Module Environments

A module system helps in managing access to the software packages and versions that you need. If there are multiple versions of a software available on a system, you can select the one that you need and enable it in your shell environment by loading the right module/s. By loading a module, certain environment variables like $PATH and $LD_LIBRARY_PATH get updated to include the required software and associated dependencies in your shell environment.

To see the modules that are currently loaded in your environment, you can use the following command:

$ module list

To see all modules that are compatible with the currently loaded modules in your shell, you can use the following command:

$ module avail

To see all installed modules on the system, you can use the following command:

$ module spider  

You can save a collection of modules as a personal default collection that can be loaded every time you log into Arc by typing the "module restore" command. To achieve this, load the modules you want in your collection, and then execute the following command:

$ module save  

When you log back into Arc, you can restore your saved modules by executing the following command:

$ module restore  

You can use the "module purge" command to unload all the currently loaded modules in your environment.

You can use the "module help" command to see any installation notes that may be available with the module of your interest:

$ module help R/4.1.0      

You can use the "module load" command to load a module in your shell environment and use "module unload" to remove a module from your environment. For example, following are the commands to load and unload the R module.

$ module load  R/4.1.0 
$ module unload R/4.1.0 

Since modules adjust your shell to accommodate for specific software packages, loading multiple modules at the same time can sometimes lead to conflicts. For example, you can only have one compiler module loaded at a time. When you try to load a module that is incompatible with one you already have loaded, you may be notified that you need to swap them out. You can use the following command to swap one module for another. This command will unload gnu8/8.3.0 and load intel/oneapi/2021.2.0.

$ module swap gnu8 intel/oneapi/2021.2.0