55.1. Introduction

Webmin is designed to allow the easy addition of new modules without changing any of the existing code. A module can be thought of as something like a Netscape or Photoshop plug-in. It can be written by someone other than the developers of Webmin and distributed under any license the developer chooses.

A module should be written to administer one service or server, such as the UNIX password file or the Apache Web server. Some complex system functions may even be split over several modules. For example, disk partitioning, mounting disks, and disk quota management are three separate modules in the standard Webmin distribution.

Theoretically modules can be written in any language. To make use of the Webmin API Perl, however, version 5.002 or greater should be used. A module should be written entirely in Perl, with no C functions or external binary programs. The goal is for modules to be as portable as possible across different UNIX systems and CPU types.

Modules written in other languages will not be displayed using the default theme included with recent versions of Webmin. This theme replaces the standard Perl header function with its own that displays category icons at the top of every page. For this reason, using Perl is strongly recommended.

At their simplest, modules are really just directories of CGI programs that Webmin's web server runs. There are certain rules, however, that should be followed to make sure that they work with the Webmin API, main menu, and access control system. Even though you can just stick any existing CGI script into a module directory, this is not a good idea.