provides a history feature. The previous items entered for a command can be recalled using the Up Arrow or M-p.

To exit the minibuffer at any time, press C-g.

After opening several files, a way to switch between them is needed. Opening a file corresponding to a buffer already available in Emacs, will cause Emacs to switch to that buffer. But this is not the most effective way. Emacs provides C-x b, which prompts for the new buffer to be displayed (tab-completion is available here). By entering the name of a buffer which does not exist, a new buffer with that name will be created.

Note: To switch to the previous buffer use C-x b <RET>, as the previous buffer is the default.

A list of all open buffers can be displayed using C-x C-b. Should a buffer no longer be required, it can be removed with C-x k.

### Editing

Many editing commands exist within Emacs. Perhaps the most important command which has not yet been introduced is 'undo', which can be performed via C-_ or C-/. Movement commands generally also have a corresponding delete command. For example, M-<backspace> can be used to delete a word backwards, and `M-d` to delete a word forwards. To delete to the end of the line, or the end of the sentence, use `C-k` or `M-k`, respectively.

It is a rule-of-thumb that no line be allowed to exceed 80 characters. This aids readability, especially in cases where the line wraps at the edge of a window. Automatically inserting (or removing) line separator(s) is known as filling in Emacs. A paragraph can be filled using `M-q`.

Characters and words can be transposed using `C-t` and `M-t`, respectively. For example: `Hello World!` to `World! Hello`.

The case of words is also readily adjustable. `M-l` downcases a word from point (`HELLO` to `hello`); `M-u` upcases a word from point (`hello` to `HELLO`) and `M-c` capitalizes the first character of a word from point while downcasing the remainder (`hElLo` to `Hello`).

### Killing, yanking and regions

A region is a section of text between two positions. One of those positions is referred to as mark, and the other is point. C-<SPC> is used to set the position of mark, after which point can be moved to create a region. Within GNU Emacs 23.1 onwards, this region is visible by default. There are a number of commands which act upon regions, among the most commonly used are killing commands.

In Emacs, cut and paste are referred to as kill and yank, respectively. Many commands which delete more than one character (including many of those in the above section, such as C-k and M-d) actually cut the text and append it to what is known as the kill-ring. The kill-ring is simply a list of killed text. The kill-ring stores up to the last 60 kills by default. Successive kills are concatenated and stored at the head of the list.

C-w and M-w can be used to kill and copy a region, respectively.

To insert killed text into a buffer (known as 'yanking'), use C-y. C-y can be used multiple times in succession to yank text repeatedly. As mentioned, previous kills are stored in a list, however C-y only retrieves the first of them. The earlier kills can be accessed via M-y. This will remove the text inserted by 'yank' initially, replacing it with the text killed earlier. M-y must be used immediately following C-y and can be used in many times succession to cycle through the kill-ring.

### Search and replace

Searching for a string is common practise in text-editing. This can be performed using C-s (to search forward) or C-r (to search backward). These commands prompt for the string for which to search. Searching is performed incrementally, and so it will match the next (or previous) occurrence as you type. To move to the next or previous match, press C-s or C-r again, respectively. Once a match has been found, <RET> can be used to end the search. Alternatively, should you wish to return to the location you initiated the search, use C-g.

Once a search is completed (i.e., was not aborted with C-g or similar), the string which was searched for will be the default for any following search. To make use of this, press C-s C-s or C-r C-r to search forward or backward again, respectively.

I-search has some useful commands. Use M-e to edit the search field. Use M-c to toggle case-sensitive matching.

Regular Expression searches behave identically to the searching described above except for the command to initiate the search. Use C-M-s or C-M-r to initiate a regexp search forward or backward, respectively. Once a Regular Expression search has commenced, C-s and C-r can be used to search forward or backward, just as with string searches.

In addition to searching, it is also possible to perform string and regular expression replacement (via M-% and C-M-%, respectively). Prompts are provided for both the initial and replacement text, and then another prompt for the action to perform on the highlighted match. Although many options are available (the full list is available by pressing ?), the most commonly used are y, to perform replacement, n, to skip this match, and ! to replace this, and all following matches.

### Prefix arguments

C-u corresponds to the 'universal-argument' command. Providing a 'universal-argument' is a way to provide more information to a command (this information is referred to as a 'prefix argument'). For instance

    C-u 80 %

will insert a line of percent signs. Or

    C-u 4 M-d

Will delete 4 words. In this case, we provided the amount of words desired to the command invoked by M-d.

You can make it a little quicker by using the equivalent M-<number> as universal argument.

    M-80 %

### Indentation

Indentation is usually performed with either <TAB>, to indent a single line, or with C-M-\, to indent a region. If the region is active (i.e. highlighted), then <TAB> will also indent region.

Exactly how text is indented usually depends on the major-mode which is active. Major-modes often define indentation styles specialising in indenting a certain type of text. (See Modes for more information.)

In some cases, a suitable major-mode may not exist for a file type, in which case, manual indentation may be necessary. Create a region (see Killing, yanking and regions) then perform indentation with C-u <n> C-x <TAB> (where '<n>' is the number of columns which the text within the region should be indented). For example:

Increase the region's indentation by four columns:

    C-u 4 C-x <TAB>

Decrease the region's indentation by two columns.

    C-u -2 C-x <TAB>

### Windows and frames

Emacs is designed for convenient editing of many files at a time. This is achieved by dividing the Emacs interface into three levels. Namely, buffers, which have already been introduced, as well as windows and frames.

A window is a viewport used for displaying a buffer. A window can display only one buffer at a time, however one buffer can be displayed in many windows. Beneath each window exists a mode-line, which displays information for that buffer.

A frame is an Emacs "window" (in standard terminology. i.e., 'window' in the sense of the modern desktop paradigm) which contains a title bar, menu bar and one or more 'windows' (in Emacs terminology. i.e., the above definition of 'window').

From now on the definition of these terms as they exist in Emacs will be used.

To split the window horizontally or vertically use C-x 2 or C-x 3, respectively. This has the effect of creating another window in the current frame. To cycle between multiple windows, use C-x o.

The opposite of splitting a window, is deleting it. To delete the current window, use C-x 0 and C-x 1 to delete all windows except the current.

As with windows, it is also possible to create and delete frames. C-x 5 2 creates a frame. With C-x 5 0 to delete the current frame and C-x 5 1 to delete all except the current frame.

Note: These commands do not affect buffers. For example, deleting a window does not kill the buffer it displays.

### Modes

An Emacs mode is an extension written in Emacs Lisp that controls the behaviour of the buffer it is attached to. Usually it provides indentation, syntax highlighting and keybindings for editing that form of text. Sophisticated modes can turn Emacs into a full-fledged IDE (Integrated Development Environment). Emacs will generally use a file's extension to determine which mode should be loaded.

Useful modes for editing shell scripts are sh-mode, line-number-mode and column-number-mode. They can be used in parallel and are invoked by:

M-x sh-mode <RET>

M-x column-number-mode <RET>

line-number-mode is enabled by default, though, it can be toggled on/off by issuing the command again:

M-x line-number-mode <RET>

sh-mode is a major-mode. Major-modes adjust Emacs, and often also provide a specialised set of commands, for editing a particular type of text. Only one major-mode can be active in each buffer. In addition to syntax highlighting, and indentation support, sh-mode defines several commands to help write shell scripts. The following shows a few of those commands:

    C-c (	 Insert a function definition

    C-c C-f	 Insert a 'for' loop

    C-c TAB	 Insert an 'if' statement

    C-c C-w	 Insert a 'while' loop

    C-c C-l	 Insert an indexed loop from 1 to n

'line-number-mode' and 'column-number-mode', are minor-modes. Minor-modes can be used to extend a major-mode and any number of minor-modes can be enabled at once.

## Tips and tricks

While the previous sections has given an overview of the basic editing commands available, it has not given an indication of the possibilities of Emacs. This section will cover some more advanced techniques and functionality.

We cannot cover everything as it would be too long. So this section will only serve as a demo for some dazzling features of Emacs.

See Documentation to get access to more in-depth detail about all features.

### TRAMP

Warning: Using TRAMP with root permissions will cause `/dev/null` to be deleted after some time. FS#47912 To prevent this, use the patch provided in the bug report, or replace `/bin/sh` with a link to `/bin/dash`. See Dash#Relinking /bin/sh.

TRAMP (Transparent Remote Access, Multiple Protocols) is an extension which, as its name suggests, provides transparent access to remote files across a number of protocols. When prompted for a filename, entering a specific form will invoke TRAMP. Some examples:

To prompt for the root password before opening /etc/hosts with root permissions:

    C-x C-f /su::/etc/hosts

To connect to 'myhost' as 'myuser' via SSH and open the file ~/example.txt:

    C-x C-f /ssh:myuser@myhost:~/example.txt

The path for TRAMP is typically of the form '/[protocol]:[[user@]host]:<file>'. TRAMP supports much more than the examples above might indicate. For more information refer to the TRAMP info manual, which is distributed with Emacs.

### Keyboard macros and registers

This section will provide a practical demonstration of the use of a couple of more powerful editing features. Namely, keyboard macros and registers.

The aim will be to produce a listing of a series of characters and their corresponding position in this list. While it is possible to format each of them by hand, this would be slow and error-prone. Alternatively, some of Emacs' more powerful editing functionality could be leveraged. Before describing a solution, some details behind the techniques which will be used follow.

The first feature which will be introduced is registers. Registers are used to store and retrieve a variety of data types ranging from numbers to window configurations. Each register is given a name of a single character: this character is used to access the register.

The other which will be demonstrated is keyboard macros. A keyboard macro stores a sequence of commands so they can be easily repeated later. These changes will now be performed step-by-step.

Starting with a buffer containing our set of characters:

    ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz

Prepare a register by invoking the `number-to-register' command (C-x r n) then storing the number '0' in register 'k':

    C-x r n k

With point at the beginning of the buffer, start a keyboard macro (C-x () and begin to format the characters:

    C-x ( C-f M-4 .

Insert (C-x r i) and increment (C-x r +) the register 'k'. The prefix argument (C-u) is used to leave point positioned after the inserted text:

    C-u C-x r i k C-x r + k

Complete the formatting by inserting a newline. Emacs can then repeat that process, beginning from the point where we started defining the keyboard macro, for the rest of the characters. C-x e completes then invokes the keyboard macro. The prefix argument, M-0, causes the macro to repeat until it comes across an error. In this case it aborts once it reaches the end of the buffer.

    <RET> M-0 C-x e

The result:

     A....0
     B....1
     C....2
     [...]
     x....49
     y....50
     z....51

If you want to save your macro for later use, you must give it a name and save it to your configuration file:

    name-last-kbd-macro
    insert-kbd-macro

All defined macros are stored in the macro ring. To cycle between macros, use

    C-x C-k C-n  next macro
    C-x C-k C-p  previous macro

You can also use registers to save virtually anything.

    C-x r SPC Copy current point (position) to register
    C-x r w   Copy current window configuration to register.
    C-x r j   Restore register.

So if you often work with windows side by side, for different project, you can save the configuration for the different projects and easily switch from one view to the other.

You can list used registers with the list-registers command.

### Regular expressions

From the Emacs Manual: "A regular expression, or regexp for short, is a pattern that denotes a (possibly infinite) set of strings." This section will not go into any detail regarding regular expressions themselves (as there is simply too much to cover). It will however provide a quick demonstration of their power. See Regular Expressions section in the Emacs Manual for further reading.

Given the same scenario presented above: A list of characters which are to be formatted to represent their respective position in the list. (see Keyboard macros and registers). Again, starting with a buffer containing.

    ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz

At the beginning of the buffer, use C-M-% (if the key-sequence is difficult to perform, it may be more comfortable to use M-x query-replace-regexp). At the prompt:

    \(.\)

which simply matches one character. Then, when prompted for the replacement:

    \1....\#^J

Note: '^J' represents where a newline should be placed, it should not be entered into the prompt. The newline must instead be inserted literally using C-q C-j.

The replacement expression reads: "Insert the matched text between the first set of parentheses (in this case, a single character), followed by 4 periods then insert an automatically incremented number followed by a newline.

Finally, press ! to apply this across the entire buffer. All of the formatting that was performed in the previous section was performed with a single regexp replacement.

### Rectangular selections

A very powerful feature you may expect from advanced text editors is the possibility to select and edit text in a rectangular area.

This also works in Emacs. Select your text as usual with C-SPC. Now you can use several rectangular command.

    C-x r t  Replace rectangle with text.
    C-x r k  Kill (and save in kill-ring) rectangle.
    C-x r y  Yank rectangle.
    C-x r o  Blank out rectangle.

Note that the command will not affect text outside the rectangle, even though it is highlighted.

### Bookmarks

Emacs can remember a list of visited files.

    C-x r m Add current buffer to bookmarks.
    C-x r b Open a buffer from bookmarks.
    C-x r l List bookmarks.

### Elisp interpreter

Evaluate an elisp expression using eval-last-sexp (C-x C-e). Emacs always spawns a *scratch* buffer when started. It will not be saved to disk, feel free to add any text / code you want. It is especially useful for elisp evaluation. Note that this buffer starts using lisp-interaction-mode by default.

Alternatively, Emacs provides a top-level elisp interpreter with the ielm command.

### Smart window switch

The traditional window switch with C-x o can be cumbersome to use in the long run. The windmove commands provide a more convenient way to do this. All you have to do is to hold down `Shift` while pointing at a window with the arrow keys.

To activate the windmove keys, use the following in your configuration file:

    ~/.emacs

    (when (fboundp 'windmove-default-keybindings)
      (windmove-default-keybindings))

### Shell calls

Use M-! to call an external command. Use a prefix argument (C-u M-!) to output the result to current buffer at point.

You can use M-| on a region to use it as input for a command. For instance

    C-u M-| sort -u RET

will sort region, remove duplicates and replace the region with the result.

### Shell buffers

You can spawn a shell buffer and execute commands just like you would do in any terminal. A classic shell buffer can be spawned with the shell command.

Emacs features a very powerful shell entirely written in Emacs Lisp, the eshell. The major advantage over shells like csh or zsh is that the native shell language is elisp itself. So you can use all advanced feature of elisp for your shell functions.

### Show matching parentheses

You can use the show-paren mode. By default, there’s a small delay before showing a matching parenthesis. Set the show-paren-delay to 0 to deactivate it.

    ~/.emacs

    (setq show-paren-delay 0)
    (show-paren-mode 1)

### Spell checking

You can choose the dictionary with

    M-x ispell-change-dictionary

To check a single work use M-$. You can start checking the whole buffer with

    M-x ispell-buffer

You can enable on-the-fly spell checking by enabling the flyspell-mode. For source code files you can restrict the mode to comments by using the flyspell-prog-mode instead. You will also need the aspell package for spelling in Emacs. There are corresponding packages for each language, so for English, you'd also want aspell-en (as well as aspell).

### Tables

Emacs comes with some powerful functions to handle and generate tables for various languages. Let's show an example.

    Fruits  Quantity
    Apples  5
    Melons  2

Now select the previous content in a region, and run

    table-capture

Use two spaces for the column delimiter, and a line break (C-q C-j) for the row delimiter. This will lead to the following result.

    +------+--------+
    |Fruits|Quantity|
    +------+--------+
    |Apples|5       |
    +------+--------+
    |Melons|2       |
    +------+--------+

You can revert back the operation with

    table-release

There is a lot of handy table-* functions, like table-insert-row, table-span-cell, table-widen-cell, etc.

Finally, the ultimate purpose of the table functions is to convert it to the desired markup language. Use the table-generate-source for that. For LaTeX, the previous table would result in

    % This LaTeX table template is generated by emacs 24.2.1
    \begin{tabular}{|l|l|}
    \hline
    Fruits & Quantity \\
    \hline
    Apples & 5 \\
    \hline
    Melons & 2 \\
    \hline
    \end{tabular}

Using the table mode you can also do some spreadsheet work like sum on rows and columns, but you will quickly find it limited. Besides it is quite slow. Have a look at the org-mode for much more powerful possibilities.

### Agenda, spreadsheet and document authoring

Emacs can offer powerful office features thanks to the famous and powerful Org mode. This mode is part of the standard Emacs distribution.

Org mode is originally a powerful TODO and Agenda agent, but has quickly evolved to a much wider set of features. There is simply too much to tell about Org that we cannot aford even to skim over all the features. So we will only whet your appetite with a few exemples.

Open a new file TODO.org file, Org mode should be loaded. If not, switch to it with M-x org-mode.

    TODO.org

    * First entry
    ** Subentry
       Some comments
    *** Subsubentry
    * Second entry
      - List item 1
      - List item 2

Now a few useful bindings.

- TAB to cycle-fold current entry.
- S-TAB to cycle-fold all entries.
- M-RET to start a new item on the same level as the current one.
- M-<left> and M-<right> to change level.
- M-<up> and M-<down> to move item together with all its subsections.
- S-<left> and S-<right> to change status. On list items it will change the item style.
- S-<up> and S-<down> to change priority.
- C-c ^ to sort all subentries of the current entry.
- C-c . to add a timestamp to the current entry. Use `Shift` and arrows to skip days or weeks. Use the mouse on the calendar or press `Enter` on a specific day to choose it.

The spreadsheet features are very comprehensive. Let's give an excerpt from the manual:

        Finally, just to whet your appetite for what can be done with the
     fantastic `calc.el' package, here is a table that computes the Taylor
     series of degree `n' at location `x' for a couple of functions.

         |---+-------------+---+-----+--------------------------------------|
         |   | Func        | n | x   | Result                               |
         |---+-------------+---+-----+--------------------------------------|
         | # | exp(x)      | 1 | x   | 1 + x                                |
         | # | exp(x)      | 2 | x   | 1 + x + x^2 / 2                      |
         | # | exp(x)      | 3 | x   | 1 + x + x^2 / 2 + x^3 / 6            |
         | # | x^2+sqrt(x) | 2 | x=0 | x*(0.5 / 0) + x^2 (2 - 0.25 / 0) / 2 |
         | # | x^2+sqrt(x) | 2 | x=1 | 2 + 2.5 x - 2.5 + 0.875 (x - 1)^2    |
         | * | tan(x)      | 3 | x   | 0.0175 x + 1.77e-6 x^3               |
         |---+-------------+---+-----+--------------------------------------|
         #+TBLFM: $5=taylor($2,$4,$3);n3

Org mode recognizes a table when the pipe | is the first non-whitespace character on line. In the previous text, no line was drawn. This is done automatically when TAB is pressed after an entry or the |- sequence. The result column was not written by hand neither, it is computed from the calc formula on the last line. Use C-u C-c C-c to recompute all values in a table.

There is also some handy row and column manipulation bindings like those for the TODO file. `Alt` plus arrows will move columns and arrows.

For more in-depth details, refer to the official manual: C-h i m Org mode RET.

### Refactoring and smart completion

If you are looking for popular programming features found in most IDE (such as Eclipse), the Semantic tool will do the job. It is part of Emacs standard distribution. Currently C, C++, Scheme, Javascript, Java, HTML, and Make are well supported. You can find a table on the current support state on the CEDET page.

Open a file in your favorite programming language supported by Semantic and turn on the Semantic minor mode with

    M-x semantic-mode

Semantic will work for a few seconds parsing the libraries included from your file (in C that would mostly be the standard library for instance).

#### Features

Once done, you can start using the great Semantic features:

Smart completion

Press C-c , SPC to complete a symbol at point. If it is an argument, it will check for type correctness.

Jump to symbol

Press C-c , j to prompt for a symbol and jump to its definition. You can use auto-completion with TAB. Use a capital J to search for symbol accross files.

List symbol calls

Press C-c , g to prompt for a symbol and list the places where it is being referred to. You can use n and p to navigate through the resulting entries. Press RET to toggle details, and RET again on a reference to jump to it. Use a capital G in the first command to work across files.

Refactoring

First list use of the symbol you want to refactor with the aforementioned command. Now press ( to start defining a macro on the symbol. This is actually much more powerful than refactoring since you can apply any function to the symbol and even act on its surrounding symbols. Press C-x ) to finish the macro and E to call it.

Describe symbol

Call the following function to display details on a symbol.

    semantic-ia-show-summary

This can be very useful for complexe data structures and function prototypes. There is no binding by default.

#### Configuration

Here follows a sample configuration for use of Semantic with all supported programming languages: an example binding and a display configuration.

    ;; Semantic with ghost display (allows M-n and M-p to browse completion).
    (semantic-mode 1)
    (define-key my-keys-minor-mode-map (kbd "C-c , d") 'semantic-ia-show-summary)
    (setq semantic-complete-inline-analyzer-displayor-class 'semantic-displayor-ghost)

You can also add some specialization for a specific language. Here for C:

    (add-hook
     'c-mode-hook
     (lambda ()
       (local-set-key (kbd "M-TAB") 'semantic-complete-analyze-inline)
       (local-set-key "." 'semantic-complete-self-insert)
       (local-set-key ">" 'semantic-complete-self-insert)))

#### Further reading

You can access the info manual directly from Emacs: C-h i m Semantic RET.

### Using Emacs as git mergetool

By default, Git provides support for using Emacs' Emerge mode as a merge tool. However you may prefer the Ediff mode. Unfortunately this mode is not supported by git for technical reasons. There is still a way to use it by evaluating some elisp code upon emacs call.

    .gitconfig

    [mergetool.ediff]
        cmd = emacs --eval \" (progn (defun ediff-write-merge-buffer () (let ((file ediff-merge-store-file)) (set-buffer ediff-buffer-C) (write-region (point-min) (point-max) file) (message \\\"Merge buffer saved in: %s\\\" file) (set-buffer-modified-p nil) (sit-for 1))) (setq ediff-quit-hook 'kill-emacs ediff-quit-merge-hook 'ediff-write-merge-buffer) (ediff-merge-files-with-ancestor \\\"$LOCAL\\\" \\\"$REMOTE\\\" \\\"$BASE\\\" nil \\\"$MERGED\\\"))\"

    [merge]
    	tool = ediff

Note that the command has to be on a single line. In the above example, we launch a new instance of Emacs. You might want to use emacsclient for quicker startup; it is not recommended though since the Ediff call is not really clean: it could mess with your current Emacs session.

If you want an instant startup you can use the -q parameter. If you want to launch Emacs quickly while preserving at least a part of your configuration, you can call Emacs with

     emacs -q -l ~/.emacs-light

where the light configuration file loads only what you need for Ediff.

See kerneltrap.org and stackoverflow for more details on this trick and the Ediff issue.

### Using Caps Lock as Control key

Some users like this behavior to avoid the so-called 'emacs pinky'. If you want to try it on X, just run

    $ setxkbmap -option 'ctrl:nocaps'

Alternatively, to swap these keys, run

    $ setxkbmap -option 'ctrl:swapcaps'

To set this permanently, consider adding it to your `.xinitrc` file.

Now, if you ever need to upcase an region, just use the default `C-x C-u` keybinding, which calls the `upcase-region` function.

See [1] for an alternative approach.

If you are missing your Caps Lock function, map it as both "Shift" at same time.

    $ setxkbmap -option "shift:both_capslock"

## Customization

Emacs can be configured by editing `~/.emacs` or using M-x customize. This section will focus on editing `~/.emacs` by hand, and provide some example customizations to demonstrate commonly-configured aspects of Emacs. The customize command provides a simple interface to make adjustments, though it may become restricting as you grow more familiar with Emacs.

All of the examples here can be performed while Emacs is running. To evaluate the expression within Emacs, use:

C-M-x with point anywhere within the expression.

or

C-x C-e with point following the last ')'

For some users, typing 'yes' and 'no' in prompts can quickly become tiring. To instead use the 'y' and 'n' keys at these prompts:

    (defalias 'yes-or-no-p 'y-or-n-p)

To stop the cursor blinking, use:

    (blink-cursor-mode -1)

Similarly, to enable column-number-mode, as discussed in the previous section:

    (column-number-mode 1)

The similarities between the previous two commands are not a coincidence: blink-cursor-mode and column-number-mode are both minor-modes. As a rule, minor-modes can be enabled given positive argument or disabled with a negative argument. Should the argument be omitted, the minor-mode will be toggled on/off.

Here are some more examples of minor-modes. The following will disable the scroll bars, menu-bar and tool-bar, respectively.

    (scroll-bar-mode -1)
    (menu-bar-mode -1)
    (tool-bar-mode -1)

The variable, 'auto-mode-alist', can be modified to change the major-mode used by default for certain file names. The following example will make the default major-mode for '.tut' and '.req' files 'text-mode'.

    (setq auto-mode-alist
      (append
        '(("\\.tut$" . text-mode)
          ("\\.req$" . text-mode))
        auto-mode-alist))

Settings can also be applied on a per-mode basis. A common method for this is to add a function to a hook. For example, to force indentation to use spaces instead of tabs, but only in text-mode:

    (add-hook 'text-mode-hook (lambda () (setq indent-tabs-mode nil)))

Similarly, to only use spaces for indentation everywhere:

    (setq-default indent-tabs-mode nil)

Keybindings can be adjusted in two ways. The first of which is 'define-key'. 'define-key' creates a keybinding for a command but only in one mode. The example below will make F8 delete any whitespace from the end of each line of a 'text-mode' buffer:

    (define-key text-mode-map (kbd "<f8>") 'delete-trailing-whitespace)

The other method is 'global-set-key'. This is used to bind a key to a command everywhere. To bind 'query-replace-regexp' (C-M-%) to '<f7>'.

    (global-set-key (kbd "<f7>") 'query-replace-regexp)

Binding a command to an alternate key does not replace any existing bindings. Which is to say, 'query-replace-regexp' would be bound to both F7 and C-M-% after the above example.

Almost anything within Emacs can be configured. Browsing through the Emacs Wiki should give a solid place to start.

### Multiplexing emacs and emacsclient

To open the new file in the same `emacs-session` its use needs use to use `emacsclient`. `emacs` command can be itself warpped to do the smarter job to open the file if the session exists.

To start session you need to `start-server`. This snippet will create server in first session of emacs. Add this to your `emacs` configuration file.

    .emacs or .emacs.d/init.el

    (require 'server)
    (unless (server-running-p)
      (server-start))

Shell alias method is not adequate for this since you also need to pass variables or start the independent session of your own. Add this to the `.bashrc` or any rc file of your shell. This will make your `$ emacs` command behave like emacsclient if the argument is passed.

    function emacs {
        if [[ $# -eq 0 ]]; then
            /usr/bin/emacs # "emacs" is function, will cause recursion
            return
        fi
        args=($*)
        for ((i=0; i <= ${#args}; i++)); do
            local a=${args[i]}
            # NOTE: -c for creating new frame
            if [[ ${a:0:1} == '-' && ${a} != '-c' ]]; then
                /usr/bin/emacs ${args[*]}
                return
            fi
        done
        setsid emacsclient -n -a /usr/bin/emacs ${args[*]}
    }

If you want to run the it in new session just do `emacs <file> -`.

### Multiple configurations

You can use several configurations and tell Emacs to load one or the other.

For example, let's define two configuration files.

    .emacs

    (load "~/.emacs.d/main" nil t)
    (load "~/.emacs.d/functions" nil t)
    (load "~/.emacs.d/modes" nil t)
    (load "~/.emacs.d/plugins" nil t)
    (load "~/.emacs.d/theme" nil t)

This is the full configuration we load for the daemon. But the plugins file is huge and slow to load. If we want to spaqn a new Emacs instance that does not need the plutings features, it can be cumbersome to load it everytime in the long time.

    .emacs-light

    (load "~/.emacs.d/main" nil t)
    (load "~/.emacs.d/functions" nil t)
    (load "~/.emacs.d/modes" nil t)
    (load "~/.emacs.d/theme" nil t)

And now we launch Emacs with

    emacs -q -l ~/.emacs-light

You can create an alias to ease the call.

### Loading extensions

You can load extensions using the require function. For instance

    (require 'mediawiki)

If you try using the same configuration file on a machine where mediawiki is not installed, Emacs will primpt for an error. Besides, all extension-specific code would be parsed for nothing.

The trick is to test the return value of require:

    (if (require 'mediawiki nil t)
        (progn
          (setq mediawiki-site-alist '(
                 ("ArchLinux" "https://wiki.archlinux.org/" "UserName" "" "Main Page")
                 )
               )
          (setq mediawiki-mode-hook
                (lambda ()
                  (visual-line-mode 1)
                  (turn-off-auto-fill)
                  ))
     ))

### Local and custom variables

You can define variables in your configuration file that can be later one modified locally for a file.

    (defcustom my-compiler "gcc" "Some documentation")

Now in any file you can define local variables in two ways:

- On the very first line, write

    // -*- my-compiler:g++; mode:c++ -*-

- If you cannot (or do not want to) write this on the first line, you can put it at the end:

    // Local Variables:
    // my-compiler: g++
    // mode: c++
    // End:

Note that the beginning characters need to be comments for the current language, that's why here we used two backslashes for C++. For Elisp you would use

    ;; -*- mode:emacs-lisp -*-

There is two functions that may help you in defining the variables: add-file-local-variable and add-file-local-variable-prop-line.

Finally, custom variable are considered insecure by default. If you try to open a file that contains local variable redefining insecure custom variables, Emacs will ask you for confirmation.

If you know what you are doing, you can declare the variable as secure, thus removing the Emacs prompt for confirmation. You need to specify a predicate that any new value has to verify so that it can be considered safe.

    (defcustom my-compiler "gcc" "Some documentation" :safe 'stringp)

In the previous example, if you attempt to set anything else than a string, Emacs will consider it insecure.

### Custom colors and theme

Colors can be easily customized using the face facility.

    (set-face-background  'region                 "color-17")
    (set-face-foreground  'region                 "white")
    (set-face-bold-p      'font-lock-builtin-face t )

You can have let Emacs tell you the name of the face where the point is. Use the customize-face function for that. The facility will show you how to set colors, bold, underline, etc.

Emacs in console can handle 256 colors, but you will have to use an appropriate terminal for that. For instance URxvt has support for 256 colors. You can use the list-colors-display for a comprehensive list of supported colors. This is highly terminal-dependent.

### SyncTeX support

Emacs is a powerful LaTeX editor. This is mostly due to the fact you can adapt or create a LaTeX mode to fit your needs best.

Still, there might be some challenges, like SyncTeX support. First you need to make sure your TeX distribution has it. If you installed TeX Live manually, you may need to install the synctex package.

    # umask 022 && tlmgr install synctex

SyncTeX support is viewer-dependent. Here we will use Zathura as an example, so the code needs to be adapted if you want to use another PDF viewer.

    (defcustom tex-my-viewer "zathura --fork -s -x \"emacsclient --eval '(progn (switch-to-buffer  (file-name-nondirectory \"'\"'\"%{input}\"'\"'\")) (goto-line %{line}))'\""
      "PDF Viewer for TeX documents. You may want to fork the viewer
    so that it detects when the same document is launched twice, and
    persists when Emacs gets closed.

    Simple command:

      zathura --fork

    We can use

      emacsclient --eval '(progn (switch-to-buffer  (file-name-nondirectory \"%{input}\")) (goto-line %{line}))'

    to reverse-search a pdf using SyncTeX. Note that the quotes and double-quotes matter and must be escaped appropriately."
    :safe 'stringp)

Here we define our custom variable. If you are using AucTeX or Emacs default LaTeX-mode, you will have to set the viewer accordingly.

Now open a LaTeX source file with Emacs, compile the document, and launch the viewer. Zathura will spawn. If you press `Ctrl+Left click` Emacs should place the point at the corresponding position.

### Syntax highlighting for systemd Files

You can use systemd-mode.

Alternatively, you can simply tell emacs to colour systemd files (services, timer, etc.), by adding this to your init file:

     (add-to-list 'auto-mode-alist '("\\.service\\'" . conf-unix-mode))
     (add-to-list 'auto-mode-alist '("\\.timer\\'" . conf-unix-mode))
     (add-to-list 'auto-mode-alist '("\\.target\\'" . conf-unix-mode))
     (add-to-list 'auto-mode-alist '("\\.mount\\'" . conf-unix-mode))
     (add-to-list 'auto-mode-alist '("\\.automount\\'" . conf-unix-mode))
     (add-to-list 'auto-mode-alist '("\\.slice\\'" . conf-unix-mode))
     (add-to-list 'auto-mode-alist '("\\.socket\\'" . conf-unix-mode))
     (add-to-list 'auto-mode-alist '("\\.path\\'" . conf-unix-mode))
     (add-to-list 'auto-mode-alist '("\\.netdev\\'" . conf-unix-mode))
     (add-to-list 'auto-mode-alist '("\\.network\\'" . conf-unix-mode))
     (add-to-list 'auto-mode-alist '("\\.link\\'" . conf-unix-mode))
     (add-to-list 'auto-mode-alist '("\\.automount\\'" . conf-unix-mode))

### Clipboard support for emacs-nox

To use the Xorg clipboard in emacs-nox, install xclip and add the following function to `~/.emacs` [2]

    ;; use xclip to copy/paste in emacs-nox
    (unless window-system
      (when (getenv "DISPLAY")
        (defun xclip-cut-function (text &optional push)
          (with-temp-buffer
    	(insert text)
    	(call-process-region (point-min) (point-max) "xclip" nil 0 nil "-i" "-selection" "clipboard")))
        (defun xclip-paste-function()
          (let ((xclip-output (shell-command-to-string "xclip -o -selection clipboard")))
    	(unless (string= (car kill-ring) xclip-output)
    	  xclip-output )))
        (setq interprogram-cut-function 'xclip-cut-function)
        (setq interprogram-paste-function 'xclip-paste-function)
        ))

Tip: You may also enable terminal mouse support by adding:

    ;; xterm mouse support
    (require 'mouse)
    (xterm-mouse-mode t)

See also mwheel.el.

## Documentation

You may find yourself overwhelmed by the amount of Emacs features. You may find it difficult to know how to use Emacs Lisp to customize your favorite modes, or even to create your own modes / packages. Thankfully Emacs takes a strong point to auto-documenting everything: its internals, current configuration, bindings, etc. Almost everything is documented.

### Contextual help

Emacs is self-documenting by design. As such, a great deal of information is available to determine the name of a specific command or its keybinding, for example. The following is a listing of some of the most helpful of these:

    C-h a        Find a command matching a description.

    C-h b        List all active keybindings.

    C-h f        Describe the given function.

    C-h k        Find which command a key is bound to.

    C-h m        Display information regarding the currently active modes.

    C-h t        Start the Emacs tutorial.

    C-h v        Describe the given variable.

    C-h w        Find which key(s) a command is bound to.

### The manuals

If you really want to master Emacs, the most recommanded source of documentation remains the official manuals:

- Emacs: the complete Emacs user manual.
- Emacs FAQ.
- Emacs Lisp Intro: if you never used any programming language before.
- Elisp: if you are already familiar with a programming language.

You can access it as PDFs from GNU.org or directly from Emacs itself thanks to the embedded 'info' reader: C-h i. Press m to choose a book.

Some users prefer to read books using 'info' because of its convenient shortcuts, its paragraphs adapting to window width and the font adapted to current screen resolution. Some find it less irritating to the eyes. Finally you can easily copy content from the book to any Emacs buffer, and you can even execute Lisp code snippets directly from the examples.

You may want to read the Info book to know more about it: C-h i m info <RET>. Press ? while in info mode for a quick list of shortcuts.

## Extensions

Emacs includes hundreds of modes, libraries and other extensions, with many more available to further Emacs' capabilities. Most of these come with instructions detailing any changes needed to be made in `~/.emacs`. These instructions are generally found in the comment block at the beginning of an elisp source file, or in a README (or similar), should the extension consist of multiple source files.

A number of popular extensions are available as packages in the 'community' repository, and more still, via AUR. The name of such packages have a 'emacs-' prefix (for example, emacs-lua-mode). In many cases, the changes which need to be made in `~/.emacs` are shown during the installation of the package.

Should instructions describing how to activate a specific extension not be available in the aforementioned location(s), check for a corresponding page in the Emacs Wiki, which will almost certainly provide an example configuration. The Emacs Wiki is also an excellent resource for discovering even more extensions.

You can also use the Emacs Lisp Package Archive (ELPA) to automatically install packages. See the website for instructions. ELPA is included with Emacs 24 (the newest version of Emacs); it is an accepted part of the Emacs ecosystem. Also, check out the Marmalade and MELPA repos.

Tip: Use `M-x list-packages` to get a list of available packages for installation.

### Emacs MediaWiki

Since we are at it, you may be a contributor to Arch Linux Wiki, or any Mediawiki-based website. Then emacs will become your best friend thanks to the Emacs Mediawiki extension. Check the dedicated page for more details.

## Troubleshooting

### Colored output issues

By default, the Emacs shell will show raw escape sequences used to print colors. In other words, it will display strange symbols in place of the desired colored output.

Including the following into `~/.emacs` amends the problem:

    (add-hook 'shell-mode-hook 'ansi-color-for-comint-mode-on)

### Menus appear empty

A bug exists in GNU Emacs 23.1 (using the GTK toolkit) which may cause some menus to appear empty. This appears to be fixed in Emacs' CVS trunk. The corresponding Debian bug report contains a workaround.

### Problems displaying characters in X Windows

If when you start emacs in X windows all the characters in the main window are white boxes with black borders (the ones you see if you try to view characters for which you do not have the correct font installed), you need to install xorg-fonts-75dpi and/or xorg-fonts-100dpi and restart X windows.

### Slow startup

Slow startup times are often caused by one of two things.

To determine which it might be, run Emacs with:

    $ emacs -q

If this solves the problem, see #Init file loads slowly.

- Mistakes, particularly in /etc/hosts, will often result in a 5+ second delay when starting Emacs. Refer to 'set the hostname' in the network configuration guide for information.

- You may need to monitor any network packets sent from your computer (using a program like Wireshark) to see if there is any strange behavior.

- A simple way to search for the cause is to comment-out (i.e., prefix lines with ';') suspect sections of your `~/.emacs` (or `~/.emacs.d/init.el`) then start Emacs again to see if there's any change. Keep in mind use of "require" and "load" can slow the startup down, especially when used with larger extensions. They should, as a rule, only be used when their target is either: needed once Emacs starts or provides little more than "autoloads" for an extension. Otherwise, use the 'autoload function directly. For example, instead of:

    (require 'anything)

you might use:

    (autoload 'anything "anything" "Select anything" t)

### Cannot open load file: ...

The most common cause of this error is the 'load-path' variable not including the path to the directory within which the extension is located. To solve this, add the appropriate path to the list to be searched prior to attempting to load the extension:

     (add-to-list 'load-path "/path/to/directory/")

When attempting to use packages for extensions and Emacs has been configured with a prefix other than '/usr', the load-path will need to be updated. Place the following in `~/.emacs` prior to the instructions provided by the package:

     (add-to-list 'load-path "/usr/share/emacs/site-lisp")

If compiling Emacs by hand, keep in mind that the default prefix is '/usr/local'.

### Dead-accent keys problem: '<dead-acute> is undefined'

Searching about this bug on Google, we find this link: http://lists.gnu.org/archive/html/help-gnu-emacs/2009-05/msg00167.html

Explaining the problem: in recent versions of b72

    Emacs, the normal way to use accent keys doesn't work as expected. Trying to accent a word like 'fiancé' will produce the message above.

A way to solve it is just put the line above on your startup file, `~/.emacs`:

      (require 'iso-transl)

And no, it isn't a bug, but a feature of new Emacs versions. Reading the subsequent messages about it on the mail list, we found it (http://lists.gnu.org/archive/html/help-gnu-emacs/2009-05/msg00179.html):

  It seems that nothing is loaded automatically because there is a choice betwee iso-transl and iso-acc. Both seem to provide an input method with C-x 8 or Alt-<accent> prefix, but what you and I are doing is just pressing a dead key (^, ´, `, ~, ¨) for the accent and then another key to "compose" the accented character. And there is no Alt key used in this! And according to documentation it seems be appropriate for 8-bit encodings, so it should be pretty useless in UTF-8. I reported this bug when it was introduced, but the bug seems to be classified as a feature ... Maybe it's just because the file is auto-loaded though pretty useless.

### C-M-% and some other bindings do not work in emacs nox

This is because terminals are more limited than Xorg. Some terminals may handle more bindings than other, though. Two solutions:

- either use the graphical version,
- or change the binding to a supported one.

Example:

    .emacs

    (global-set-key (kbd "C-M-y") 'query-replace-regexp)

### Emacs client gets stuck when switching back to it

If you are using Emacs daemon, then you should know that input is blocking. If one Emacs instance is in the minibuffer (after an M-x for instance), then all other instance will wait for it to finish. Press C-g to cancel any input to make sure this Emacs session is not blocking.

### Emacs-nox output gets messy

When working in a terminal, the color, indentation, or anything related to the output might become crazy. This is (probably?) because Emacs was sent a special character at some point which may conflict with the current terminal. There is not much to be done but restarting emacs. If someone has a workaround or a more detailed explanation on the issue, feel free to contribute.

Graphical Emacs does not suffer from this issue.

### Shift + Arrow keys not working in emacs within tmux

First you must enable xterm-keys in your tmux config.

    .tmux.conf

    setw -g xterm-keys on

But, this will break other key combinations. To fix them, put the following in your emacs config.

    .emacs

    ;; handle tmux's xterm-keys
    ;; put the following line in your ~/.tmux.conf:
    ;;   setw -g xterm-keys on
    (if (getenv "TMUX")
        (progn
          (let ((x 2) (tkey ""))
    	(while (<= x 8)
    	  ;; shift
    	  (if (= x 2)
    	      (setq tkey "S-"))
    	  ;; alt
    	  (if (= x 3)
    	      (setq tkey "M-"))
    	  ;; alt + shift
    	  (if (= x 4)
    	      (setq tkey "M-S-"))
    	  ;; ctrl
    	  (if (= x 5)
    	      (setq tkey "C-"))
    	  ;; ctrl + shift
    	  (if (= x 6)
    	      (setq tkey "C-S-"))
    	  ;; ctrl + alt
    	  (if (= x 7)
    	      (setq tkey "C-M-"))
    	  ;; ctrl + alt + shift
    	  (if (= x 8)
    	      (setq tkey "C-M-S-"))

    	  ;; arrows
    	  (define-key key-translation-map (kbd (format "M-[ 1 ; %d A" x)) (kbd (format "%s<up>" tkey)))
    	  (define-key key-translation-map (kbd (format "M-[ 1 ; %d B" x)) (kbd (format "%s<down>" tkey)))
    	  (define-key key-translation-map (kbd (format "M-[ 1 ; %d C" x)) (kbd (format "%s<right>" tkey)))
    	  (define-key key-translation-map (kbd (format "M-[ 1 ; %d D" x)) (kbd (format "%s<left>" tkey)))
    	  ;; home
    	  (define-key key-translation-map (kbd (format "M-[ 1 ; %d H" x)) (kbd (format "%s<home>" tkey)))
    	  ;; end
    	  (define-key key-translation-map (kbd (format "M-[ 1 ; %d F" x)) (kbd (format "%s<end>" tkey)))
    	  ;; page up
    	  (define-key key-translation-map (kbd (format "M-[ 5 ; %d ~" x)) (kbd (format "%s<prior>" tkey)))
    	  ;; page down
    	  (define-key key-translation-map (kbd (format "M-[ 6 ; %d ~" x)) (kbd (format "%s<next>" tkey)))
    	  ;; insert
    	  (define-key key-translation-map (kbd (format "M-[ 2 ; %d ~" x)) (kbd (format "%s<delete>" tkey)))
    	  ;; delete
    	  (define-key key-translation-map (kbd (format "M-[ 3 ; %d ~" x)) (kbd (format "%s<delete>" tkey)))
    	  ;; f1
    	  (define-key key-translation-map (kbd (format "M-[ 1 ; %d P" x)) (kbd (format "%s<f1>" tkey)))
    	  ;; f2
    	  (define-key key-translation-map (kbd (format "M-[ 1 ; %d Q" x)) (kbd (format "%s<f2>" tkey)))
    	  ;; f3
    	  (define-key key-translation-map (kbd (format "M-[ 1 ; %d R" x)) (kbd (format "%s<f3>" tkey)))
    	  ;; f4
    	  (define-key key-translation-map (kbd (format "M-[ 1 ; %d S" x)) (kbd (format "%s<f4>" tkey)))
    	  ;; f5
    	  (define-key key-translation-map (kbd (format "M-[ 15 ; %d ~" x)) (kbd (format "%s<f5>" tkey)))
    	  ;; f6
    	  (define-key key-translation-map (kbd (format "M-[ 17 ; %d ~" x)) (kbd (format "%s<f6>" tkey)))
    	  ;; f7
    	  (define-key key-translation-map (kbd (format "M-[ 18 ; %d ~" x)) (kbd (format "%s<f7>" tkey)))
    	  ;; f8
    	  (define-key key-translation-map (kbd (format "M-[ 19 ; %d ~" x)) (kbd (format "%s<f8>" tkey)))
    	  ;; f9
    	  (define-key key-translation-map (kbd (format "M-[ 20 ; %d ~" x)) (kbd (format "%s<f9>" tkey)))
    	  ;; f10
    	  (define-key key-translation-map (kbd (format "M-[ 21 ; %d ~" x)) (kbd (format "%s<f10>" tkey)))
    	  ;; f11
    	  (define-key key-translation-map (kbd (format "M-[ 23 ; %d ~" x)) (kbd (format "%s<f11>" tkey)))
    	  ;; f12
    	  (define-key key-translation-map (kbd (format "M-[ 24 ; %d ~" x)) (kbd (format "%s<f12>" tkey)))
    	  ;; f13
    	  (define-key key-translation-map (kbd (format "M-[ 25 ; %d ~" x)) (kbd (format "%s<f13>" tkey)))
    	  ;; f14
    	  (define-key key-translation-map (kbd (format "M-[ 26 ; %d ~" x)) (kbd (format "%s<f14>" tkey)))
    	  ;; f15
    	  (define-key key-translation-map (kbd (format "M-[ 28 ; %d ~" x)) (kbd (format "%s<f15>" tkey)))
    	  ;; f16
    	  (define-key key-translation-map (kbd (format "M-[ 29 ; %d ~" x)) (kbd (format "%s<f16>" tkey)))
    	  ;; f17
    	  (define-key key-translation-map (kbd (format "M-[ 31 ; %d ~" x)) (kbd (format "%s<f17>" tkey)))
    	  ;; f18
    	  (define-key key-translation-map (kbd (format "M-[ 32 ; %d ~" x)) (kbd (format "%s<f18>" tkey)))
    	  ;; f19
    	  (define-key key-translation-map (kbd (format "M-[ 33 ; %d ~" x)) (kbd (format "%s<f19>" tkey)))
    	  ;; f20
    	  (define-key key-translation-map (kbd (format "M-[ 34 ; %d ~" x)) (kbd (format "%s<f20>" tkey)))

    	  (setq x (+ x 1))
    	  ))
          )
      )

### Improper window resizing in KDE

This article or section is a candidate for merging with KDE.

Notes: Applicable to other applications (Discuss in Talk:Emacs#)

KDE users may observe that the Emacs window does not resize properly, but rather, the resized portion is transparent and mouse clicks are sent to the underlying window. To correct this behavior, change KDE's GTK3 theme to something other than oxygen-gtk. For instance, use the Emacs theme which is included with gtk3.

To force Emacs to maximize completely in KDE, click the Emacs icon in the title bar, and select More Actions > Special Window Settings. Then in the "Size & Position" tab, select "Obey geometry restrictions", choose "Force" in the dropdown menu, and select "No" from the radio buttons on the right.

### Invalid font name for Oxygen-Sans

When emacs (24.5-2) and ttf-oxygen (1:5.4.3-1) are installed, you will get an error like:

    Error:invalid font name.-unknown-Oxygen-Sans-nolmal-normal--15----*-0-iso10646-1

when setting font attributes. This seems to be a bug in emacs, which is fixed in emacs-git (25.1.50.r125104-1).

## Alternatives

There are numerous "smaller" implementations of Emacs. GNU/Emacs is probably the most popular. Some lightweight Emacs compatible alternatives will be listed here:

### mg

mg (originally called MicroGnuEmacs) is a lightweight implementation of Emacs written in C.

mg is available in the official repositories and it is also possible to download its source from its upstream page. Beware mg has no UTF-8 support.

### zile

According to the official web page "GNU Zile is a lightweight Emacs clone. Zile is short for "Zile Is Lossy Emacs". Zile has been written to be as similar as possible to Emacs; every Emacs user should feel at home.". Zile has no UTF-8 support.

zile can be found in the official repositories.

The latest upstream tarballs can be found in official GNU mirrors.

### uemacs

uemacs is a "Micro-emacs" version customized by Linus Torvalds . Available as uemacs-gitAUR in the AUR.

The latest (2005) tarball can be found here.

## See also

- GNU Emacs home page
- GNU Emacs manual
- Emacs Wiki
- WikEmacs - a more readable, but less complete Emacs wiki
- Useful introduction to Emacs and its shortcuts
- The Church of Emacs (via Google drive)
- Official reference card

Categories:

- Development
- Text editors

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