Difference between revisions of "Emacs"

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[[Category:Development]]
 
[[Category:Text editors]]
 
[[Category:Text editors]]
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[[ja:Emacs]]
 
[[sr:Emacs]]
 
[[sr:Emacs]]
{{Article summary start|Summary}}
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[[zh-hans:Emacs]]
{{Article summary text|Tutorial on acquiring and using the Emacs text editor.}}
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[[Wikipedia:Emacs|Emacs]] is an extensible, customizable, self-documenting real-time display editor. At the core of Emacs lies an [[Wikipedia:Emacs Lisp|Emacs Lisp]] interpreter, the language in which the majority of Emacs' built-in functionality and extensions are implemented. GNU Emacs uses GTK as its X toolkit, though it functions equally well within a CLI environment. The text-editing capabilities of Emacs are often compared to that of [[vim]].
{{Article summary end}}
 
  
[[Wikipedia:Emacs|Emacs]] is the extensible, customizable, self-documenting real-time display editor.  At the core of Emacs lies an [[Wikipedia:Emacs Lisp|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 ==
  
== Installation ==
 
 
Emacs comes in several variants (sometimes referred to as ''emacsen''). The most common of these is [http://www.gnu.org/software/emacs/ GNU Emacs].
 
Emacs comes in several variants (sometimes referred to as ''emacsen''). The most common of these is [http://www.gnu.org/software/emacs/ GNU Emacs].
  
[[pacman|Install]] {{Pkg|emacs}}, available in the [[Official Repositories]].
+
[[Install]] {{Pkg|emacs}}, available in the [[official repositories]]. If you usually work in a terminal, you may prefer the {{Pkg|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).
  
Another common variant is {{Pkg|xemacs}}.
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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 {{ic|gtk3}} you can get rid of gconf. Image and sound support can be disabled as well. Run {{ic|./configure --help}} in Emacs source folder to list all available options.
 +
{{hc|PKGBUILD|<nowiki>
 +
# ...
 +
  ./configure --prefix=/usr --sysconfdir=/etc --libexecdir=/usr/lib \
 +
    --localstatedir=/var --with-x-toolkit=gtk2 --with-xft \
 +
    --without-gconf --without-sound
 +
# ...
 +
</nowiki>}}
  
== Quick Start ==
+
== Running Emacs ==
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.
+
Before launching emacs, you should know how to close it (especially if you run it in a terminal): use the
 
+
{{ic|Ctrl+x}}{{ic|Ctrl+c}} key sequence.
Emacs also includes a set of reference cards, useful for beginners and experts alike, see {{ic|/usr/share/emacs/<version>/etc/refcards/}} (substitute <version> for your version of emacs).
 
  
===Running Emacs===
 
====Normal way====
 
 
To start Emacs run:
 
To start Emacs run:
  
Line 30: Line 37:
  
 
  $ emacs -nw
 
  $ emacs -nw
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 +
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:
 
A file name can also be provided to open that file immediately:
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  $ emacs filename.txt
 
  $ emacs filename.txt
  
====As a daemon====
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=== No Colors ===
Emacs can take some time to start since it has to load the .emacs file each time. Since version 23, Emacs is capable to run as a daemon to which users can connect. To run Emacs as a daemon:
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 +
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 ===
 +
 
 +
In order to avoid reloading the Emacs config file every time Emacs starts, you can run Emacs as a daemon:
  
 
  $ emacs --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.
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You may then connect to the daemon by running:
 +
 
 +
$ emacsclient -nc
 +
 
 +
Which creates a new frame {{ic|-c}} (use {{ic|-t}} if you prefer to use it in the terminal) and does not hog the terminal {{ic|-n}} ({{ic|--no-wait}}).
 +
Note that some programs such as Mutt or Git (for commit messages) wait for the editor to finish, so you cannot use the {{ic|-n}} parameter.
 +
If your default editor is set to use it, you will have to specify an alternate editor (''e.g.'' {{ic|emacsclient -a "" -t}}) for those programs.
  
If you want to connect to the daemon simply use the folowing 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):
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=== As a systemd unit ===
  
$ emacsclient
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The old system unit method had some caveats. It gave a limited shell environment which restricted shell calls, so we will be using a user unit, which tends to work a lot better than naively calling ''emacs --daemon''.
  
If you still want a console client no matter you are in a graphical environment then use:
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Create a systemd unit for emacs:
  
$ emacsclient -t
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{{Note|1=Such a unit file is planned for inclusion in Emacs 26.1, see [https://debbugs.gnu.org/cgi/bugreport.cgi?bug=16507 emacs bug 16507].}}
  
Furthermore, you can add the {{ic|-a ""}} parameter.
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{{hc|~/.config/systemd/user/emacs.service|<nowiki>
Now, the first time you call the command, it will start emacs as a daemon, so that it remains running in background to improve startup time for future calls (and to remember buffers as well).
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[Unit]
 +
Description=Emacs: the extensible, self-documenting text editor
  
In the end, you could use the following alias:
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[Service]
 +
Type=forking
 +
ExecStart=/usr/bin/emacs --daemon
 +
ExecStop=/usr/bin/emacsclient --eval "(kill-emacs)"
 +
Restart=always
  
$ alias emacs='emacsclient -t -a ""'
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[Install]
 +
WantedBy=default.target
 +
</nowiki>}}
  
With xfce, if you want to tell it to use emacsclient -c instead of emacs %f when opening a new file, you can change your /usr/share/applications/emacs.desktop and change the line
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You need to start and enable the unit so that it gets started on every boot (note - DO ''NOT'' run this as root - we want them for our user, not for the root user):
  
  $ Exec=emacs %f
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  $ systemctl --user enable --now emacs
  
To
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Note that systemd user units do not inherit environment variables from a login shell (like {{ic|~/.bash_profile}}), so you may want to set the variables in {{ic|~/.pam_environment}} instead. See [[Systemd/User]] for more information.
  
$ Exec=emacsclient -c
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== Usage ==
  
This way, a client will be called each time you open up a file and so be very fast!
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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.
  
===Basic terminology and convention===
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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'.
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'.
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Emacs is self-documenting by designAs such, a great deal of information is available to determine the name of a specific command or its keybinding, for example. See all contextual help bindings with '''C-h C-h'''.
  
The convention for key sequences in Emacs may be unfamiliar. Namely:
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Emacs also includes a set of reference cards, useful for beginners and experts alike, see {{ic|/usr/share/emacs/<version>/etc/refcards/}} (substitute <version> for your version of emacs).
  
'''C-x''' refers to Control-x
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Emacs empowers the users with a tremendous amount of features, including:
 +
keyboards macros, rectangular regions, whitespace cleanup, bookmarks, desktop session, various shells, spell checking, tables, semantic analysis...
  
'''M-x''' refers to Meta-x
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=== The manuals ===
  
{{Note|'Meta' corresponds to the Alt key in most cases. Alternatively, the Esc key can be used.}}
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If you really want to master Emacs, the most recommended 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.
  
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.
+
You can access it as PDFs from [http://www.gnu.org/software/emacs/manual/ GNU.org] or directly from Emacs itself thanks to the embedded 'info' reader: '''C-h i'''. Press '''m''' to choose a book.
  
===Movement===
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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.
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.
+
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.
  
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.
+
== Tips and tricks ==
  
{{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 [[Emacs#Modes|Modes]] for more information.}}
+
=== TRAMP ===
  
===Files and buffers===
+
TRAMP (Transparent Remote Access, Multiple Protocols) is an extension which, as its name suggests, provides transparent access to remote files across a number of protocolsWhen prompted for a filename, entering a specific form will invoke TRAMPSome examples:
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 bufferTo 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 diskIt 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, kill the buffer ('''C-x k''') prior to '''C-x C-f''' or use '''M-x revert-buffer'''.}}
+
To prompt for the root password before opening /etc/hosts with root permissions:
  
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.
+
C-x C-f /sudo::/etc/hosts
  
The minibuffer also provides a history feature.  The previous items entered for a command can be recalled using the '''Up Arrow''' or '''C-p'''.
+
To connect to 'remotehost' as 'you' via SSH and open the file ~/example.txt:
  
To exit the minibuffer at any time, press '''C-g'''.
+
C-x C-f /ssh:you@remotehost:~/example.txt
  
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.
+
The path for TRAMP is typically of the form '/[protocol]:[[user@]host]:<file>'.   
  
{{Note|To switch to the previous buffer use '''C-x b <RET>''', as the previous buffer is the default.}}
+
To connect to 'myhost' as 'you' and edit /etc/hosts with sudo:
  
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'''.
+
  /ssh:you@remotehost|sudo:remotehost:/etc/hosts
  
===Editing===
+
TRAMP supports much more than the examples above might indicate.  For more information refer to the TRAMP info manual, which is distributed with Emacs.
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'''.
+
=== Using Emacs as git mergetool ===
  
Characters and words can be transposed using '''C-t''' and '''M-t''', respectively. For example: <code>Hello World!</code> → <code>World! Hello</code>
+
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.
  
The case of words is also readily adjustable. '''M-l''' downcases a word from point (<code>HELLO</code> → <code>hello</code>); '''M-u''' upcases a word from point (<code>hello</code> → <code>HELLO</code>) and '''M-c''' capitalizes the first character of a word from point while downcasing the remainder (<code>hElLo</code> → <code>Hello</code>).
+
{{hc|.gitconfig|<nowiki>
 +
[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\\\"))\"
  
===Killing, yanking and regions===
+
[merge]
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.
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tool = ediff
 +
</nowiki>}}
  
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.
+
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.
  
'''C-w''' and '''M-w''' can be used to kill and copy a region, respectively.
+
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.
  
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.
+
See [http://kerneltrap.org/mailarchive/git/2007/7/1/250424 kerneltrap.org]{{Dead link|2017|06|02}} and [http://stackoverflow.com/questions/1817370/using-ediff-as-git-mergetool stackoverflow] for more details on this trick and the Ediff issue.
  
===Search and replace===
+
=== Using Caps Lock as Control key ===
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.
+
Some users like this behavior to avoid the so-called 'emacs pinky'. If you want to try it on X, just run
  
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.
+
  $ setxkbmap -option 'ctrl:nocaps'
  
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.
+
Alternatively, to '''swap''' these keys, run
  
===Indentation and prefix arguments===
+
$ setxkbmap -option 'ctrl:swapcaps'
Indentation is usually performed with either '''<TAB>''', to indent a single line, or with '''C-M-\''', to indent a 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 [[Emacs#Modes|Modes]] for more information.)
+
To set this permanently, consider adding it to your {{ic|.xinitrc}} file.  
  
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 [[Emacs#Killing, yanking and regions|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:
+
Now, if you ever need to upcase an region, just use the default {{ic|C-x C-u}} keybinding, which calls the {{ic|upcase-region}} function.
  
Increase the region's indentation by four columns:
+
See [http://ergoemacs.org/emacs/swap_CapsLock_Ctrl.html] for an alternative approach.
  
C-u 4 C-x <TAB>
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If you are missing your Caps Lock function, map it as both "Shift" at same time.
  
Decrease the region's indentation by two columns.
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$ setxkbmap -option "shift:both_capslock"
  
C-u -2 C-x <TAB>
+
=== Multiplexing emacs and emacsclient ===
  
{{Note|The trick behind this is '''C-u''', which 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').  In this case, we provided the amount of indentation desired to the command invoked by '''C-x <TAB>'''. Without providing an argument, '''C-x <TAB>''' will only increase indentation by 1 column.}}
+
Opening a new file in the same {{ic|emacs-session}} requires the use of {{ic|emacsclient}}. {{ic|emacs}} command can be itself wrapped to do the smarter job to open the file if the session exists.
  
===Windows and frames===
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To start session you need to {{ic|start-server}}. This snippet will create server in first session of emacs. Add this to your {{ic|emacs}} configuration file.
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''.
+
{{hc|.emacs or .emacs.d/init.el|
 +
(require 'server)
 +
(unless (server-running-p)
 +
  (server-start))
 +
}}
  
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.
+
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 {{ic|.bashrc}} or any rc file of your shell. This will make your {{ic|$ emacs}} command behave like emacsclient if the argument is passed.
  
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').
+
<nowiki>
 +
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[*]}
 +
} </nowiki>
  
From now on the definition of these terms as they exist in Emacs will be used.
+
If you want to run the it in new session just do {{ic|emacs <file> -}}.
  
To split the window vertically or horizontally, 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'''.
+
=== Multiple configurations ===
  
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.
+
You can use several configurations and tell Emacs to load one or the other.
  
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.
+
For example, let us define two configuration files.
  
{{Note|These commands do not affect buffers. For example, deleting a window does not kill the buffer it displays.}}
+
{{hc|.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)
 +
}}
  
===Getting help===
+
This is the full configuration  we load for the daemon. But the ''plugins'' file is huge and slow to load. If we want to spawn a new Emacs instance that does not need the ''plugins'' features, it can be cumbersome to load it everytime in the long run.
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 t'''        Start the Emacs tutorial
+
{{hc|.emacs-light|
+
(load "~/.emacs.d/main" nil t)
'''C-h b'''        List all active keybindings
+
(load "~/.emacs.d/functions" nil t)
+
(load "~/.emacs.d/modes" nil t)
'''C-h k'''        Find which command a key is bound to
+
(load "~/.emacs.d/theme" nil t)
+
}}
'''C-h w'''        Find which key(s) a command is bound to
+
 
+
And now we launch Emacs with
'''C-h a'''        Find a command matching a description
+
  emacs -q -l ~/.emacs-light
+
You can create an alias to ease the call.
  '''C-h m'''        Display information regarding the currently active modes
+
 
+
=== Local and custom variables ===
'''C-h f'''        Describe the given function
+
 
 +
You can define variables in your configuration file that can be later one modified locally for a file.
  
===Modes===
+
(defcustom my-compiler "gcc" "Some documentation")
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:
+
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:
  
'''M-x sh-mode <RET>'''
+
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 -*-
  
'''M-x column-number-mode <RET>'''
+
There is two functions that may help you in defining the variables: ''add-file-local-variable'' and ''add-file-local-variable-prop-line''.
  
line-number-mode is enabled by default, though, it can be toggled on/off by issuing the command again:
+
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.
  
'''M-x line-number-mode <RET>'''
+
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.
  
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:
+
  (defcustom my-compiler "gcc" "Some documentation" :safe 'stringp)
  
'''C-c (''' Insert a function definition
+
In the previous example, if you attempt to set anything else than a string, Emacs will consider it insecure.
 
'''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.
+
=== Custom colors and theme ===
  
==Tips and tricks==
+
Colors can be easily customized using the ''face'' facility.
While the previous sections has given an overview of the basic editing commands available, it has not given an indication of the possibilities of EmacsThis section will cover some more advanced techniques and functionality.
+
  (set-face-background  'region                "color-17")
 +
(set-face-foreground  'region                "white")
 +
(set-face-bold-p      'font-lock-builtin-face t )
  
===TRAMP===
+
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.
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:
+
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.
  
C-x C-f /su::/etc/hosts
+
See also:
  
To connect to 'myhost' as 'myuser' via SSH and open the file ~/example.txt:
+
* https://www.emacswiki.org/emacs/ColorThemes
 +
* https://www.gnu.org/software/emacs/manual/html_node/emacs/Custom-Themes.html
  
C-x C-f /ssh:myuser@myhost:~/example.txt
+
=== SyncTeX support ===
  
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.
+
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.
  
===Keyboard macros and registers===
+
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.
This section will provide a practical demonstration of the use of a couple of more powerful editing features. Namely, ''keyboard macros'' and ''registers''.
+
# umask 022 && tlmgr install synctex
  
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.
+
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.
  
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.
+
(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)
  
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.
+
Here we define our custom variable. If you are using AucTeX or Emacs default LaTeX-mode, you will have to set the viewer accordingly.
  
Starting with a buffer containing our set of characters:
+
Now open a LaTeX source file with Emacs, compile the document, and launch the viewer. Zathura will spawn. If you press {{ic|Ctrl+Left click}} Emacs should place the point at the corresponding position.
ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz
 
  
Prepare a register by invoking the `number-to-register' command ('''C-x r n''') then storing the number '0' in register 'k':
+
=== Syntax highlighting for systemd Files ===
  
C-x r n k
+
You can use [https://github.com/holomorph/systemd-mode systemd-mode].
  
With point at the beginning of the buffer, start a keyboard macro ('''C-x (''') and begin to format the characters:
+
Alternatively, you can simply tell emacs to colour systemd files (services, timer, etc.), by adding this to your init file:
  
C-x ( C-f M-4 .
+
  (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))
  
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:
+
=== Clipboard support for emacs-nox ===
  
C-u C-x r i k C-x r + k
+
To use the [[Xorg]] clipboard in emacs-nox, [[install]] {{Pkg|xclip}} and add the following function to {{ic|~/.emacs}} [https://lists.gnu.org/archive/html/help-gnu-emacs/2014-08/msg00189.html]
  
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.
+
{{bc|1=
 +
;; 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)
 +
    ))
 +
}}
  
<RET> M-0 C-x e
+
{{Tip|You may also enable terminal mouse support by adding:
 +
{{bc|1=
 +
;; xterm mouse support
 +
(require 'mouse)
 +
(xterm-mouse-mode t)
 +
}}
 +
See also [http://www.opensource.apple.com/source/emacs/emacs-51/emacs/lisp/mwheel.el mwheel.el].}}
  
The result:
+
== Extensions ==
  
  A....0
+
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 {{ic|~/.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.
  B....1
 
  C....2
 
  [...]
 
  x....49
 
  y....50
 
  z....51
 
  
===Regular expressions===
+
You can use the [http://tromey.com/elpa/ Emacs Lisp Package Archive (ELPA)] to automatically install packagesSee the manual for instructionsELPA is included with Emacs 24 and above; it is an accepted part of the Emacs ecosystem. Also, check out [http://melpa.milkbox.net/ MELPA] for additional packages.
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 [http://www.gnu.org/software/emacs/manual/html_node/elisp/Regular-Expressions.html#Regular-Expressions 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 [[Emacs#Keyboard macros and registers|Keyboard macros and registers]]).  Again, starting with a buffer containing.
+
{{Tip|Use {{ic|M-x list-packages}} to get a list of available packages for installation.}}
  
  ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz
+
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 {{ic|~/.emacs}} are shown during the installation of the package.
  
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:
+
You can load extensions using the ''require'' function. For instance
  \(.\)
+
  (require 'mediawiki)
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.
+
If you try using the same configuration file on a machine where the extension is not installed, Emacs will primpt for an error. Besides, all extension-specific code would be parsed for nothing.
  
===Customization===
+
The trick is to test the return value of ''require'':
Emacs can 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:
+
  (when (require 'mediawiki nil t)
 +
  (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)))))
  
'''C-M-x''' with point anywhere within the expression.
+
Should instructions describing how to activate a specific extension not be available in the aforementioned location(s), check for a corresponding page in the [http://emacswiki.org/ Emacs Wiki], which will almost certainly provide an example configuration.  The Emacs Wiki is also an excellent resource for discovering even more extensions.
  
or
+
{{Tip|A few popular extensions worth checking out: AucTeX, auto-complete, company, el-doc, emms, helm, Magit, multiple-cursors, Org-mode, Projectile, yasnippet.}}
  
'''C-x C-e''' with point following the last ')'
+
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.
  
For some users, typing 'yes' and 'no' in prompts can quickly become tiring.  To instead use the 'y' and 'n' keys at these prompts:
+
== Troubleshooting ==
  
(defalias 'yes-or-no-p 'y-or-n-p)
+
=== Colored output issues ===
  
To stop the cursor blinking, use:
+
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.
  
  (blink-cursor-mode -1)
+
Including the following into {{ic|~/.emacs}} amends the problem:
 +
  (add-hook 'shell-mode-hook 'ansi-color-for-comint-mode-on)
  
Similarly, to enable column-number-mode, as discussed in the previous section:
+
=== Problems displaying characters in X Windows ===
  
(column-number-mode 1)
+
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 {{Pkg|xorg-fonts-75dpi}} and/or {{Pkg|xorg-fonts-100dpi}} and restart X windows.
  
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.
+
=== Slow startup ===
  
Here are some more examples of minor-modes.  The following will disable the scroll bars, menu-bar and tool-bar, respectively.
+
{{Tip|To eliminate startup time, users may want to consider running Emacs [[#As a systemd unit]].}}
  
(scroll-bar-mode -1)
+
Slow startup times are often caused by one of two things.
(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'.
+
To determine which it might be, run Emacs with:
  
  (setq auto-mode-alist
+
  $ emacs -q
  (append
 
    '(("\\.tut$" . text-mode)
 
      ("\\.req$" . text-mode))
 
    auto-mode-alist))
 
  
Settings can also be applied on a per-mode basisA 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:
+
* Mistakes, particularly in /etc/hosts, will often result in a 5+ second delay when starting EmacsRefer to '[[Configuring_network#Set_the_hostname|set the hostname]]' in the network configuration guide for information.  
  
(add-hook 'text-mode-hook (lambda () (setq indent-tabs-mode nil)))
+
* 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.
  
Similarly, to only use spaces for indentation everywhere:
+
* A simple way to search for the cause is to comment-out (i.e., prefix lines with ';') suspect sections of your {{ic|~/.emacs}} (or {{ic|~/.emacs.d/init.el}}) then start Emacs again to see if there is 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:
  
  (setq-default indent-tabs-mode nil)
+
  (require 'anything)
  
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:
+
you might use:
  
  (define-key text-mode-map (kbd "<f8>") 'delete-trailing-whitespace)
+
  (autoload 'anything "anything" "Select anything" t)
  
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>'.
+
=== Cannot open load file: ... ===
  
(global-set-key (kbd "<f7>") 'query-replace-regexp)
+
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:
  
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.
+
  (add-to-list 'load-path "/path/to/directory/")
  
Almost anything within Emacs can be configuredBrowsing through the [http://emacswiki.org/ Emacs Wiki] should give a solid place to start.
+
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 updatedPlace the following in {{ic|~/.emacs}} prior to the instructions provided by the package:
  
=== Extensions ===
+
  (add-to-list 'load-path "/usr/share/emacs/site-lisp")
  
While Emacs includes hundreds of modes, libraries and other extensions, there are many more available to further Emacs' capabilities.  The majority of these come with instructions detailing any changes needed to be made to ~/.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.
+
If compiling Emacs by hand, keep in mind that the default prefix is '/usr/local'.
  
A number of popular extensions are available as packages in the 'community' repository, and more still are available via the [[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 to ~/.emacs are shown during the installation of the package.
+
=== Dead-accent keys problem: '<dead-acute> is undefined' ===
  
Should instructions describing how to activate a specific extension not be available in the aforementioned location(s), check for a corresponding page in the [http://emacswiki.org/ Emacs Wiki], which will almost certainly provide an example configuration.  The Emacs Wiki is also an excellent resource for discovering even more extensions.
+
Searching about this bug on Google, we find this link:
 +
http://lists.gnu.org/archive/html/help-gnu-emacs/2009-05/msg00167.html
  
You can also use the [http://tromey.com/elpa/ 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.
+
Explaining the problem: in recent versions of
 +
b72
 +
Emacs, the normal way to use accent keys does not work as expected. Trying to accent a word like 'fiancé' will produce the message above.
  
== Troubleshooting ==
+
A way to solve it is just put the line above on your startup file, {{ic|~/.emacs}}:
  
===Colored output issues===
+
  (require 'iso-transl)
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 {{ic|~/.emacs}} amends the problem:
+
And no, it is not 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):
(add-hook 'shell-mode-hook 'ansi-color-for-comint-mode-on)
 
  
===Menus appear empty===
+
:''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. ''
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 [http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=550541 Debian bug report] contains a workaround.
 
  
=== Problems displaying characters in X Windows ===
+
=== C-M-% and some other bindings do not work in emacs nox ===
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 {{pkg|xorg-fonts-75dpi}} and/or {{pkg|xorg-fonts-100dpi}} and restart X windows.
 
  
=== Slow startup ===
+
This is because terminals are more limited than Xorg. Some terminals may handle more bindings than other, though. Two solutions:
Slow startup times are often caused by one of two things.
+
* either use the graphical version,
 +
* or change the binding to a supported one.
  
To determine which it might be, run Emacs with:
+
Example:
 +
{{hc|.emacs|
 +
(global-set-key (kbd "C-M-y") 'query-replace-regexp)
 +
}}
  
$ emacs -q
+
=== Emacs client gets stuck when switching back to it ===
  
If Emacs still starts slowly, refer to [[Emacs#Incorrect network configuration|Incorrect network configuration]]. If not, it is almost certainly a [[Emacs#Init file loads slowly|problem in your .emacs]].
+
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.
  
====Incorrect network configuration====
+
=== Emacs-nox output gets messy ===
  
Mistakes, particularly in /etc/hosts, will often result in a 5+ second delay when starting Emacs. Refer to '[[Configuring_network#Set_the_hostname|set the hostname]]' in the network configuration guide for information.
+
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.
  
====Init file loads slowly====
+
Graphical Emacs does not suffer from this issue.
  
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:
+
=== Shift + Arrow keys not working in emacs within tmux ===
  
(require 'anything)
+
Enable xterm-keys in your [[tmux]] configuration:
  
you might use:
+
{{hc|~/.tmux.conf|
 +
setw -g xterm-keys on
 +
}}
  
(autoload 'anything "anything" "Select anything" t)
+
Because this will break other key combinations, put the following in your emacs config.
  
=== Cannot open load file: ... ===
+
{{hc|~/.emacs|
 +
(defadvice terminal-init-screen
 +
  ;; The advice is named `tmux', and is run before `terminal-init-screen' runs.
 +
  (before tmux activate)
 +
  ;; Docstring. This describes the advice and is made available inside emacs;
 +
  ;; for example when doing C-h f terminal-init-screen RET
 +
  "Apply xterm keymap, allowing use of keys passed through tmux."
 +
  ;; This is the elisp code that is run before `terminal-init-screen'.
 +
  (if (getenv "TMUX")
 +
    (let ((map (copy-keymap xterm-function-map)))
 +
    (set-keymap-parent map (keymap-parent input-decode-map))
 +
(set-keymap-parent input-decode-map map))))
 +
}}
  
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:
+
See [https://github.com/tmux/tmux/blob/master/FAQ#L242 tmux FAQ] for details.
  
  (add-to-list 'load-path "/path/to/directory/")
+
=== Improper window resizing in KDE ===
  
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:
+
{{Merge|KDE|Applicable to other applications}}
  
  (add-to-list 'load-path "/usr/share/emacs/site-lisp")
+
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 {{Pkg|gtk3}}.
  
If compiling Emacs by hand, keep in mind that the default prefix is '/usr/local'.
+
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.
  
 
== Alternatives ==
 
== Alternatives ==
  
There are numerous implementations of Emacs. GNU/Emacs is probably the most popular. <br>
+
There are numerous "smaller" implementations of Emacs. GNU/Emacs is probably the most popular. Some lightweight Emacs compatible alternatives will be listed here:
Lighter Emacs compatibile alternatives can be found in Arch repositories or in [https://aur.archlinux.org/ AUR].
 
  
 
=== mg ===
 
=== mg ===
  
mg (originally called MicroGnuEmacs) is lightweight implementation of Emacs written in C.
+
'''mg''' (originally called MicroGnuEmacs) is a lightweight implementation of Emacs written in C.
  
It's possible to install mg right away from {{ic|community}}
+
{{Pkg|mg}} is available in the [[official repositories]] and it is also possible to download its source from its upstream [http://homepage.boetes.org/software/mg/ page]. Beware '''mg''' has no UTF-8 support.
# pacman -S mg
 
or download source from official [http://homepage.boetes.org/software/mg/ page].
 
  
 
=== zile ===
 
=== zile ===
  
According to the offical web [https://www.gnu.org/software/zile/ 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.".
+
According to the official web [https://www.gnu.org/software/zile/ 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 {{ic|extra}}
+
{{Pkg|zile}} can be found in the official repositories.
  
# pacman -S zile
+
The latest upstream tarballs can be found in official GNU [http://ftp.sh.cvut.cz/MIRRORS/gnu/pub/gnu/zile/ mirrors].{{Dead link|2017|06|02}}
  
the latest taballs can be found in official GNU [http://ftp.sh.cvut.cz/MIRRORS/gnu/pub/gnu/zile/ mirrors].
+
=== uemacs ===
  
=== uemacs ===
+
'''uemacs''' is a "Micro-emacs" version customized by Linus Torvalds . Available as {{AUR|uemacs-git}} in the [[AUR]].
  
uemacs is "Micro-emacs version customized by Linus Torvalds".
+
The latest (2005) tarball can be found [ftp://ftp.cs.helsinki.fi/pub/Software/Local/uEmacs-PK/ here].
It can be found in [https://aur.archlinux.org/ AUR] as [https://aur.archlinux.org/packages.php?ID=31502 uemacs].
 
  
 
== See also ==
 
== See also ==
 +
 
* [http://www.gnu.org/software/emacs/ GNU Emacs home page]
 
* [http://www.gnu.org/software/emacs/ GNU Emacs home page]
* [http://www.gnu.org/software/emacs/manual/emacs.html GNU Emacs Manual]
+
* [http://www.gnu.org/software/emacs/manual/emacs.html GNU Emacs manual]
* [http://www.emacswiki.org/cgi-bin/wiki/ Emacs Wiki]
+
* [http://www.emacswiki.org/cgi-bin/wiki/ Emacs Wiki]{{Dead link|2017|06|02}}
* [http://wikemacs.org WikEmacs - a more readable, but less complete Emacs Wiki]
+
* [http://wikemacs.org WikEmacs - a more readable, but less complete Emacs wiki]
 
* [http://www2.lib.uchicago.edu/keith/tcl-course/emacs-tutorial.html Useful introduction to Emacs and its shortcuts]
 
* [http://www2.lib.uchicago.edu/keith/tcl-course/emacs-tutorial.html Useful introduction to Emacs and its shortcuts]
* [http://www.dina.kvl.dk/~abraham/religion/ The Church of Emacs]
+
* [https://d0edfcdc0ccc1cd13cdab5eb986fb92e8660dbef.googledrive.com/host/0B6LMD0u8OhYYZEotN2QyR1hwR1k/ The Church of Emacs (via Google drive)]{{Dead link|2017|06|02}}
* [http://repo.or.cz/w/emacs.git/blob/HEAD:/etc/refcards/refcard.pdf Official reference card]
+
* [http://www.gnu.org/software/emacs/refcards/pdf/refcard.pdf Official reference card]

Latest revision as of 06:50, 10 July 2017

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. GNU Emacs uses GTK as its X toolkit, 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
# ...

Running Emacs

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

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

In order to avoid reloading the Emacs config file every time Emacs starts, you can run Emacs as a daemon:

$ emacs --daemon

You may then connect to the daemon by running:

$ emacsclient -nc

Which creates a new frame -c (use -t if you prefer to use it in the terminal) and does not hog the terminal -n (--no-wait). 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.

As a systemd unit

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

Create a systemd unit for emacs:

Note: Such a unit file is planned for inclusion in Emacs 26.1, see emacs bug 16507.
~/.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 start and enable the unit so that it gets started on every boot (note - DO NOT run this as root - we want them for our user, not for the root user):

$ systemctl --user enable --now emacs

Note that systemd user units do not inherit environment variables from a login shell (like ~/.bash_profile), so you may want to set the variables in ~/.pam_environment instead. See Systemd/User for more information.

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'.

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. See all contextual help bindings with C-h C-h.

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).

Emacs empowers the users with a tremendous amount of features, including: keyboards macros, rectangular regions, whitespace cleanup, bookmarks, desktop session, various shells, spell checking, tables, semantic analysis...

The manuals

If you really want to master Emacs, the most recommended 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.

Tips and tricks

TRAMP

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 /sudo::/etc/hosts

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

C-x C-f /ssh:you@remotehost:~/example.txt

The path for TRAMP is typically of the form '/[protocol]:[[user@]host]:<file>'.

To connect to 'myhost' as 'you' and edit /etc/hosts with sudo:

/ssh:you@remotehost|sudo:remotehost:/etc/hosts

TRAMP supports much more than the examples above might indicate. For more information refer to the TRAMP info manual, which is distributed with Emacs.

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[dead link 2017-06-02] 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"

Multiplexing emacs and emacsclient

Opening a new file in the same emacs-session requires the use of emacsclient. emacs command can be itself wrapped 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 us 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 spawn a new Emacs instance that does not need the plugins features, it can be cumbersome to load it everytime in the long run.

.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.

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.

See also:

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.

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.

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

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

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.

You can load extensions using the require function. For instance

(require 'mediawiki)

If you try using the same configuration file on a machine where the extension 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:

(when (require 'mediawiki nil t)
  (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)))))

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.

Tip: A few popular extensions worth checking out: AucTeX, auto-complete, company, el-doc, emms, helm, Magit, multiple-cursors, Org-mode, Projectile, yasnippet.

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)

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

Tip: To eliminate startup time, users may want to consider running Emacs #As a systemd unit.

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

To determine which it might be, run Emacs with:

$ emacs -q
  • 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 is 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 does not 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 is not 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

Enable xterm-keys in your tmux configuration:

~/.tmux.conf
setw -g xterm-keys on

Because this will break other key combinations, put the following in your emacs config.

~/.emacs
(defadvice terminal-init-screen
  ;; The advice is named `tmux', and is run before `terminal-init-screen' runs.
  (before tmux activate)
  ;; Docstring.  This describes the advice and is made available inside emacs;
  ;; for example when doing C-h f terminal-init-screen RET
  "Apply xterm keymap, allowing use of keys passed through tmux."
  ;; This is the elisp code that is run before `terminal-init-screen'.
  (if (getenv "TMUX")
    (let ((map (copy-keymap xterm-function-map)))
    (set-keymap-parent map (keymap-parent input-decode-map))
(set-keymap-parent input-decode-map map))))

See tmux FAQ for details.

Improper window resizing in KDE

Merge-arrows-2.pngThis article or section is a candidate for merging with KDE.Merge-arrows-2.png

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.

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.[dead link 2017-06-02]

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