Environment modules are used on HPC to allow multiple versions of any given piece of software to sit on the same OS, giving you the ability to choose a version of software.

To view software under environment modules control, use the command:

module avail

To list the environment modules you have loaded, use the command:

module list

To load the contents of environment module (easier use of software) use the module load command.  For example, to load the contents of the module associated with the latest version of Oracle Java/JDK 1.8.0, you can use:

module load java/1.8.0-oracle

If you want to change the version of software you wish to use, the module switch command can be used.  For example, lets say that you have already loaded python/2.7.13 and want to switch to python/3.6.1.  This can be done with:

module switch python/3.6.1

To unload a module, use the module unload command.  For example:

module unload java/1.8.0-oracle

will backout changes made to your environment from a previous module load java/1.8.0-oracle command.  To  unload (purge) all modules you have loaded, use the command:

module purge