Modules
=======

.. admonition:: Overview
    :class: Overview

    **Tutorial:** 10 min

    **Objectives:**
    Learn how to find and load modules on Gadi.

Modules are the standard way software is managed on most HPC systems. They allow users to dynamically 
configure their environment so that required applications, libraries, and dependencies can be 
accessed without user installation or environment setup.

On Gadi, a wide range of software applications is centrally installed and maintained. These are stored 
in the `/apps` directory to provide a shared, consistent, and optimised software environment for 
all users. Keeping software in a central location avoids duplication, ensures consistent versions 
across users, simplifies maintenance and updates, and supports performance tuning for the HPC 
architecture. 

.. admonition:: Info
    :class: info

    You can check this page for Licence Live Status: `my.nci.org.au/licence-status <https://my.nci.org.au/licence-status>`_


Module Commands
***************

We can see all the available modules using the command

.. code-block:: console
    
    module avail

To see all the versions of a module, we can use the command

.. code-block:: console

    module avail python3


If we want load a module *python3/3.11.0* we can use the command

.. code-block:: console

    module load python3/3.11.0

If we want to unload the same module use the command

.. code-block:: console
    
    module unload python3/3.11.0

We can unload all the modules using the command

.. code-block:: console
    
    module purge

Practice: Load the openmpi module
*********************************

To build and compile the program from our last practice (``hello_mpi.c``) into something that can run on Gadi, we need to use the module ``openmpi`` to help with the compilation.  

.. admonition:: Exercise
    :class: attention

    #. Check if the openmpi module is available, if so, which versions are available?
    #. Load the openmpi module verison ``4.1.5`` and check if it is loaded using the command ``module list``.
    #. Once successfully loaded, we can compile the program using the command 

    .. code-block:: console

        mpicc hello_mpi.c -o hello_mpi

    This will compile a binary file for you, named ``hello_mpi``. Check the binary file is created.