Lmod: A New Environment Module System¶
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.
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.
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.
- How to report a bug in Lmod
- How to use a Software Module hierarchy
- Configuring Lmod for your site
- How does Lmod convert TCL modulefile into Lua
- Generic Modules
- The Interaction between Modules, MPI and Parallel Filesystems
- Lmod on Shared Home File Systems
- User Spider Cache
- System Spider Cache
- Deprecating Modules
- Kitchen Sink Modulefiles
- The Properties File: lmodrc.lua
- Debugging Modulefiles
- SitePackage.lua and hooks
- Choices in handling module dependencies
- Lmod Localization
- Integration of EasyBuild and Lmod
- Providing Custom Labels for Avail
- Load Storms: Long load times or Fails to Load
- Tracing Lmod
Topics yet to be written¶
- Optional Software layout, two digit rule
- Module naming conventions
- Advanced Topics: priority path, .modulerc tricks
- tracking module usage
- converting shell scripts into modulefiles
- module command and a parallel a file system.
- internal structure of lmod.