Lmod: A New Environment Module System

PURPOSE

Lmod is a Lua based module system that easily handles the MODULEPATH Hierarchical problem. Environment Modules provide a convenient way to dynamically change the users’ environment through modulefiles. This includes easily adding or removing directories to the PATH environment variable. Modulefiles for Library packages provide environment variables that specify where the library and header files can be found.

OVERVIEW

This guide is written to explain what Environment Modules are and why they are very useful for both users and system administrators. Lmod is an implementation of Environment Modules, much of what is said here is true for any environment modules system but there are many features which are unique to Lmod.

Environment Modules provide a convenient way to dynamically change the users’ environment through modulefiles. This includes easily adding or removing directories to the PATH environment variable.

A modulefile contains the necessary information to allow a user to run a particular application or provide access to a particular library. All of this can be done dynamically without logging out and back in. Modulefiles for applications modify the user’s path to make access easy. Modulefiles for Library packages provide environment variables that specify where the library and header files can be found.

Packages can be loaded and unloaded cleanly through the module system. All the popular shells are supported: bash, ksh, csh, tcsh, zsh. Also available for perl and python.

It is also very easy to switch between different versions of a package or remove it.

Introduction to Lmod

If you are new to Lmod then please read the User Guide and possibly the Frequently Asked Questions Guide. Users who wish to read about how to have their own personal modules should read the Advanced User Guide.

Installing Lmod

Anyone wishing to install Lmod on a personal computer or for a system should read the Installation Guide as well as the Transitioning to Lmod Guide. The rest of the guides can be read as needed.

Topics yet to be written

  1. Optional Software layout, two digit rule
  2. Advanced Topics: priority path, .modulerc tricks
  3. settarg
  4. module command and a parallel a file system.
  5. inherit
  6. internal structure of lmod.

Indices and tables