AUCTeX

This manual is for AUCTeX (version 13.3 from 2024-01-14), a sophisticated TeX environment for Emacs.

Copyright © 1992-1995, 2001, 2002, 2004-2023 Free Software Foundation, Inc.

Permission is granted to copy, distribute and/or modify this document under the terms of the GNU Free Documentation License, Version 1.3 or any later version published by the Free Software Foundation; with no Invariant Sections, no Front-Cover Texts and no Back-Cover Texts. A copy of the license is included in the section entitled “GNU Free Documentation License.”

AUCTeX is an integrated environment for editing LaTeX, ConTeXt, docTeX, Texinfo, and TeX files.

Although AUCTeX contains a large number of features, there are no reasons to despair. You can continue to write TeX and LaTeX documents the way you are used to, and only start using the multiple features in small steps. AUCTeX is not monolithic, each feature described in this manual is useful by itself, but together they provide an environment where you will make very few LaTeX errors, and makes it easy to find the errors that may slip through anyway.

It is a good idea to make a printout of AUCTeX’s reference card ‘tex-ref.tex’ or one of its typeset versions.

If you want to make AUCTeX aware of style files and multifile documents right away, insert the following in your init file (usually ‘~/.emacs.d/init.el’).

(setq TeX-auto-save t)
(setq TeX-parse-self t)
(setq-default TeX-master nil)

Another thing you should enable is RefTeX, a comprehensive solution for managing cross references, bibliographies, indices, document navigation and a few other things. (See (reftex)Installation section ‘Installation’ in The RefTeX manual.)

For detailed information about the preview-latex subsystem of AUCTeX, see (preview-latex)Top section ‘Introduction’ in The preview-latex Manual.

There is a mailing list for general discussion about AUCTeX: write a mail with “subscribe” in the subject to auctex-request@gnu.org to join it. Send contributions to auctex@gnu.org.

Bug reports should go to bug-auctex@gnu.org, suggestions for new features, and pleas for help should go to either auctex-devel@gnu.org (the AUCTeX developers), or to auctex@gnu.org if they might have general interest. Please use the command M-x TeX-submit-bug-report <RET> to report bugs if possible. You can subscribe to a low-volume announcement list by sending “subscribe” in the subject of a mail to info-auctex-request@gnu.org.

 — The Detailed Node Listing —

Introduction

Editing the Document Source

Inserting Environment Templates

Controlling Screen Display

Font Locking

Starting Processors, Viewers and Other Programs

Viewing the Formatted Output

Catching the errors

Customization and Extension

Language Support

Automatic Customization

Writing Your Own Style Support

Copying, Changes, Development, FAQ

Copying this Manual

Indices

Copying

AUCTeX primarily consists of Lisp files for Emacs, but there are also installation scripts and files and TeX support files. All of those are free; this means that everyone is free to use them and free to redistribute them on a free basis. The files of AUCTeX are not in the public domain; they are copyrighted and there are restrictions on their distribution, but these restrictions are designed to permit everything that a good cooperating citizen would want to do. What is not allowed is to try to prevent others from further sharing any version of these programs that they might get from you.

Specifically, we want to make sure that you have the right to give away copies of the files that constitute AUCTeX, that you receive source code or else can get it if you want it, that you can change these files or use pieces of them in new free programs, and that you know you can do these things.

To make sure that everyone has such rights, we have to forbid you to deprive anyone else of these rights. For example, if you distribute copies of parts of AUCTeX, you must give the recipients all the rights that you have. You must make sure that they, too, receive or can get the source code. And you must tell them their rights.

Also, for our own protection, we must make certain that everyone finds out that there is no warranty for AUCTeX. If any parts are modified by someone else and passed on, we want their recipients to know that what they have is not what we distributed, so that any problems introduced by others will not reflect on our reputation.

The precise conditions of the licenses for the files currently being distributed as part of AUCTeX are found in the General Public Licenses that accompany them. This manual specifically is covered by the GNU Free Documentation License (see Copying this Manual).

1. Introduction

1.1 Overview of AUCTeX

AUCTeX is a comprehensive customizable integrated environment for writing input files for TeX, LaTeX, ConTeXt, Texinfo, and docTeX using Emacs.

It supports you in the insertion of macros, environments, and sectioning commands by providing completion alternatives and prompting for parameters. It automatically indents your text as you type it and lets you format a whole file at once. The outlining and folding facilities provide you with a focused and clean view of your text.

AUCTeX lets you process your source files by running TeX and related tools (such as output filters, post processors for generating indices and bibliographies, and viewers) from inside Emacs. AUCTeX lets you browse through the errors TeX reported, while it moves the cursor directly to the reported error, and displays some documentation for that particular error. This will even work when the document is spread over several files.

One component of AUCTeX that LaTeX users will find attractive is preview-latex, a combination of folding and in-source previewing that provides true “What You See Is What You Get” experience in your sourcebuffer, while letting you retain full control.

More detailed information about the features and usage of AUCTeX can be found in the remainder of this manual.

AUCTeX is written entirely in Emacs Lisp, and hence you can easily add new features for your own needs. It is a GNU project and distributed under the ‘GNU General Public License Version 3’.

The most recent version is always available at https://ftp.gnu.org/pub/gnu/auctex/.

WWW users may want to check out the AUCTeX page at https://www.gnu.org/software/auctex/.

For comprehensive information about how to install AUCTeX See Installation, or Installation under MS Windows, respectively.

If you are considering upgrading AUCTeX, the recent changes are described in Changes.

If you want to discuss AUCTeX with other users or its developers, there are several mailing lists you can use.

Send a mail with the subject “subscribe” to auctex-request@gnu.org in order to join the general discussion list for AUCTeX. Articles should be sent to auctex@gnu.org. In a similar way, you can subscribe to the info-auctex@gnu.org list for just getting important announcements about AUCTeX. The list bug-auctex@gnu.org is for bug reports which you should usually file with the M-x TeX-submit-bug-report <RET> command. If you want to address the developers of AUCTeX themselves with technical issues, they can be found on the discussion list auctex-devel@gnu.org.

1.2 Installing AUCTeX

The modern and strongly recommended way of installing AUCTeX is by using the Emacs package manager integrated in Emacs 24 and greater (ELPA). Simply do M-x list-packages <RET>, mark the auctex package for installation with i, and hit x to execute the installation procedure. That’s all.

use-package users can use this simple recipe in their user-init-file which essentially does the same as the manual installation explained above.

(use-package tex
  :ensure auctex)

Using the ELPA version has several advantages. Besides being platform and OS independent, you will receive intermediate bugfix releases between major AUCTeX releases conveniently. For past ELPA releases, see https://elpa.gnu.org/packages/auctex.html. Once the installation is completed, you can skip the rest of this section and proceed to Quick Start.

The remainder of this section is about installing AUCTeX from a release tarball or from a checkout of the AUCTeX repository.

Installing AUCTeX should be simple: merely ./configure, make, and make install for a standard site-wide installation (most other installations can be done by specifying a ‘--prefix=…’ option).

On many systems, this will already activate the package, making its modes the default instead of the built-in modes of Emacs. If this is not the case, consult Loading the package. Please read through this document fully before installing anything. The installation procedure has changed as compared to earlier versions. Users of MS Windows are asked to consult See Installation under MS Windows.

1.2.1 Prerequisites

• GNU Emacs 26.1 or higher

  Using preview-latex requires a version of Emacs compiled with image support.

  Windows

  Precompiled versions are available from https://ftp.gnu.org/gnu/emacs/windows/.

  macOS

  For an overview of precompiled versions of Emacs for macOS see for example https://www.emacswiki.org/emacs/EmacsForMacOS.

  GNU/Linux

  Most GNU/Linux distributions nowadays provide a recent variant of Emacs via their package repositories.

  Self-compiled

  Compiling Emacs yourself requires a C compiler and a number of tools and development libraries. Details are beyond the scope of this manual. Instructions for checking out the source code can be found at https://savannah.gnu.org/git/?group=emacs.

• A working TeX installation

  Well, AUCTeX would be pointless without that. Processing documentation requires TeX, LaTeX and Texinfo during installation. preview-latex requires Dvips or dvipng for its operation in DVI mode. The default configuration of AUCTeX is tailored for TeX Live-based distributions, but can be adapted easily.

• A recent Ghostscript

  This is needed for operation of preview-latex in both DVI and PDF mode. Ghostscript version 7.07 or newer is required.

• GNU make

  Recent AUCTeX uses GNU make specific capabilities in the Makefiles. If your OS’s default make command is not GNU make, you have to obtain it in order to build AUCTeX by yourself. GNU make is sometimes provided under the name gmake in your OS’s binary package system.

• The Texinfo package

  Strictly speaking, you can get away without it if you are building from the distribution tarball, have not modified any files and don’t need a printed version of the manual: the pregenerated info file is included in the tarball. At least version 4.0 is required.

For some known issues with various software, see (preview-latex)Known problems section ‘Known problems’ in the preview-latex manual.

1.2.2 Configure

The first step is to configure the source code, telling it where various files will be. To do so, run

./configure options

(Note: if you have fetched AUCTeX from Git rather than a regular release, you will have to first follow the instructions in ‘README.GIT’).

On many machines, you will not need to specify any options, but if configure cannot determine something on its own, you’ll need to help it out with one of these options:

--prefix=prefix

All automatic placements for package components will be chosen from sensible existing hierarchies below this: directories like ‘man’, ‘share’ and ‘bin’ are supposed to be directly below prefix.

Only if no workable placement can be found there, in some cases an alternative search will be made in a prefix deduced from a suitable binary.

‘/usr/local’ is the default prefix, intended to be suitable for a site-wide installation. If you are packaging this as an operating system component for distribution, the setting ‘/usr’ will probably be the right choice. See Advice for package providers for detail.

If you are planning to install the package as a single non-priviledged user, you will typically set prefix to your home directory. Consult Advice for non-privileged users for additional instructions.

--with-emacs=/path/to/emacs

If you are using a pretest which isn’t in your PATH, or configure is not finding the right Emacs executable, you can specify it with this option.

--with-lispdir=lispdir

This option specifies the location of the ‘site-lisp’ directory within load-path under which the files will get installed (the bulk will get installed in a subdirectory). ./configure should figure this out by itself.

--with-auctexstartfile=‘auctex.el’

--with-previewstartfile=‘preview-latex.el’

This is the name of the respective startup files. If lispdir contains a subdirectory ‘site-start.d’, the start files are placed there, and ‘site-start.el’ should load them automatically. Please be aware that you must not move the start files after installation since other files are found relative to them.

--with-packagelispdir=‘auctex’

This is the directory where the bulk of the package gets located. The startfile adds this into load-path.

--with-auto-dir=/dir

You can use this option to specify the directory containing automatically generated information by M-x TeX-auto-generate-global <RET>. It is not necessary for most TeX installs, but may be used if you don’t like the directory that configure is suggesting.

--help

This is not an option specific to AUCTeX. A number of standard options to configure exist, and we do not have the room to describe them here; a short description of each is available, using ‘--help’.

--disable-preview

This disables configuration and installation of preview-latex. This option is not actually recommended. If your Emacs does not support images, you should really upgrade to a newer version. Distributors should, if possible, refrain from distributing AUCTeX and preview-latex separately in order to avoid confusion and upgrade hassles if users install partial packages on their own.

--with-texmf-dir=/dir

--without-texmf-dir

This option is used for specifying a TDS-compliant directory hierarchy. Using --with-texmf-dir=/dir you can specify where the TeX TDS directory hierarchy resides, and the TeX files will get installed in ‘/dir/tex/latex/preview/’.

If you use the ‘--without-texmf-dir’ option, the TeX-related files will be kept in the Emacs Lisp tree, and at runtime the TEXINPUTS environment variable will be made to point there. You can install those files into your own TeX tree at some later time with M-x preview-install-styles <RET>.

--with-tex-dir=/dir

If you want to specify an exact directory for the preview TeX files, use --with-tex-dir=/dir. In this case, the files will be placed in ‘/dir’, and you’ll also need the following option:

--with-doc-dir=/dir

This option may be used to specify where the TeX documentation goes. It is to be used when you are using --with-tex-dir=/dir, but is normally not necessary otherwise.

1.2.3 Build/install and uninstall

Once configure has been run, simply enter

make

at the prompt to byte-compile the lisp files, extract the TeX files and build the documentation files. To install the files into the locations chosen earlier, type

make install

You may need special privileges to install, e.g., if you are installing into system directories.

Should you want to completely remove the installed package, in the same directory you built AUCTeX run

make uninstall

You will need administration privileges if you installed the package into system directories.

1.2.4 Loading the package

You can detect the successful activation of AUCTeX and preview-latex in the menus after loading a LaTeX file like ‘circ.tex’: AUCTeX then gives you a ‘Command’ menu, and preview-latex gives you a ‘Preview’ menu.

With Emacs (or if you explicitly disabled use of the package system), the startup files ‘auctex.el’ and ‘preview-latex.el’ may already be in a directory of the ‘site-start.d/’ variety if your Emacs installation provides it. In that case they should be automatically loaded on startup and nothing else needs to be done. If not, they should at least have been placed somewhere in your load-path. You can then load them by placing the lines

(load "auctex.el" nil t t)
(load "preview-latex.el" nil t t)

into your init file such as ‘init.el’ or ‘.emacs’.

If you explicitly used --with-lispdir, you may need to add the specified directory into Emacs’ load-path variable by adding something like

(add-to-list 'load-path "~/elisp")

before the above lines into your Emacs startup file.

For site-wide activation in GNU Emacs, see See Advice for package providers.

Once activated, the modes provided by AUCTeX are used per default for all supported file types. If you want to change the modes for which it is operative instead of the default, use

M-x customize-option <RET> TeX-modes <RET>

If you want to remove a preinstalled AUCTeX completely before any of its modes have been used,

(unload-feature 'tex-site)

should accomplish that.

1.2.5 Providing AUCTeX as a package

As a package provider, you should make sure that your users will be served best according to their intentions, and keep in mind that a system might be used by more than one user, with different preferences.

There are people that prefer the built-in Emacs modes for editing TeX files, in particular plain TeX users. There are various ways to tell AUCTeX even after auto-activation that it should not get used, and they are described in Introduction to AUCTeX.

So if you have users that don’t want to use the preinstalled AUCTeX, they can easily get rid of it. Activating AUCTeX by default is therefore a good choice.

If the installation procedure did not achieve this already by placing ‘auctex.el’ and ‘preview-latex.el’ into a possibly existing ‘site-start.d’ directory, you can do this by placing

(load "auctex.el" nil t t)
(load "preview-latex.el" nil t t)

in the system-wide ‘site-start.el’.

The ‘--without-texmf-dir’ option can be convenient for systems that are intended to support more than a single TeX distribution. Since more often than not TeX packages for operating system distributions are either much more outdated or much less complete than separately provided systems like TeX Live, this method may be generally preferable when providing packages.

The following package structure would be adequate for a typical fully supported Unix-like installation:

‘preview-tetex’

Style files and documentation for ‘preview.sty’, placed into a TeX tree where it is accessible from the teTeX executables usually delivered with a system. If there are other commonly used TeX system packages, it might be appropriate to provide separate packages for those.

‘auctex-emacs-tetex’

This package will require the installation of ‘preview-tetex’ and will record in TeX-macro-global where to find the TeX tree. It is also a good idea to run

emacs -batch -f TeX-auto-generate-global

when either AUCTeX or teTeX get installed or upgraded. If your users might want to work with a different TeX distribution (nowadays pretty common), instead consider the following:

‘auctex-emacs’

This package will be compiled with ‘--without-texmf-dir’ and will consequently contain the ‘preview’ style files in its private directory. It will probably not be possible to initialize TeX-macro-global to a sensible value, so running TeX-auto-generate-global does not appear useful. This package would neither conflict with nor provide ‘preview-tetex’.

1.2.6 Installation for non-privileged users

Often people without system administration privileges want to install software for their private use. In that case you need to pass more options to the configure script.

The main expedient is using the ‘--prefix’ option to the configure script, and let it point to the personal home directory. In that way, resulting binaries will be installed under the ‘bin’ subdirectory of your home directory, manual pages under ‘man’ and so on. It is reasonably easy to maintain a bunch of personal software, since the prefix argument is supported by most configure scripts.

You often need to specify ‘--with-lispdir’ option as well. If you haven’t installed Emacs under your home directory and use Emacs installed in system directories, the configure script might not be able to figure out suitable place to install lisp files under your home directory. In that case, the configure script would silently choose, by default, the ‘site-lisp’ directory within load-path for the place, where administration privileges are usually required to put relevant files. Thus you will have to tell the configure script explicitly where to put those files by, e.g., --with-lispdir=‘/home/myself/share/emacs/site-lisp’.

You’ll have to add something like ‘/home/myself/share/emacs/site-lisp’ to your load-path variable, if it isn’t there already.

In addition, you will have to tell configure script where to install TeX-related files such as ‘preview.sty’ if preview-latex isn’t disabled. It is enough to specify ‘--with-texmf-dir=‘$HOME/texmf’’ for most typical cases, but you have to create the direcotry ‘$HOME/texmf’ in advance if it doesn’t exist. If this prescription doesn’t work, consider using one or more of the options --with-texmf-dir=/dir, --without-texmf-dir, --with-tex-dir=/dir and --with-doc-dir=/dir. See Configure for detail of these options.

Now here is another thing to ponder: perhaps you want to make it easy for other users to share parts of your personal Emacs configuration. In general, you can do this by writing ‘~myself/’ anywhere where you specify paths to something installed in your personal subdirectories, not merely ‘~/’, since the latter, when used by other users, will point to non-existent files.

For yourself, it will do to manipulate environment variables in your ‘.profile’ resp. ‘.login’ files. But if people will be copying just Elisp files, their copies will not work. While it would in general be preferable if the added components where available from a shell level, too (like when you call the standalone info reader, or try using ‘preview.sty’ for functionality besides of Emacs previews), it will be a big help already if things work from inside of Emacs.

Here is how to do the various parts:

Making the Elisp available

In GNU Emacs, it should be sufficient if people just do

(load "~myself/share/emacs/site-lisp/auctex.el" nil t t)
(load "~myself/share/emacs/site-lisp/preview-latex.el" nil t t)

where the path points to your personal installation. The rest of the package should be found relative from there without further ado.

Making the Info files available

For making the info files accessible from within Elisp, something like the following might be convenient to add into your or other people’s startup files:

(eval-after-load 'info
   '(add-to-list 'Info-directory-list "~myself/info"))

Making the LaTeX style available

If you want others to be able to share your installation, you should configure it using ‘--without-texmf-dir’, in which case things should work as well for them as for you.

1.2.6.1 Using AUCTeX from local Git repo

With the techniques described above, it is also possible to use AUCTeX directly from a local Git repository. Let’s assume you have your Git repositories under ‘~/development/’.

First, you have to fetch a copy of the AUCTeX Git repository. In a shell, change directory to ‘~/development/’ and do:

git clone https://git.savannah.gnu.org/git/auctex.git

Now change directory to ‘~/development/auctex’ and run ‘./autogen.sh’. Next thing is to run configure like this:

./configure --without-texmf-dir --with-lispdir=.

When finished, simply enter

make

and you’re finished. Note that the ‘make install’ step is not necessary.

Now you have to tell Emacs about the plan. The following variables must be set in your init file because their normal values are only correct when AUCTeX is installed:

(setq TeX-data-directory "~/development/auctex"
      TeX-lisp-directory TeX-data-directory)

The info files will be available with this:

(eval-after-load 'info
   '(add-to-list 'Info-additional-directory-list
                 "~/development/auctex/doc"))

Now you’re ready to load ‘auctex.el’ and ‘preview-latex.el’ out of this directory:

(load "~/development/auctex/auctex.el" nil t t)
(load "~/development/auctex/preview-latex.el" nil t t)

1.2.7 Installation under MS Windows

In a Nutshell

The following are brief installation instructions for the impatient. In case you don’t understand some of this, run into trouble of some sort, or need more elaborate information, refer to the detailed instructions further below.

1. Install the prerequisites, i.e. GNU Emacs, MSYS or Cygwin, a TeX system, and Ghostscript.
2. Open the MSYS shell or a Cygwin shell and change to the directory containing the unzipped file contents.
3. Configure AUCTeX:

   For Emacs: Many people like to install AUCTeX into the pseudo file system hierarchy set up by the Emacs installation. Assuming Emacs is installed in ‘C:/Program Files/Emacs’ and the directory for local additions of your TeX system, e.g. MiKTeX, is ‘C:/localtexmf’, you can do this by typing the following statement at the shell prompt:

   ./configure --prefix='C:/Program Files/Emacs' \ --infodir='C:/Program Files/Emacs/info' \ --with-texmf-dir='C:/localtexmf'

   The commands above is example for common usage. More on configuration options can be found in the detailed installation instructions below.

   If the configuration script failed to find all required programs, make sure that these programs are in your system path and add directories containing the programs to the PATH environment variable if necessary. Here is how to do that in W2000/XP:

   2. On the desktop, right click “My Computer” and select properties.
   3. Click on “Advanced” in the “System Properties” window.
   4. Select “Environment Variables”.
   5. Select “path” in “System Variables” and click “edit”. Move to the front in the line (this might require scrolling) and add the missing path including drive letter, ended with a semicolon.
4. If there were no further error messages, type

   make

   In case there were, please refer to the detailed description below.

5. Finish the installation by typing

   make install

Detailed Installation Instructions

Installation of AUCTeX under Windows is in itself not more complicated than on other platforms. However, meeting the prerequisites might require more work than on some other platforms, and feel less natural.

If you are experiencing any problems, even if you think they are of your own making, be sure to report them to auctex-devel@gnu.org so that we can explain things better in future.

Windows is a problematic platform for installation scripts. The main problem is that the installation procedure requires consistent file names in order to find its way in the directory hierarchy, and Windows path names are a mess.

The installation procedure tries finding stuff in system search paths and in Emacs paths. For that to succeed, you have to use the same syntax and spelling and case of paths everywhere: in your system search paths, in Emacs’ load-path variable, as argument to the scripts. If your path names contain spaces or other ‘shell-unfriendly’ characters, most notably backslashes for directory separators, place the whole path in ‘"double quote marks"’ whenever you specify it on a command line.

Avoid ‘helpful’ magic file names like ‘/cygdrive/c’ and ‘C:\PROGRA~1\’ like the plague. It is quite unlikely that the scripts will be able to identify the actual file names involved. Use the full paths, making use of normal Windows drive letters like ‘ 'C:/Program Files/Emacs' ’ where required, and using the same combination of upper- and lowercase letters as in the actual files. File names containing shell-special characters like spaces or backslashes (if you prefer that syntax) need to get properly quoted to the shell: the above example used single quotes for that.

Ok, now here are the steps to perform:

1. You need to unpack the AUCTeX distribution (which you seemingly have done since you are reading this). It must be unpacked in a separate installation directory outside of your Emacs file hierarchy: the installation will later copy all necessary files to their final destination, and you can ultimately remove the directory where you unpacked the files.

   Line endings are a problem under Windows. The distribution contains only text files, and theoretically most of the involved tools should get along with that. However, the files are processed by various utilities, and it is conceivable that not all of them will use the same line ending conventions. If you encounter problems, it might help if you try unpacking (or checking out) the files in binary mode, if your tools allow that.

   If you don’t have a suitable unpacking tool, skip to the next step: this should provide you with a working ‘unzip’ command.

2. The installation of AUCTeX will require the MSYS tool set from http://www.mingw.org/ or the Cygwin tool set from https://cygwin.com/. The latter is slower and larger (the download size of the base system is about 15 MB) but comes with a package manager that allows for updating the tool set and installing additional packages like, for example, the spell checker aspell.

   If Cygwin specific paths like ‘/cygdrive/c’ crop up in the course of the installation, using a non-Cygwin Emacs could conceivably cause trouble. Using Cygwin either for everything or nothing might save headaches, if things don’t work out.

3. Install a current version of Emacs from https://ftp.gnu.org/gnu/emacs/windows/.
4. You need a working TeX installation. One popular installation under Windows is MiKTeX. Another much more extensive system is TeX Live which is rather close to its Unix cousins.
5. A working copy of Ghostscript is required for preview-latex operation. Examining the output from

   gswin32c -h

   on a Windows command line should tell you whether your Ghostscript supports the png16m device needed for PNG support. MiKTeX apparently comes with its own Ghostscript called ‘mgs.exe’.

6. Perl is needed for rebuilding the documentation if you are working with a copy from Git or have touched documentation source files in the preview-latex part. If the line endings of the file ‘preview/latex/preview.dtx’ don’t correspond with what Perl calls \n when reading text files, you’ll run into trouble.
7. Now the fun stuff starts. If you have not yet done so, unpack the AUCTeX distribution into a separate directory after rereading the instructions for unpacking above.
8. Ready for takeoff. Start some shell (typically bash) capable of running configure, change into the installation directory and call ./configure with appropriate options.

   Typical options you’ll want to specify will be

   --prefix=drive:/path/to/emacs-hierarchy

   which tells configure where to perform the installation. It may also make configure find Emacs automatically; if this doesn’t happen, try ‘--with-emacs’ as described below. All automatic detection of files and directories restricts itself to directories below the prefix or in the same hierarchy as the program accessing the files. Usually, directories like ‘man’, ‘share’ and ‘bin’ will be situated right under prefix.

   This option also affects the defaults for placing the Texinfo documentation files (see also ‘--infodir’ below) and automatically generated style hooks.

   If you have a central directory hierarchy (not untypical with Cygwin) for such stuff, you might want to specify its root here. You stand a good chance that this will be the only option you need to supply, as long as your TeX-related executables are in your system path, which they better be for AUCTeX’s operation, anyway.

   --with-emacs

   if you are installing for a version of Emacs. You can use ‘--with-emacs=drive:/path/to/emacs’ to specify the name of the installed Emacs executable, complete with its path if necessary (if Emacs is not within a directory specified in your PATH environment setting).

   --with-lispdir=drive:/path/to/site-lisp

   This option tells a place in load-path below which the files are situated. The startup files ‘auctex.el’ and ‘preview-latex.el’ will get installed here unless a subdirectory ‘site-start.d’ exists which will then be used instead. The other files from AUCTeX will be installed in a subdirectory called ‘auctex’.

   If you think that you need a different setup, please refer to the full installation instructions in Configure.

   --infodir=drive:/path/to/info/directory

   If you are installing into an Emacs directory, info files have to be put into the ‘info’ folder below that directory. The configuration script will usually try to install into the folder ‘share/info’, so you have to override this by specifying something like ‘--infodir='C:/Program Files/info'’ for the configure call.

   --with-auto-dir=drive:/dir

   Directory containing automatically generated information. You should not normally need to set this, as ‘--prefix’ should take care of this.

   --disable-preview

   Use this option if your Emacs version is unable to support image display.

   --with-texmf-dir=drive:/dir

   This will specify the directory where your TeX installation sits. If your TeX installation does not conform to the TDS (TeX directory standard), you may need to specify more options to get everything in place.

   For more information about any of the above and additional options, see Configure.

   Some executables might not be found in your path. That is not a good idea, but you can get around by specifying environment variables to configure:

   GS="drive:/path/to/gswin32c.exe" ./configure …

   should work for this purpose. ‘gswin32c.exe’ is the usual name for the required command line executable under Windows; in contrast, ‘gswin32.exe’ is likely to fail.

   As an alternative to specifying variables for the configure call you can add directories containing the required executables to the PATH variable of your Windows system. This is especially a good idea if Emacs has trouble finding the respective programs later during normal operation.

9. Run make in the installation directory.
10. Run make install in the installation directory.
11. With Emacs, activation of AUCTeX and preview-latex depends on a working ‘site-start.d’ directory or similar setup, since then the startup files ‘auctex.el’ and ‘preview-latex.el’ will have been placed there. If this has not been done, you should be able to load the startup files manually with

    (load "auctex.el" nil t t) (load "preview-latex.el" nil t t)

    in either a site-wide ‘site-start.el’ or your personal startup file (usually accessible as ‘~/.emacs’ or ‘~/.emacs.d/init.el’ from within Emacs).

    The default configuration of AUCTeX is probably not the best fit for Windows systems with MiKTeX. You might want to add

    (require 'tex-mik)

    after loading ‘auctex.el’ and ‘preview-latex.el’ in order to get more appropriate values for some customization options.

    You can always use

    M-x customize-group <RET> AUCTeX <RET>

    in order to customize more stuff, or use the ‘Customize’ menu.

12. Load ‘circ.tex’ into Emacs and see if you get the ‘Command’ menu. Try using it to LaTeX the file.
13. Check whether the ‘Preview’ menu is available in this file. Use it to generate previews for the document.

    If this barfs and tells you that image type ‘png’ is not supported, you can either add PNG support to your Emacs installation or choose another image format to be used by preview-latex.

    Adding support for an image format usually involves the installation of a library, e.g. from http://gnuwin32.sf.net/. If you got your Emacs from https://www.gnu.org/ you might want to check its README file for details.

    A different image format can be chosen by setting the variable preview-image-type. While it is recommended to keep the ‘dvipng’ or ‘png’ setting, you can temporarily select a different format like ‘pnm’ to check if the lack of PNG support is the only problem with your Emacs installation.

    Try adding the line

    (setq preview-image-type 'pnm)

    to your init file for a quick test. You should remove the line after the test again, because PNM files take away vast amounts of disk space, and thus also of load/save time.

Well, that about is all. Have fun!

1.2.8 Customizing

Most of the site-specific customization should already have happened during configuration of AUCTeX. Any further customization can be done with customization buffers directly in Emacs. Just type M-x customize-group <RET> AUCTeX <RET> to open the customization group for AUCTeX or use the menu entries provided in the mode menus. Editing the file ‘tex-site.el’ as suggested in former versions of AUCTeX should not be done anymore because the installation routine will overwrite those changes.

You might check some options with a special significance. They are accessible directly by typing M-x customize-option <RET> <option> <RET>.

User Option: TeX-macro-global

Directories containing the site’s TeX style files.

Normally, AUCTeX will only allow you to complete macros and environments which are built-in, specified in AUCTeX style files or defined by yourself. If you issue the M-x TeX-auto-generate-global command after loading AUCTeX, you will be able to complete on all macros available in the standard style files used by your document. To do this, you must set this variable to a list of directories where the standard style files are located. The directories will be searched recursively, so there is no reason to list subdirectories explicitly. Automatic configuration will already have set the variable for you if it could use the program kpsewhich. In this case you normally don’t have to alter anything.

1.3 Quick Start

AUCTeX is a powerful program offering many features and configuration options. If you are new to AUCTeX this might be deterrent. Fortunately you do not have to learn everything at once. This Quick Start Guide will give you the knowledge of the most important commands and enable you to prepare your first LaTeX document with AUCTeX after only a few minutes of reading.

In this introduction, we assume that AUCTeX is already installed on your system. If this is not the case, you should read the file ‘INSTALL’ in the base directory of the unpacked distribution tarball. These installation instructions are available in this manual as well, Installation. We also assume that you are familiar with the way keystrokes are written in Emacs manuals. If not, have a look at the Emacs Tutorial in the Help menu.

If AUCTeX is installed in any other way than from the Emacs package manager (ELPA), you might still need to activate it, by inserting

(load "auctex.el" nil t t)

in your user init file.(1)

If AUCTeX is installed from ELPA, the installation procedure already cares about loading AUCTeX correctly and you must not have the line above in your init file. Note that this also applies if you have the following line in your init file

(package-initialize)

In order to get support for many of the LaTeX packages you will use in your documents, you should enable document parsing as well, which can be achieved by putting

(setq TeX-auto-save t)
(setq TeX-parse-self t)

into your init file. Finally, if you often use \include or \input, you should make AUCTeX aware of the multifile document structure. You can do this by inserting

(setq-default TeX-master nil)

into your init file. Each time you open a new file, AUCTeX will then ask you for a master file.

1.3.1 Functions for editing TeX files

1.3.1.1 Making your TeX code more readable

AUCTeX can do syntax highlighting of your source code, that means commands will get special colors or fonts. This is enabled by default. You can disable it locally by typing M-x font-lock-mode <RET>.

AUCTeX will indent new lines to indicate their syntactical relationship to the surrounding text. For example, the text of a \footnote or text inside of an environment will be indented relative to the text around it. If the indenting has gotten wrong after adding or deleting some characters, use <TAB> to reindent the line, M-q for the whole paragraph, or M-x LaTeX-fill-buffer <RET> for the whole buffer.

1.3.1.2 Entering sectioning commands

Insertion of sectioning macros, that is ‘\chapter’, ‘\section’, ‘\subsection’, etc. and accompanying ‘\label’ commands may be eased by using C-c C-s. You will be asked for the section level. As nearly everywhere in AUCTeX, you can use the <TAB> or <SPC> key to get a list of available level names, and to auto-complete what you started typing. Next, you will be asked for the printed title of the section, and last you will be asked for a label to be associated with the section.

1.3.1.3 Inserting environments

Similarly, you can insert environments, that is ‘\begin{}’–‘\end{}’ pairs: Type C-c C-e, and select an environment type. Again, you can use <TAB> or <SPC> to get a list, and to complete what you type. Actually, the list will not only provide standard LaTeX environments, but also take your ‘\documentclass’ and ‘\usepackage’ commands into account if you have parsing enabled by setting TeX-parse-self to t. If you use a couple of environments frequently, you can use the <up> and <down> arrow keys (or M-p and M-n) in the minibuffer to get back to the previously inserted commands.

Some environments need additional arguments. Often, AUCTeX knows about this and asks you to enter a value.

1.3.1.4 Inserting macros

C-c C-m, or simply C-c <RET> will give you a prompt that asks you for a LaTeX macro. You can use <TAB> for completion, or the <up>/<down> arrow keys (or M-p and M-n) to browse the command history. In many cases, AUCTeX knows which arguments a macro needs and will ask you for that. It even can differentiate between mandatory and optional arguments—for details, see Completion.

An additional help for inserting macros is provided by the possibility to complete macros right in the buffer. With point at the end of a partially written macro, you can complete it by typing M-<TAB>.

1.3.1.5 Changing the font

AUCTeX provides convenient keyboard shortcuts for inserting macros which specify the font to be used for typesetting certain parts of the text. They start with C-c C-f, and the last C- combination tells AUCTeX which font you want:

C-c C-f C-b

Insert bold face ‘\textbf{∗}’ text.

C-c C-f C-i

Insert italics ‘\textit{∗}’ text.

C-c C-f C-e

Insert emphasized ‘\emph{∗}’ text.

C-c C-f C-s

Insert slanted ‘\textsl{∗}’ text.

C-c C-f C-r

Insert roman ‘\textrm{∗}’ text.

C-c C-f C-f

Insert sans serif ‘\textsf{∗}’ text.

C-c C-f C-t

Insert typewriter ‘\texttt{∗}’ text.

C-c C-f C-c

Insert SMALL CAPS ‘\textsc{∗}’ text.

C-c C-f C-d

Delete the innermost font specification containing point.

If you want to change font attributes of existing text, mark it as an active region, and then invoke the commands. If no region is selected, the command will be inserted with empty braces, and you can start typing the changed text.

Most of those commands will also work in math mode, but then macros like \mathbf will be inserted.

1.3.1.6 Other useful features

AUCTeX also tries to help you when inserting the right “quote” signs for your language, dollar signs to typeset math, or pairs of braces. It offers shortcuts for commenting out text (C-c ; for the current region or C-c % for the paragraph you are in). The same keystrokes will remove the % signs, if the region or paragraph is commented out yet. With TeX-fold-mode, you can hide certain parts (like footnotes, references etc.) that you do not edit currently. Support for Emacs’ outline mode is provided as well. And there’s more, but this is beyond the scope of this Quick Start Guide.

1.3.2 Creating and viewing output, debugging

1.3.2.1 One Command for LaTeX, helpers, viewers, and printing

If you have typed some text and want to run LaTeX (or TeX, or other programs—see below) on it, type C-c C-c. If applicable, you will be asked whether you want to save changes, and which program you want to invoke. In many cases, the choice that AUCTeX suggests will be just what you want: first latex, then a viewer. If a latex run produces or changes input files for makeindex, the next suggestion will be to run that program, and AUCTeX knows that you need to run latex again afterwards—the same holds for BibTeX.

When no processor invocation is necessary anymore, AUCTeX will suggest to run a viewer, or you can chose to create a PostScript file using dvips, or to directly print it.

Actually, there is another command which comes in handy to compile documents: type C-c C-a (TeX-command-run-all) and AUCTeX will compile the document for you until it is ready and then run the viewer. This is the same as issuing repeatedly C-c C-c and letting AUCTeX guess the next command to run.

At this place, a warning needs to be given: First, although AUCTeX is really good in detecting the standard situations when an additional latex run is necessary, it cannot detect it always. Second, the creation of PostScript files or direct printing currently only works when your output file is a DVI file, not a PDF file.

Ah, you didn’t know you can do both? That brings us to the next topic.

1.3.2.2 Choosing an output format

From a LaTeX file, you can produce DVI output, or a PDF file directly via pdflatex. You can switch on source specials for easier navigation in the output file, or tell latex to stop after an error (usually ‘--noninteractive’ is used, to allow you to detect all errors in a single run).

These options are controlled by toggles, the keystrokes should be easy to memorize:

C-c C-t C-p

This command toggles between DVI and PDF output

C-c C-t C-i

toggles interactive mode

C-c C-t C-s

toggles SyncTeX (or source specials) support

C-c C-t C-o

toggles usage of Omega/lambda.

There is also another possibility: compile the document with tex (or latex) and then convert the resulting DVI file to PDF using dvips–ps2pdf sequence or dvipdfmx command. If you want to go by this route, customize TeX-PDF-from-DVI option. Then AUCTeX will suggest you to run the appropriate command when you type C-C C-c. For details, see Processor Options.

1.3.2.3 Debugging LaTeX

When AUCTeX runs a program, it creates an output buffer in which it displays the output of the command. If there is a syntactical error in your file, latex will not complete successfully. AUCTeX will tell you that, and you can get to the place where the first error occured by pressing C-c ` (the last character is a backtick). The view will be split in two windows, the output will be displayed in the lower buffer, and both buffers will be centered around the place where the error ocurred. You can then try to fix it in the document buffer, and use the same keystrokes to get to the next error. This procedure may be repeated until all errors have been dealt with. By pressing C-c C-w (TeX-toggle-debug-boxes) you can toggle whether AUCTeX should notify you of overfull and underfull boxes in addition to regular errors.

Issue M-x TeX-error-overview <RET> to see a nicely formatted list of all errors and warnings reported by the compiler.

If a command got stuck in a seemingly infinite loop, or you want to stop execution for other reasons, you can use C-c C-k (for “kill”). Similar to C-l, which centers the buffer you are in around your current position, C-c C-l centers the output buffer so that the last lines added at the bottom become visible.

1.3.2.4 Running LaTeX on parts of your document

If you want to check how some part of your text looks like, and do not want to wait until the whole document has been typeset, then mark it as a region and use C-c C-r. It behaves just like C-c C-c, but it only uses the document preamble and the region you marked.

If you are using \include or \input to structure your document, try C-c C-b while you are editing one of the included files. It will run latex only on the current buffer, using the preamble from the master file.

2. Editing the Document Source

The most commonly used commands/macros of AUCTeX are those which simply insert templates for often used TeX, LaTeX, or ConTeXt constructs, like font changes, handling of environments, etc. These features are very simple, and easy to learn, and help you avoid mistakes like mismatched braces, or ‘\begin{}’-‘\end{}’ pairs.

Apart from that this chapter contains a description of some features for entering more specialized sorts of text, for formatting the source by indenting and filling and for navigating through the document.

2.1 Insertion of Quotes, Dollars, and Braces

Quotation Marks

In TeX, literal double quotes ‘"like this"’ are seldom used, instead two single quotes are used ‘``like this''’. To help you insert these efficiently, AUCTeX allows you to continue to press " to insert two single quotes. To get a literal double quote, press " twice.

Command: TeX-insert-quote count

(") Insert the appropriate quote marks for TeX.

Inserts the value of TeX-open-quote (normally ‘``’) or TeX-close-quote (normally ‘''’) depending on the context. With prefix argument, always inserts ‘"’ characters.

User Option: TeX-open-quote

String inserted by typing " to open a quotation. (See European, for language-specific quotation mark insertion.)

User Option: TeX-close-quote

String inserted by typing " to close a quotation. (See European, for language-specific quotation mark insertion.)

User Option: TeX-quote-after-quote

Determines the behavior of ". If it is non-nil, typing " will insert a literal double quote. The respective values of TeX-open-quote and TeX-close-quote will be inserted after typing " once again.

The ‘babel’ package provides special support for the requirements of typesetting quotation marks in many different languages. If you use this package, either directly or by loading a language-specific style file, you should also use the special commands for quote insertion instead of the standard quotes shown above. AUCTeX is able to recognize several of these languages and will change quote insertion accordingly. See European, for details about this feature and how to control it.

In case you are using the ‘csquotes’ package, you should customize LaTeX-csquotes-open-quote, LaTeX-csquotes-close-quote and LaTeX-csquotes-quote-after-quote. The quotation characters will only be used if both variables—LaTeX-csquotes-open-quote and LaTeX-csquotes-close-quote—are non-empty strings. But then the ‘csquotes’-related values will take precedence over the language-specific ones.

Dollar Signs

In AUCTeX, dollar signs should match like they do in TeX. This has been partially implemented, we assume dollar signs always match within a paragraph. By default, the first ‘$’ you insert in a paragraph will do nothing special. The second ‘$’ will match the first. This will be indicated by moving the cursor temporarily over the first dollar sign.

Command: TeX-insert-dollar arg

($) Insert dollar sign.

Show matching dollar sign if this dollar sign end the TeX math mode.

With optional arg, insert that many dollar signs.

TeX and LaTeX users often look for a way to insert inline equations like ‘$...$’ or ‘\(...\)’ simply typing $. AUCTeX helps them through the customizable variable TeX-electric-math.

User Option: TeX-electric-math

If the variable is non-nil and you type $ outside math mode, AUCTeX will automatically insert the opening and closing symbols for an inline equation and put the point between them. The opening symbol will blink when blink-matching-paren is non-nil. If TeX-electric-math is nil, typing $ simply inserts ‘$’ at point, this is the default.

Besides nil, possible values for this variable are ("$" . "$") for TeX inline equations ‘$...$’, and ("\(" . "\)") for LaTeX inline equations ‘\(...\)’.

If the variable is non-nil and point is inside math mode right between a couple of single dollars, pressing $ will insert another pair of dollar signs and leave the point between them. Thus, if TeX-electric-math is set to ("$" . "$") you can easily obtain a TeX display equation ‘$$...$$’ by pressing $ twice in a row. (Note that you should not use double dollar signs in LaTeX because this practice can lead to wrong spacing in typeset documents.)

In addition, when the variable is non-nil and there is an active region outside math mode, typing $ will put around the active region symbols for opening and closing inline equation and keep the region active, leaving point after the closing symbol. By pressing repeatedly $ while the region is active you can toggle between an inline equation, a display equation, and no equation. To be precise, ‘$...$’ is replaced by ‘$$...$$’, whereas ‘\(...\)’ is replaced by ‘\[...\]’.

If you want to automatically insert ‘$...$’ in plain TeX files, and ‘\(...\)’ in LaTeX files by pressing $, add the following to your init file

(add-hook 'plain-TeX-mode-hook
          (lambda () (set (make-local-variable 'TeX-electric-math)
                          (cons "$" "$"))))
(add-hook 'LaTeX-mode-hook
          (lambda () (set (make-local-variable 'TeX-electric-math)
                          (cons "\\(" "\\)"))))

Math mode which didn’t start with dollar(s) shouldn’t be closed with dollar.

User Option: TeX-refuse-unmatched-dollar

This option determines the behavior when the user types $ at a position where AUCTeX thinks that it is in math mode which didn’t start with dollar(s).

When this option is nil, AUCTeX behaves in the same way as non-math mode, assuming that the user knows it isn’t in math mode actually. This is the default.

When this option is non-nil, AUCTeX refuses to insert ‘$’ to prevent unmatched dollar.

Note that Texinfo mode does nothing special for $. It inserts dollar sign(s) just in the same way as the other normal keys do.

Braces

To avoid unbalanced braces, it is useful to insert them pairwise. You can do this by typing C-c {.

Command: TeX-insert-braces

(C-c {) Make a pair of braces and position the cursor to type inside of them. If there is an active region, put braces around it and leave point after the closing brace.

When writing complex math formulas in LaTeX documents, you sometimes need to adjust the size of braces with pairs of macros like ‘\left’-‘\right’, ‘\bigl’-‘\bigr’ and so on. You can avoid unbalanced pairs with the help of TeX-insert-macro, bound to C-c C-m or C-c <RET> (see Completion). If you insert left size adjusting macros such as ‘\left’, ‘\bigl’ etc. with TeX-insert-macro, it asks for left brace to use and supplies automatically right size adjusting macros such as ‘\right’, ‘\bigr’ etc. and corresponding right brace in addtion to the intended left macro and left brace.

The completion by TeX-insert-macro also applies when entering macros such as ‘\langle’, ‘\lfloor’ and ‘\lceil’, which produce the left part of the paired braces. For example, inserting ‘\lfloor’ by C-c C-m is immediately followed by the insertion of ‘\rfloor’. In addition, if the point was located just after ‘\left’ or its friends, the corresponding ‘\right’ etc. will be inserted in front of ‘\rfloor’. In both cases, active region is honored.

As a side effect, when LaTeX-math-mode (see Mathematics) is on, just typing `( inserts not only ‘\langle’, but also ‘\rangle’.

If you do not like such auto completion at all, it can be disabled by a user option.

User Option: TeX-arg-right-insert-p

If this option is turned off, the automatic supply of the right macros and braces is suppressed.

When you edit LaTeX documents, you can enable automatic brace pairing when typing (, { and [.

User Option: LaTeX-electric-left-right-brace

If this option is on, just typing (, { or [ immediately adds the corresponding right brace ‘)’, ‘}’ or ‘]’. The point is left after the opening brace. If there is an active region, braces are put around it.

They recognize the preceding backslash or size adjusting macros such as ‘\left’, ‘\bigl’ etc., so the following completions will occur:

• (when typing single left brace)
  • - ‘(’ -> ‘()’
  • - ‘{’ -> ‘{}’
  • - ‘[’ -> ‘[]’
• (when typing left brace just after a backslash)
  • - ‘\(’ -> ‘\(\)’
  • - ‘\{’ -> ‘\{\}’
  • - ‘\[’ -> ‘\[\]’
• (when typing just after ‘\left’ or ‘\bigl’)
  • - ‘\left(’ -> ‘\left(\right)’
  • - ‘\bigl[’ -> ‘\bigl[\bigr]’
• (when typing just after ‘\Bigl\’)
  • - ‘\Bigl\{’ -> ‘\Bigl\{\Bigr\}’

This auto completion feature may be a bit annoying when editing an already existing LaTeX document. In that case, use C-u 1 or C-q before typing (, { or [. Then no completion is done and just a single left brace is inserted. In fact, with optional prefix arg, just that many open braces are inserted without any completion.

2.2 Inserting Font Specifiers

Perhaps the most used keyboard commands of AUCTeX are the short-cuts available for easy insertion of font changing macros.

If you give an argument (that is, type C-u) to the font command, the innermost font will be replaced, i.e. the font in the TeX group around point will be changed. The following table shows the available commands, with ∗ indicating the position where the text will be inserted.

C-c C-f C-b

Insert bold face ‘\textbf{∗}’ text.

C-c C-f C-m

Insert medium face ‘\textmd{∗}’ text.

C-c C-f C-i

Insert italics ‘\textit{∗}’ text.

C-c C-f C-e

Insert emphasized ‘\emph{∗}’ text.

C-c C-f C-s

Insert slanted ‘\textsl{∗}’ text.

C-c C-f C-r

Insert roman ‘\textrm{∗}’ text.

C-c C-f C-f

Insert sans serif ‘\textsf{∗}’ text.

C-c C-f C-t

Insert typewriter ‘\texttt{∗}’ text.

C-c C-f C-c

Insert SMALL CAPS ‘\textsc{∗}’ text.

C-c C-f C-l

Insert upper lower case ‘\textulc{∗}’ text.

C-c C-f C-w

Insert SWASH ‘\textsw{∗}’ text.

C-c C-f C-n

Insert normal ‘\textnormal{∗}’ text.

C-c C-f C-d

Delete the innermost font specification containing point.

Command: TeX-font replace what

(C-c C-f) Insert template for font change command.

If replace is non-nil, replace current font. what determines the font to use, as specified by TeX-font-list.

User Option: TeX-font-list

List of fonts used by TeX-font.

Each entry is a list with three elements. The first element is the key to activate the font. The second element is the string to insert before point, and the third element is the string to insert after point. An optional fourth element means always replace if non-nil.

User Option: LaTeX-font-list

List of fonts used by TeX-font in LaTeX mode. It has the same structure as TeX-font-list.

2.3 Inserting chapters, sections, etc.

Insertion of sectioning macros, that is ‘\chapter’, ‘\section’, ‘\subsection’, etc. and accompanying ‘\label’’s may be eased by using C-c C-s. This command is highly customizable, the following describes the default behavior.

When invoking you will be asked for a section macro to insert. An appropriate default is automatically selected by AUCTeX, that is either: at the top of the document; the top level sectioning for that document style, and any other place: The same as the last occurring sectioning command.

Next, you will be asked for the actual name of that section, and last you will be asked for a label to be associated with that section. The label will be prefixed by the value specified in LaTeX-section-hook.

Command: LaTeX-section arg

(C-c C-s) Insert a sectioning command.

Determine the type of section to be inserted, by the argument arg.

• If arg is nil or missing, use the current level.
• If arg is a list (selected by C-u), go downward one level.
• If arg is negative, go up that many levels.
• If arg is positive or zero, use absolute level:
  • + 0 : part
  • + 1 : chapter
  • + 2 : section
  • + 3 : subsection
  • + 4 : subsubsection
  • + 5 : paragraph
  • + 6 : subparagraph

The following variables can be set to customize the function.

LaTeX-section-hook

Hooks to be run when inserting a section.

LaTeX-section-label

Prefix to all section references.

The precise behavior of LaTeX-section is defined by the contents of LaTeX-section-hook.

User Option: LaTeX-section-hook

List of hooks to run when a new section is inserted.

The following variables are set before the hooks are run

LaTeX-level

Numeric section level, default set by prefix arg to LaTeX-section.

LaTeX-name

Name of the sectioning command, derived from LaTeX-level.

LaTeX-title

The title of the section, default to an empty string.

LaTeX-toc

Entry for the table of contents list, default nil.

LaTeX-done-mark

Position of point afterwards, default nil meaning after the inserted text.

A number of hooks are already defined. Most likely, you will be able to get the desired functionality by choosing from these hooks.

LaTeX-section-heading

Query the user about the name of the sectioning command. Modifies LaTeX-level and LaTeX-name.

LaTeX-section-title

Query the user about the title of the section. Modifies LaTeX-title.

LaTeX-section-toc

Query the user for the toc entry. Modifies LaTeX-toc.

LaTeX-section-section

Insert LaTeX section command according to LaTeX-name, LaTeX-title, and LaTeX-toc. If LaTeX-toc is nil, no toc entry is inserted. If LaTeX-toc or LaTeX-title are empty strings, LaTeX-done-mark will be placed at the point they should be inserted.

LaTeX-section-label

Insert a label after the section command. Controlled by the variable LaTeX-section-label.

To get a full featured LaTeX-section command, insert

(setq LaTeX-section-hook '(LaTeX-section-heading LaTeX-section-title LaTeX-section-toc LaTeX-section-section LaTeX-section-label))

in your init file such as ‘init.el’ or ‘.emacs’.

The behavior of LaTeX-section-label is determined by the variable LaTeX-section-label.

User Option: LaTeX-section-label

Default prefix when asking for a label.

If it is a string, it is used unchanged for all kinds of sections. If it is nil, no label is inserted. If it is a list, the list is searched for a member whose car is equal to the name of the sectioning command being inserted. The cdr is then used as the prefix. If the name is not found, or if the cdr is nil, no label is inserted.

By default, chapters have a prefix of ‘cha:’ while sections and subsections have a prefix of ‘sec:’. Labels are not automatically inserted for other types of sections.

2.4 Inserting Environment Templates

A large apparatus is available that supports insertions of environments, that is ‘\begin{}’ — ‘\end{}’ pairs.

AUCTeX is aware of most of the actual environments available in a specific document. This is achieved by examining your ‘\documentclass’ command, and consulting a precompiled list of environments available in a large number of styles.

Most of these are described further in the following sections, and you may easily specify more. See Customizing Environments.

You insert an environment with C-c C-e, and select an environment type. Depending on the environment, AUCTeX may ask more questions about the optional parts of the selected environment type. With C-u C-c C-e you will change the current environment.

Command: LaTeX-environment arg

(C-c C-e) AUCTeX will prompt you for an environment to insert. At this prompt, you may press <TAB> or <SPC> to complete a partially written name, and/or to get a list of available environments. After selection of a specific environment AUCTeX may prompt you for further specifications.

If the optional argument arg is non-nil (i.e. you have given a prefix argument), the current environment is modified and no new environment is inserted.

AUCTeX helps you adding labels to environments which use them, such as ‘equation’, ‘figure’, ‘table’, etc… When you insert one of the supported environments with C-c C-e, you will be automatically prompted for a label. You can select the prefix to be used for such environments with the LaTeX-label-alist variable.

User Option: LaTeX-label-alist

List the prefixes to be used for the label of each supported environment.

This is an alist whose car is the environment name, and the cdr either the prefix or a symbol referring to one.

If the name is not found, or if the cdr is nil, no label is automatically inserted for that environment.

If you want to automatically insert a label for a environment but with an empty prefix, use the empty string "" as the cdr of the corresponding entry.

As a default selection, AUCTeX will suggest the environment last inserted or, as the first choice the value of the variable LaTeX-default-environment.

User Option: LaTeX-default-environment

Default environment to insert when invoking LaTeX-environment first time. When the current environment is ‘document’, it is overriden by LaTeX-default-document-environment.

Variable: LaTeX-default-document-environment

Default environment when invoking ‘LaTeX-environment’ and the current environment is ‘document’. It is intended to be used in LaTeX class style files. For example, in ‘beamer.el’ it is set to frame, in ‘letter.el’ to letter, and in ‘slides.el’ to slide.

If the document is empty, or the cursor is placed at the top of the document, AUCTeX will default to insert a ‘document’ environment prompting also for the insertion of ‘\documentclass’ and ‘\usepackage’ macros. You will be prompted for a new package until you enter nothing. If you do not want to insert any ‘\usepackage’ at all, just press <RET> at the first ‘Packages’ prompt.

AUCTeX distinguishes normal and expert environments. By default, it will offer completion only for normal environments. This behavior is controlled by the user option TeX-complete-expert-commands.

User Option: TeX-complete-expert-commands

Complete macros and environments marked as expert commands.

Possible values are nil, t, or a list of style names.

nil

Don’t complete expert commands (default).

t

Always complete expert commands.

(styles …)

Only complete expert commands of styles.

You can close the current environment with C-c ], but we suggest that you use C-c C-e to insert complete environments instead.

Command: LaTeX-close-environment

(C-c ]) Insert an ‘\end’ that matches the current environment.

AUCTeX offers keyboard shortcuts for moving point to the beginning and to the end of the current environment.

Command: LaTeX-find-matching-begin

(C-M-a) Move point to the ‘\begin’ of the current environment.

If this command is called inside a comment and LaTeX-syntactic-comments is enabled, try to find the environment in commented regions with the same comment prefix.

The key bind C-M-a actually calls beginning-of-defun, which in turn calls LaTeX-find-matching-begin.

Command: LaTeX-find-matching-end

(C-M-e) Move point to the ‘\end’ of the current environment.

If this command is called inside a comment and LaTeX-syntactic-comments is enabled, try to find the environment in commented regions with the same comment prefix.

The key bind C-M-e actually calls end-of-defun, which in turn calls LaTeX-find-matching-end.

2.4.1 Equations

When inserting equation-like environments, the ‘\label’ will have a default prefix, which is controlled by the following variables:

User Option: LaTeX-equation-label

Prefix to use for ‘equation’ labels.

User Option: LaTeX-eqnarray-label

Prefix to use for ‘eqnarray’ labels.

User Option: LaTeX-amsmath-label

Prefix to use for amsmath equation labels. Amsmath equations include ‘align’, ‘alignat’, ‘xalignat’, ‘multline’, ‘flalign’ and ‘gather’.

2.4.2 Floats

Figures and tables (i.e., floats) may also be inserted using AUCTeX. After choosing either ‘figure’ or ‘table’ in the environment list described above, you will be prompted for a number of additional things.

float position

This is the optional argument of float environments that controls how they are placed in the final document. In LaTeX this is a sequence of the letters ‘htbp’ as described in the LaTeX manual. The value will default to the value of LaTeX-float.

caption

This is the caption of the float. The default is to insert the caption at the bottom of the float. You can specify floats where the caption should be placed at the top with LaTeX-top-caption-list.

short caption

If the specified caption is greater than a specific length, then a short caption is prompted for and it is inserted as an optional argument to the ‘\caption’ macro. The length that a caption needs to be before prompting for a short version is controlled by LaTeX-short-caption-prompt-length.

label

The label of this float. The label will have a default prefix, which is controlled by the variables LaTeX-figure-label and LaTeX-table-label.

Moreover, you will be asked if you want the contents of the float environment to be horizontally centered. Upon a positive answer a ‘\centering’ macro will be inserted at the beginning of the float environment.

User Option: LaTeX-float

Default placement for floats.

User Option: LaTeX-figure-label

Prefix to use for figure labels.

User Option: LaTeX-table-label

Prefix to use for table labels.

User Option: LaTeX-top-caption-list

List of float environments with top caption.

User Option: LaTeX-short-caption-prompt-length

Number of chars a caption should be before prompting for a short caption.

2.4.3 Itemize-like Environments

In an itemize-like environment, nodes (i.e., ‘\item’s) may be inserted using C-c <LFD> or M-<RET>. The latter is only defined as an alias if the key binding is still available.

Command: LaTeX-insert-item

(C-c <LFD> or M-<RET>) Close the current item, move to the next line and insert an appropriate ‘\item’ for the current environment. That is, ‘itemize’ and ‘enumerate’ will have ‘\item ’ inserted, while ‘description’ will have ‘\item[] ’ inserted.

User Option: TeX-arg-item-label-p

If non-nil, you will always be asked for optional label in items. Otherwise, you will be asked only in description environments.

2.4.4 Tabular-like Environments

When inserting Tabular-like environments, that is, ‘tabular’ ‘array’ etc., you will be prompted for a template for that environment. Related variables:

User Option: LaTeX-default-format

Default format string for array and tabular environments.

User Option: LaTeX-default-width

Default width for minipage and tabular* environments.

User Option: LaTeX-default-position

Default position string for array and tabular environments. If nil, act like the empty string is given, but don’t prompt for a position.

AUCTeX calculates the number of columns from the format string and inserts the suitable number of ampersands.

You can use C-c <LFD> or M-<RET> (LaTeX-insert-item) to terminate rows in these environments. It supplies line break macro ‘\\’ and inserts the suitable number of ampersands on the next line. AUCTeX also supports the ‘*{num}{cols}’ notation (which may contain another ‘*’-expression) in the format string when calculating the number of ampersands. Please note that ‘num’ and ‘cols’ must be enclosed in braces; expressions like ‘*2l’ are not recognized correctly by the algorithm.

Command: LaTeX-insert-item

(C-c <LFD> or M-<RET>) Close the current row with ‘\\’, move to the next line and insert an appropriate number of ampersands for the current environment.

Similar supports are provided for various amsmath environments such as ‘align’, ‘gather’, ‘alignat’, ‘matrix’ etc. Try typing C-c <LFD> or M-<RET> in these environments. It recognizes the current environment and does the appropriate job depending on the context.

2.4.5 Customizing Environments

See Adding Environments, for how to customize the list of known environments.

2.5 Entering Mathematics

TeX is written by a mathematician, and has always contained good support for formatting mathematical text. AUCTeX supports this tradition, by offering a special minor mode for entering text with many mathematical symbols. You can enter this mode by typing C-c ~.

Command: LaTeX-math-mode

(C-c ~) Toggle LaTeX Math mode. This is a minor mode rebinding the key LaTeX-math-abbrev-prefix to allow easy typing of mathematical symbols. ` will read a character from the keyboard, and insert the symbol as specified in LaTeX-math-default and LaTeX-math-list. If given a prefix argument, the symbol will be surrounded by dollar signs.

You can use another prefix key (instead of `) by setting the variable LaTeX-math-abbrev-prefix.

To enable LaTeX Math mode by default, add the following in your init file such as ‘init.el’ or ‘.emacs’:

(add-hook 'LaTeX-mode-hook #'LaTeX-math-mode)

User Option: LaTeX-math-abbrev-prefix

A string containing the prefix of LaTeX-math-mode commands; This value defaults to `.

The string has to be a key or key sequence in a format understood by the kbd macro. This corresponds to the syntax usually used in the manuals for Emacs Lisp.

The variable LaTeX-math-list allows you to add your own mappings.

User Option: LaTeX-math-list

A list containing user-defined keys and commands to be used in LaTeX Math mode. Each entry should be a list of two to four elements.

First, the key to be used after LaTeX-math-abbrev-prefix for macro insertion. The key can be a character (e.g. ‘?o’) for a single stroke or a string (e.g. ‘"o a"’) for a multi-stroke binding. If it is nil, the symbol has no associated keystroke (it is available in the menu, though).

Second, a string representing the name of the macro (without a leading backslash.)

Third, a string representing the name of a submenu the command should be added to. Use a list of strings in case of nested menus.

Fourth, the position of a Unicode character to be displayed in the menu alongside the macro name. This is an integer value.

User Option: LaTeX-math-menu-unicode

Whether the LaTeX Math menu should try using Unicode for effect. Your Emacs built must be able to display include Unicode characters in menus for this feature.

AUCTeX’s reference card ‘tex-ref.tex’ includes a list of all math mode commands.

AUCTeX can help you write subscripts and superscripts in math constructs by automatically inserting a pair of braces after typing <_> or <^> respectively and putting point between the braces. In order to enable this feature, set the variable TeX-electric-sub-and-superscript to a non-nil value.

User Option: TeX-electric-sub-and-superscript

If non-nil, insert braces after typing <^> and <_> in math mode.

You can automatically turn off input methods, used to input non-ascii characters, when you begin to enter math constructs.

User Option: TeX-math-input-method-off-regexp

Input method matching this regular expression is turned off when $ is typed to begin math mode or a math environment is inserted by C-c C-e (LaTeX-environment).

2.6 Completion

Emacs lisp programmers probably know the lisp-complete-symbol command which was bound to M-<TAB> until completion-at-point became the new standard completion facility (see below). Users of the wonderful ispell mode know and love the ispell-complete-word command from that package. Similarly, AUCTeX has a TeX-complete-symbol command, by default bound to M-<TAB> which is equivalent to C-M-i. Using TeX-complete-symbol makes it easier to type and remember the names of long LaTeX macros.

In order to use TeX-complete-symbol, you should write a backslash and the start of the macro. Typing M-<TAB> will now complete as much of the macro, as it unambiguously can. For example, if you type ‘‘\renewc’’ and then M-<TAB>, it will expand to ‘‘\renewcommand’’. But there’s more: if point is just after ‘\begin{’, then TeX-complete-symbol will complete LaTeX environments, etc. This is controlled by TeX-complete-list.

Command: TeX-complete-symbol

(M-<TAB>) Complete TeX symbol before point.

Variable: TeX-complete-list

List of ways to complete the preceding text.

Each entry is a list with the following elements:

1. Regexp matching the preceding text or a predicate of arity 0 which returns non-nil and sets ‘match-data’ appropriately if it is applicable.
2. A number indicating the subgroup in the regexp containing the text.
3. A function returning an alist of possible completions.
4. Text to append after a succesful completion.

Or alternatively:

1. Regexp matching the preceding text.
2. Function to do the actual completion.

More recent Emacs versions have a new completion mechanism. Modes may define and register custom completion-at-point functions and when the user invokes completion-at-point (usually bound to M-<TAB>), all such registered functions are consulted for checking for possible completions. Modern completion UIs like company-mode or corfu support this completion-at-point facility.

Function: TeX--completion-at-point

AUCTeX’s completion-at-point function which is automatically added to completion-at-point-functions in TeX and LaTeX buffers.

It offers the same completion candidates as would TeX-complete-symbol (and is also controlled by TeX-complete-list) except that it doesn’t fall back on ispell-complete-word which would be awkward with completion UIs like company-mode.

Function: LaTeX--arguments-completion-at-point

AUCTeX’s completion-at-point function inside arguments which is automatically added to completion-at-point-functions in LaTeX buffers.

It offers the completion candidates stored in the variables TeX-symbol-list and LaTeX-environment-list for single candidate, multiple candidates separated by commas, or key-value candidates separated by commas and/or equal signs.

A more direct way to insert a macro is with TeX-insert-macro, bound to C-c C-m which is equivalent to C-c <RET>. It has the advantage over completion that it knows about the argument of most standard LaTeX macros, and will prompt for them. It also knows about the type of the arguments, so it will for example give completion for the argument to ‘\include’. Some examples are listed below.

Command: TeX-insert-macro

(C-c C-m or C-c <RET>) Prompt (with completion) for the name of a TeX macro, and if AUCTeX knows the macro, prompt for each argument.

As a default selection, AUCTeX will suggest the macro last inserted or, as the first choice the value of the variable TeX-default-macro.

User Option: TeX-default-macro

Default macro to insert when invoking TeX-insert-macro first time.

User Option: TeX-insert-macro-default-style

Specifies whether TeX-insert-macro will ask for all optional arguments.

If set to the symbol show-optional-args, TeX-insert-macro asks for optional arguments of TeX marcos, unless the previous optional argument has been rejected. If set to show-all-optional-args, TeX-insert-macro asks for all optional arguments. mandatory-args-only, TeX-insert-macro asks only for mandatory arguments. When TeX-insert-macro is called with prefix argument (C-u), it’s the other way round.

Note that for some macros, there are special mechanisms, e.g. TeX-arg-cite-note-p and LaTeX-includegraphics-options-alist.

A faster alternative is to enable the option TeX-electric-escape.

User Option: TeX-electric-escape

If this is non-nil, typing the TeX escape character \ will invoke the command TeX-electric-macro.

In Texinfo mode, the command is invoked by @ instead.

The difference between TeX-insert-macro and TeX-electric-macro is that space key <SPC> will complete and exit from the minibuffer in TeX-electric-macro. Use <TAB> if you merely want to complete.

Command: TeX-electric-macro

Prompt (with completion) for the name of a TeX macro, and if AUCTeX knows the macro, prompt for each argument. Space (<SPC>) will complete and exit.

By default AUCTeX will put an empty set braces ‘{}’ after a macro with no arguments to stop it from eating the next whitespace. This is suppressed inside math mode and can be disabled totally by setting TeX-insert-braces to nil.

User Option: TeX-insert-braces

If non-nil, append a empty pair of braces after inserting a macro with no arguments.

User Option: TeX-insert-braces-alist

Control the insertion of a pair of braces after a macro on a per macro basis.

This variable is an alist. Each element is a cons cell, whose car is the macro name, and the cdr is non-nil or nil, depending on whether a pair of braces should be, respectively, appended or not to the macro.

If a macro has an element in this variable, AUCTeX will use its value to decide what to do, whatever the value of the variable TeX-insert-braces.

Completions work because AUCTeX can analyze TeX files, and store symbols in Emacs Lisp files for later retrieval. See Automatic, for more information.

AUCTeX distinguishes normal and expert macros. By default, it will offer completion only for normal commands. This behavior can be controlled using the user option TeX-complete-expert-commands.

User Option: TeX-complete-expert-commands

Complete macros and environments marked as expert commands.

Possible values are nil, t, or a list of style names.

nil

Don’t complete expert commands (default).

t

Always complete expert commands.

(styles …)

Only complete expert commands of styles.

AUCTeX will also make completion for many macro arguments, for example existing labels when you enter a ‘\ref’ macro with TeX-insert-macro or TeX-electric-macro, and BibTeX entries when you enter a ‘\cite’ macro. For this kind of completion to work, parsing must be enabled as described in Parsing Files. For ‘\cite’ you must also make sure that the BibTeX files have been saved at least once after you enabled automatic parsing on save, and that the basename of the BibTeX file does not conflict with the basename of one of TeX files.

2.7 Marking Environments, Sections, or Texinfo Nodes

You can mark the current environment by typing C-c ., or the current section by typing C-c *.

In Texinfo documents you can type C-M-h to mark the current node.

When the region is set, the point is moved to its beginning and the mark to its end.

2.7.1 LaTeX Commands for Marking Environments and Sections

Command: LaTeX-mark-section

(C-c *) Set mark at end of current logical section, and point at top.

With a non-nil prefix argument, mark only the region from the current section start to the next sectioning command. Thereby subsections are not being marked. Otherwise, any included subsections are also marked along with current section.

Command: LaTeX-mark-environment

(C-c .) Set mark to the end of the current environment and point to the matching beginning.

If a prefix argument is given, mark the respective number of enclosing environments. The command will not work properly if there are unbalanced begin-end pairs in comments and verbatim environments.

2.7.2 Texinfo Commands for Marking Environments and Sections

Command: Texinfo-mark-section

(C-c *) Mark the current section, with inclusion of any containing node.

The current section is detected as starting by any of the structuring commands matched by the regular expression in the variable outline-regexp which in turn is a regular expression matching any element of the variable texinfo-section-list.

With a non-nil prefix argument, mark only the region from the current section start to the next sectioning command. Thereby subsections are not being marked. Otherwise, any included subsections are also marked.

Note that when the current section is starting immediately after a node command, then the node command is also marked as part of the section.

Command: Texinfo-mark-environment

(C-c .) Set mark to the end of the current environment and point to the matching beginning.

If a prefix argument is given, mark the respective number of enclosing environments. The command will not work properly if there are unbalanced begin-end pairs in comments and verbatim environments.

Command: Texinfo-mark-node

(C-M-h) Mark the current node. This is the node in which point is located. It is starting at the previous occurrence of the keyword @node and ending at next occurrence of the keywords @node or @bye.

2.8 Commenting

It is often necessary to comment out temporarily a region of TeX or LaTeX code. This can be done with the commands C-c ; and C-c %. C-c ; will comment out all lines in the current region, while C-c % will comment out the current paragraph. Type C-c ; again to uncomment all lines of a commented region, or C-c % again to uncomment all comment lines around point. These commands will insert or remove a single ‘%’ respectively.

Command: TeX-comment-or-uncomment-region

(C-c ;) Add or remove ‘%’ from the beginning of each line in the current region. Uncommenting works only if the region encloses solely commented lines. If AUCTeX should not try to guess if the region should be commented or uncommented the commands TeX-comment-region and TeX-uncomment-region can be used to explicitly comment or uncomment the region in concern.

Command: TeX-comment-or-uncomment-paragraph

(C-c %) Add or remove ‘%’ from the beginning of each line in the current paragraph. When removing ‘%’ characters the paragraph is considered to consist of all preceding and succeeding lines starting with a ‘%’, until the first non-comment line.

2.9 Indenting

Indentation means the addition of whitespace at the beginning of lines to reflect special syntactical constructs. This makes it easier to see the structure of the document, and to catch errors such as a missing closing brace. Thus, the indentation is done for precisely the same reasons that you would indent ordinary computer programs.

Indentation is done by LaTeX environments and by TeX groups, that is the body of an environment is indented by the value of LaTeX-indent-level (default 2). Also, items of an ‘itemize-like’ environment are indented by the value of LaTeX-item-indent, default -2. (Items are identified with the help of LaTeX-item-regexp.) If more environments are nested, they are indented ‘accumulated’ just like most programming languages usually are seen indented in nested constructs.

You can explicitly indent single lines, usually by pressing <TAB>, or marked regions by calling indent-region on it. If you have auto-fill-mode enabled and a line is broken while you type it, Emacs automatically cares about the indentation in the following line. If you want to have a similar behavior upon typing <RET>, you can customize the variable TeX-newline-function and change the default of newline which does no indentation to newline-and-indent which indents the new line or reindent-then-newline-and-indent which indents both the current and the new line.

There are certain LaTeX environments which should be indented in a special way, like ‘tabular’ or ‘verbatim’. Those environments may be specified in the variable LaTeX-indent-environment-list together with their special indentation functions. Taking the ‘verbatim’ environment as an example you can see that current-indentation is used as the indentation function. This will stop AUCTeX from doing any indentation in the environment if you hit <TAB> for example.

There are environments in LaTeX-indent-environment-list which do not bring a special indentation function with them. This is due to the fact that first the respective functions are not implemented yet and second that filling will be disabled for the specified environments. This shall prevent the source code from being messed up by accidently filling those environments with the standard filling routine. If you think that providing special filling routines for such environments would be an appropriate and challenging task for you, you are invited to contribute. (See Filling, for further information about the filling functionality.)

The check for the indentation function may be enabled or disabled by customizing the variable LaTeX-indent-environment-check.

For tabular-like environments, AUCTeX has a built-in function to indent according to preceding ‘&’ signs and assigns it to all known tabular-like environments in the default value of LaTeX-indent-environment-list.

As a side note with regard to formatting special environments: Newer Emacsen include ‘align.el’ and therefore provide some support for formatting ‘tabular’ and ‘tabbing’ environments with the function align-current which will nicely align columns in the source code.

AUCTeX is able to format commented parts of your code just as any other part. This means LaTeX environments and TeX groups in comments will be indented syntactically correct if the variable LaTeX-syntactic-comments is set to t. If you disable it, comments will be filled like normal text and no syntactic indentation will be done.

Following you will find a list of most commands and variables related to indenting with a small summary in each case:

<TAB>

LaTeX-indent-line will indent the current line.

<LFD>

C-j

newline-and-indent inserts a new line (much like <RET>) and moves the cursor to an appropriate position by the left margin.

Most keyboards nowadays lack a linefeed key and C-j may be tedious to type. Therefore you can customize AUCTeX to perform indentation upon typing <RET> as well. The respective option is called TeX-newline-function.

User Option: LaTeX-indent-environment-list

List of environments with special indentation. The second element in each entry is the function to calculate the indentation level in columns.

User Option: LaTeX-indent-level

Number of spaces to add to the indentation for each ‘\begin’ not matched by a ‘\end’.

User Option: LaTeX-item-indent

Number of spaces to add to the indentation for ‘\item’’s in list environments.

User Option: TeX-brace-indent-level

Number of spaces to add to the indentation for each ‘{’ not matched by a ‘}’.

User Option: LaTeX-syntactic-comments

If non-nil comments will be filled and indented according to LaTeX syntax. Otherwise they will be filled like normal text.

User Option: TeX-newline-function

Used to specify the function which is called when <RET> is pressed. This will normally be newline which simply inserts a new line. In case you want to have AUCTeX do indentation as well when you press <RET>, use the built-in functions newline-and-indent or reindent-then-newline-and-indent. The former inserts a new line and indents the following line, i.e. it moves the cursor to the right position and therefore acts as if you pressed <LFD>. The latter function additionally indents the current line. If you choose ‘Other’, you can specify your own fancy function to be called when <RET> is pressed.

AUCTeX treats by default ‘\[...\]’ math mode as a regular environment and indents it accordingly. If you do not like such behavior you only need to remove \|\[ and \|\] from LaTeX-begin-regexp and LaTeX-end-regexp variables respectively.

A closely related topic is indenting of text enclosed in square brackets, parentheses and other pairs. AUCTeX offers two variables which control if indentation happens inside these pairs.

User Option: TeX-indent-open-delimiters

This variable contains additional opening delimiters which increase indentation. For example add [ to this variable to get text after a square bracket indented.

User Option: TeX-indent-close-delimiters

This is the accompanying variable to TeX-indent-open-delimiters decreasing the indentation again. This variable should contain ] if TeX-indent-open-delimiters is set like described above.

Note that this is an opt-in feature, both variables are initially set to an empty string. That is because it introduces non-trivial side effects to include [ and ] in TeX-indent-open-delimiters and TeX-indent-close-delimiters; if you only have an opening square bracket in your text without closing it, wrong indentation persists in the following text. For example, in math expression, half-open intervals are frequently written as ‘[0,10)’ or ‘[0,10[’. In such cases, you can put the closing part as a comment in the same line in order to have correct indentation after that:

$[0,10)$ % ]
$[0,10[$ % ]]

Another example is ‘\left’-‘\right’ pair in equations. Similar workarounds are available:

\begin{equation}
  \left[ % ]
    xyz
  \right] % [
  abc
\end{equation}

You can include parens ‘()’ also in TeX-indent-open-delimiters and TeX-indent-close-delimiters to enable indent inside them. Be prepared for similar side effects when you do.

Note that commented curly braces { and } aren’t counted when AUCTeX computes indentation.

In docTeX-mode, TeX code is enclosed in ‘macrocode’ environment like this:

%    \begin{macrocode}
\def\foo#1{%
  $#1$%
}
%    \end{macrocode}

Sometimes, the code is long and one wants to insert comments inside the TeX code like this:

%    \begin{macrocode}
\def\foo#1{%
%    \end{macrocode}
%   Comment the next line of code
%    \begin{macrocode}
  $#1$%
}
%    \end{macrocode}

Usually, the comment inside the code interrupts the indentation. This behavior can be controlled by setting the variable docTeX-indent-across-comments.

User Option: docTeX-indent-across-comments

If non-nil, indentation in docTeX is done across comments. This option is disabled by default.

2.10 Filling

Filling deals with the insertion of line breaks to prevent lines from becoming wider than what is specified in fill-column. The linebreaks will be inserted automatically if auto-fill-mode is enabled. In this case the source is not only filled but also indented automatically as you write it.

auto-fill-mode can be enabled for AUCTeX by calling turn-on-auto-fill in one of the hooks AUCTeX is running. See Modes and Hooks. As an example, if you want to enable auto-fill-mode in LaTeX-mode, put the following into your init file:

(add-hook 'LaTeX-mode-hook #'turn-on-auto-fill)

You can manually fill explicitly marked regions, paragraphs, environments, complete sections, or the whole buffer. (Note that manual filling in AUCTeX will indent the start of the region to be filled in contrast to many other Emacs modes.)

There are some syntactical constructs which are handled specially with regard to filling. These are so-called code comments and paragraph commands.

Code comments are comments preceded by code or text in the same line. Upon filling a region, code comments themselves will not get filled. Filling is done from the start of the region to the line with the code comment and continues after it. In order to prevent overfull lines in the source code, a linebreak will be inserted before the last non-comment word by default. This can be changed by customizing LaTeX-fill-break-before-code-comments. If you have overfull lines with code comments you can fill those explicitly by calling LaTeX-fill-paragraph or pressing M-q with the cursor positioned on them. This will add linebreaks in the comment and indent subsequent comment lines to the column of the comment in the first line of the code comment. In this special case M-q only acts on the current line and not on the whole paragraph.

Lines with ‘\par’ are treated similarly to code comments, i.e. ‘\par’ will be treated as paragraph boundary which should not be followed by other code or text. But it is not treated as a real paragraph boundary like an empty line where filling a paragraph would stop.

Paragraph commands like ‘\section’ or ‘\noindent’ (the list of commands is defined by LaTeX-paragraph-commands) are often to be placed in their own line(s). This means they should not be consecuted with any preceding or following adjacent lines of text. AUCTeX will prevent this from happening if you do not put any text except another macro after the end of the last brace of the respective macro. If there is other text after the macro, AUCTeX regards this as a sign that the macro is part of the following paragraph.

Here are some examples:

\begin{quote}
  text text text text

\begin{quote}\label{foo}
  text text text text

If you press M-q on the first line in both examples, nothing will change. But if you write

\begin{quote} text
  text text text text

and press M-q, you will get

\begin{quote} text text text text text

Besides code comments and paragraph commands, another speciality of filling in AUCTeX involves commented lines. You should be aware that these comments are treated as islands in the rest of the LaTeX code if syntactic filling is enabled. This means, for example, if you try to fill an environment with LaTeX-fill-environment and have the cursor placed on a commented line which does not have a surrounding environment inside the comment, AUCTeX will report an error.

The relevant commands and variables with regard to filling are:

C-c C-q C-p

LaTeX-fill-paragraph will fill and indent the current paragraph.

M-q

Alias for C-c C-q C-p

C-c C-q C-e

LaTeX-fill-environment will fill and indent the current environment. This may e.g. be the ‘document’ environment, in which case the entire document will be formatted.

C-c C-q C-s

LaTeX-fill-section will fill and indent the current logical sectional unit.

C-c C-q C-r

LaTeX-fill-region will fill and indent the current region.

User Option: LaTeX-fill-break-at-separators

List of separators before or after which respectively linebreaks will be inserted if they do not fit into one line. The separators can be curly braces, brackets, switches for inline math (‘$’, ‘\(’, ‘\)’) and switches for display math (‘\[’, ‘\]’). Such formatting can be useful to make macros and math more visible or to prevent overfull lines in the LaTeX source in case a package for displaying formatted TeX output inside the Emacs buffer, like preview-latex, is used.

User Option: LaTeX-fill-break-before-code-comments

Code comments are comments preceded by some other text in the same line. When a paragraph containing such a comment is to be filled, the comment start will be seen as a border after which no line breaks will be inserted in the same line. If the option LaTeX-fill-break-before-code-comments is enabled (which is the default) and the comment does not fit into the line, a line break will be inserted before the last non-comment word to minimize the chance that the line becomes overfull.

User Option: LaTeX-fill-excluded-macros

A list of macro names (without leading backslash) for whose arguments filling should be disabled. Typically, you will want to add macros here which have long, multi-line arguments. An example is \pgfplotstabletypeset from the pgfplotstable package which is used as shown in the following listing:

\pgfplotstabletypeset[skip first n=4]{%
  XYZ Format,
  Version 1.234
  Date 2010-09-01
  @author Mustermann
  A B C
  1 2 3
  4 5 6
}

3. Controlling Screen Display

It is often desirable to get visual help of what markup code in a text actually does without having to decipher it explicitly. For this purpose Emacs and AUCTeX provide font locking (also known as syntax highlighting) which visually sets off markup code like macros or environments by using different colors or fonts. For example text to be typeset in italics can be displayed with an italic font in the editor as well, or labels and references get their own distinct color.

While font locking helps you grasp the purpose of markup code and separate markup from content, the markup code can still be distracting. AUCTeX lets you hide those parts and show them again at request with its built-in support for hiding macros and environments which we call folding here.

Besides folding of macros and environments, AUCTeX provides support for Emacs’ outline mode which lets you narrow the buffer content to certain sections of your text by hiding the parts not belonging to these sections.

Moreover, you can focus in a specific portion of the code by narrowing the buffer to the desired region. AUCTeX provides also functions to narrow the buffer to the current group and to LaTeX environments.

AUCTeX also provides some WYSIWYG features.

First, you can customize font-latex-fontify-script to enable special formatting of ^ superscripts and _ subscripts (see Font Locking).

Secondly, AUCTeX with GNU Emacs 25 or later can display certain math macros using Unicode characters, e.g., \alpha as α. This is called prettification and is lightweight and reasonable robust (see Prettifying).

A more accurate approach is provided by preview-latex, a subsystem of AUCTeX, see (preview-latex)Top section ‘Introduction’ in The preview-latex Manual. This system uses LaTeX to generate images that are then displayed in your buffer. It is extremely accurate but can be fragile with some packages (like older pgf versions).

Please note that you can use prettification and preview-latex together.

3.1 Font Locking

Font locking is supposed to improve readability of the source code by highlighting certain keywords with different colors or fonts. It thereby lets you recognize the function of markup code to a certain extent without having to read the markup command. For general information on controlling font locking with Emacs’ Font Lock mode, see (emacs)Font Lock section ‘Font Lock Mode’ in GNU Emacs Manual.

User Option: TeX-install-font-lock

Once font locking is enabled globally or for the major modes provided by AUCTeX, the font locking patterns and functionality of font-latex are activated by default. You can switch to a different font locking scheme or disable font locking in AUCTeX by customizing the variable TeX-install-font-lock.

Besides font-latex AUCTeX ships with a scheme which is derived from Emacs’ default LaTeX mode and activated by choosing tex-font-setup. Be aware that this scheme is not coupled with AUCTeX’s style system and not the focus of development. Therefore and due to font-latex being much more feature-rich the following explanations will only cover font-latex.

In case you want to hook in your own fontification scheme, you can choose other and insert the name of the function which sets up your font locking patterns. If you want to disable fontification in AUCTeX completely, choose ignore.

font-latex provides many options for customization which are accessible with M-x customize-group <RET> font-latex <RET>. For this description the various options are explained in conceptional groups.

3.1.1 Fontification of macros

Highlighting of macros can be customized by adapting keyword lists which can be found in the customization group font-latex-keywords.

Three types of macros can be handled differently with respect to fontification:

1. Commands of the form ‘\foo[bar]{baz}’ which consist of the macro itself, optional arguments in square brackets and mandatory arguments in curly braces. For the command itself the face font-lock-keyword-face will be used and for the optional arguments the face font-lock-variable-name-face. The face applied to the mandatory argument depends on the macro class represented by the respective built-in variables.
2. Declaration macros of the form ‘{\foo text}’ which consist of the macro which may be enclosed in a TeX group together with text to be affected by the macro. In case a TeX group is present, the macro will get the face font-lock-keyword-face and the text will get the face configured for the respective macro class. If no TeX group is present, the latter face will be applied to the macro itself.
3. Simple macros of the form ‘\foo’ which do not have any arguments or groupings. The respective face will be applied to the macro itself.

Customization variables for ‘\foo[bar]{baz}’ type macros allow both the macro name and the sequence of arguments to be specified. The latter is done with a string which can contain the characters

‘*’

indicating the existence of a starred variant for the macro,

‘[’

for optional arguments in brackets,

‘{’

for mandatory arguments in braces,

‘\’

for mandatory arguments consisting of a single macro and

‘|’

as a prefix indicating that two alternatives are following.

For example the specifier for ‘\documentclass’ would be ‘[{’ because the macro has one optional followed by one mandatory argument. The specifier for ‘\newcommand’ would be ‘*|{\[[{’ because there is a starred variant, the mandatory argument following the macro name can be a macro or a TeX group which can be followed by two optional arguments and the last token is a mandatory argument in braces.

Customization variables for the ‘{\foo text}’ and ‘\foo’ types are simple lists of strings where each entry is a macro name (without the leading backslash).

General macro classes

font-latex provides keyword lists for different macro classes which are described in the following table:

font-latex-match-function-keywords

Keywords for macros defining or related to functions, like ‘\newcommand’.
Type: ‘\macro[...]{...}’
Face: font-lock-function-name-face

font-latex-match-reference-keywords

Keywords for macros defining or related to references, like ‘\ref’.
Type: ‘\macro[...]{...}’
Face: font-lock-constant-face

font-latex-match-textual-keywords

Keywords for macros specifying textual content, like ‘\caption’.
Type: ‘\macro[...]{...}’
Face: font-lock-type-face

font-latex-match-variable-keywords

Keywords for macros defining or related to variables, like ‘\setlength’.
Type: ‘\macro[...]{...}’
Face: font-lock-variable-name-face

font-latex-match-warning-keywords

Keywords for important macros, e.g. affecting line or page break, like ‘\clearpage’.
Type: ‘\macro’
Face: font-latex-warning-face

Sectioning commands

Sectioning commands are macros like ‘\chapter’ or ‘\section’. For these commands there are two fontification schemes which may be selected by customizing the variable font-latex-fontify-sectioning.

User Option: font-latex-fontify-sectioning

Per default sectioning commands will be shown in a larger, proportional font, which corresponds to a number for this variable. The font size varies with the sectioning level, e.g. ‘\part’ (font-latex-sectioning-0-face) has a larger font than ‘\paragraph’ (font-latex-sectioning-5-face). Typically, values from 1.05 to 1.3 for font-latex-fontify-sectioning give best results, depending on your font setup. If you rather like to use the base font and a different color, set the variable to the symbol ‘color’. In this case the face font-lock-type-face will be used to fontify the argument of the sectioning commands.

You can make font-latex aware of your own sectioning commands be adding them to the keyword lists: font-latex-match-sectioning-0-keywords (font-latex-sectioning-0-face) … font-latex-match-sectioning-5-keywords (font-latex-sectioning-5-face).

Related to sectioning there is special support for slide titles which may be fontified with the face font-latex-slide-title-face. You can add macros which should appear in this face by customizing the variable font-latex-match-slide-title-keywords.

Commands for changing fonts

LaTeX provides various macros for changing fonts or font attributes. For example, you can select an italic font with ‘\textit{...}’ or bold with ‘\textbf{...}’. An alternative way to specify these fonts is to use special macros in TeX groups, like ‘{\itshape ...}’ for italics and ‘{\bfseries ...}’ for bold. As mentioned above, we call the former variants commands and the latter declarations.

Besides the macros for changing fonts provided by LaTeX there is an infinite number of other macros—either defined by yourself for logical markup or defined by macro packages—which affect the font in the typeset text. While LaTeX’s built-in macros and macros of packages known by AUCTeX are already handled by font-latex, different keyword lists per type style and macro type are provided for entering your own macros which are listed in the table below.

font-latex-match-bold-command-keywords

Keywords for commands specifying a bold type style.
Face: font-latex-bold-face

font-latex-match-italic-command-keywords

Keywords for commands specifying an italic font.
Face: font-latex-italic-face

font-latex-match-underline-command-keywords

Keywords for commands specifying an underlined text.
Face: font-latex-underline-face

font-latex-match-math-command-keywords

Keywords for commands specifying a math font.
Face: font-latex-math-face

font-latex-match-type-command-keywords

Keywords for commands specifying a typewriter font.
Face: font-lock-type-face

font-latex-match-bold-declaration-keywords

Keywords for declarations specifying a bold type style.
Face: font-latex-bold-face

font-latex-match-italic-declaration-keywords

Keywords for declarations specifying an italic font.
Face: font-latex-italic-face

font-latex-match-type-declaration-keywords

Keywords for declarations specifying a typewriter font.
Face: font-latex-type-face

Deactivating defaults of built-in keyword classes

font-latex ships with predefined lists of keywords for the classes described above. You can disable these defaults per class by customizing the variable font-latex-deactivated-keyword-classes. This is a list of strings for keyword classes to be deactivated. Valid entries are "warning", "variable", "biblatexnoarg", "biblatex", "reference", "function", "function-noarg", "sectioning-0", "sectioning-1", "sectioning-2", "sectioning-3", "sectioning-4", "sectioning-5", "slide-title", "textual", "bold-command", "italic-command", "underline-command", "math-command", "type-command", "bold-declaration", "italic-declaration" or "type-declaration".

You can also get rid of certain keywords only. For example if you want to remove highlighting of footnotes as references you can put the following stanza into your init file:

(eval-after-load "font-latex"
  '(setq-default
    font-latex-match-reference-keywords-local
    (remove (assoc-string "footnote"
            font-latex-match-reference-keywords-local)
                font-latex-match-reference-keywords-local)))

But note that this means fiddling with font-latex’s internals and is not guaranteed to work in future versions of font-latex.

User-defined keyword classes

In case the customization options explained above do not suffice for your needs, you can specify your own keyword classes by customizing the variable font-latex-user-keyword-classes.

User Option: font-latex-user-keyword-classes

Every keyword class consists of four parts, a name, a list of keywords, a face and a specifier for the type of macros to be highlighted.

When adding new entries, you have to use unique values for the class names, i.e. they must not clash with names of the built-in keyword classes or other names given by you. Additionally the names must not contain spaces.

The list of keywords defines which commands and declarations should be covered by the keyword class. A keyword can either be a simple command name omitting the leading backslash or a list consisting of the command name and a string specifying the sequence of arguments for the command.

The face argument can either be an existing face or face attributes made by you.

There are three alternatives for the type of keywords—“Command with arguments”, “Declaration inside TeX group” and “Command without arguments”—which correspond with the macro types explained above.

3.1.2 Fontification of quotes

Text in quotation marks is displayed with the face font-latex-string-face. Besides the various forms of opening and closing double and single quotation marks, so-called guillemets (<<, >>) can be used for quoting. Because there are two styles of using them—French style: << text >>; German style: >>text<<—you can customize the variable font-latex-quotes to tell font-latex which type you are using if the correct value cannot be derived from document properties.

User Option: font-latex-quotes

The default value of font-latex-quotes is ‘auto’ which means that font-latex will try to derive the correct type of quotation mark matching from document properties like the language option supplied to the babel LaTeX package.

If the automatic detection fails for you and you mostly use one specific style you can set it to a specific language-dependent value as well. Set the value to ‘german’ if you are using >>German quotes<< and to ‘french’ if you are using << French quotes >>. font-latex will recognize the different ways these quotes can be given in your source code, i.e. (‘"<’, ‘">’), (‘<<’, ‘>>’) and the respective 8-bit variants.

If you set font-latex-quotes to nil, quoted content will not be fontified.

3.1.3 Fontification of mathematical constructs

In LaTeX mathematics can be indicated by a variety of different methods: toggles (like dollar signs), macros and environments. Math constructs known by font-latex are displayed with the face font-latex-math-face. Support for dollar signs and shorthands like ‘\(...\)’ or ‘\[...\]’ is built-in and not customizable. Support for other math macros and environments can be adapted by customizing the variables font-latex-match-math-command-keywords and texmathp-tex-commands respectively. It is no longer recommended to customize font-latex-math-environments.

To convert your customization in font-latex-math-environments into texmathp-tex-commands, please register your own math environments, together with starred variants if any, as entries of env-on type in texmathp-tex-commands, then clear out font-latex-math-environments. You have to restart Emacs for this new customization to take effect for fontification.

In order to make math constructs more readable, font-latex displays subscript and superscript parts in a smaller font and raised or lowered respectively. This fontification feature can be controlled with the variables font-latex-fontify-script and font-latex-script-display.

User Option: font-latex-fontify-script

If non-nil, fontify subscript and superscript strings. Concretely, this means that the scripts are raised or lowered.

Another possiblity is setting this variable to the symbol multi-level. In this case, in a formula x^{y^z}, y is raised above and smaller than x, and z is raised above and smaller than y. With many script levels, the text might become too small to be readable. (See font-latex-fontify-script-max-level below.)

Lastly, you can set this variable to invisible whose behavior is like multi-level, and in addition the super-/subscript characters ^ and _ are not displayed.

User Option: font-latex-fontify-script-max-level

Maximum scriptification level for which script faces are applied.

The faces font-latex-superscript-face and font-latex-subscript-face define custom :height values < 1.0. Therefore, scripts are displayed with a slightly smaller font than normal math text. If font-latex-fontify-script is multi-level or invisible, the font size becomes too small to be readable after a few levels. This option allows to specify the maximum level after which the size of the script text won’t be shrunken anymore.

For example, in the expression x^{y^{z^a_b}}, x has scriptification level 0, y has level 1, z has level 2, and both a and b have scriptification level 3.

If font-latex-fontify-script-max-level was 2, then z, a, and b would have the same font size. If it was 3 or more, then a and b were smaller than z just in the same way as z is smaller than y and y is smaller than x.

The script characters ‘^’ and ‘_’ themselves are also fontified with an own face named font-latex-script-char-face.

User Option: font-latex-script-display

Display specification for subscript and superscript content. The car is used for subscript, the cdr is used for superscript. The feature is implemented using so-called display properties. For information on what exactly to specify for the values, see (elisp)Other Display Specs section ‘Other Display Specifications’ in GNU Emacs Lisp Reference Manual.

3.1.4 Verbatim macros and environments

Usually it is not desirable to have content to be typeset verbatim highlighted according to LaTeX syntax. Therefore this content will be fontified uniformly with the face font-latex-verbatim-face.

font-latex differentiates three different types of verbatim constructs for fontification. Macros with special characters like | as delimiters, macros with braces, and environments. Which macros and environments are recognized is controlled by the variables LaTeX-verbatim-macros-with-delims, LaTeX-verbatim-macros-with-braces, and LaTeX-verbatim-environments respectively.

3.1.5 Faces used by font-latex

In case you want to change the colors and fonts used by font-latex please refer to the faces mentioned in the explanations above and use M-x customize-face <RET> <face> <RET>. All faces defined by font-latex are accessible through a customization group by typing M-x customize-group <RET> font-latex-highlighting-faces <RET>.

3.1.6 Known fontification problems

In certain cases the fontification machinery fails to interpret buffer contents correctly. This can lead to color bleed, i.e. large parts of a buffer get fontified with an inappropriate face. A typical situation for this to happen is the use of a dollar sign (‘$’) in a verbatim macro or environment. If font-latex is not aware of the verbatim construct, it assumes the dollar sign to be a toggle for mathematics and fontifies the following buffer content with the respective face until it finds a closing dollar sign or till the end of the buffer.

As a remedy you can make the verbatim construct known to font-latex (see Verbatim content). If this is not possible, you can insert a commented dollar sign (‘%$’) at the next suitable end of line as a quick workaround. In docTeX documents, ‘^^A$’ is also available for similar purpose.

3.2 Folding Macros and Environments

A popular complaint about markup languages like TeX and LaTeX is that there is too much clutter in the source text and that one cannot focus well on the content. There are macros where you are only interested in the content they are enclosing, like font specifiers where the content might already be fontified in a special way by font locking. Or macros the content of which you only want to see when actually editing it, like footnotes or citations. Similarly you might find certain environments or comments distracting when trying to concentrate on the body of your document.

With AUCTeX’s folding functionality you can collapse those items and replace them by a fixed string, the content of one of their arguments, or a mixture of both. If you want to make the original text visible again in order to view or edit it, move point sideways onto the placeholder (also called display string) or left-click with the mouse pointer on it. The macro or environment will unfold automatically, stay open as long as point is inside of it and collapse again once you move point out of it. (Note that folding of environments currently does not work in every AUCTeX mode.)

In order to use this feature, you have to activate TeX-fold-mode which will activate the auto-reveal feature and the necessary commands to hide and show macros and environments. You can activate the mode in a certain buffer by typing the command M-x TeX-fold-mode <RET> or using the keyboard shortcut C-c C-o C-f. If you want to use it every time you edit a LaTeX document, add it to a hook:

(add-hook 'LaTeX-mode-hook (lambda ()
                             (TeX-fold-mode 1)))

If it should be activated in all AUCTeX modes, use TeX-mode-hook instead of LaTeX-mode-hook.

Once the mode is active there are several commands available to hide and show macros, environments and comments:

Command: TeX-fold-buffer

(C-c C-o C-b) Hide all foldable items in the current buffer according to the setting of TeX-fold-type-list.

If you want to have this done automatically every time you open a file, add it to a hook and make sure the function is called after font locking is set up for the buffer. The following code should accomplish this:

(add-hook 'find-file-hook #'TeX-fold-buffer t)

The command can be used any time to refresh the whole buffer and fold any new macros and environments which were inserted after the last invocation of the command.

User Option: TeX-fold-type-list

List of symbols determining the item classes to consider for folding. This can be macros, environments and comments. Per default only macros and environments are folded.

User Option: TeX-fold-force-fontify

In order for all folded content to get the right faces, the whole buffer has to be fontified before folding is carried out. TeX-fold-buffer therefore will force fontification of unfontified regions. As this will prolong the time folding takes, you can prevent forced fontification by customizing the variable TeX-fold-force-fontify.

User Option: TeX-fold-auto

By default, a macro inserted with TeX-insert-macro (C-c C-m) will not be folded. Set this variable to a non-nil value to aumatically fold macros as soon as they are inserted.

User Option: TeX-fold-preserve-comments

By default items found in comments will be folded. If your comments often contain unfinished code this might lead to problems. Give this variable a non-nil value and foldable items in your comments will be left alone.

User Option: TeX-fold-unfold-around-mark

When this variable is non-nil and there is an active regione, text around the mark will be kept unfolded.

Command: TeX-fold-region

(C-c C-o C-r) Hide all configured macros in the marked region.

Command: TeX-fold-paragraph

(C-c C-o C-p) Hide all configured macros in the paragraph containing point.

Command: TeX-fold-macro

(C-c C-o C-m) Hide the macro on which point currently is located. If the name of the macro is found in TeX-fold-macro-spec-list, the respective display string will be shown instead. If it is not found, the name of the macro in sqare brackets or the default string for unspecified macros (TeX-fold-unspec-macro-display-string) will be shown, depending on the value of the variable TeX-fold-unspec-use-name.

Command: TeX-fold-env

(C-c C-o C-e) Hide the environment on which point currently is located. The behavior regarding the display string is analogous to TeX-fold-macro and determined by the variables TeX-fold-env-spec-list and TeX-fold-unspec-env-display-string respectively.

Command: TeX-fold-math

Hide the math macro on which point currently is located. If the name of the macro is found in TeX-fold-math-spec-list, the respective display string will be shown instead. If it is not found, the name of the macro in sqare brackets or the default string for unspecified macros (TeX-fold-unspec-macro-display-string) will be shown, depending on the value of the variable TeX-fold-unspec-use-name.

Command: TeX-fold-comment

(C-c C-o C-c) Hide the comment point is located on.

Command: TeX-fold-clearout-buffer

(C-c C-o b) Permanently unfold all macros and environments in the current buffer.

Command: TeX-fold-clearout-region

(C-c C-o r) Permanently unfold all macros and environments in the marked region.

Command: TeX-fold-clearout-paragraph

(C-c C-o p) Permanently unfold all macros and environments in the paragraph containing point.

Command: TeX-fold-clearout-item

(C-c C-o i) Permanently show the macro or environment on which point currently is located. In contrast to temporarily opening the macro when point is moved sideways onto it, the macro will be permanently unfolded and will not collapse again once point is leaving it.

Command: TeX-fold-dwim

(C-c C-o C-o) Hide or show items according to the current context. If there is folded content, unfold it. If there is a marked region, fold all configured content in this region. If there is no folded content but a macro or environment, fold it.

In case you want to use a different prefix than C-c C-o for these commands you can customize the variable TeX-fold-command-prefix. (Note that this will not change the key binding for activating the mode.)

The commands above will only take macros or environments into consideration which are specified in the variables TeX-fold-macro-spec-list or TeX-fold-env-spec-list respectively.

User Option: TeX-fold-macro-spec-list

List of replacement specifiers and macros to fold. The specifier can be a string, an integer or a function symbol.

If you specify a string, it will be used as a display replacement for the whole macro. Numbers in braces, brackets, parens or angle brackets will be replaced by the respective macro argument. For example ‘{1}’ will be replaced by the first mandatory argument of the macro. One can also define alternatives within the specifier which are used if an argument is not found. Alternatives are separated by ‘||’. They are most useful with optional arguments. As an example, the default specifier for ‘\item’ is ‘[1]:||*’ which means that if there is an optional argument, its value is shown followed by a colon. If there is no optional argument, only an asterisk is used as the display string.

If you specify a number as the first element, the content of the respective mandatory argument of a LaTeX macro will be used as the placeholder.

If the first element is a function symbol, the function will be called with all mandatory arguments of the macro and the result of the function call will be used as a replacement for the macro. Such functions typically return a string, but may also return the symbol abort to indicate that the macro should not be folded.

The placeholder is made by copying the text from the buffer together with its properties, i.e. its face as well. If fontification has not happened when this is done (e.g. because of lazy font locking) the intended fontification will not show up. As a workaround you can leave Emacs idle a few seconds and wait for stealth font locking to finish before you fold the buffer. Or you just re-fold the buffer with TeX-fold-buffer when you notice a wrong fontification.

User Option: TeX-fold-env-spec-list

List of display strings or argument numbers and environments to fold. Argument numbers refer to the ‘\begin’ statement. That means if you have e.g. ‘\begin{tabularx}{\linewidth}{XXX} ... \end{tabularx}’ and specify 3 as the argument number, the resulting display string will be “XXX”.

User Option: TeX-fold-math-spec-list

List of display strings and math macros to fold.

The variables TeX-fold-macro-spec-list, TeX-fold-env-spec-list, and TeX-fold-math-spec-list apply to any AUCTeX mode. If you want to make settings which are only applied to LaTeX mode, you can use the mode-specific variables LaTeX-fold-macro-spec-list, LaTeX-fold-env-spec-list, and LaTeX-fold-math-spec-list

User Option: TeX-fold-unspec-macro-display-string

Default display string for macros which are not specified in TeX-fold-macro-spec-list.

User Option: TeX-fold-unspec-env-display-string

Default display string for environments which are not specified in TeX-fold-env-spec-list.

User Option: TeX-fold-unspec-use-name

If non-nil the name of the macro or environment surrounded by square brackets is used as display string, otherwise the defaults specified in TeX-fold-unspec-macro-display-string or TeX-fold-unspec-env-display-string respectively.

When you hover with the mouse pointer over folded content, its original text will be shown in a tooltip or the echo area depending on Tooltip mode being activate. In order to avoid exorbitantly big tooltips and to cater for the limited space in the echo area the content will be cropped after a certain amount of characters defined by the variable TeX-fold-help-echo-max-length.

User Option: TeX-fold-help-echo-max-length

Maximum length of original text displayed in a tooltip or the echo area for folded content. Set it to zero in order to disable this feature.

3.3 Outlining the Document

AUCTeX supports the standard outline minor mode using LaTeX/ConTeXt sectioning commands as header lines. See (emacs)Outline Mode section ‘Outline Mode’ in GNU Emacs Manual.

You can add your own headings by setting the variable TeX-outline-extra.

Variable: TeX-outline-extra

List of extra TeX outline levels.

Each element is a list with two entries. The first entry is the regular expression matching a header, and the second is the level of the header. A ‘^’ is automatically prepended to the regular expressions in the list, so they must match text at the beginning of the line.

See LaTeX-section-list or ConTeXt-interface-section-list for existing header levels.

The following example add ‘\item’ and ‘\bibliography’ headers, with ‘\bibliography’ at the same outline level as ‘\section’, and ‘\item’ being below ‘\subparagraph’.

(setq TeX-outline-extra
      '(("[ \t]*\\\\\\(bib\\)?item\\b" 7)
        ("\\\\bibliography\\b" 2)))

You may want to check out the unbundled ‘out-xtra’ package for even better outline support. It is available from your favorite emacs lisp archive.

3.4 Narrowing

Sometimes you want to focus your attention to a limited region of the code. You can do that by restricting the text addressable by editing commands and hiding the rest of the buffer with the narrowing functions, see (emacs)Narrowing section ‘Narrowing’ in GNU Emacs Manual. In addition, AUCTeX provides a couple of other commands to narrow the buffer to a group, i.e. a region enclosed in a pair of curly braces, and to LaTeX environments.

Command: TeX-narrow-to-group

(C-x n g) Make text outside current group invisible.

Command: LaTeX-narrow-to-environment count

(C-x n e) Make text outside current environment invisible. With optional argument count keep visible that number of enclosing environmens.

Like other standard narrowing functions, the above commands are disabled. Attempting to use them asks for confirmation and gives you the option of enabling them; if you enable the commands, confirmation will no longer be required for them.

3.5 Prettifying

Emacs 25 is able to prettify symbols in programming language buffers, see (emacs)Misc for Programs section ‘Misc for Programs’ in GNU Emacs Manual. The canonical example is to display (lambda () ...) as (λ () ...) in Lisp buffers.

AUCTeX can use this feature in order to display certain math macros and greek letters using their Unicode representation, too. For example, the TeX code \alpha \times \beta will be displayed as α × β. When point is on one of the characters, it’ll be unprettified automatically, meaning you see the verbatim text again. For this behaviour however you need to set prettify-symbols-unprettify-at-point to t or right-edge which will unprettify the symbol when point moves into or near it.

To enable prettification in AUCTeX, simply add prettify-symbols-mode to TeX-mode-hook. If you enabled prettification globally with global-prettify-symbols-mode, then it’s automatically enabled in AUCTeX, too.

You can also add custom symbol unicode-character pairs for prettification by adding to tex--prettify-symbols-alist. Note that this variable is part of Emacs’ stock tex-mode.el and used by that and AUCTeX.

4. Starting Processors, Viewers and Other Programs

The most powerful features of AUCTeX may be those allowing you to run TeX, LaTeX, ConTeXt and other external commands like BibTeX and makeindex from within Emacs, viewing and printing the results, and moreover allowing you to debug your documents.

AUCTeX comes with a special tool bar for TeX and LaTeX which provides buttons for the most important commands. You can enable or disable it by customizing the options plain-TeX-enable-toolbar and LaTeX-enable-toolbar in the TeX-tool-bar customization group. You can also customize the buttons by the options TeX-bar-TeX-buttons, TeX-bar-TeX-all-button-alists, TeX-bar-LaTeX-buttons and TeX-bar-LaTeX-button-alist.

4.1 Executing Commands

Formatting the document with TeX, LaTeX or ConTeXt, viewing with a previewer, printing the document, running BibTeX, making an index, or checking the document with lacheck or chktex all require running an external command.

4.1.1 Starting a Command on a Document or Region

There are two ways to run an external command, you can either run it on the current document with TeX-command-master, or on the current region with TeX-command-region. A special case of running TeX on a region is TeX-command-buffer which differs from TeX-command-master if the current buffer is not its own master file.

Command: TeX-command-master

(C-c C-c) Query the user for a command, and run it on the master file associated with the current buffer. The name of the master file is controlled by the variable TeX-master. The available commands are controlled by the variable TeX-command-list.

Command: TeX-command-region

(C-c C-r) Query the user for a command, and run it on the contents of the selected region. The region contents are written into the region file, after extracting the header and trailer from the master file. If mark is inactive (which can happen with Transient Mark mode), use the old region. See also the command TeX-pin-region about how to fix a region.

The name of the region file is controlled by the variable TeX-region. The name of the master file is controlled by the variable TeX-master. The header is all text up to the line matching the regular expression TeX-header-end. The trailer is all text from the line matching the regular expression TeX-trailer-start. The available commands are controlled by the variable TeX-command-list.

Command: TeX-command-buffer

(C-c C-b) Query the user for a command, and apply it to the contents of the current buffer. The buffer contents are written into the region file, after extracting the header and trailer from the master file. The command is then actually run on the region file. See above for details.

Command: LaTeX-command-section

(C-c C-z) Query the user for a command, and apply it to the current section (or part, chapter, subsection, paragraph, or subparagraph). What makes the current section is determined by LaTeX-command-section-level which can be enlarged/shrunken using LaTeX-command-section-change-level (C-c M-z). The given numeric prefix arg is added to the current value of LaTeX-command-section-level. By default, LaTeX-command-section-level is initialized with the current document’s LaTeX-largest-level. The buffer contents are written into the region file, after extracting the header and trailer from the master file. The command is then actually run on the region file. See TeX-command-region for details.

It is also possible to compile automatically the whole document until it is ready with a single command: TeX-command-run-all.

Command: TeX-command-run-all

(C-c C-a) Compile the current document until an error occurs or it is finished. If compilation finishes successfully, run the viewer at the end.

Here are some relevant variables.

User Option: TeX-region

The name of the file for temporarily storing the text when formatting the current region.

User Option: TeX-header-end

A regular expression matching the end of the header. By default, this is ‘\begin{document}’ in LaTeX mode and ‘%**end of header’ in plain TeX mode.

User Option: TeX-trailer-start

A regular expression matching the start of the trailer. By default, this is ‘\end{document}’ in LaTeX mode and ‘\bye’ in plain TeX mode.

If you want to change the values of TeX-header-end and TeX-trailer-start you can do this for all files by setting the variables in a mode hook or per file by specifying them as file variables (see (emacs)File Variables section ‘File Variables’ in The Emacs Editor).

Command: TeX-pin-region

(C-c C-t C-r) If you don’t have a mode like Transient Mark mode active, where marks get disabled automatically, the region would need to get properly set before each call to TeX-command-region. If you fix the current region with C-c C-t C-r, then it will get used for more commands even though mark and point may change. An explicitly activated mark, however, will always define a new region when calling TeX-command-region.

If the last process you started was on the region, the commands described in Debugging and Control will work on that process, otherwise they will work on the process associated with the current document.

Don’t run more than one process at the same time. AUCTeX doesn’t support simultaneous typeset including region typeset. Wait for the previous process to finish before you start a new process, in particular when you are editing multiple documents in parallel. This limitation applies for preview by preview-latex as well.

4.1.2 Selecting and Executing a Command

Once you started the command selection with C-c C-c, C-c C-r or C-c C-b you will be prompted for the type of command. AUCTeX will try to guess which command is appropriate in the given situation and propose it as default. Usually this is a processor like ‘TeX’ or ‘LaTeX’ if the document was changed or a viewer if the document was just typeset. Other commands can be selected in the minibuffer with completion support by typing <TAB>.

The available commands are defined by the variable TeX-command-list. Per default it includes commands for typesetting the document (e.g. ‘LaTeX’), for viewing the output (‘View’), for printing (‘Print’), for generating an index (‘Index’) or for spell checking (‘Spell’) to name but a few. You can also add your own commands by adding entries to TeX-command-list. Refer to its doc string for information about its syntax. You might also want to look at TeX-expand-list to learn about the expanders you can use in TeX-command-list.

Note that the default of the variable occasionally changes. Therefore it is advisable to add to the list rather than overwriting it. You can do this with a call to add-to-list in your init file. For example, if you wanted to add a command for running a program called ‘foo’ on the master or region file, you could do this with the following form.

(eval-after-load "tex"
  '(add-to-list 'TeX-command-list
                '("Foo" "foo %s" TeX-run-command t t :help "Run foo")
                t))

As mentioned before, AUCTeX will try to guess what command you want to invoke. If you want to use another command than ‘TeX’, ‘LaTeX’ or whatever processor AUCTeX thinks is appropriate for the current mode, set the variable TeX-command-default. You can do this for all files by setting it in a mode hook or per file by specifying it as a file variable (see (emacs)File Variables section ‘File Variables’ in The Emacs Editor).

User Option: TeX-command-default

The default command to run in this buffer. Must be an entry in TeX-command-list.

In case you use biblatex in a document, when automatic parsing is enabled AUCTeX checks the value of ‘backend’ option given to biblatex at load time to decide whether to use BibTeX or Biber for bibliography processing. Should AUCTeX fail to detect the right backend, you can use the file local LaTeX-biblatex-use-Biber variable.

Variable: LaTeX-biblatex-use-Biber

If this boolean variable is set as file local, it tells to AUCTeX whether to use Biber with biblatex. In this case, the autodetection of the biblatex backend will be overridden. You may want to set locally this variable if automatic parsing is not enabled.

After confirming a command to execute, AUCTeX will try to save any buffers related to the document, and check if the document needs to be reformatted. If the variable TeX-save-query is non-nil, AUCTeX will query before saving each file. By default AUCTeX will check emacs buffers associated with files in the current directory, in one of the TeX-macro-private directories, and in the TeX-macro-global directories. You can change this by setting the variable TeX-check-path.

User Option: TeX-check-path

Directory path to search for dependencies.

If nil, just check the current file. Used when checking if any files have changed.

When performing spell checking on a document or a region (invoked through AUCTeX’s ‘Spell’ command or M-x ispell <RET>), you want the spell checking program to skip certain macro arguments and environments, most notably the arguments of referencing macros and the contents of verbatim environments. The skipped parts are controlled by variable ispell-tex-skip-alists provided by ‘ispell.el’. AUCTeX has a library which can be added to this variable depending on the value of TeX-ispell-extend-skip-list which is set to t by default.

User Option: TeX-ispell-extend-skip-list

This boolean option controls whether AUCTeX activates its extension for skipping certain macro arguments and environments when spell checking.

When non-nil, AUCTeX loads the file ‘tex-ispell.el’ and adds its content to ispell-tex-skip-alists. This library can and will never be complete, but the interface can be used to add selected and private macro names within your init file or on a file local basis.

ispell-tex-skip-alists has the following structure:

(defvar ispell-tex-skip-alists '((;; First list ("\\\\addcontentsline" ispell-tex-arg-end 2) ("\\\\\\([aA]lph\\|arabic\\)" ispell-tex-arg-end) ("\\\\makebox" ispell-tex-arg-end 0) ("\\\\documentclass" . "\\\\begin{document}")) (;; Second list ("\\(figure\\|table\\)\\*?" ispell-tex-arg-end 0) ("list" ispell-tex-arg-end 2) ("verbatim\\*?" . "\\\\end{verbatim\\*?}"))) "Lists of regions to be skipped in TeX mode. First list is used raw. Second list has key placed inside \\begin{}.")

Each item is an alist and the structure of it is described in ispell-skip-region-alist:

(defvar ispell-skip-region-alist '((...)) "Alist expressing beginning and end of regions not to spell check. The alist key must be a regular expression. Valid forms include: (KEY) - just skip the key. (KEY . REGEXP) - skip to the end of REGEXP. REGEXP may be string or symbol. (KEY REGEXP) - skip to end of REGEXP. REGEXP must be a string. (KEY FUNCTION ARGS) - FUNCTION called with ARGS returns end of region.")

Let’s go through the first list of ispell-tex-skip-alists line by line:

("\\\\addcontentsline" ispell-tex-arg-end 2)

KEY is the string "\\\\addcontentsline", FUNCTION is ispell-tex-arg-end called with ARGS, here 2. ispell-tex-arg-end is a function provided by ‘ispell.el’ which skips as many subsequent optional arguments in square brackets as it sees and then skips ARGS number of mandatory arguments in braces. Omitting ARGS means skip 1 mandatory argument. In practice, when you have something like this in your document:

\addcontentsline{toc}{chapter}{Some text}

The first two arguments are left out and ‘Some text’ will be spell checked. For the next line

("\\\\\\([aA]lph\\|arabic\\)" ispell-tex-arg-end)

the name of the counter as argument is skipped. Next line is

("\\\\makebox" ispell-tex-arg-end 0)

where only optional arguments are skipped, the first mandatory argument is checked, e.g.

\makebox[0pt][l]{Some text}

Finally, the next line

("\\\\documentclass" . "\\\\begin{document}"))

ensures that the entire preamble of a document is discarded. Second list works the same; it is more convenient for environments since KEY is wrapped inside \begin{}.

AUCTeX provides two functions to add items to car and cdr of ispell-tex-arg-end, namely TeX-ispell-skip-setcar and TeX-ispell-skip-setcdr. The argument of these functions is exactly as in ispell-tex-skip-alists. Additions can be done via init file, e.g.:

(eval-after-load "tex-ispell" '(progn (TeX-ispell-skip-setcar '(("\\\\mymacro" ispell-tex-arg-end))) (TeX-ispell-skip-setcdr '(("myverbatim" . "\\\\end{myverbatim}")))))

Another possibility is to use file local additions at the end of your TeX file, e.g.:

%%% Local Variables: %%% mode: latex %%% TeX-master: t %%% eval: (TeX-ispell-skip-setcar '(("\\\\mymacro" . "{[-0-9]+}"))) %%% End:

Finally, AUCTeX provides a function called TeX-ispell-tex-arg-end which sees more arguments than ispell-tex-arg-end. Refer to its doc string for more information.

AUCTeX also provides a facility to skip the argument of in-line verbatim macros like ‘\Verb’ from ‘fancyvrb.sty’ or ‘\mintinline’ from ‘minted.sty’. Characters delimiting the verbatim text are stored in TeX-ispell-verb-delimiters.

User Option: TeX-ispell-verb-delimiters

String with delimiters recognized for in-line verbatim macros. This variable is initialized to ‘!|#~"*/+^-’. Since this string is used to build a character alternative inside a regular expression, special characters ‘^’ and ‘-’ should come last. Other characters like opening brace ‘{’, asterisk ‘*’ or at sign ‘@’ should be avoided as they are not recognized by ‘font-latex.el’.

4.1.3 Options for TeX Processors

There are some options you can customize affecting which processors are invoked or the way this is done and which output they produce as a result. These options control if DVI or PDF output should be produced, if TeX should be started in interactive or nonstop mode, if source specials or a SyncTeX file should be produced for making inverse and forward search possible or which TeX engine should be used instead of regular TeX, like PDFTeX, Omega or XeTeX, and the style error messages are printed with.

Command: TeX-PDF-mode

(C-c C-t C-p) This command toggles the PDF mode of AUCTeX, a buffer-local minor mode which is enabled by default. You can customize TeX-PDF-mode to give it a different default or set it as a file local variable on a per-document basis. This option usually results in calling either PDFTeX or ordinary TeX.

User Option: TeX-DVI-via-PDFTeX

If this is set, DVI will also be produced by calling PDFTeX, setting \pdfoutput=0. This makes it possible to use PDFTeX features like character protrusion even when producing DVI files. Contemporary TeX distributions do this anyway, so that you need not enable the option within AUCTeX.

Command: TeX-interactive-mode

(C-c C-t C-i) This command toggles the interactive mode of AUCTeX, a global minor mode. You can customize TeX-interactive-mode to give it a different default. In interactive mode, TeX will pause with an error prompt when errors are encountered and wait for the user to type something.

Command: TeX-source-correlate-mode

(C-c C-t C-s) Toggles support for forward and inverse search. Forward search refers to jumping to the place in the previewed document corresponding to where point is located in the document source and inverse search to the other way round. See I/O Correlation.

You can permanently activate TeX-source-correlate-mode by customizing the variable TeX-source-correlate-mode. There is a bunch of customization options for the mode, use M-x customize-group <RET> TeX-view <RET> to find out more.

AUCTeX is aware of three different means to do I/O correlation: source specials (only DVI output), the pdfsync LaTeX package (only PDF output) and SyncTeX. The choice between source specials and SyncTeX can be controlled with the variable TeX-source-correlate-method.

Should you use source specials it has to be stressed very strongly however, that source specials can cause differences in page breaks and spacing, can seriously interfere with various packages and should thus never be used for the final version of a document. In particular, fine-tuning the page breaks should be done with source specials switched off.

Sometimes you are requested, by journal rules or packages, to compile the document into DVI output. Thus, if you want a PDF document in the end you can either use XeTeX engine, see below for information about how to set engines, or compile the document with tex and then convert to PDF with dvips–ps2pdf before viewing it. In addition, current Japanese TeX engines cannot generate PDF directly so they rely on DVI-to-PDF converters. Usually dvipdfmx command is used for this purpose. You can use the TeX-PDF-from-DVI variable to let AUCTeX know you want to generate the final PDF by converting a DVI file.

User Option: TeX-PDF-from-DVI

This option controls if and how to produce a PDF file by converting a DVI file.

When TeX-PDF-mode is non-nil, if TeX-PDF-from-DVI is non-nil too the document is compiled to DVI instead of PDF. When the document is ready, C-c C-c will suggest to run the converter to PDF or an intermediate format.

If non-nil, TeX-PDF-from-DVI should be the name of the command in TeX-command-list, as a string, used to convert the DVI file to PDF or to an intermediate format. Values currently supported are:

• "Dvips": the DVI file is converted to PS with dvips. After successfully running it, ps2pdf will be the default command to convert the PS file to PDF.
• "Dvipdfmx": the DVI file is converted to PDF with dvipdfmx.

(case is significant; note the uppercase ‘D’ in both strings) When the PDF file is finally ready, the next suggested command will be ‘View’ to open the viewer.

This option can also be set as a file local variable, in order to use this conversion on a per-document basis.

Recall the whole sequence of C-c C-c commands can be replaced by the single C-c C-a.

AUCTeX also allows you to easily select different TeX engines for processing, either by using the entries in the ‘TeXing Options’ submenu below the ‘Command’ menu or by calling the function TeX-engine-set. These eventually set the variable TeX-engine which you can also modify directly.

User Option: TeX-engine

This variable allows you to choose which TeX engine should be used for typesetting the document, i.e. the executables which will be used when you invoke the ‘TeX’ or ‘LaTeX’ commands. The value should be one of the symbols defined in TeX-engine-alist-builtin or TeX-engine-alist. The symbols ‘default’, ‘xetex’, ‘luatex’ and ‘omega’ are available from the built-in list.

Note that TeX-engine is buffer-local, so setting the variable directly or via the above mentioned menu or function will not take effect in other buffers. If you want to activate an engine for all AUCTeX modes, set TeX-engine in your init file, e.g. by using M-x customize-option <RET>. If you want to activate it for a certain AUCTeX mode only, set the variable in the respective mode hook. If you want to activate it for certain files, set it through file variables (see (emacs)File Variables section ‘File Variables’ in The Emacs Editor).

Should you need to change the executable names related to the different engine settings, there are some variables you can tweak. Those are TeX-command, LaTeX-command, TeX-Omega-command, LaTeX-Omega-command, ConTeXt-engine and ConTeXt-Omega-engine. The rest of the executables is defined directly in TeX-engine-alist-builtin. If you want to override an entry from that, add an entry to TeX-engine-alist that starts with the same symbol as that the entry in the built-in list and specify the executables you want to use instead. You can also add entries to TeX-engine-alist in order to add support for engines not covered per default.

User Option: TeX-engine-alist

Alist of TeX engines and associated commands. Each entry is a list with a maximum of five elements. The first element is a symbol used to identify the engine. The second is a string describing the engine. The third is the command to be used for plain TeX. The fourth is the command to be used for LaTeX. The fifth is the command to be used for the ‘--engine’ parameter of ConTeXt’s ‘texexec’ program. Each command can either be a variable or a string. An empty string or nil means there is no command available.

In some systems, Emacs cannot inherit the PATH environment variable from the shell and thus AUCTeX may not be able to run TeX commands. Before running them, AUCTeX checks if it is able to find those commands and will warn you in case it fails. You can skip this test by changing the option TeX-check-TeX.

User Option: TeX-check-TeX

If non-nil, AUCTeX will check if it is able to find a working TeX distribution before running TeX, LaTeX, ConTeXt, etc. It actually checks if can run TeX-command command or the shell returns a command not found error. The error code returned by the shell in this case can be set in TeX-check-TeX-command-not-found option.

Some LaTeX packages requires the document to be compiled with a specific engine. Notable examples are ‘fontspec’ and ‘polyglossia’ packages, which require LuaTeX and XeTeX engines. If you try to compile a document which loads one of such packages and the set engine is not one of those allowed you will be asked to select a different engine before running the LaTeX command. If you do not want to be warned by AUCTeX in these cases, customize the option TeX-check-engine.

User Option: TeX-check-engine

This boolean option controls whether AUCTeX should check the correct engine has been set before running LaTeX commands.

As shown above, AUCTeX handles in a special way most of the main options that can be given to the TeX processors. When you need to pass to the TeX processor arbitrary options not handled by AUCTeX, you can use the file local variable TeX-command-extra-options.

User Option: TeX-command-extra-options

String with the extra options to be given to the TeX processor. For example, if you need to enable the shell escape feature to compile a document, add the following line to the list of local variables of the source file:

%%% TeX-command-extra-options: "-shell-escape"

By default this option is not safe as a file-local variable because a specially crafted document compiled with shell escape enabled can be used for malicious purposes.

You can customize AUCTeX to show the processor output as it is produced.

User Option: TeX-show-compilation

If non-nil, the output of TeX compilation is shown in another window.

You can instruct TeX to print error messages in the form ‘file:line:error’ which is similar to the way many compilers format them.

User Option: TeX-file-line-error

If non-nil, TeX will produce ‘file:line:error’ style error messages.

ConTeXt users can choose between Mark II and Mark IV versions. This is controlled by ConTeXt-Mark-version option.

User Option: ConTeXt-Mark-version

This variables specifies which version of Mark should be used. Values currently supported are "II", the default, and "IV". It can be set globally using customization interface or on a per-file basis, by specifying it as a file variable.

4.2 Viewing the Formatted Output

AUCTeX allows you to start external programs for previewing the formatted output of your document.

4.2.1 Starting Viewers

Viewers are normally invoked by pressing C-c C-c once the document is formatted, which will propose the ‘View’ command, or by activating the respective entry in the Command menu. Alternatively you can type C-c C-v which calls the function TeX-view.

Command: TeX-view

(C-c C-v) Start a viewer without confirmation. The viewer is started either on a region or the master file, depending on the last command issued. This is especially useful for jumping to the location corresponding to point in the viewer when using TeX-source-correlate-mode.

AUCTeX will try to guess which type of viewer (DVI, PostScript or PDF) has to be used and what options are to be passed over to it. This decision is based on the output files present in the working directory as well as the class and style options used in the document. For example, if there is a DVI file in your working directory, a DVI viewer will be invoked. In case of a PDF file it will be a PDF viewer. If you specified a special paper format like ‘a5paper’ or use the ‘landscape’ option, this will be passed to the viewer by the appropriate options. Especially some DVI viewers depend on this kind of information in order to display your document correctly. In case you are using ‘pstricks’ or ‘psfrag’ in your document, a DVI viewer cannot display the contents correctly and a PostScript viewer will be invoked instead.

The association between the tests for the conditions mentioned above and the viewers is made in the variable TeX-view-program-selection. Therefore this variable is the starting point for customization if you want to use other viewers than the ones suggested by default.

User Option: TeX-view-program-selection

This is a list of predicates and viewers which is evaluated from front to back in order to find out which viewer to call under the given conditions. In the first element of each list item you can reference one or more predicates defined in TeX-view-predicate-list or TeX-view-predicate-list-builtin. In the second element you can reference a viewer defined in TeX-view-program-list or TeX-view-program-list-builtin. The viewer of the first item with a positively evaluated predicate is selected.

So TeX-view-program-selection only contains references to the actual implementations of predicates and viewer commands respectively which can be found elsewhere. AUCTeX comes with a set of preconfigured predicates and viewer commands which are stored in the variables TeX-view-predicate-list-builtin and TeX-view-program-list-builtin respectively. If you are not satisfied with those and want to overwrite one of them or add your own definitions, you can do so via the variables TeX-view-predicate-list and TeX-view-program-list.

User Option: TeX-view-predicate-list

This is a list of predicates for viewer selection and invocation. The first element of each list item is a symbol and the second element a Lisp form to be evaluated. The form should return nil if the predicate is not fulfilled.

A built-in predicate from TeX-view-predicate-list-builtin can be overwritten by defining a new predicate with the same symbol.

User Option: TeX-view-program-list

This is a list of viewer specifications each consisting of a symbolic name and either a command line or a function to be invoked when the viewer is called. If a command line is used, parts of it can be conditionalized by prefixing them with predicates from TeX-view-predicate-list or TeX-view-predicate-list-builtin. (See the doc string for the exact format to use.) The command line can also contain placeholders as defined in TeX-expand-list and TeX-expand-list-builtin which are expanded before the viewer is called.

The third element of each item is a string, or a list of strings, with the name of the executable, or executables, needed to open the output file in the viewer. Placeholders defined in TeX-expand-list and TeX-expand-list-builtin can be used here. This element is optional and is used to check whether the viewer is actually available on the system.

A built-in viewer spec from TeX-view-program-list-builtin can be overwritten by defining a new viewer spec with the same name.

After the viewer is called via either the ‘View’ command or the key stroke C-c C-v, the window system focus goes and stays on the viewer. If you prefer that the focus is pulled back to Emacs immediately after that and you are using evince-compatible viewer, customize the option TeX-view-enince-keep-focus.

User Option: TeX-view-evince-keep-focus

When this option is non-nil and the viewer is compatible with evince, the focus is pulled back to Emacs immediately after the viewer is invoked or refreshed from within AUCTeX.

Note that the viewer selection and invocation as described above will only work if certain default settings in AUCTeX are intact. For one, the whole viewer selection machinery will only be triggered if there is no ‘%V’ expander in TeX-expand-list. So if you have trouble with the viewer invocation you might check if there is an older customization of the variable in place. In addition, the use of a function in TeX-view-program-list only works if the ‘View’ command in TeX-command-list makes use of the hook TeX-run-discard-or-function.

4.2.2 Forward and Inverse Search

Forward and inverse search refer to the correlation between the document source in the editor and the typeset document in the viewer. Forward search allows you to jump to the place in the previewed document corresponding to a certain line in the document source and inverse search vice versa.

AUCTeX supports three methods for forward and inverse search: source specials (only DVI output), the pdfsync LaTeX package (only PDF output) and SyncTeX (any type of output). If you want to make use of forward and inverse searching with source specials or SyncTeX, switch on TeX-source-correlate-mode. See Processor Options, on how to do that. The use of the pdfsync package is detected automatically if document parsing is enabled. Customize the variable TeX-source-correlate-method to select the method to use.

User Option: TeX-source-correlate-method

Method to use for enabling forward and inverse search. This can be ‘source-specials’ if source specials should be used, ‘synctex’ if SyncTeX should be used, or ‘auto’ if AUCTeX should decide.

When the variable is set to ‘auto’, AUCTeX will always use SyncTeX if your latex processor supports it, source specials otherwise. You must make sure your viewer supports the same method.

It is also possible to specify a different method depending on the output, either DVI or PDF, by setting the variable to an alist of the kind

((dvi . ‘<source-specials or synctex>’) (pdf . ‘<source-specials or synctex>’))

in which the CDR of each entry is a symbol specifying the method to be used in the corresponding mode. The default value of the variable is

((dvi . source-specials) (pdf . synctex))

which is compatible with the majority of viewers.

Forward search happens automatically upon calling the viewer, e.g. by typing C-c C-v (TeX-view). This will open the viewer or bring it to front and display the output page corresponding to the position of point in the source file. AUCTeX will automatically pass the necessary command line options to the viewer for this to happen.

You can also make special mouse event do forward search at the clicked position. Use TeX-source-correlate-map(2) and TeX-view-mouse like this:

(eval-after-load "tex"
  '(define-key TeX-source-correlate-map [C-down-mouse-1]
               #'TeX-view-mouse))

This example binds C-down-mouse-1, which usually opens a concise menu to select buffer, to the command to do forward search.

Upon opening the viewer you will be asked if you want to start a server process (Gnuserv or Emacs server) which is necessary for inverse search. This happens only if there is no server running already. You can customize the variable TeX-source-correlate-start-server to inhibit the question and always or never start the server respectively.

User Option: TeX-source-correlate-start-server

If TeX-source-correlate-mode is active and a viewer is invoked, the default behavior is to ask if a server process should be started. Set this variable to t if the question should be inhibited and the server should always be started. Set it to nil if the server should never be started. Inverse search will not be available in the latter case.

Inverse search, i.e. jumping to the part of your document source in Emacs corresponding to a certain position in the viewer, is triggered from the viewer, typically by a mouse click. Refer to the documentation of your viewer to find out how it has to be configured and what you have to do exactly. In xdvi you normally have to use C-down-mouse-1.

Note that inverse search with the Evince PDF viewer or its MATE fork Atril might fail in raising the Emacs frame after updating point in your document’s buffer. There is simply no way to raise the Emacs frame reliably accross different operating systems and different window managers with their different focus stealing policies. If the Emacs frame is not raised after performing an inverse search from Evince or Atril, you can customize the following option.

User Option: TeX-raise-frame-function

A function that will be called after performing an inverse search from Evince or Atril in order to raise the current Emacs frame.

If your Emacs frame is already raised in that situation, just leave this variable set to its default value raise-frame. Otherwise, here are some alternative settings that work for some users.

;; Alternative 1: For some users, `x-focus-frame' works. (setq TeX-raise-frame-function #'x-focus-frame) ;; Alternative 2: Under GNOME 3.20 (and probably others), it ;; seems some focus stealing prevention policy prohibits that ;; some window gets the focus immediately after the user has ;; clicked in some other window. Here waiting a bit before ;; issuing the request seems to work. (setq TeX-raise-frame-function (lambda () (run-at-time 0.5 nil #'x-focus-frame))) ;; Alternative 3: Use the external wmctrl tool in order to ;; force Emacs into the focus. (setq TeX-raise-frame-function (lambda () (call-process "wmctrl" nil nil nil "-i" "-R" (frame-parameter (selected-frame) 'outer-window-id))))

4.3 Catching the errors

Once you’ve formatted your document you may ‘debug’ it, i.e. browse through the errors (La)TeX reported. You may also have a look at a nicely formatted list of all errors and warnings reported by the compiler.

Command: TeX-next-error arg reparse

(C-c `) Go to the next error reported by TeX. The view will be split in two, with the cursor placed as close as possible to the error in the top view. In the bottom view, the error message will be displayed along with some explanatory text.

An optional numeric arg, positive or negative, specifies how many error messages to move. A negative arg means to move back to previous error messages, see also TeX-previous-error.

The optional reparse argument makes AUCTeX reparse the error message buffer and start the debugging from the first error. This can also be achieved by calling the function with a prefix argument (C-u).

Command: TeX-previous-error arg

(M-g p) Go to the previous error reported by TeX. An optional numeric arg specifies how many error messages to move backward. This is like calling TeX-next-error with a negative argument.

The command TeX-previous-error works only if AUCTeX can parse the whole TeX log buffer. This is controlled by the TeX-parse-all-errors variable.

User Option: TeX-parse-all-errors

If t, AUCTeX automatically parses the whole output log buffer right after running a TeX command, in order to collect all warnings and errors. This makes it possible to navigate back and forth between the error messages using TeX-next-error and TeX-previous-error. This is the default. If nil, AUCTeX does not parse the whole output log buffer and TeX-previous-error cannot be used.

As default, AUCTeX will display a special help buffer containing the error reported by TeX along with the documentation. There is however an ‘expert’ option, which allows you to display the real TeX output.

User Option: TeX-display-help

If t, AUCTeX will automatically display a help text whenever an error is encountered using TeX-next-error (C-c `). If nil, a terse information about the error is displayed in the echo area. If expert AUCTeX will display the output buffer with the raw TeX output.

4.3.1 Controlling warnings to be reported

Normally AUCTeX will only report real errors, but you may as well ask it to report ‘bad boxes’ and warnings as well.

Command: TeX-toggle-debug-bad-boxes

(C-c C-t C-b) Toggle whether AUCTeX should stop at bad boxes (i.e. overfull and underfull boxes) as well as normal errors. The boolean option TeX-debug-bad-boxes is set accordingly.

Command: TeX-toggle-debug-warnings

(C-c C-t C-w) Toggle whether AUCTeX should stop at warnings as well as normal errors. The boolean option TeX-debug-warnings is set accordingly.

While many users desire to have warnings reported after compilation, there are certain warnings that are considered unimportant and users want to ignore them. For a more fine-grained control of what kinds of warnings should be shown after compilation, AUCTeX provides other options.

User Option: TeX-ignore-warnings

Controls which warnings are to be ignored.

It can be a regexp matching the message of the warnings to be ignored.

More advanced users can set also this option to a symbol with the name of a custom function taking as arguments all the information of the warning listed in TeX-error-list variable, except the last one about whether to ignore the warning. See the code of TeX-warning function and the documentation of TeX-error-list for more details.

Command: TeX-toggle-suppress-ignored-warnings

(C-c C-t C-x) Toggle whether AUCTeX should actually hide the ignored warnings specified with TeX-ignore-warnings. The boolean option TeX-suppress-ignored-warnings is set accordingly. If this is nil, all warnings are shown, even those matched by TeX-ignore-warnings, otherwise these are hidden.

Note that TeX-debug-warnings takes the precedence: if it is nil, all warnings are hidden in any case.

4.3.2 List of all errors and warnings

When the option TeX-parse-all-errors is non-nil, you will be also able to open an overview of all errors and warnings reported by the TeX compiler.

Command: TeX-error-overview

Show an overview of the errors and warnings occurred in the last TeX run.

In this window you can visit the error on which point is by pressing <RET>, and visit the next or previous issue by pressing <n> or <p> respectively. A prefix argument to these keys specifies how many errors to move forward or backward. You can visit an error also by clicking on its message. Jump to error point in the source code with <j>, and use <l> see the error in the log buffer. In addition, you can toggle visibility of bad boxes, generic warnings, and ignored warnings with <b>, <w>, and <x>, respectively (see Ignoring warnings for details). Press <q> to quit the overview.

User Option: TeX-error-overview-open-after-TeX-run

When this boolean variable is non-nil, the error overview will be automatically opened after running TeX if there are errors or warnings to show.

The error overview is opened in a new window of the current frame by default, but you can change this behavior by customizing the option TeX-error-overview-setup.

User Option: TeX-error-overview-setup

Controls the frame setup of the error overview. The possible value is: separate-frame; with a nil value the current frame is used instead.

The parameters of the separate frame can be set with the TeX-error-overview-frame-parameters option.

If the display does not support multi frame, the current frame will be used regardless of the value of this variable.

4.4 Checking for problems

Running TeX or LaTeX will only find regular errors in the document, not examples of bad style. Furthermore, description of the errors may often be confusing. The utilities lacheck and chktex can be used to find style errors, such as forgetting to escape the space after an abbreviation or using ‘...’ instead of ‘\ldots’ and other similar problems. You start lacheck with C-c C-c Check <RET> and chktex with C-c C-c ChkTeX <RET>. The result will be a list of errors in the ‘*compilation*’ buffer. You can go through the errors with C-x ` (next-error, see (emacs)Compilation section ‘Compilation’ in The Emacs Editor), which will move point to the location of the next error.

Alternatively, you may want in-buffer notation. AUCTeX provides support for this using the Flymake package in Emacs 26 or newer (see (Flymake)Using Flymake section ‘Using Flymake’ in GNU Flymake for details). To enable, call M-x flymake-mode <RET> in the buffer or enable it in all buffers by adding this to your init file:

(add-hook 'LaTeX-mode-hook #'flymake-mode)

Note that AUCTeX currently only provides support for using chktex as the flymake backend.

Each of the two utilities lacheck and chktex will find some errors the other doesn’t, but chktex is more configurable, allowing you to create your own errors. You may need to install the programs before using them. You can get lacheck from URL:https://www.ctan.org/pkg/lacheck and chktex from URL:https://www.ctan.org/pkg/chktex. TeX Live contains both.

4.5 Controlling the output

A number of commands are available for controlling the output of an application running under AUCTeX

Command: TeX-kill-job

(C-c C-k) Kill currently running external application. This may be either of TeX, LaTeX, previewer, BibTeX, etc.

Command: TeX-recenter-output-buffer

(C-c C-l) Recenter the output buffer so that the bottom line is visible.

Command: TeX-home-buffer

(C-c ^) Go to the ‘master’ file in the document associated with the current buffer, or if already there, to the file where the current process was started.

Additionally, output files produced by AUCTeX can be placed in a separate directory.

User Option: TeX-output-dir

Set this option to the path of a directory where output files will be placed. The output files include those that are produced by applications running under AUCTeX, temporary files related to region processing and the preview-latex files. If a relative path is specified, it is interpreted as being relative to the master file in a mutlifile document.

This is a buffer local variable and must be set separately for all documents and all files in a multifile document. For example,

%%% Local Variables: %%% mode: latex %%% TeX-output-dir: "build" %%% End:

Alternatively, you may use setq-default to set the default value of this option or set it as a directory local variable (see (emacs)Directory Variables section ‘Directory Variables’ in The Emacs Editor).

Note that a non-nil value of TeX-output-dir might be incompatible with some TeX commands and macros. In particular, the LaTeX macro ‘\include’ is known to not work with this option. Some TeX packages which produce intermediary files might also be incompatible. A possible workaround for those packages is to append the value of TeX-output-dir to the environment variables TEXINPUTS and BIBINPUTS.

4.6 Cleaning intermediate and output files

Command: TeX-clean

Remove generated intermediate files. In case a prefix argument is given, remove output files as well.

Canonical access to the function is provided by the ‘Clean’ and ‘Clean All’ entries in TeX-command-list, invokable with C-c C-c or the Command menu.

The patterns governing which files to remove can be adapted separately for each AUCTeX mode by means of the following variables:

• plain-TeX-clean-intermediate-suffixes
• plain-TeX-clean-output-suffixes
• LaTeX-clean-intermediate-suffixes
• LaTeX-clean-output-suffixes
• docTeX-clean-intermediate-suffixes
• docTeX-clean-output-suffixes
• Texinfo-clean-intermediate-suffixes
• Texinfo-clean-output-suffixes
• ConTeXt-clean-intermediate-suffixes
• ConTeXt-clean-output-suffixes
• AmSTeX-clean-intermediate-suffixes
• AmSTeX-clean-output-suffixes

User Option: TeX-clean-confirm

Control if deletion of intermediate and output files has to be confirmed before it is actually done. If non-nil, ask before deleting files.

4.7 Documentation about macros and packages

Command: TeX-documentation-texdoc

(C-c ?) Get documentation about the packages installed on your system, using texdoc to find the manuals. The function will prompt for the name of packages. If point is on a word, this will be suggested as default.

If the command is called with a prefix argument, you will be shown a list of manuals of the given package among to choose.

The command can be invoked by the key binding mentioned above as well as the ‘Find Documentation...’ entry in the mode menu.

Note that this command assumes TeX Live, not MiKTeX; according to ‘Texdoc’ site,

A command named texdoc is also available in MiKTeX, but it is merely a shortcut for an independent program, mthelp.

Thus it isn’t sure whether this command works for MiKTeX or not.

5. Customization and Extension

5.1 Modes and Hooks

AUCTeX supports a wide variety of derivatives and extensions of TeX. Besides plain TeX those are LaTeX, AMS-TeX, ConTeXt, Texinfo and docTeX. For each of them there is a separate major mode in AUCTeX and each major mode runs text-mode-hook, TeX-mode-hook as well as a hook special to the mode in this order. (As an exception, Texinfo mode does not run TeX-mode-hook.) The following table provides an overview of the respective mode functions and hooks.

If you need to make a customization via a hook which is only relevant for one of the modes listed above, put it into the respective mode hook, if it is relevant for any AUCTeX mode, add it to TeX-mode-hook and if it is relevant for all text modes, append it to text-mode-hook.

Other useful hooks are listed below.

Variable: TeX-after-compilation-finished-functions

Hook which is run after the TeX/LaTeX processor has successfully finished compiling your document. (See Processing, for finding out how to compile your document.) Each function in the hook is run with the compiled output document as its argument.

This is useful for automatically refreshing the viewer after re-compilation especially when using Emacs viewers such as DocView or PDF Tools. The function TeX-revert-document-buffer can be added to the hook for this purpose.

5.2 Multifile Documents

You may wish to spread a document over many files (as you are likely to do if there are multiple authors, or if you have not yet discovered the power of the outline commands (see Outline)). This can be done by having a “master” file in which you include the various files with the TeX macro ‘\input’ or the LaTeX macro ‘\include’. These files may also include other files themselves. However, to format the document you must run the commands on the top level master file.

When you, for example, ask AUCTeX to run a command on the master file, it has no way of knowing the name of the master file. By default, it will assume that the current file is the master file. If you insert the following in your init file (‘init.el’ or ‘.emacs’), AUCTeX will use a more advanced algorithm.

(setq-default TeX-master nil) ; Query for master file.

In this case, AUCTeX will ask for the name of the master file associated with the buffer. To avoid asking you again, AUCTeX will automatically insert the name of the master file as a file variable (see (emacs)File Variables section ‘File Variables’ in The Emacs Editor). You can also insert the file variable yourself, by putting the following text at the end of your files.

%%% Local Variables:
%%% TeX-master: "master"
%%% End:

You should always set this variable to the name of the top level document. If you always use the same name for your top level documents, you can set TeX-master in your init file such as ‘init.el’ or ‘.emacs’.

(setq-default TeX-master "master") ; All master files called "master".

User Option: TeX-master

The master file associated with the current buffer. If the file being edited is actually included from another file, then you can tell AUCTeX the name of the master file by setting this variable. If there are multiple levels of nesting, specify the top level file.

If this variable is nil, AUCTeX will query you for the name.

If the variable is t, then AUCTeX will assume the file is a master file itself.

If the variable is shared, then AUCTeX will query for the name, but will not change the file.

If the variable is dwim, AUCTeX will try to avoid querying by attempting to “do what I mean”; and then change the file.

User Option: TeX-one-master

Regular expression matching ordinary TeX files.

You should set this variable to match the name of all files, for which it is a good idea to append a TeX-master file variable entry automatically. When AUCTeX adds the name of the master file as a file variable, it does not need to ask next time you edit the file.

If you dislike AUCTeX automatically modifying your files, you can set this variable to ‘"<none>"’. By default, AUCTeX will modify any file with an extension of ‘.tex’, ‘.texi’ or ‘.dtx’.

Command: TeX-master-file-ask

(C-c _) Query for the name of a master file and add the respective File Variables (see (emacs)File Variables section ‘File Variables’ in The Emacs Editor) to the file for setting this variable permanently.

AUCTeX will not ask for a master file when it encounters existing files. This function shall give you the possibility to insert the variable manually.

AUCTeX keeps track of macros, environments, labels, and style files that are used in a given document. For this to work with multifile documents, AUCTeX has to have a place to put the information about the files in the document. This is done by having an ‘auto’ subdirectory placed in the directory where your document is located. Each time you save a file, AUCTeX will write information about the file into the ‘auto’ directory. When you load a file, AUCTeX will read the information in the ‘auto’ directory about the file you loaded and the master file specified by TeX-master. Since the master file (perhaps indirectly) includes all other files in the document, AUCTeX will get information from all files in the document. This means that you will get from each file, for example, completion for all labels defined anywhere in the document.

AUCTeX will create the ‘auto’ directory automatically if TeX-auto-save is non-nil. Without it, the files in the document will not know anything about each other, except for the name of the master file. See Automatic Local.

Command: TeX-save-document

(C-c C-d) Save all buffers known to belong to the current document.

User Option: TeX-save-query

If non-nil, then query the user before saving each file with TeX-save-document.

5.3 Automatic Parsing of TeX Files

AUCTeX depends heavily on being able to extract information from the buffers by parsing them. Since parsing the buffer can be somewhat slow, the parsing is initially disabled. You are encouraged to enable them by adding the following lines to your init file such as ‘init.el’ or ‘.emacs’.

(setq TeX-parse-self t) ; Enable parse on load.
(setq TeX-auto-save t) ; Enable parse on save.

The latter command will make AUCTeX store the parsed information in an ‘auto’ subdirectory in the directory each time the TeX files are stored, see Automatic Local. If AUCTeX finds the pre-parsed information when loading a file, it will not need to reparse the buffer. The information in the ‘auto’ directory is also useful for multifile documents, see Multifile, since it allows each file to access the parsed information from all the other files in the document. This is done by first reading the information from the master file, and then recursively the information from each file stored in the master file.

The variables can also be set on a per file basis, by changing the file local variables.

%%% Local Variables:
%%% TeX-parse-self: t
%%% TeX-auto-save: t
%%% End:

Even when you have disabled the automatic parsing, you can force the generation of style information by pressing C-c C-n. This is often the best choice, as you will be able to decide when it is necessary to reparse the file.

User Option: TeX-parse-self

Parse file after loading it if no style hook is found for it.

User Option: TeX-auto-save

Automatically save style information when saving the buffer.

Command: TeX-normal-mode arg

(C-c C-n) Remove all information about this buffer, and apply the style hooks again. Save buffer first including style information. With optional argument, also reload the style hooks.

When AUCTeX saves your buffer, it can optionally convert all tabs in your buffer into spaces. Tabs confuse AUCTeX’s error message parsing and so should generally be avoided. However, tabs are significant in some environments, and so by default AUCTeX does not remove them. To convert tabs to spaces when saving a buffer, insert the following in your init file such as ‘init.el’ or ‘.emacs’:

(setq TeX-auto-untabify t)

User Option: TeX-auto-untabify

Automatically remove all tabs from a file before saving it.

Instead of disabling the parsing entirely, you can also speed it significantly up by limiting the information it will search for (and store) when parsing the buffer. You can do this by setting the default values for the buffer local variables TeX-auto-regexp-list and TeX-auto-parse-length in your init file such as ‘init.el’ or ‘.emacs’.

;; Only parse LaTeX class and package information.
(setq-default TeX-auto-regexp-list 'LaTeX-auto-minimal-regexp-list)
;; The class and package information is usually near the beginning.
(setq-default TeX-auto-parse-length 2000)

This example will speed the parsing up significantly, but AUCTeX will no longer be able to provide completion for labels, macros, environments, or bibitems specified in the document, nor will it know what files belong to the document.

These variables can also be specified on a per file basis, by changing the file local variables.

%%% Local Variables:
%%% TeX-auto-regexp-list: TeX-auto-full-regexp-list
%%% TeX-auto-parse-length: 999999
%%% End:

User Option: TeX-auto-regexp-list

List of regular expressions used for parsing the current file.

User Option: TeX-auto-parse-length

Maximal length of TeX file that will be parsed.

The pre-specified lists of regexps are defined below. You can use these before loading AUCTeX by quoting them, as in the example above.

Constant: TeX-auto-empty-regexp-list

Parse nothing

Constant: LaTeX-auto-minimal-regexp-list

Only parse LaTeX class and packages.

Constant: LaTeX-auto-label-regexp-list

Only parse LaTeX labels.

Constant: LaTeX-auto-index-regexp-list

Only parse LaTeX index and glossary entries.

Constant: LaTeX-auto-class-regexp-list

Only parse macros in LaTeX classes and packages.

Constant: LaTeX-auto-pagestyle-regexp-list

Only parse LaTeX pagestyles.

Constant: LaTeX-auto-counter-regexp-list

Only parse LaTeX counters.

Constant: LaTeX-auto-length-regexp-list

Only parse LaTeX lengths.

Constant: LaTeX-auto-savebox-regexp-list

Only parse LaTeX saveboxes.

Constant: LaTeX-auto-regexp-list

Parse common LaTeX commands.