Modules¶

Overview¶

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.

Warning

Do not use personalized start files to load environment modules; it can cause conflicts. Instead, set up any unique environments that you need as described in the customized environments section below. Use that approach to create and save different environments for various aspects of your work – one for model runs and another for data analysis, for example.

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. Typical output:

In the example above, (L) indicates which modules are currently loaded. The modules deployed at NCAR are hierarchical, with a base of common compilers and core software. The remainder of the output is dependent on what core software (namely, compilers) are chosen.

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 reset - Reset the system default modules.
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 spider modulefile_name/n.n.n – List all occurrences of modulefile_name/n.n.n on the system, including its module dependences. For example, to determine which compiler/MPI combinations provide netcdf-mpi/4.9.2:

module spider netcdf-mpi/4.9.2

------------------------------------------------------------------------------------------------------
  netcdf-mpi: netcdf-mpi/4.9.2
------------------------------------------------------------------------------------------------------

    You will need to load all module(s) on any one of the lines below before the "netcdf-mpi/4.9.2"
    module is available to load.

      ncarenv/23.09  gcc/12.2.0  cray-mpich/8.1.25
      ncarenv/23.09  gcc/12.2.0  mvapich/3.0b
      ncarenv/23.09  intel-classic/2023.2.1  cray-mpich/8.1.25
      ncarenv/23.09  intel-classic/2023.2.1  intel-mpi/2021.10.0
      ncarenv/23.09  intel-oneapi/2023.2.1  cray-mpich/8.1.25
      ncarenv/23.09  intel-oneapi/2023.2.1  intel-mpi/2021.10.0
      ncarenv/23.09  intel/2023.2.1  cray-mpich/8.1.25
      ncarenv/23.09  intel/2023.2.1  intel-mpi/2021.10.0
      ncarenv/23.09  nvhpc/23.7      cray-mpich/8.1.25
      ...

Each output line is a consistent set of modules that when loaded will provide access to the requested netcdf-mpi package.

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 reuse.

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

Remove a customized environment¶

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

Revise a customized environment¶

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~.

Troubleshooting tips

Situation: You load a custom default module collection (for example, module restore myenvironment). You receive a warning similar to this:

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

What to do: “Re-save” the customized module collection by running module save and using the same environment name, as follows.

module save myenvironment