Goal: Highlight the modules have defaults, and good practices such as purging and defining module versions.

1 Defaults: Why Consider?
2 What are the Defaults?
3 Good Practice: Module Purging
4 Why do versions matter?
5 Can I Automatically Load Modules at the Start of a Session?
6 Updates to Modules

Defaults: Why Consider?

Modules change and are updated.

The defaults will change and update – you might not realize.

Please define the version of a module you’re using.

Helps to replicate and triage.

What are the Defaults?

Performing a module avail, anything with a (D) will indicate it will act as the default. Anything labelled with a (L) indicates it is already loaded.

[]$ module avail
...
--------------- /apps/s/lmod/mf/opt/linux-rhel9-x86_64/compilers ---------------
   gcc/13.2.0    gcc/14.2.0 (D)    nvhpc-sdk/24.3    oneapi/2024.1.0


[]$ module load gcc/14.2.0
[]$ module avail
...
[salexan5@mblog2 ~]$ module load gcc/14.2.0
[salexan5@mblog2 ~]$ module avail
...
------------- /apps/s/lmod/mf/spack/linux-rhel9-x86_64/gcc/14.2.0 --------------
...
   boost/1.83.0__filesystem_False
   boost/1.83.0__filesystem_True      (D)
...
   flex/2.6.3
   flex/2.6.4                         (D)
...
   gmp/6.2.1_x86_64                   (L)
...
--------------- /apps/s/lmod/mf/opt/linux-rhel9-x86_64/compilers ---------------
   gcc/13.2.0    gcc/14.2.0 (L,D)    nvhpc-sdk/24.3    oneapi/2024.1.0
...

Good Practice: Module Purging

Over the course of a session, over many hours, you might be loading a number of different modules/software, you might be trying to install Python/R packages, you might be compiling source code…

We’d suggest when you switch context to a different application to perform a module purge and only load what is explicitly required.

This will avoid dependency hell.

Why do versions matter?

Consider Python Packages installed using pip:

You install a package with respect to the version of python you are using.
A packages is not automatically available/installed across different versions.
If you start using python/3.9 and then swap to python/3.10 you will need to re-install any packages.

# Example:
[lib]$ pwd
/home/<username>/.local/lib
[]$ ls
python2.7  python3.9  python3.10  python3.12
# These folders will only be created if you use that version.
# Each child folder has its own site-packages folder.

Can I Automatically Load Modules at the Start of a Session?

[~] vim .bashrc
...
module load gcc/14.2.0 r/4.4.0
...

Updates to Modules

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Intro to using the Module System

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Using Modules: FAQs

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Using Modules: Considerations and Defaults