GTML - an HTML pre-processor

GTML is a simple yet powerful HTML pre-processor written in Perl. Its syntax is very close to the C language preprocessor, and it supports macros, conditional processing, file inclusion, sitemap generation, and more. It was designed in the 1990s, for a world where HTML files were still regularly maintained by hand, but some of us still find it useful today.

Bug Reports & Feature Requests

This repository is meant to offer a reliable home for the gtml source code, and a place to report bugs if necessary. SourceForge is a mess, and isn't really viable for that purpose any more.

This source code is more than 25 years old. At this point in its lifecycle, my primary goal is stability for existing users. I do not intend to implement or maintain any feature requests or enhancements myself. However, I will accept pull requests for new features. New features must follow the existing code style and must maintain 100% backwards compatibility in the behavior of existing features. The submitter must agree to maintain and support their new feature.

History

GTML was originally written in 1996 by Gihan Perera and was enhanced starting in 1999 by Bruno Beaufils. In 2004, Andrew E. Schulman took it over and moved the code to SourceForge, where older releases still live today. I have maintained the Debian package for GTML since 2010. In 2014, Andrew communicated to me that he had abandoned the code, so I began to maintain the Debian packages independently. In early 2022, Bruno and I got some questions about GTML from a user. I decided to fork the code to GitHub so there would be a real home for it again.

The HISTORY.md file contains some additional history taken from the original README file on SourceForge. The original website on SourceForge is maintained using GTML itself, and the source code for that website is found in the docs/sourceforge/src directory.

How does it work?

You embed GTML commands among the HTML in your source files. GTML reads and processes the GTML commands, but leaves the rest of the text unchanged (so it will work straight away on your existing web pages). HTML files generated by GTML are just like any other HTML files. Because GTML doesn't attempt to interpret your HTML commands in any way, it's fully compatible with all versions of HTML, and doesn't require any specific browser or server.

Is GTML for you?

If you write the HTML in your web pages by hand using a simple text editor, then you'll find GTML useful. If, on the other hand, you use a sophisticated graphical tool to generate your HTML, you probably won't be able to use GTML. There are three reasons for this:

Your sophisticated tool won't understand the GTML commands, and might even complain violently about them
GTML operates in a command-line batch mode, and your sophisticated tool probably operates from a graphical environment
The source for GTML is in files ending in .gtm (or .gtml), and it generates the .html files, while your sophisticated tool probably generates the .html files itself

Features

Here are some of the things you can do with GTML:

Create a project file with the names of all your web pages, so you can update them all with one simple click or command
Process only files which sources have changed directly, or with the help of makefiles
Generate a makefile to control the process of your web pages, based on their dependencies
Give a specific alias to a filename, useable as constants, so that it is easy to move files and have links preserved
Specify a tree-like hierarchy of web pages, so you can add next, previous and up links automatically to your site
Automatically generate a map of your site, with the possibility of customizing the way this table of contents will look like
Use named constants for HTML fragments to save typing, ensure consistency and make changes easily
Use environment variables as named constants
Include header, footer and other common files into all your HTML files without server-side includes
Include timestamps (in any format you like) to show the time of last process, or of last modification
Use conditional commands to create different versions of the output under different circumstances
Generate output to different directories to generate different versions of your site (for example, a frames version and a non-frames version)
Change extensions of output files from .html to whatever you want, so that you may, for instance, use MultiViews options of Apache server, or create non-HTML files
Guard special characters <, >, and & in normal text so that they don't get confused with HTML commands
Define your own characters translations, so that you may easily input your non-ASCII characters into GTML source
Embed Perl or shell code into your source, so that you may easily generate pages with computed information
Generate pages with all superfluous HTML code removed, so that readers retrieve them faster and may save bandwidth

See REFERENCE.md for a complete description of these features and how to use them.