The module utility helps you identify software that is available on the system and then load compatible packages. It manages complex combinations of paths, variables, and dependencies so you can compile and run jobs efficiently and make the most of your allocation.

Some modules are loaded by default. To see which modules those are, run module list when you log in. Depending on the work you need to do, you can load additional modules or different modules, or you can create and save multiple customized environments as described below.

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Essential module commands

Following are descriptions of commonly used module commands.

module av – Show which modules are available for use with the currently loaded compiler.

module help – List options and subcommands for the module utility; or specify a modulefile by name for help with an individual module.

module help
module help netcdf

module list – List the modules that are loaded.

module load – Load the default version of a software package, or load a specified version.

module load modulefile_name
module load modulefile_name/n.n.n

module purge – Unload all modules. Some users include this command in a batch script, followed by a sequence of module load commands to establish a customized environment for the job being submitted.

module spider – List all modules that exist on the system. This does not give you information on module dependencies or tell you which modules can be loaded without conflicts at that point.

module swap – Unload one module and load a different one. Example:

module swap netcdf pnetcdf

module unload – Unload the specified software package.

module unload modulefile_name

module whatis – Get a short description of a module.

Customized environments

If you have created your own environment or want to have multiple collections of modules for various tasks, you can save those customized environments for easy re-use.

To save a customized environment as your default environment, load the modules that you want to use, then simply run module save or module s.

module save

The cluster you are using will append a suffix to the name you provide. For example, on Casper your example will include .dav as a suffix.

If you plan to set up additional custom environments for other needs, give each collection of modules a unique name.

module save environment_name

To use one of the custom environments from that list, use module restore, or module r, followed by the name.

module restore environment_name

To see a list of your customized, saved environments, use module savelist.

module savelist

To see which modules you've saved in a custom environment, use module describe as shown.

module describe environment_name.xyz

To remove a customized environment that you have saved:

• Change to your .lmod.d directory.
• List the files.
• Use rm to delete what you no longer need.

cd /glade/u/home/username/.lmod.d 
ls -l 
rm environment_name.xyz

To revise a customized environment:

• Restore (change to) that environment.
• Unload, load, or swap modules as needed.
• Save the environment as a default environment again with the same name.

module restore myenvironment 
module load additional_module 
module save myenvironment

The previously saved environment will be renamed automatically with the addition of a tilde (~). In the example just above, the previously saved environment would be renamed to myenvironment~.

Lmod Warning: The following modules have changed: pgi
Lmod Warning: Please re-save this collection

module save myenvironment