Environment modules TCL#

DEPRECATED

Due to update of the computing nodes operating system this documentation page will be obsolete. The new tool will be Lmod

You are in an environment shared by hundreds of users, so the way to provide multiple applications in their multiple versions to a multitude of users in a distributed computing environment is not the same as on a personal computer or your own server.

The tool for managing these environments is called Environment Modules. You can find an extensive explanation about Environment Modules at the following links:

Basically Environment modules are a set of scripts that allow us to easily modify the user environment (the shell) making available to the user only the applications we want to use. For these reason, it will be the tool to load / unload applications you want to use.

How to use environment modules?#

You will see in later sections how they are used in conjunction with job scheduler Slurm. To familiarize yourself with this tool you can log in and run the following commands and examples to understand how it works:

$module avail (o av)                -- shows available modules

$module load modulename  (o add)    -- load a specific module / application

$module unload modulename (o rm)    -- remove a loaded module

$module purge                       -- remove all loaded modules

$module list                        -- list the modules loaded by the user

$module show modulename             -- show module information

$module whatis modulename           -- show modulefile information

$module update modulename           -- reload module

$module help                        -- show module help

Examples#

$ which gcc                -> /usr/bin/gcc
$ module load gcc/10.2.0
$ which gcc                -> /opt/envhpc/utils/rhel6/gcc/10.2.0/bin/gcc

You can see how the application executable is being used before and after loading the module.

$ module av python

------------------------ /opt/envhpc/modulefiles/.rhel6 ------------------------
python/2.7.18/gcc python/3.5.4/gcc  python/3.7.9/gcc  python/3.8.11/gcc

$ which python                -> /usr/bin/python
$ which python3               -> /usr/bin/which: no python3 in (/usr/local/bin:...)

$ module load python/3.7.9/gcc -> Requisito cargar openssl/1.1.1k/gcc

python/3.7.9/gcc(10):ERROR:151: Module 'python/3.7.9/gcc' depends on one of the module(s) 'openssl/1.1.1k/gcc'.
python/3.7.9/gcc(10):ERROR:102: Tcl command execution failed: prereq openssl/1.1.1k/gcc.

$ module load openssl/1.1.1k/gcc python/3.7.9/gcc
$ which python3             -> /opt/envhpc/utils/rhel6/python/3.7.9/gcc-10.2.0/bin/python3

As first step, look for some version of python available on the system.

Next, you will notice that python3 command is not available.

When loading the python module, say openssl / 1.1.1k / gcc is a requirement to load python/3.7.9/gcc.

After these two modules are loaded, you can see how python version 3.7.9 is available.

¿How to use modules modules with a script?