# 1. Introduction¶

## 1.1. Thanks¶

I first created latexindent.pl to help me format chapter files in a big project. After I blogged about it on the TeX stack exchange (“A Perl Script for Indenting Tex Files” n.d.) I received some positive feedback and follow-up feature requests. A big thank you to Harish Kumar (Kumar 2013) who helped to develop and test the initial versions of the script.

The YAML-based interface of latexindent.pl was inspired by the wonderful arara tool; any similarities are deliberate, and I hope that it is perceived as the compliment that it is. Thank you to Paulo Cereda and the team for releasing this awesome tool; I initially worried that I was going to have to make a GUI for latexindent.pl, but the release of arara has meant there is no need.

There have been several contributors to the project so far (and hopefully more in the future!); thank you very much to the people detailed in Section 11 for their valued contributions, and thank you to those who report bugs and request features at (“Home of Latexindent.pl” n.d.).

latexindent.pl is free and open source, and it always will be; it is released under the GNU General Public License v3.0.

Before you start using it on any important files, bear in mind that latexindent.pl has the option to overwrite your .tex files. It will always make at least one backup (you can choose how many it makes, see page page:onlyonebackup) but you should still be careful when using it. The script has been tested on many files, but there are some known limitations (see Section 10). You, the user, are responsible for ensuring that you maintain backups of your files before running latexindent.pl on them. I think it is important at this stage to restate an important part of the license here:

This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.

There is certainly no malicious intent in releasing this script, and I do hope that it works as you expect it to; if it does not, please first of all make sure that you have the correct settings, and then feel free to let me know at (“Home of Latexindent.pl” n.d.) with a complete minimum working example as I would like to improve the code as much as possible.

Warning

Before you try the script on anything important (like your thesis), test it out on the sample files in the test-case directory (“Home of Latexindent.pl” n.d.).

If you have used any version 2.* of latexindent.pl, there are a few changes to the interface; see :numref:app:differences and the comments throughout this document for details.

## 1.3. Quick start¶

If you’d like to get started with latexindent.pl then simply type

latexindent.pl myfile.tex


from the command line.

We give an introduction to latexindent.pl using Listing 1; there is no explanation in this section, which is deliberate for a quick start. The rest of the manual is more verbose.

Listing 1 quick-start.tex
A quick start
demonstration for latexindent.pl.
\begin{myenv}
The body of environments and
other code blocks
\end{myenv}


Running

latexindent.pl quick-start.tex


gives Listing 2.

Listing 2 quick-start-default.tex
A quick start
demonstration for latexindent.pl.
\begin{myenv}
The body of environments and
other code blocks
\end{myenv}

Example 1

Running

latexindent.pl -l quick-start1.yaml quick-start.tex


gives Listing 4.

Listing 3 quick-start1.yaml
defaultIndent: " "

Listing 4 quick-start-mod1.tex
A quick start
demonstration for latexindent.pl.
\begin{myenv}
The body of environments and
other code blocks
\end{myenv}

Example 2

Running

latexindent.pl -l quick-start2.yaml quick-start.tex


gives Listing 6.

Listing 5 quick-start2.yaml
indentRules:
myenv: "   "

Listing 6 quick-start-mod2.tex
A quick start
demonstration for latexindent.pl.
\begin{myenv}
The body of environments and
other code blocks
\end{myenv}

Example 3

Running

latexindent.pl -l quick-start3.yaml quick-start.tex


gives Listing 8.

Listing 7 quick-start3.yaml
noAdditionalIndent:
myenv: 1

Listing 8 quick-start-mod3.tex
A quick start
demonstration for latexindent.pl.
\begin{myenv}
The body of environments and
other code blocks
\end{myenv}

Example 4

Running

latexindent.pl -m -l quick-start4.yaml quick-start.tex


gives Listing 10.

Listing 9 quick-start4.yaml
modifyLineBreaks:
textWrapOptions:
columns: 20

Listing 10 quick-start-mod4.tex
A quick start
demonstration for
latexindent.pl.
\begin{myenv}
The body of environments and
other code blocks
\end{myenv}


Full details of text wrapping in Section 6.1.

Example 5

Running

latexindent.pl -m -l quick-start5.yaml quick-start.tex


gives Listing 12.

Listing 11 quick-start5.yaml
modifyLineBreaks:
textWrapOptions:
columns: 20
blocksFollow:
other: '\\begin\{myenv\}'

Listing 12 quick-start-mod5.tex
A quick start
demonstration for
latexindent.pl.
\begin{myenv}
The body of
environments and
other code blocks
indentation.
\end{myenv}


Full details of text wrapping in Section 6.1.

Example 6

Running

latexindent.pl -m -l quick-start6.yaml quick-start.tex


gives Listing 14.

Listing 13 quick-start6.yaml
modifyLineBreaks:
environments:
BeginStartsOnOwnLine: -1

Listing 14 quick-start-mod6.tex
A quick start
demonstration for latexindent.pl.\begin{myenv}
The body of environments and
other code blocks
\end{myenv}


This is an example of a poly-switch; full details of poly-switches are covered in Section 6.3.

Example 7

Running

latexindent.pl -m -l quick-start7.yaml quick-start.tex


gives Listing 16.

Listing 15 quick-start7.yaml
modifyLineBreaks:
environments:
EndStartsOnOwnLine: -1

Listing 16 quick-start-mod7.tex
A quick start
demonstration for latexindent.pl.
\begin{myenv}
The body of environments and
other code blocks


Full details of poly-switches are covered in Section 6.3.

## 1.4. Required perl modules¶

If you receive an error message such as that given in Listing 17, then you need to install the missing perl modules.

Listing 17 Possible error messages
Can't locate File/HomeDir.pm in @INC (@INC contains: /Library/Perl/5.12/darwin-thread-multi-2level /Library/Perl/5.12 /Network/Library/Perl/5.12/darwin-thread-multi-2level /Network/Library/Perl/5.12 /Library/Perl/Updates/5.12.4/darwin-thread-multi-2level /Library/Perl/Updates/5.12.4 /System/Library/Perl/5.12/darwin-thread-multi-2level /System/Library/Perl/5.12 /System/Library/Perl/Extras/5.12/darwin-thread-multi-2level /System/Library/Perl/Extras/5.12 .) at helloworld.pl line 10.
BEGIN failed--compilation aborted at helloworld.pl line 10.


latexindent.pl ships with a script to help with this process; if you run the following script, you should be prompted to install the appropriate modules.

perl latexindent-module-installer.pl


You might also like to see https://stackoverflow.com/questions/19590042/error-cant-locate-file-homedir-pm-in-inc, for example, as well as Section 12.1.

As you read through this documentation, you will see many listings; in this version of the documentation, there are a total of 569. This may seem a lot, but I deem it necessary in presenting the various different options of latexindent.pl and the associated output that they are capable of producing.

The different listings are presented using different styles:

Listing 18 demo-tex.tex
demonstration .tex file


This type of listing is a .tex file.

Listing 19 fileExtensionPreference
 44 45 46 47 48 fileExtensionPreference: .tex: 1 .sty: 2 .cls: 3 .bib: 4 

This type of listing is a .yaml file; when you see line numbers given (as here) it means that the snippet is taken directly from defaultSettings.yaml, discussed in detail in Section 5.

Listing 20 modifyLineBreaks
 495 496 497 modifyLineBreaks: preserveBlankLines: 1 condenseMultipleBlankLinesInto: 1 

This type of listing is a .yaml file, but it will only be relevant when the -m switch is active; see Section 6 for more details.

Listing 21 replacements
 609 610 611 612 613 614 615 616 617 replacements: - amalgamate: 1 - this: 'latexindent.pl' that: 'pl.latexindent' lookForThis: 0 when: before 

This type of listing is a .yaml file, but it will only be relevant when the -r switch is active; see Section 7 for more details.

## 1.6. A word about regular expressions¶

As you read this documentation, you may encounter the term regular expressions. I’ve tried to write this documentation in such a way so as to allow you to engage with them or not, as you prefer. This documentation is not designed to be a guide to regular expressions, and if you’d like to read about them, I recommend (Friedl, n.d.).

“A Perl Script for Indenting Tex Files.” n.d. Accessed January 23, 2017. http://tex.blogoverflow.com/2012/08/a-perl-script-for-indenting-tex-files/.
Friedl, Jeffrey E. F. n.d. Mastering Regular Expressions.
“Home of Latexindent.pl.” n.d. Accessed January 23, 2017. https://github.com/cmhughes/latexindent.pl.
Kumar, Harish. 2013. “Early Version Testing.” November 10, 2013. https://github.com/harishkumarholla.