Modules

What are modules?

• A tool that simplify the use of different software (versions) in a precise and controlled manner by initializing and configuring your shell environment without manual intervention. They allow users easily modify their shell environment during the session with modulefiles.

• Modulefiles

  • Each modulefile contains the information needed to configure the shell environment for an application. (PATH, LD_LIBRARY_PATH, CPATH, etc).

  • By loading a modulefile, the system automatically adjusts these variables so that the chosen application is ready to use.

  • Modules are useful in managing different versions of applications.

  • Modules can also be bundled into meta-modules that will load an entire set of different applications.

Why Use Modules?

• Using modules simplifies managing your computational environment, making it easy to ensure that all necessary software and their correct versions are available for your tasks. This reduces potential conflicts and errors, streamlining your workflow and improving efficiency on the HPC cluster.

How to use modules?

Module Cheat Sheet

module av

module av <software>

module spider <software>

module list

module load <software>

module unload <software>

module swap <loaded_software> <new_software>

module purge

• To check available modules installed on the cluster:

   $ module av
  

  or

  $ module spider
  

module av vs. module spider

Feature	module av	module spider
Search Scope	Only shows modules currently available to load based on your environment.	Searches the entire software hierarchy, including hidden or nested modules.
Hierarchy Aware	Yes; it only shows what matches your current compiler/MPI stack.	No; it finds software regardless of whether its dependencies are loaded.
Common Use Case	Checking what you can use right now.	Finding if a piece of software exists and how to load it.
Output Detail	Lists available versions briefly.	Provides detailed instructions on required parent modules for specific versions.

Example: Using gcc Compiler

• Check what versions of gcc compiler is available: load the version I would like to use, and use it:

  $ module avail gcc
  ------ /cluster/tufts/apps/modules/9/x86_64/Core -------
    gcc/12.4.0    gcc/15.1.0 (D)
  
  Where:
  D:  Default Module
  

• Load the desired version of gcc:

  $ module load gcc/12.4.0
  

• Use module list to check loaded modules in current environment:

  $ module list
  
  Currently Loaded Modules:
  1) gmp/6.3.0-gt7twni (H)   2) gcc/12.4.0
  

• Verify the gcc Version:

  $ which gcc
  /cluster/tufts/apps/spack/9/x86_64/apps/linux-broadwell/gcc-12.4.0-c4qsn6yjbnde4mdnr6wlplee454jnden/bin/gcc
  
  $ gcc --version
  gcc (Spack GCC) 12.4.0
  Copyright (C) 2022 Free Software Foundation, Inc.
  This is free software; see the source for copying conditions.  There is NO
  warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
  

• switch a module for another (doesn’t have to be the same software):

  $ module switch gcc/12.4.0 gcc/15.1.0
  $ module list
  Currently Loaded Modules:
  1) gmp/6.3.0-gt7twni (H)   2) gcc/15.1.0
  
  Where:
   H:  Hidden Module
  

• unload loaded modules:

  $ module unload gcc
  

• unload ALL of the loaded modules:

  $ module purge
  

​

Private Modules

Users can create Private Modules for the software installed locally.