Environment
=============

Shells
-------

On CRESCO clusters the supported shells are **bash/sh**, **ksh**, and **tcsh/csh**.

The behavior of shells may vary depending on the type of shell. A shell can be of three different types:

- **login shell**: the shell that starts when logging into the system after entering a username and password;
- **interactive shell**: a shell that allows commands to be entered; it may also be a login shell;
- **non-interactive shell**: a shell that is launched whenever a script is executed.

Depending on the shell type, the system reads different configuration files. Ignoring system scripts, the user-level configuration files are summarized in the following table.

.. list-table::
   :header-rows: 1
   :align: center

   * - Shell
     - interactive
     - non-interactive
     - login
   * - t(csh)
     - ~/.cshrc
     - ~/.cshrc
     - ~/.login
   * - ba(sh)
     - ~/.bashrc
     - $BASH_ENV
     - ~/.profile
   * - ksh
     - ~/.kshrc
     - nothing
     - ~/.profile

From this scheme it is possible to determine which configuration files are read by each shell type.

Modules
--------

Modules allows you to configure a shell environment. The main advantages of Modules, which make it particularly suitable for an infrastructure such as ENEAGRID, are:

- independence from the shell and the platform used;
- modular configuration, which makes environment management simple and clean;
- convenience and clarity when dynamically modifying the environment.

CRESCO clusters provide a wide variety of compilers, libraries, and other software, some of which are available in multiple versions.

Each module contains the information required to configure an application by modifying or setting shell environment variables such as PATH, MANPATH, etc.

All information regarding Modules can be found at the `link <http://modules.sourceforge.net/>`_

Environment Initialization
~~~~~~~~~~~~~~~~~~~~~~~~~~~

When logging into CRESCO clusters, the user's environment is loaded.

The configuration files are:

- ``~/.profile`` for bash and ksh, which contain a call to /afs/enea.it/profile/common/profile

- ``~/.login`` for tcsh and csh, which contain a call to /afs/enea.it/profile/common/login

Using Modules
~~~~~~~~~~~~~~~

The following commands are available to show or initialize your environment:

.. list-table::
   :header-rows: 1
   :widths: 30 25

   * - COMMAND
     - DESCRIPTION

   * - module avail
     - List all or matching available modules

   * - module list
     - List all or matching loaded modules

   * - module whatis
     - Print whatis information of modulefile

   * - module add | load
     - Load modulefile

   * - module rm | unload
     - Remove modulefile

   * - module reload
     - Unload then load all loaded modulefiles

   * - module switch | swap [mod1] mod2
     - Unload mod1 and load mod2

   * - module is-loaded
     - Test if any of the modulefiles are loaded

.. note::

   To check all the avaiable commands with their description use ``module`` command. 

Custom Modules
~~~~~~~~~~~~~~~

It is possible to override the defaults set by administrators and load a preferred *modulefile* at login.

Each cluster has an environment variable ``{ENEAGRID_CLUSTER_ID}`` that identifies the cluster where the user is currently working. For example, on CRESCO8:

.. code-block:: bash

   echo $ENEAGRID_CLUSTER_ID
   cresco8

To create custom modules, simply access the hidden ``.Modules`` directory in your ``HOME`` and create or edit the file ``{ENEAGRID_CLUSTER_ID}.default``.

.. note::

   Each cluster can have its own user-specific configuration, distinguished by the ``{ENEAGRID_CLUSTER_ID}`` variable. For example, on the CRESCO8 cluster, the file will be named ``cresco8.default``.

Inside this file, you can define the modules to be loaded:

.. code-block:: tcl

   #%Module1.0

   module-version mpi_flavour/mvapich2_gcc_qlc-1.7 default

   #At the next login, Modules will load mpi_flavour with mvapich2_gcc_qlc-1.7 as the default version

.. code-block:: bash

   module avail

    mpi_flavour/mvapich2_gcc_qlc-1.7(default) mpi_flavour/openmpi_gcc-1.5.4 mpi_flavour/openmpi_open64-1.5.4

Within the same file ``.Modules/cresco8.default``, the user can load additional *modulefiles* among those available and optionally add custom ones.

To make a custom script **visible** to Modules, simply add the directory containing it to the ``ModulePath`` using the ``module use`` command:

.. code-block:: bash

   module use /afs/enea.it/fra/user/USER/.Modules/

   module avail

   cresco8.default custom_modules

Writing a Modules script is quite simple:

* the first line must be ``#%Module1.0``
* it must follow ``tcl`` syntax
* it should use the commands provided by Modules

For more information, you can refer to existing *modulefiles* and the following documentation:

* `General Modules commands <https://modules.readthedocs.io/en/stable/module.html>`_
* `Modulefile-specific commands <https://modules.readthedocs.io/en/stable/modulefile.html>`_


Other Environment
------------------

.. grid:: 3
   :gutter: 3

   .. grid-item-card:: **SPACK**
      :class-card: card-cluster-dism
      :link: spack.html

   .. grid-item-card:: **SCIPY**
      :class-card: card-cluster-dism
      :link: scipy.html

   .. grid-item-card:: **PYTHON ENV**
      :class-card: card-cluster-dism
      :link: python_env.html



.. toctree::
   :hidden:
   :maxdepth: 1

   spack
   scipy
   python_env