Software Module Scheme

Since a HPC cluster is shared among many users, and also holds a significant size in contrast to most desktop computers, the amount of installed software spans many applications in many different versions. It is not possible (nor desirable) to use them all at the same time, since different versions of the same application may conflict with each other. Therefore, it is practical to provide the production environment, outside of the application itself. This is done using a set of instructions and variable settings that are specific for the given application called an application module. This also simplifies control of which application versions are available in a specific session.

The main command for using this system is the module command. You can find a list of all its options by typing:

module --help

Which modules are currently loaded?

To see the modules currently active in your session, use the command:

module list

Which modules are available?

In order to see a complete list of available modules, issue the command:

module av

How to load a module

In order to make, for instance, the openmpi (default version) available, issue the command::

module load OpenMPI

This will load OpenMPI/4.1.1-GCC-10.3.0 and its dependencies.  

How to unload a module

module unload OpenMPI

Search in available modules

To search for GGG modules as an example:

module spider gcc

Note the spider argument is case-insensitive.

The ml alias

Module system provides different commands for working with installed softwares/libraries. Please note we can use the ml alias with slightly different syntax, for rapid typing.

Module names auto-completion

The module command supports auto-completion, so you can just start typing the name of a module, and press Tab to let the shell automatically complete the module name and/or version.

These commands and more can be summarized as:

Module command	Short version	Description
module avail	ml av	List available software
module load OpenBLAS	ml OpenBLAS	Load a module to use the associated software
module load GCC/12.3.0	ml GCC/12.3.0	Load specific version of a module
module unload Siesta	ml -Siesta	Unload a module
module spider fftw	ml spider fftw	Search for particular library/software (here FFTW). Search is done case-insensitively.
module keyword lapack	ml key lapack	Search for lapack in module names and descriptions
module whatis ScaLAPACK	ml whatis ScaLAPACK	Display information about the ScaLAPACK module
module help ScaLAPACK	ml help ScaLAPACK	Display module specific help
module purge	ml purge	Remove all modules
module save foo	ml save foo	Save the state of all loaded modules in a collection named foo
module restore foo	ml restore foo	Restore the state of saved modules from the foo collection