Modular Environment
===================

On PSMN, we use `Lua Environment Modules (lmod) <https://lmod.readthedocs.io/en/latest/>`_.

There is **no default** pre-loaded environment, because everything is separate by cluster/partition (See :doc:`../clusters_usage/partitions_overview`). See :doc:`../modules_list` for a list of all available modules, by cluster/partition.

.. important::

    It is a **3 steps process**:
      - Initialize,
      - choose a list of modules (ie choose a cluster/partition),
      - load one or many modules.


**At first, you need to initialize:**

.. code-block:: bash

    # into ~/.profile
    source /usr/share/lmod/lmod/init/bash


**Then use one modules list within a partition:**

.. code-block:: bash

    # for E5 partition
    module use /applis/PSMN/debian11/E5/modules/all

    # for Cascade partition
    module use /applis/PSMN/debian11/Cascade/modules/all

Show available modules:

.. code-block:: bash

    module avail

What is / help / show on a module (ex: foss/2021a):

.. code-block:: bash

    module whatis foss/2021a
    module help foss/2021a
    module show foss/2021a

**Load a module (ex: foss/2021a):**

.. code-block:: bash

    module load foss/2021a

List loaded modules:

.. code-block:: bash

    module list

Unload a module:

.. code-block:: bash

    module unload foss/2021a

Unload any loaded modules:

.. code-block:: bash

    module purge

Change from one cluster/partition to another (ex: E5 -> Cascade):

.. code-block:: bash

    # modules for E5 partition where previously choosen
    module unuse /applis/PSMN/debian11/E5/modules/all
    module use /applis/PSMN/debian11/Cascade/modules/all

.. important::

    You cannot have two list of modules from different cluster/partition loaded at the same time. ``lmod`` will choose either one, and it will not be the right one. If you do so, best of luck.


In a script:

.. code-block:: bash

    # init
    source /usr/share/lmod/lmod/init/bash
    # for E5 partition
    module use /applis/PSMN/debian11/E5/modules/all
    # for Lake partition
    #module use /applis/PSMN/debian11/Lake/modules/all
    module load foss/2021a

See :doc:`../modules_list` for a list of all available modules.